Mescaline is a naturally occurring psychoactive phenethylamine found inseveral cacti and historically used ceremonially by Indigenous and LatinAmerican populations. Broader recognition of its possible therapeutic valuein Western science began in the 1950s; however, knowledge of the safetyprofile of mescaline and the extent of its use remains limited. The primaryaim of this study is to examine the epidemiology of mescaline use amongEnglish-speaking adults.About 452 respondents completed a web-based survey designed to assess theirprevious experience with mescaline .moderate,”ego-dissolution and psychological insight effects as“slight,” and challenging effects as “veryslight.” Most respondents reported that they used Peyote andSan Pedro in their most memorable mescaline experience. Overall, theintensity of acute mescaline effects did not differ between mescaline types.About 50% of the sample reported having a psychiatric condition , and most (>67%) reported improvements inthese conditions following their most memorable experience withmescaline.Most respondents reported that they had consumed mescaline infrequently(⩽once/year), for spiritual exploration or to connect with nature (74%). Asmall number of respondents reported drug craving/desire (9%), whereas veryfew reported legal (1%), or psychological problems (1%) related to its use,and none reported seeking any medical attention. Overall, respondents ratedthe acute mystical-type effects as “Findings indicate that the mescaline in any form may produce a psychedelicexperience that is associated with the spiritual significance andimprovements in the mental health with low potential for abuse. Lophophora williamsii, alsoknown as Peyote, and the South American Trichocereus pachanoi, alsoknown as San Pedro or “huachuma”  is a naturally occurring psychoactivealkaloid within the substituted phenethylamine class and is typically consumed asraw plant material, extractions from plants, or synthetic preparations . In itsuachuma” . Severals genera . Mescali Heffter , and lat Heffter .Direct  Heffter . Evidenc Heffter ,despite Heffter . The fir Heffter , with th Heffter .1A, 5-HT2A, andalpha-2 adrenergic receptors  . OralinPreclinical data have provided the understanding of the pharmacological mechanisms ofaction, but less is known about the acute subjective and enduring effects associatedwith the consumption of mescaline and whether these effects differ among syntheticmescaline or varieties of mescaline-containing cacti. Reported visual effects fromdried Peyote and synthetic mescaline include spatial distortion, distortion ofcolor, closed-eye visual hallucinations, and synesthesia . Some chAs with other psychedelics, the main adverse effects of mescaline are psychologicaland include anxiety, panic, and disorganized behavior . DespiteThe prevalence of use and the access and availability of mescaline varies dependingon several factors. Specifically, a 2016 survey estimated that eight million people(3%) aged 12 or older in the United States (US) had used mescaline in their lifetime. The samToday, members of the NAC report using Peyote anywhere from once per year to two tothree times per week . Though Anecdotal Internet reports from the US describe the mescaline use for recreational,spiritual, and therapeutic purposes . RecogniThe pharmacology of mescaline has been assessed in animal models , and theThe relative absence of information about the scope of mescaline use limitsunderstanding of the safety profile of this substance, which is needed to inform thedesign of future studies with this compound. Therefore, the primary aim of thisstudy is to examine the epidemiology of mescaline use  among English-speaking adults who have consumed mescaline atleast once in their lifetime. As a secondary aim, we examined whether there werechanges in medical and psychological functioning following mescaline use. The finalaim involved examining differences in the subjective effects and the patterns andmotivations of use as a function of the type of mescaline consumed .Erowid.org, Facebook.com, etc.). Authors also shared links to the survey viapersonal networks. All advertisements contained the information regarding thepurpose of the study and the approximate time required to complete the survey(45–60 min), and that participating in the survey was anonymous. Upon clickingany of our advertisements potential respondents were sent to a secured surveysite  where they viewed the informed consent document thatrepeated the purpose of the study and described the following eligibilitycriteria: at least 18 years of age, able to read and understand English, andhaving used mescaline at least once in their lifetime. All study procedures wereapproved by the Local Standing Ethical Committee at Maastricht University in theNetherlands.From January 2019 to October 2019, we posted written recruitment advertisementson multiple Internet platforms , how the mescaline was obtained , age at the time of themescaline experience, location of their experience, whether there were otherpeople present when they consumed mescaline, and if so, how many otherpeople were also using mescaline. Additionally, the survey asked about themain reason for consuming mescaline, how participants would characterize thequantity of the dose(s) , how many times they ingestedmescaline during the session, the duration of effects, how they prepared fortheir experience, and how many times they used mescaline before and afterthis session. Moreover, respondents were asked about theirmedical/psychological history , and whether their condition had improved, remained the same, orworsened following mescaline use.The survey was introduced with a description of the various types ofmescaline  of interest.During the first portion of the survey, respondents were asked to answer aquestion in the context of the most memorable experience with one of theseof these mescaline types. That question was phrased in the following way:“Take a few moments now to recollect and bring to mind your Mescalineexperience. If you have had multiple such experiences, please answer thefollowing with respect to the The second part of the survey included questions about “lifetime use ofmescaline.” Respondents were asked what types of mescaline had ever beeningested in their lifetime, age at first use, administration route,frequency, reason, and location of use. Furthermore, this part of the surveyalso included variables assessing several aspects of abuse potential, suchas frequency of repeated consumption in the same session, craving/desire formescaline, possible consequences they may have experienced related tomescaline use (e.g. a visit to the Emergency Department or Urgent care), andfinally whether they ever attempted to quit, reduce, or increase theirconsumption. This section also asked about dose, source, and preparation, aswell as how many people were present during the session and whether theywere also consuming mescaline. In addition, respondents were asked aboutpsychological or spiritual applications of the use of mescaline, and toestimate the use of other (psychoactive) substances they had used duringtheir lifetime. The full survey is available upon request from thecorresponding author.The psychological insight questionnaire (PIQ) consists of 23 items thatassess the intensity with which respondents experienced a broad range ofinsights  after taking a classic psychedelic , 2020b. The acute mystical experiences (MEQ-30) is a 30-item self-report scale ofmystical experience .RespondThe challenging experience questionnaire (CEQ) is a 26-item self-reportmeasure that assesses the intensity of challenging experiences aftertaking a psychedelic .RespondThe ego-dissolution inventory (EDI) is an eight-item self-report measurethat assesses the level of ego-dissolution after ingesting ahallucinogen . We alteThe persisting effects questionnaire (PEQ) assesses desirable andundesirable enduring effects of a hallucinogenic experience . RespondThese questions assessed a variety of demographic variables.z-tests examinationswith the Bonferroni corrections), we examined differences in demographiccharacteristics , mescaline usevariables , and other backgroundvariables  as a function of the type of mescalinethat respondents reported they had the most memorable experience with . Furthermore, using a series ofone-way ANOVA (with follow-up post-hoc tests with the Bonferroni corrections)tests, we examined differences in demographic characteristics (i.e. age ofrespondent), mescaline use variables , subjective acute effects , and enduring effects  as a function of the typeof mescaline that respondents reported they had the most memorable experiencewith . Analyses were conductedusing the IBM SPSS Statistics v.25 and v.26 .The first step of the analysis consisted of calculating frequency counts andanalyzing descriptive demographic characteristics, patterns of mescaline use,subjective mystical, challenging, ego-dissolution, psychological insighteffects, and psychological harms/benefits variables related to the type ofmescaline that respondents reported they had the most memorable experience with. Later, using a series ofchi-square tests (with follow-up post-hoc During recruitment (January 2019 to October 2019), a total of 2025 people clickedone of the recruitment ads and were presented with the information about theresearch study. Of these individuals, 788 consented to participate and beganfilling out the survey; however, only 477 completed all the main studyquestionnaires (described above) and reported that their responses were “valid.”Of these respondents, we excluded 22 because they did not know or were unable toidentify what form of mescaline, they had the most memorable experience with, and therefore they wouldhave been excluded in analyses of subgroup differences. Of the remaining 455, anadditional three were excluded because they reported being under the age of 18(exclusion criteria). Thus, the final sample was comprised of 452respondents.t-tests, chi-square, and effect sizedata.As shown in As shown in Regarding abuse potential, most respondents (55%) indicated that they neverconsumed more than one dose of mescaline in a session, and approximatelyone-third (32%) reported that they have consumed mescaline with other substanceson one or two occasions. Additionally, very few respondents reported craving formescaline (9%), ever being arrested or in legal trouble due to mescaline use(1%), or ever being in therapy or psychiatric treatment (<1%), and nonereported seeking medical attention (0%), as a result of mescaline use. Moreover,most respondents (90%) reported that their mescaline use in the past year haddecreased or remained the same, and almost all (97%) reported that they neverattempted to quit using mescaline or to reduce their use.N = 218), and almost one-quarter  reported having the most memorable experience withPeyote. The remainder of the sample reported that they had the most memorableexperience with synthetic  or extracted  mescaline. As shown in Overall, most respondents reported having the most memorable experience with SanPedro , whichcould explain these average ratings. There were no significant differences inthe ratings of the intensity of these acute subjective effects as a function ofa mescaline subgroup. See Regarding the enduring effects associated with ones most memorable mescalineexperience, approximately one-quarter to one-third (rates varied from 28% to35%) of the sample rated their mescaline experience as one of the top five orsingle most personally meaningful, spiritually significant, or psychologicallyinsightful experiences of their entire lives. A smaller proportion ofrespondents (11%) rated the experience as one of the top five or single mostpsychologically challenging. There were no significant differences in theseproportions as a function of a mescaline subgroup.Almost half of respondents reported that prior to the most memorable mescalineexperience, they had anxiety (49%) or depression (44%), with smaller proportionsreporting a history of drug misuse or use disorder (20%), post-traumatic stressdisorder (17%), and alcohol misuse or use disorder (17%) see . There wTo the best of our knowledge, this is the first international epidemiological studyon mescaline use. The present data indicate that most people infrequently used SanPedro or Peyote orally through self-administration  for spiritual and nature connection. Theinfrequent pattern of use is similar to findings in a former survey-based study on5-MeO-DMT  of the various subjective effects are inconsistentwith that of other psychedelics (ayahuasca and psilocybin)  and theMost respondents with prior psychiatric conditions  reported improvementsin these conditions following their most memorable experience with mescaline. Onecan speculate whether the experience was memorable due to the improvement in suchhealth functioning. Nevertheless, this result is consistent with previous findingsfrom observational and clinical research that demonstrated subjective and objectiveimprovements in mental health-related variables, following the use of psychedelics, 2019b, Results from this study also showed no significant differences in the subjectiveacute and enduring effects between mescaline types. Although this may indicaterelatively minimal or no differences in the acute and enduring effects of differenttypes of mescaline, rigorous controlled studies could reveal potential differencesbetween them. While all groups exhibited broad similarities, the Peyote subgroupreported consuming more doses compared to other groups. This might be due to thebitter taste of Peyote, which is known to induce nausea and vomiting .It is pmost memorable experience with mescaline”;however, we did not control for period of memory recall, attitudes toward mescaline,lifetime use of mescaline, and potential confounds associated with concurrent use ofother compounds. Furthermore, the cross-sectional nature of the data precludes anyinterpretation of causality regarding the short-term and long-term effects ofmescaline. Additionally, we used a different scoring scale of the EDI created byThis study is not without limitations. For example, the present survey aimed toassess a person’s “It is also noteworthy that the research team made explicit attempts at reaching outto the NA population and other Indigenous communities internationally. However,<10 respondents completed surveys identified as being either NA or as Indigenous.Though a much larger survey sample would have been optimal, it is not surprisingthat a limited number of submissions were received due to historical trust issuesthat NA and Indigenous people carry regarding the impacts that Western scientificstudies can have on these cultures. For NA people of the US, Peyote is and has beena sensitive and controversial topic. Peyote is revered by NA people for itsmedicinal qualities, but its reverence holds a deep connection with the people tothe land and the environment. Due to these relationships, Western scientific studiesthat involve Peyote with NA and Indigenous people are limited. There is not only areluctance to take part in Western studies with plants that are consideredsacrilegious to the NA population but also hesitancy with plants like Peyote. WherePeyote is a foundational element of the NAC and a recognized religious right andceremonial practice, the knowledge about the ceremony and ceremonial experiences isnot easily shared with outsiders.Finally, although we have compared mescaline experiences by mescaline type of use inthe present study, we do not intend for these data to be interpreted to mean thatfurther rigorous, clinical research are not needed. We cannot conclude thatsimilarities or differences observed in this dataset may have also been caused by avariety of additional factors, such as participant demographics, “set and setting” that might co-vary with the type of use. Therefore, thepresent observations should be replicated in controlled clinical trials to allow anystrong conclusion.Despite the limitations described above, the present findings indicate thatmescaline, in any form, may produce a psychedelic experience that is associated withmeaningful and spiritually significant experiences, improvements in mental health,and has low probability for increased use and misuse. Further research among NA andother Indigenous populations could provide further understanding of their historicaland long-term ceremonial use. Finally, future examination in naturalistic andclinical settings are also needed to confirm and expand on the current findings ofthe overall study.


Consumers are shifting towards plant-based diets, driven by both environmental and health reasons. This has led to the development of new plant-based meat alternatives (PBMAs) that are marketed as being sustainable and good for health. However, it remains unclear whether these novel PBMAs to replace animal foods carry the same established nutritional benefits as traditional plant-based diets based on pulses, legumes and vegetables. We modelled a reference omnivore diet using NHANES 2017–2018 data and compared it to diets that substituted animal products in the reference diet with either traditional or novel plant-based foods to create flexitarian, vegetarian and vegan diets matched for calories and macronutrients. With the exception of the traditional vegan diet, all diets with traditional plant-based substitutes met daily requirements for calcium, potassium, magnesium, phosphorus, zinc, iron and Vitamin B12 and were lower in saturated fat, sodium and sugar than the reference diet. Diets based on novel plant-based substitutes were below daily requirements for calcium, potassium, magnesium, zinc and Vitamin B12 and exceeded the reference diet for saturated fat, sodium and sugar. Much of the recent focus has been on protein quality and quantity, but our case study highlights the risk of unintentionally increasing undesirable nutrients while reducing the overall nutrient density of the diet when less healthy plant-based substitutes are selected. Opportunities exist for PBMA producers to enhance the nutrient profile and diversify the format of future plant-based foods that are marketed as healthy, sustainable alternatives to animal-based products. Global concerns around the consumption of animal products and their adverse effects on health and the environment have led to significant growth in the plant-based protein space, particularly for new products to replace traditional meat and dairy ,2,3,4. TA concern for many consumers seeking to decrease their meat intake and switch to plant-based diets is potentially compromising their protein intake in terms of quality and quantity ,15. To aFrequent red and processed meat intake is linked to greater risks of cardiovascular disease and cancer ,27; howeAnimal and plant proteins are both nutritious, and protein quality and quantity are often not compromised when switching to well-designed plant-based diets . This apOn-pack nutritional composition represents the nutrients of the unprepared product and often does not reflect actual nutrients consumed when products require further preparations that influence their final composition. This is especially true for most novel plant-based products. Whereas many traditional vegetarian dishes require minimal oil and salt such as lentil stews and stir-fried tofu, by contrast, most of the current PBMA products are sold in formats such as burgers, sausages or nuggets that require preparation with more oil  and salt and are often consumed with nutrient-poor sides, condiments and beverages. Regularly consuming these products could potentially lead to higher calorie, fat and salt intakes. Similarly, non-dairy milks targeted towards vegetarians or vegans are often high in added sugar , while mSimilar to all diet and lifestyle changes, switching to plant-based substitutes for meat can be beneficial or not for health. In the absence of clear data on the nutritional impact of such a change, the current case study sought to compare the health impact of substituting animal products  for both traditional and emerging non-animal alternatives. We chose a standard omnivore diet based on NHANES 2017–2018 data (reference diet) and substituted animal products with either traditional plant-based foods or novel non-animal protein alternatives to create flexitarian, vegetarian and vegan diets matched for energy, protein, carbohydrate and fat, to focus on changes in micronutrient intake over a given day. The goal of these comparisons was to establish whether reducing the consumption of animal products using novel PBMA and dairy alternatives results in equivalent nutrient intakes for flexitarian, vegetarian and vegan diets, in comparison to a reference omnivore diet.We compared changes in nutrient intakes when moving from an animal-based diet (omnivore) to plant-based diets . For the comparison, we selected a reference diet based on the average nutrient intake pattern for an American adult male aged 20–49, based on the NHANES 2017–2018 dietary survey  Table 1Table 1. We compared the reference omnivore diet to traditional and newer versions of flexitarian diets with reduced meat intake (Flex-Trad and Flex-New), traditional and newer versions of a vegetarian diet with no meat (Veg-Trad and Veg-New), and traditional and newer versions of a vegan diet without meat, dairy or eggs (Vegan-Trad and Vegan-New) . The FleFlexitarian, vegetarian and vegan diets with less meat and dairy intakes were lower in cholesterol, Vitamin B12 and zinc . All dieThe flexitarian diets (Flex-Trad and Flex-New) had a reduced proportion of meat and dairy while increasing plant-based foods, and both were lower in cholesterol, Vitamin B12 and zinc and higher in fibre than the reference diet. The traditional flexitarian diet met daily requirements for all seven micronutrients compared and was lower in saturated fat (27%) and sodium (↓17%) and higher in calcium (↑32%) and magnesium (↑19%) than the reference diet. This was due to a higher proportion of low-fat dairy and plant-based foods such as legumes, which were important protein sources for this diet. The flexitarian diet based on more novel products (Flex-New) only met daily requirements for phosphorus and iron and was the diet highest overall for saturated fat. This was due to a greater proportion of novel plant-based convenience foods such as plant-based snacks, coconut-based products and lower dairy intake. Flex-New had 60% less Vitamin B12, 37% less zinc and 31% less potassium than the reference diet while increasing saturated fat intake by 46% and sodium by 28% , Table 2Removing meat entirely, while retaining dairy and increasing the proportion of energy derived from plant-based foods, resulted in traditional (Veg-Trad) and novel (Veg-New) vegetarian diets, both of which were lower than the reference diet for cholesterol, Vitamin B12 and zinc, and higher in dietary fibre and iron. As with the traditional flexitarian diet, the traditional vegetarian diet met daily requirements for all micronutrients compared and was lower in saturated fat (↓24%) and sodium (↓25%) and higher in calcium (↑40%) and magnesium (↑26%) than the reference diet. This was due to increased intake of dairy and plant-based products such as vegetables, beans, tofu and nuts. The novel vegetarian diet only met daily requirements for phosphorus and iron and not the other micronutrients, due to a greater quantity of novel PBMAs and coconut-based snack products. As a result, the novel vegetarian diet was markedly lower in Vitamin B12 (↓79%), zinc (↓43%), potassium (↓27%) and calcium (↓25%) compared to the reference diet. The novel vegetarian diet also exceeded the reference diet for saturated fat (↑32%) and sodium (↑42%).Excluding all meat and dairy resulted in vegan diets with no cholesterol and lower Vitamin B12, calcium and zinc content compared to the reference diet. These vegan diets were also higher than the reference diet for iron and sugar. The traditional vegan diet had the highest quantity of legumes and seeds and was the diet highest for iron and fiber, and higher in potassium (↑15%) and magnesium (↑59%) compared to the reference diet. However, the traditional vegan diet also had less Vitamin B12 (↓59%) and calcium (↓52%) than the reference diet. Soymilk was the sole source of Vitamin B12 for both vegan diets. The traditional vegan diet (Vegan-Trad) met all daily micronutrient requirements with the exception of Vitamin B12 and calcium. The novel vegan diet (Vegan-New) provided adequate phosphorus and iron but was the diet lowest for calcium, potassium, phosphorus, zinc and Vitamin B12. Removing all dairy and meat products resulted in daily requirements not being met for Vitamin B12 (79% less than reference diet), calcium (↓62%), potassium (↓36%), magnesium (↓16%) and zinc (↓54%). The novel vegan diet was higher than the reference diet for saturated fat (↑34%) and sodium (↑43%) and had the lowest fibre of all the diets due to the greatest proportion of novel PBMAs and plant-based snack foods. Since many novel PBMAs were rich in iron due to the inclusion of vegetable haem or ferrous sulfate, the novel vegan diet had one of the highest overall iron contents.The traditional flexitarian diet reduced meat using traditional plant-based substitutes and met all daily micronutrient requirements. Retaining dairy and eggs with a smaller portion of meat maintained protein intakes, as well as sustained high micronutrient intakes. This diet did not require the addition of high-protein snacks to meet protein needs, as was needed for vegetarian and vegan diets. An added challenge when making the transition to vegetarian and vegan diets is that unlike meat, many plant-based protein sources tended to be high in carbohydrates, such as dairy and legumes. Similarly, plant sources such as tofu are often lower in protein compared to meats like chicken and need to be consumed in larger portions or supplemented with high-protein snacks such as nuts and yogurt to achieve sufficient intakes, which can increase dietary fat and carbohydrate. The novel vegetarian and vegan diets with PBMAs and dairy alternatives such as coconut ice cream and coconut yogurt were matched for protein intake with the other diets. PBMAs often had lower protein and higher fat, carbohydrate and sodium compared to meat, while dairy alternatives tended to have lower protein yet higher calories, carbohydrate and fat compared to traditional dairy. Non-dairy milk had more added sugar. Accommodating protein from PBMAs and dairy alternatives while matching for energy intake required a reduction in carbohydrate-rich foods such as French fries, rice and bread.For vegans to go dairy-free, this required the removal of nutrient-rich foods such as cheese and replacing these with dairy-free cheese, which was higher in calories, carbohydrate, fat and sodium but lacked protein. Several foods used to replace animal-source foods in each diet were also low in micronutrients such as coconut yogurt, plant-based egg and dairy-free cheese. To match the reference diet for protein, the novel vegan diet required “supplementation” with protein-rich plant-based snacks such as vegan “beef jerky”. Significant protein sources in the vegan diets such as legumes, seeds and PBMAs increased carbohydrate and fat intakes. Whereas vegan diets are known for their low Vitamin B12 content ,44, thisWhen modelling the various diets to be used in our comparisons, we were mindful of the high variability in nutritional characteristics among products such as plant-based drinks or dairy alternatives . TherefoThe reference diet against which all other diets were compared reflects a typical daily diet for an American adult male. When calories and % energy from macronutrients were matched, all diets exceeded requirements for macronutrients, sodium and sugar. Only the traditional flexitarian and vegetarian diets met all daily micronutrient requirements, with better intakes than the reference diet. The diets selected for comparison aimed to illustrate in a practical way the possible nutritional implications of adopting flexitarian, vegetarian or vegan diets for the long term. Often, when comparing animal- and plant-based diets, the focus tends to be exclusively on protein quality and quantity. While this is important, the current comparison highlights important implications of selecting plant-based foods believed to be “healthier”, and the need to consider non-animal alternatives that are nutrient-dense, and lower in calories, fat, sugar and sodium.The current case study demonstrates that traditional plant-based replacements for animal products support the transition to nutritionally adequate flexitarian or vegetarian diets, with flexitarian diets being the most feasible overall. Plant-based diets with larger proportions of novel PBMA substitutes and vegan diets in the absence of nutritional supplements run the risk of being inadequate in a number of important micronutrients.A diet that reduces or excludes meat and dairy may have unintended nutritional consequences that arise through selecting foods of lower nutrient density or foods requiring preparation with oil or salt. The current case study shows that diets that increasingly avoid animal-based products result in nutritionally adequate diets if traditional plant-based foods are used as substitutes, with the exception of vegan diets. However, we identified risks when the move to vegetarian and vegan diets was achieved by including novel PBMAs and plant-based dairy, with significantly decreased Vitamin B12, calcium, potassium, magnesium and zinc.The current comparisons were based on a single day’s consumption, which suggests that the continued consumption of diets high in novel PBMAs and plant-based dairy carry the potential risk of increasing intakes of public health-sensitive nutrients while also promoting nutritional deficiencies for a range of micronutrients. For the uninformed consumer, caution should be exercised when making wholesale transitions from diets containing food of animal origin to plant-based diets, particularly those moving to a vegan diet. A diet with sustained low calcium content can increase the risk of low bone mineral density, osteoporosis and fractures. The vegan diets in our case study were the lowest in calcium and the Vegan-New diet was lowest in zinc. These findings are in agreement with a recent cross-sectional comparison that found poorer bone health in vegans compared to omnivores, as well as lower nutritional biomarkers including calcium and zinc . Recent Previous research using dietary data modelling has estimated the impact of switching from animal- to plant-based diets on nutrient intakes. A Canadian study found that increasing the intake of PBMAs by 100% and reducing red and processed meat by 50% improved diet quality as measured by the Nutrient-Rich Foods (NRF) index, but decreased intakes of important nutrients including protein, zinc and Vitamin B12 . SimilarFindings from the current case study align with existing literature that flexitarian diets may be the easiest for consumers to transition to in terms of nutritional adequacy and improved health, whereas nutritionally adequate vegetarian and vegan diets require more knowledge and planning. Consuming a mix of proteins from animals and plants while reducing meat and increasing healthful plants is a practical approach for many ,52. HoweMuch of the commentary around shifting from animal- to plant-based protein diets has centered on the poor protein quantity and quality of plant-based foods ,30. HoweAlongside the rapid rise of PBMAs, meat consumption has continued to increase. Global per capita meat consumption has increased approximately 20 kg since 1961 , raisingNovel PBMAs are marketed to appeal to consumers looking to adopt a “clean” eating dietary regime as part of a global trend to simplify food production and formulations in favour of more natural food products . HoweverRather than classifying foods by the degree to which they are processed to determine their healthfulness, measures have been developed that better reflect not only the nutrient density but also the sustainability of foods, which could be used to better inform consumers. Measures such as the plant-based diet index (PDI) may better reflect the nutrient density and impact of dietary changes on health . High-quThis case study’s strength was the modelling of seven diets  in a practical manner that follows current nutrient intakes to represent the average consumer. However, it had its limitations. We did not include supplements or fortified products in order to create an equivalent comparison across diets. Therefore, this case study will not fully represent the diets of plant-based consumers who use supplements and fortified products. However, cross-sectional and survey data suggest that supplement use may be lower than expected ,44 despiThe current case study highlights that traditional plant-based substitutes can improve nutrient intakes and help consumers to eat more sustainably. However, our findings suggest that it is easy for the uninformed consumer to unintentionally increase public health-sensitive nutrients such as fat, sodium and sugar while also decreasing the nutrient density of the diet. Recent innovation in the plant-based product space has focused more on organoleptic properties  and formats (nuggets and burgers), rather than developing innovative ways to enhance the nutrient density of plant-derived foods, and ensuring a balanced nutrient profile similar to products of animal origin. Many newer plant-based products are similar to animal products in calories, but lower in protein, calcium, potassium, magnesium, zinc and Vitamin B12 while being higher in sodium and fat after being prepared. If habitually consumed, this could create nutrient shortfalls for consumers motivated to follow healthier, more sustainable diets .Research is needed on how best to guide consumers to choose nutrient-dense plant-based diets that support reduced consumption of public health-sensitive nutrients while sustaining protein quantity and quality. For food producers, there is potential to innovate for the next generation of plant-based foods that provide adequate nutrient intakes alongside protein, and for the development of product formats that do not require the addition of salt, sugar and fat to enhance their sensory appeal.


Fracture non-union is a challenging orthopaedic issue and a socio-economic global burden. Several biological therapies have been introduced to improve traditional surgical approaches. Among these, the latest research has been focusing on adipose tissue as a powerful source of mesenchymal stromal cells, namely, adipose-derived stem cells (ADSCs). ADSC are commonly isolated from the stromal vascular fraction (SVF) of liposuctioned hypodermal adipose tissue, and their applications have been widely investigated in many fields, including non-union fractures among musculoskeletal disorders. This review aims at providing a comprehensive update of the literature on clinical application of ADSCs for the treatment of non-unions in humans. The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Only three articles met our inclusion criteria, with a total of 12 cases analyzed for demographics and harvesting, potential manufacturing and implantation of ADSCs. The review of the literature suggests that adipose derived cell therapy can represent a promising alternative in bone regenerative medicine for the enhancement of non-unions and bone defects. The low number of manuscripts reporting ADSC-based therapies for long bone fracture healing suggests some critical issues that are discussed in this review. Nevertheless, further investigations on human ADSC therapies are needed to improve the knowledge on their translational potential and to possibly achieve a consensus on their use for such applications. Bone fractures are the most common traumatic injuries affecting large organs in humans. Approximately 5–10% of patients experience impaired fracture healing, and a subset of them will develop non-union . FracturThe present study is a systematic literature review reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines  Figure . MEDLINEAll studies published as full-text articles in indexed journals describing the application of adipose derived stem cells for the treatment of aseptic non-unions in humans were considered eligible. Only articles written in English were included. No date limits publication was established. Expert opinions, in vitro investigations, studies on animals, unpublished reports, abstracts from scientific meetings and book chapters were excluded from review.Two observers (A.S. and S.P.) independently searched and collected data from the included studies. Any discordances were solved by consensus with a third author (F.L.). The following data were extracted by included studies: year of publication, types of research studies, demographic features of patients, diagnosis and symptoms, treatment performed, possible complications and outcomes and follow-up. All data concerning adipose stem cell harvesting, manipulation and application were carefully reviewed and collected. Numbers software  was used to tabulate the obtained data. Categorical variables are presented as frequency and percentages. Continuous variables are presented as means and standard deviation. Only one decimal digit was reported and was rounded up.The electronic search of the literature consisted of 576 studies. After duplicate removal, 555 articles were screened for title and abstract, but only 134 papers were considered eligible, as all others were off topic. Two non-English written studies, 31 reviews and one book chapter were excluded. Ninety five studies were considered not eligible because they were performed on animal models and two studies were considered not eligible as they were performed in vitro. Therefore, full-text papers were carefully evaluated. Finally, three articles met our inclusion criteria ,21,22. TAs regards complications, two patients underwent bone graft and plate removal after Staphylococcus aureus and Enterococcus faecalis infection at more than 10 months post-transplantation. One patient had a subcutaneous collection due to Staphylococcus aureus, successfully treated without graft removal. No further complications were reported. Outcomes were described as general clinical conditions as none of the selected studies used clinical completed scores or patients reported outcomes measures (PROMs). During follow-up, all patients had good general clinical outcomes with fracture healing and bone defects filling, apart from three patients who revealed absence of consolidation demanding further surgery. The main demographical and clinical data of the included studies are shown in Treatment of aseptic non-unions is a very challenging issue in the orthopaedic field. Giannoudis and co-workers in 2007  describeADSCs are multipotent cells originated by mesoderm: they have the potential to differentiate towards adipogenic, osteogenic and chondrogenic lineages, in vitro . AdiposeA number of clinical devices are currently available for the rapid separation of adipose tissue fractions in closed systems, enabling the enzyme-free collection of a clinical grade ADSC-enriched SVF through minimal tissue manipulation for regenerative medicine applications in single surgical procedures .Many studies in the literature investigated the efficacy of ADSC-based approaches for inducing bone regeneration and healing in in vitro and in vivo models. Animal models employed for bone tissue regeneration include critical-size calvarial defects, ectopic bone formation, long bone segmental defects, vertebral defects or fusions and mandibular defects ,31.However, according to our review of the literature, only three studies to date, have reported clinical outcomes after ADSCs application for bone healing in non-unions and bone defects, which represents an inherent limitation in this review. The limited clinical application of ADSCs in bone regeneration, despite the significant results obtained in preclinical studies, is mainly due to the limitations imposed by national regulatory frameworks. In fact, over the past two decades, Countries are facing the challenges of introducing advanced therapy medicinal products (ATMPs)—biological products with the deriving legislation and regulatory limitations—in the clinical practice. The European Union (EU) and the United States, (US) with their respective authorities, European Medicines Agency (EMA) and Food and Drug Administration (FDA), applied the concepts of “substantial manipulation” and “homo-functionality” for the classification and consequent regulation of ATMPs. For instance, cell separation, concentration, and purification do not represent a substantial manipulation whereas cell-culture expansion and activation with growth factors is a “more than minimally manipulation”. As far as homo-functionality is concerned, if the cells or tissues maintain their original function in the same anatomical or histological environment, they are meant to have “same essential functionality”. On the other hand, in case of non-homologous use, the cells or tissues are not intended to be used for the same essential function as in the donor site.In this regard, the use of ADSC, SVF or other adipose tissue-derived bioactive fractions for treating bone defects inherently refers to “more than minimally manipulated” tissues for “non homologous use”. In the absence of substantial preclinical data from animal models supporting the efficacy of a given experimental therapy, the translation into clinical products is still hampered.These considerations reflect the need to implement future scientific research in the field.In the papers considered in this review, the most frequent indication was represented by bone defects resulting from wide bone tumor resections ,21 whileRegarding the ADSCs application, two of the selected papers assessed the safety and feasibility of a scaffold-free osteogenic 3D adipose derived graft for the treatment of bone non-union ,21. TheyKhalpey et al. in 2015  describeIn aseptic nonunion, when there is a concomitant bone defect, grafts are decisive to achieve bone healing ,34 as thDespite the presence of many alternatives, autograft is still considered the gold standard for the treatment of aseptic non unions regardless of the morbidity of the donor site . In factMoreover, tissue engineering allows to seed ADSCs on biocompatible scaffolds or biomaterials to generate bone regenerative grafts . In factAdvanced cell therapy is more than a promise for orthopaedic surgery. Despite the still limited clinical reports, significant cues come from the numerous in vitro and in vivo preclinical studies, documenting the osteogenic properties of ADSCs and their interactions with different scaffolds, along with the search for osteo-inductive molecules, in the design of innovative tissue engineering strategies. Growth factors as FGF-2, TGF-β combined with ADSC on a polysaccharide-based tissue engineered periosteum have shown promising results as they promote a more stable harvesting and integration in murine models . FurtherInnovative scaffolds are investigated as stable supports for ADSC harvesting. Some of the newest scaffolds include decellularized matrices as decellularized human adipose tissue (DAT) hydrogel , ceramicA significant amount of data from basic and translational research suggests that ADSC/SVF grafting and implantation is a promising strategy for bone regeneration. This complex tissue fraction holds ADSCs within an enriched trophic environment that sustains ADSCs biological properties and niche homeostasis. Current literature demonstrates that clinical application of SVF and ADSCs-derived grafts is safe and feasible though it cannot be routinely performed, as it requires experienced stem cells GMP manufacturing laboratories. Moreover, limitations imposed by national regulatory frameworks are severe in the case of non-homologous tissue implantation and non-homo-functionality application, thus affecting the number of the clinic studies on the topic. However, some clinical devices for minimal manipulation of the adipose tissue to isolate SVF and uncultured ADSCs currently represent a valid option to be exploited for the enhancement of long bones non-union healing. Further efforts are needed to investigate the role of ADSCs for the treatment of post-traumatic non-unions of the long bones.


Advanced biomaterials can be designed to non-destructively measure these stresses in vitro, and here, we review mechanical characterizations and force-sensing biomaterial-based technologies to provide insight into the mechanical nature of tissue processes. We specifically and uniquely focus on the use of these techniques to identify characteristics of cell and tissue “tensegrity:” the hierarchical and modular interplay between tension and compression that provide biological tissues with remarkable mechanical properties and behaviors. Based on these observed patterns, we highlight and discuss the emerging role of tensegrity at multiple length scales in tissue dynamics from homeostasis, to morphogenesis, to pathological dysfunction.Cell-generated forces play a foundational role in tissue dynamics and homeostasis and are critically important in several biological processes, including cell migration, wound healing, morphogenesis, and cancer metastasis. Quantifying such forces  I.The human body is a dynamic and self-stabilizing structure formed through intricate connections between hierarchical building blocks. The mechanical structure of intra- and extracellular proteins, cells, and tissues plays a key role in achieving structural stability in response to widely varying mechanical challenges, while simultaneously enabling biological systems to actively transduce and respond to these mechanical stimuli.in vivo or in vivo-like contexts, resulting in unclear translational relevance.Cell-generated forces play critical roles in virtually all biological processes, including cell migration,in vivo at varying length scales. These technologies can measure compressive, tensile, shear, anisotropic, and isotropic stresses within highly realistic and biologically relevant contexts. Moreover, in principle, active biomaterials can be designed to apply local mechanical stimuli and actively probe biological structures while passively quantifying cell-generated forces.Biomaterials can be defined as nonviable materials, natural or manufactured, designed to interact with biological systems as part of a living structure or medical device.Local tissue architecture and integrity is maintained by a delicate balance of forces generated through various mechanisms and by various organizing units in the body. Tensional integrity, frequently referred to by the portmanteau tensegrity, uses both compressive and tensile stresses to create a stabilizing prestress, which allows for considerable deformation under externally applied loads and restoration of the original shape after load release. This framework has been used to describe biological architectures across molecules, cells, and tissues in a hierarchical and modular fashion.Tensegrity was first defined and discussed by Fuller in the late 1950s as an architectural principle relying on balancing continuous tension and discontinuous compression forces to provide a stably prestressed structure.At the cellular length scale, the tensegral nature of biological systems has been well-defined, most notably by Ingber and colleagues, whereas tensegrity in molecular and tissue scale systems remains more speculative. Many mechanical elements contribute to the structural stability of cells, including osmotic pressure, actin contractility, filament polymerization, and cell distention through adhesions to the ECM or to neighboring cells. Among other components, microtubules balance cytoskeletal prestress with a decreasing contribution during cell spreading.In this review, we summarize recent biomaterials-based methods to study cell-generated forces at the molecular, cellular, and tissue scale within biological tissues. We also revisit the implications of the tensegrity model at the molecular, cellular, and tissue length scales, based on the read-outs of cell-generated forces. Finally, we highlight how a tensegral balance between forces plays an important role in stabilizing local architecture and generating morphological and biological responses to microenvironmental stimuli, and theorize that large imbalances in cell-generated forces may lead to disease.II.Measuring forces at the molecular scale requires similarly sized probes. In this section, we consider tools that have recently been developed by engineering DNA (deoxyribonucleic acid) and proteins to provide unique force-readout capabilities ; Table IA.DNA-based techniques use DNA oligonucleotide sequences that can be custom-synthesized to measure molecular forces between cells and their substrates within the 10–100 pN range.These cell-substrate DNA-based sensors have been used to control and quantify the tension between an integrin–ligand bond,B.Molecular forces can be directly read out by designing protein-based probes that use fluorescence resonance energy transfer (FRET) technology to optically image forces .43 FRET Protein-based biomaterials for mechanical measurements have been validated and compared against single-molecular force spectroscopy techniques such as optical tweezers, magnetic tweezers, and atomic force microscopy. While the details of these techniques are beyond the scope of this review, single molecule techniques have been applied to biological molecules to quantify protrusive cell forces,C.in silico modeling, and supporting experimental data remains sparse. Thus, biomaterial-based approaches to quantifying cell-generated forces at the molecular scale provide a unique opportunity to uncover molecular tensegral patterns.Molecular scale tensegrity structures have been significantly less studied in comparison to cellular structures, but the concept has provided a model for rationalizing protein foldingDesigning molecules present at the anchoring sites between cells and their surroundings can, hence, provide considerable information on tensile forces around a cell as well as a robust means of controlling cell shape and overall tissue architecture. Hierarchically organized and modular tensegrity structures are present throughout this process. Since a cell's ability to probe its mechanical microenvironment largely depends on receptor binding, these conformational changes to molecular tensegrity redistribute forces upon loading and therefore tightly couple mechanical and chemical signaling mechanisms at this length scale. Proteins, such as ATP (adenosine triphosphate) synthase and dynein, have been modelled as tensegrity structures to simulate conformational shifts involved in phosphorylation and sperm motility, respectively.III.et al. to directly visualize cellular contractile behavior [Adherent cells will actively bind to surrounding materials and produce cell traction forces strong enough to deform a sufficiently flexible material. Cells grown on silicone rubber films, for example, will wrinkle the substrate, which allowed Harris behavior .71–73 CoA.In traction force microscopy (TFM), fiducial markers are introduced into mechanically defined compliant substrates and tracked to quantify both the magnitude and direction of cell traction forces .76,79–87The mechanical behavior of cells on surfaces demonstrates characteristics of tensegrity in which tensile forces are balanced against compressive loads. Cells attached to gel surfaces establish mechanical homeostasis by using their endogenously generated cytoskeletal tension, or prestress, to pull in when generating contractile forces, effectively inducing a compressional component in the underlying substrate. Traction forces correlate with cytoskeletal tension,Cells also exhibit larger traction forces on stiffer substrates, further suggesting that external mechanics exogenously promote the development of cell prestress as well as the formation of stress fibers and focal adhesions.TFM can also be applied to multicellular sheets, to measure traction stresses exerted on the substrate, and also to quantify cell–cell forces.B.et al., which can deflect under the action of cell-generated traction forces [The capabilities of TFM can be greatly expanded by fabricating silicone rubber substrates into arrays of flexible micropillars, pioneered by Tan n forces .77,114–1Micropost arrays can also be actuated to subject cells to external mechanical stimulation through local magnetic micropost deflectionsC.Although monolayer TFM and micropost array systems have proven invaluable in understanding the structural aspects of the dynamic prestressed cell cytoskeleton as well as its response to active perturbations, they are inherently limited to measuring contractile and shear stresses in 2D. Cells have the capability of generating out-of-plane traction forces in 3D contexts, and 3D culture is known to significantly affect cell function.in vivo-like conditions to the same extent as natural matrices, cells grown in these synthetic gels still behave realistically. They produce larger inward tractions in stiffer matrices that increase at the cell periphery and are localized to the cell's slender protrusions.To facilitate the measurement of 3D traction forces, engineered matrices such as polyethylene glycol diacrylate,Interestingly, and similar to molecular force sensors, these cellular scale methods also generally quantify tensile forces, and measuring piconewton-scale compressive stresses remains a challenge. To provide compressive stress readouts, compliant sensors can be designed to sustain compressive loads and deform in a measurable ways. Recently, subcellular hydrogel microparticles have been used to quantify compressive stresses during phagocytosis,IV.While cellular length scale tensegrities have been quite well-established, understanding tensegrity at intermediate length scales between cells and organs remains challenging, primarily due to technical limitations in quantifying forces within small tissues. Forces at the tissue scale are more complex than the simple sum of cellular scale forces, as additional factors such as collective behaviors, spatial profiles, and supracellular elements must be considered. Measuring forces at the tissue length scale generally requires some knowledge of the mechanical properties of the tissue, which typically depends on tissue state and composition, and are usually non-linear and time-variant. Furthermore, these properties can be highly heterogenous, particularly at the length scale of individual cells. Hence, recent strategies to resolve tissue-scale forces have involved designing tissues with small regions of precisely defined properties, and measuring the deformation of these defined zones to quantify generated forces. These techniques can be broadly split into two categories: tissue-scale measurement of average forces  or celluA.in vivo-like conditions, encompassing cell–ECM and cell–cell interactions. Developing such tissues typically requires the cells to remodel, reorganize and structure the tissues, through processes such as matrix contraction [Microengineered tissues are a powerful tool to recreate and study cellular behavior in traction .147,153–1.Collective tissue forces can be quantified by embedding complex tissues such as breast ducts2.Integrating deformable structures into an otherwise mechanically complex tissue provides a convenient method to quantify contractile forces, as the mechanical properties of the deformable structures can be well-defined. For example, thin films can be designed to quantify tissue-scale contractile forces of self-assembled myocardial cell sheets by measuring how much they curl up under contractile forces  and can et al. first developed microfabricated pillars with integrated anchoring structures [While this method is limited to measuring tension generation in a sheet of cultured cells, the concept can be extended by designing more advanced structure geometries. Legant ructures ,149 wherructures .189 In eSimilarly, the deflection of suspended polymer wires during the formation of a tissue can be used to quantify forces across the tissue in a high-throughput well-plate format . This syRecently developed filamentous matrices provide a way to make similar measurements to the Biowire II platform with higher resolution within the tissue since fibers span single cell widths and are compliant under cell-generated forces . MatriceInternal tissue prestress can also be controlled by designing actuatable structures that apply local forces on demand. By mounting nickel microbeadsB.The techniques discussion in Sec. 1.To achieve high spatial resolution within microtissues, deformable structures must be both small enough and compliant enough to observably deform under cell-generated stresses. Injectable oil microdroplets were first developed and introduced between cells in mammary epithelial aggregates and embryonic tissues to quantify anisotropic forces at the droplet location .207,208 2.in vivo. Tracking the deformation of beads within multi-layered cell sheets,et al. used this system to demonstrate that a “skin” of tension forms on the periphery, while compressive stresses build up towards the core of fibroblast spheroids [Oil microdroplets are incompressible and can only be used to quantify anisotropic forces. In contrast, deformable hydrogel beads can be both porous and compressible, thus offering a way of quantifying absolute stresses within tissues . The stipheroids . InhibitV.Spatial force profiles within tissues, cells, and molecules are essential in dictating the progression of tissue shape and function in homeostasis, morphogenesis, and pathogenesis. During development, cell-generated forces are well-established to drive key changes in tissue configurations, such as gastrulation,While classical tensegrity structures are composed of both rigid (load-bearing) and linearly elastic components that return to their initial shape after external loads are removed, biological tissues do not exhibit this general behavior. Instead, the elastic response is typically observed immediately after mechanical load, and viscoelastic behavior dominates over the long-term, leading to creep, release of internal stress, and plastic or permanent remodeling. When stretched, both cellsThe role of tensegrity in pathological processes is less well-established and may prove to be a novel line of inquiry in understanding the mechanics of disease progression. In luminal cancers, such as breast carcinomas, the tissue begins as a hollow duct structure. The basal side on the outside of the duct and the apical side on the inside of the duct can both be considered as tensile skins balanced by the pressurized fluid within the lumen. Luminal collapse on the apical side is a structural failure which occurs in early breast cancer progression,The importance of tensegrity during pathological processes may be more directly considered by correlating the invasive properties of cells with their spatial distribution within tumors. Cells at the periphery of breast cancer spheroids are softer and more motile than those under compressional load at the core. This compressive load is hypothesized to push intracellular fluid through intercellular gap junctions, effectively swelling cells under less compressive stresses, yielding a more invasive phenotype at the periphery.Taken together, this mechanical analysis of disease progression suggests that when the balance between tensional and compressional stresses is affected, this can lead to disease progression. We propose that the normal, developmental, and pathological balance between tensegral force balances range across a spectrum . A perfeVI.Cell-generated forces have been quantified across the biological length scales from the molecular to the tissue level by engineering designer biomaterials to provide insight into the location, direction, and magnitude of these forces. Molecular probes have uncovered patterns in tensile stresses within single cells and cell–cell junctions, highlighting the importance of cytoskeletal prestress for cell shapes and functions. Quantifying forces at the cellular level further confirms the significance of internal prestress within cells in order to exert forces on their surroundings and also develops a better understanding of mechanotransductive pathways involved in cell signaling and disease. Novel developments to measure these forces in highly realistic 3D engineered tissues further suggest that tensegrity is a fundamental, modular, and hierarchical characteristic across biological length scales. These studies confirm and reinforce the ubiquitous presence of tensegrity as an organizing principle for biological systems. Given the accumulating evidence that tissue stability, morphogenesis, and pathogenesis of several diseases and organ systems are associated with tensegral imbalances, there remains a fundamental need to further develop the techniques necessary to measure these complex features of tissues in development and disease.


Drosophila flies), and genomic evidence for natural selection consistent with sustained exposure to dietary ethanol in diverse taxa (including hominids and the genus Homo) over tens of millions of years. We also describe our current field studies in Uganda of ethanol content within fruits consumed by free-ranging chimpanzees, which suggest chronic low-level exposure to this psychoactive molecule in our closest living relatives.The “drunken monkey” hypothesis posits that attraction to ethanol derives from an evolutionary linkage among the sugars of ripe fruit, associated alcoholic fermentation by yeast, and ensuing consumption by human ancestors. First proposed in 2000, this concept has received increasing attention from the fields of animal sensory biology, primate foraging behavior, and molecular evolution. We undertook a review of English language citations subsequent to publication of the original paper and assessed research trends and future directions relative to natural dietary ethanol exposure in primates and other animals. Two major empirical themes emerge: attraction to and consumption of fermenting fruits (and nectar) by numerous vertebrates and invertebrates (e.g.,  The argument of the “drunken monkey” hypothesis is that alcohol (and primarily the ethanol molecule) is a low-level but routine component of the diet for all animals that consume fruits and nectar ,2. In adThe natural role of ethanol in animal nutrition has been largely underestimated in the zoological literature. For example, ethanol in ripe and fermenting fruits has been proposed to be largely aversive to vertebrate consumers . More reSugars within ripe and over-ripe fruits serve as caloric motivation for consumption by animals, primarily mammals and birds, that subsequently disperse the seeds. Ripe fruits must be attractive to these consumers and must also present sufficient nutritional reward so as to elicit consumption. However, the ubiquity of yeasts in natural environments indicates the potential for fermentation prior to consumption by vertebrates ,35. AnaeAstrocaryum standleyanum) contain ~0.6% ethanol within the pulp, but over-ripe fruits have much higher levels, averaging 4.5% [Eugeissona tristis) in Malaysia that contain significant levels of ethanol within the nectar [Fermentation of fruit crops is most pronounced in warm, humid environments such as tropical rainforests, the habitat of most frugivorous primates today. For example, ripe palm fruits , then selection will favor the evolution of metabolic adaptations that maximize physiological benefits but minimize costs of exposure. Higher concentrations of ethanol may, by contrast, be stressful and cause harm. Such a nonlinear dose-response curve is termed hormesis and is an evolutionary outcome that increases overall organismal fitness given natural exposure to various compounds at low concentrations ,42,43. AIn support of this claim, longevity  of fruit flies is increased at low atmospheric concentrations of ethanol but decreases at zero exposure and at higher concentrations ,29,30. LDrosophila flies are well-known to correlate with natural levels of environmental ethanol exposure [ADH7 allele), starting at about 10 Mya [Evolutionary arguments also predict that intra- and interspecific variation in the ability to metabolize ethanol will correspond to its relative dietary inclusion. Alcohol dehydrogenase (ADH) initially converts ethanol to acetaldehyde, which then is acted upon by aldehyde dehydrogenase (ALDH) to yield acetate used for energy yield in oxidative pathways. Both ADH and ALDH exist in a number of different allelic forms characterized by varying catalytic efficiencies, which in exposure ,39. Furtt 10 Mya . ADH4, at 10 Mya . The samt 10 Mya .ADH7  and relaxed selection on this allele were found for those taxa with little or no presumed dietary exposure to ethanol . Contrariwise, natural selection was apparently intensified on ADH7 for those species specializing on either fruit or nectar [Moreover, a recent study  evaluater nectar . AlthougHominoids  also exhibit an evolutionary loss of uricase as a consequence of accumulating deleterious mutations in the corresponding gene . ModIn addition to aforementioned interspecific studies of ethanol metabolism, there is also substantial intraspecific genetic variation in physiological responses to ethanol, at least among modern human populations. In particular, slow-acting ALDH occurs at high frequencies in East Asian humans, and yields toxic acetaldehyde buildup following the consumption of ethanol ,53. SuchFinally, multigenerational exposure to high levels of dietary ethanol can result in significant changes to the gut microbiome, at least in laboratory rodents . This inP. troglodytes schweinfurthii) in Kibale National Park reside in a forest with a low density of a high-output, asynchronously fruiting fig species (Ficus mucuso), which is consumed preferentially more than any other fruit . We also collected unripe F. mucuso during part of the field season, which the chimpanzees eat during periods of food shortage. Collected figs were frozen at the field station to arrest fermentation. We determined ethanol concentrations within individual fruits using an infrared gas analyzer on homogenized pulp samples, and also via ethanol vapor measurements in the headspace over pulp samples. Prior to these measurements, for each fruit we also assessed its mass, puncture resistance, sugar concentration, surface reflectance, and presence or absence of fig wasps, so as to correlate quantitatively ethanol content with stages of ripeness, and to assess which factors most influence microbial ethanol production. Data obtained to date indicate ethanol levels within ripe figs ranging from negligible amounts to as high as several percent (weight of ethanol/weight of fruit), consistent with values determined for other primate-consumed fruits [Recent field studies of chimpanzee-consumed fruits in Uganda suggest a chronic low-level ingestion of ethanol, albeit at sub-inebriating levels that are nonetheless consistent with physiological consequences. The Ngogo population of Eastern chimpanzees . In d fruits ,13.Levels of ethanol consumption are determined both by ingested food volume and by intrinsic concentration. A typical daily consumption of ~6 kg of fruit at an ethanol content of only 0.23% would correspond to ingestion of one standard drink . Moreover, adult Eastern chimpanzees in the wild weigh substantially less than humans , suggesFicus: Moraceae). Both short-range olfactory and tactile cues are thus more important in identifying ripe fruits, with reduced use of visual cues [Further assessment of dosage via dietary ingestion would require knowledge of rates of ethanol absorption and catabolism in chimpanzees, which are not necessarily the same as those in humans. Enzymatic activity relative to ethanol degradation is variable among mammalian taxa, and even among modern human populations ,61,62. Dual cues . Equallyual cues  and possMoreover, fig wasps are the mutualistic tenants and obligate pollinators of figs and may influence fermentation outcomes via different microbiota that they vector into fruits. Fig wasp behavior and ecology are highly variable among species, as are the chemical and structural features of different figs, which may, in turn, influence outcomes of microbial colonization and growth. Finally, endogenous fermentation of sugars is likely to vary with local climate, and in particular with average ambient temperatures. Lower elevations likely yield fruits with higher ethanol concentrations, given faster yeast growth in hotter climates. Our data for Ngogo (situated at 1400 m above sea level) likely represent conservative values for fruit-ethanol concentrations relative to those within lowland tropical rainforests where most frugivorous animals are found. Nonetheless, these preliminary measurements suggest sustained exposure of our closest living relatives to dietary ethanol and establish a methodological framework for further investigation into the natural consumption of fermented fruits.Behavioral responses to naturally occurring ethanol can be advantageous for many animals, may be ancestral in primates, and have substantial implications for modern humans relative to both benign consumption of alcohol and excessive levels of drinking. A number of empirical questions can be posed to further assess the generality of these evolutionary arguments. In natural ecosystems, how do animals localize fermenting nutritional resources, and what are typical blood-ethanol levels within frugivores and nectarivores? Do the hormetic effects of low-level ethanol consumption extend more generally to all species exposed to this molecule over evolutionary time? Are there particular sensory mechanisms in some species that predispose them to excessive ethanol ingestion under artificial conditions of high supply? For example, ethanol evokes hyperactivity in the brain-feeding circuits of rodents, consistent with a general role as an appetitive stimulant . Ferment


Results: Ethnic differences in the abundance of 12 genera were significantly mediated by one or more of eight dietary factors, most frequently by overall diet quality and intakes of vegetables and red meat. Lower vegetable intake mediated differences in Lachnospira  and Ruminococcus-1  compared to Native Hawaiians who consumed the highest amount. Higher red meat intake mediated differences in Lachnospira (−41%) and Ruminococcus-1 (36%) in Native Hawaiians over African Americans, who consumed the least. Dairy and alcohol intakes appeared to mediate and counterbalance the difference in Bifidobacterium between Whites and Japanese Americans. Conclusions: Overall diet quality and component food intakes may contribute to ethnic differences in GM composition and to GM-related racial/ethnic health disparities. Background: The human gut microbiome (GM) has been observed to vary by race/ethnicity. Objective: Assess whether racial/ethnic GM variation is mediated by differences in diet. Design: Stool samples collected from 2013 to 2016 from 5267 healthy Multiethnic Cohort participants (age 59–98) were analyzed using 16S rRNA gene sequencing to estimate the relative abundance of 152 bacterial genera. For 63 prevalent genera (>50% in each ethnic group), we analyzed the mediation of GM differences among African Americans, Japanese Americans, Latinos, Native Hawaiians, and Whites by overall diet quality ) and intake amounts of 14 component foods/nutrients assessed from 2003 to 2008. For each significant mediation ( The human gut microbiome and its alterations have been associated with a wide array of metabolic and neuro-behavioral disorders, with especially strong evidence for obesity, inflammatory bowel disease, and colorectal cancer ,2,3. TheA key feature of the human gut microbiome is the remarkable stability of its compositional structure within an individual over time while exhibiting large variability between individuals ,10. ConvChristensenellaceae, known to be highly heritable  ventriosum ranked high in their importance to differentiate race/ethnic groups (data not shown) but showed little mediation by dietary intake differences. Similarly, others found no association between diet and Christensenellaceae [We found that the magnitude of dietary mediation was not proportional to the ethnic difference in individual genera, indicating varying effects of non-dietary determinants on the gut microbiome. For example, ellaceae . Flavonifractor, Ruminiclostridium-5, and Ruminococcaceae uncultured. Flavonifractor is known to catabolize catechin flavonoids in the gut [Flavonifractor plautii has specifically been associated with a high-fat/low-fiber diet [Flavonifractor OTU41, was reduced in a randomized trial of cranberry supplementation rich in polyphenols [Ruminiclostridium-5 can metabolize complex polymers such as cellulose, xylan, and N-acetylglucosamine as an energy source [Overall diet quality had the largest mediation effect on the ethnic variation in the abundance of  the gut . Flavoniber diet , increasber diet , and colber diet , while ay source  and was y source . Thus, oLachnospira and Ruminococcus-1 were mediated substantially and in opposite directions by the intake of vegetables and red meat. Lachnospira, a member of short-chain fatty acid (SCFA) producer Lachnospiraceae, has been inversely associated with weight gain and obesity [Ruminococcus species within the phylum Firmicutes have been linked to inflammatory bowel diseases [Lachnospira and the deleterious profile of Ruminococcus-1, we observed that African Americans and Latinos, groups with low vegetable intake, had lower abundance of Lachnospira and higher abundance of Ruminococcus-1 compared with Native Hawaiians who reported the highest vegetable intake; 35–43% of these differences was mediated by the vegetable intake difference. In contrast, red meat intake, reported to be higher in Native Hawaiians than African Americans, showed a counter-balancing mediation effect for the ethnic difference in Lachnospira and Ruminococcus-1 abundance.We also found that the racial/ethnic differences in the abundance of  obesity  and was  obesity . Enrichediseases  and was diseases . ConsistBifidobacterium between Whites and Japanese Americans was mediated by their dairy and alcohol intake [Bifidobacterium, and the genus difference compared to Japanese Americans was mediated in part (16%) by higher alcohol intake among Whites, indicating that alcohol had a suppressing effect on the genus [Bifidobacterium over Whites had they increased their low intake of fermented dairy foods (−20%). Bifidobacterium members are widely commercialized as probiotics, known for their SCFA-producing and beneficial immunomodulatory properties [Bifidobacterium abundance has been consistently linked to human genetic variation such as for lactase persistence (lower in Asian Americans than in Whites), it has been suggested that the influence of environment prevails over host genetics [The difference in l intake . Whites he genus . It is loperties . While Bgenetics . Our finThere are several important strengths to this study. A large number of diverse participants were included. Stool samples were collected into a nucleic acid fixative, which has been shown to provide high-quality and reproducible results comparable to that obtained from fresh-frozen collection protocols ,53. Dietn = 1484), where similar mediation trends were observed but did not reach statistical significance after adjustment for multiple tests (On the other hand, there were some limitations in our analyses. We analyzed the dietary intake data from 10 years prior to the stool collections, which may have yielded different associations than a more recent diet. We had information on concurrent diet only for the APS subset (le tests , likely le tests . In addiIn conclusion, we made a novel observation of substantial dietary mediation for the significant racial/ethnic variation in gut microbial composition. This is an important finding to understand the biological underpinning of racial/ethnic health disparities and to identify relevant targetable dietary interventions.


Vitis vinifera) caused by Xylella fastidiosa, a bacterium that is spread by certain species of xylem feeding leafhoppers. During its colonization of the xylem network, Xylella forms a biofilm within the intervessel pit fields and secretes cell wall-digesting enzymes  to breach the pit membranes, thereby facilitating migration of the bacteria to adjacent vessels. While pit membranes impose a resistance to water flow, they also are believed to prevent the spread of air bubbles that may arise during extended periods of water deficit. As such, plant vascular systems may be compromised during Xylella infection by either drought-induced embolism, clogging by the vascular pathogens themselves, or both, ultimately leading to hydraulic dysfunction. On the other hand, with the pit membranes pores enlarged, the effects on water transport should lead to both higher xylem hydraulic conductivity and lowered resistance to axial flow. As a further complication, the presence of Xylella in the xylem may trigger ethylene production and a subsequent production of tyloses. To eliminate the effects of both the presence of Xylella in the xylem and the plant response to Xylella , Fanton and Broderson (pp. 1919–1931) perfused the xylem of grapevines with polygalacturonase alone, an enzyme known to be produced by the bacterial biofilm. Six grapevine genotypes with varying levels of resistance to Pierce’s Disease were studied, with the expectation that pit membrane resistance to degradation by polygalacturonase may play a role in resistance to this disease. The authors report that pit membrane damage did occur in stems perfused with polygalacturonase alone. Although the damaged pit membrane area was small, membrane digestion led to significant changes in air-seeding thresholds and a universal reduction in stem hydraulic conductivity, suggesting that the development of tyloses and the presence of the bacteria themselves may not be the only contributing factors to reduced hydraulic conductivity in infected grapevines.Pierce’s Disease is a deadly disease of grapevines  have successfully generated transgenic Dendrobium orchids, in which Dendrobium Orchid TERMINAL FLOWER1 (DOTFL1), an ortholog of TFL1 in Arabidopsis , is either overexpressed or downregulated. TFL1 is a phosphatidylethanolamine-binding protein, and its orthologs in other species are known to function in regulating diverse developmental processes, including seed development, flowering time, and inflorescence development. In some species, TFL1 suppresses floral transitioning, and this appears to be the case in Dendrobium as well. The authors report that the overexpression of DOTFL1 in Dendrobium delays flowering and pseudobulb formation and produces defective inflorescence meristems and flowers with vegetative traits. In contrast, the knockdown of DOTFL1 accelerates flowering and perturbs the maintenance of the inflorescence meristem. These findings suggest that DOTFL1 promotes vegetative growth in Dendrobium and has a previously unknown role in pseudobulb formation in the Orchidaceae.Most orchid genera, including the commercially popular genus Capsicum annuum) with special emphasis on NAC. NAC-type transcription factor CaNAC2c was induced both by thermal stress and by infection with Ralstonia solanacearum, a pathogenic bacterium. CaNAC2c-inhibited growth and promoted immunity against Ralstonia by activating jasmonate-mediated immunity and H2O2 accumulation. In a markedly different manner, CaNAC2c promoted thermal stress responses by activating Heat Shock Factor A5 (CaHSFA5) transcription and blocking H2O2 accumulation. In response to thermal stress, CaNAC2c-CaHSP70 interaction in the nucleus protected CaNAC2c from degradation and resulted in the activation of thermotolerance by increasing CaNAC2c binding and transcriptional activation of its target promoters. In contrast, in response to bacterial infection, CaNAC2c interacted with CaNAC029 in the nucleus and activated jasmonate-mediated immunity but was prevented from activating thermotolerance-related genes. Thus, CaNAC2c physically interacts with either CaHSP70 or CaNAC029 in a context-specific manner.High-temperature stress and pathogen attack are frequently encountered by plants growing in tropical or subtropical climates and can lead to severe retardation in growth and development, sometimes even death. To maximize fitness, such plants need to prioritize the allocation of their limited resources between growth and stress responses. The resulting trade-off is thought to be regulated by crosstalk between signaling pathways. The NAC family of transcription factors have been implicated in the regulation of plant responses to stress. Cai et al. (pp. 2169–2189) now describe the mechanism underlying trade-offs between growth, immunity, and thermotolerance in pepper (Tanacetum cinerariifolium (herbaceous Asteraceae) and Callitris rhomboidea (woody conifer). Optical dendrometers were used to record stem water potential at high temporal resolution and enabled noninvasive measurements of hydraulic conductance. During the early stages of water stress, there were parallel declines in both species in both hydraulic conductance and canopy conductance parameters. The recovery of both the hydraulic conductance and the canopy conductance after rewatering, however, differed between the two species. Tanacetum cinerariifolium recovered relatively quickly, while the recovery of C. rhomboidea was much slower. These findings suggest that the pronounced sensitivity of hydraulic conductance to drought is a common feature among different plant species, but recovery may vary between species.Xylem cavitation, due to the formation of xylem embolisms, is thought to be the main factor limiting the hydraulic conductance of plant organs during acute episodes of drought. There are reports, however, that decreases in root hydraulic conductance often precede the formation of xylem embolisms. These pre-embolism declines in hydraulic conductance in response to mild drought stress have been attributed to a range of factors including, cortical lacunae formation involving cellular dehydration and collapse, suberization, and reduced aquaporin activity. The extents of these varied root responses, all of which lead to reduced hydraulic conductivity, have been found to increase with increasing water stress severity, suggesting perhaps that the severity of water stress may dictate the speed of root recovery responses following soil water replenishment. It has also been found that in response to intensifying soil water deficit in the soil, the root hydraulic conductance of some plant species decreases, triggering stomatal closure. However, it is unknown in such cases, how the dynamics of hydraulic conductance recovery following rewatering after drought might influence gas exchange. Bourbia et al. (pp. 1908–1918) have examined the decline and recovery of the whole root hydraulic conductance and canopy conductance during exposure to moderate water stress in two species with contrasting types of root systems: ANAC017 show strongly repressed mitochondrial retrograde signaling. Recent studies in Arabidopsis , however, have reported conflicting roles for ANAC017, and its closest paralog NAC DOMAIN CONTAINING PROTEIN 16 (ANAC016), in the process of leaf senescence. Unlike these previous studies, Broda et al. (pp. 2205–2221) have used a different experimental approach to determine the role of ANAC017 in plant senescence. By darkening only individual attached leaves, while keeping the rest of the plant under optimal conditions for plant growth, the authors were able to analyze dark-induced senescence, while maintaining systemic communication, a situation that mimics partial shadowing by a neighboring plant. By comparing the different ANAC017 mutants that had been used in the previous conflicting studies, the authors provide clear evidence that the overexpression of ANAC017 positively regulates leaf senescence and cell death. A time-resolved transcriptome analysis revealed that senescence-associated pathways such as autophagy are not constitutively activated in ANAC017 overexpression lines but require a senescence-stimulus to trigger accelerated induction. ANAC017 transcript and ANAC017-target genes are constitutively upregulated in ANAC017 overexpression lines, whereas knockout mutants of ANAC017 showed lowered senescence-induced induction of ANAC017 target genes during the late stages of dark-induced senescence.A group of NAC domain-containing transcription factors, including ANAC017, have been shown to play an important role during retrograde signaling in plants. Knock-out mutants of Arabidopsis thaliana. This was achieved by the constitutive overexpression of three biosynthesis genes responsible for B1 synthesis, HMP-P synthase, HET-P synthase, and HMP-P kinase/TMP pyrophosphorylase, either separately or in combination. By monitoring the levels of thiamin, its phosphorylated entities, and its biosynthetic intermediates, the authors provide insight into the efficacy of these strategies in enhancing thiamin biosynthesis. A general conclusion reached by these studies is the necessity of balancing the pyrimidine and thiazole branches of thiamin biosynthesis. A second finding of importance is that the accumulation of certain metabolites appears to be tolerated in planta, whereas others are subject to stricter control mechanisms. These results are an important step toward acquiring a better understanding of the complex regulation of plant B1 biosynthesis and can serve as a guideline to develop novel B1 metabolic engineering strategies.Thiamin (or thiamine) is a water-soluble B-vitamin (B1), which is required, in the form of thiamin pyrophosphate (TPP), as an essential cofactor in many crucial enzymatic steps in carbon metabolism, including glycolysis, the tricarboxylic acid cycle, nucleotide metabolism, and the synthesis of branched-chain amino acids. Humans, lacking the ability to synthesize this vitamin de novo, require adequate dietary supplies of B1 vitamins to ensure normal cell functioning. Unfortunately, thiamin deficiency is a persistent global health problem that can lead to neurodegenerative and cardiovascular pathologies. Increasing thiamin levels in plants via metabolic engineering may help to alleviate vitamin B1 malnutrition and thus improve global human health. These engineering strategies rely on comprehensive knowledge of plant thiamin metabolism and its regulation. With this goal in mind, Strobbe et al. (pp. 1832–1847) have examined multiple metabolic engineering strategies in the model plant


From invertebrates to vertebrates, the ability to sense nutrient availability is critical for survival. Complex organisms have evolved numerous signaling pathways to sense nutrients and dietary fluctuations, which influence many cellular processes. Although both overabundance and extreme depletion of nutrients can lead to deleterious effects, dietary restriction without malnutrition can increase lifespan and promote overall health in many model organisms. In this review, we focus on age-dependent changes in stem cell metabolism and dietary interventions used to modulate stem cell function in aging.Over the last half-century, seminal studies have illustrated that dietary restriction confers beneficial effects on longevity in many model organisms. Many researchers have now turned to dissecting the molecular mechanisms by which these diets affect aging at the cellular level. One subpopulation of cells of particular interest are adult stem cells, the most regenerative cells of the body. It is generally accepted that the regenerative capacity of stem cells declines with age, and while the metabolic requirements of each vary across tissues, the ability of dietary interventions to influence stem cell function is striking.In this review, we will focus primarily on how metabolism plays a role in adult stem cell homeostasis with respect to aging, with particular emphasis on intestinal stem cells while also touching on hematopoietic, skeletal muscle, and neural stem cells. We will also discuss key metabolic signaling pathways influenced by both dietary restriction and the aging process, and will examine their role in improving tissue homeostasis and lifespan. Understanding the mechanisms behind the metabolic needs of stem cells will help bridge the divide between a basic science interpretation of stem cell function and a whole-organism view of nutrition, thereby providing insight into potential dietary or therapeutic interventions. One of the most accessible means of influencing lifespan has involved modulating caloric or dietary intake. Many early studies examining the effects of diet on age have focused on the abilities of caloric restriction, generally considered a 20–40% reduction in calorie intake on a whole, or restriction of specific dietary components such as protein or carbohydrates, to increase lifespan –4. Diet In many tissues, healthy state is maintained by populations of stem cells, whose metabolic requirements are varied and complex, and which often lose their self-renewal capacity with age –12. NumeSomatic stem cells are a unique population of undifferentiated cells that have the ability to self-renew and give rise to progenitors that subsequently replenish specialized cells within tissues. The rate at which adult somatic stem cells can proliferate and contribute to tissue regeneration and homeostasis can vary between tissues and with age. Perhaps the best studied and most defined adult stem cell population is hematopoietic stem cells (HSCs). HSCs are located in the complex niche microenvironment of the bone marrow  and haveIn the 1970s, several influential discoveries were also made in epidermal stem cell biology, where long-lived epidermal cells could be maintained in culture over long periods of time and were shown to express specific keratin markers . Later, +) intestinal stem cells (ISCs) that are present both in the small and large intestines. ISCs either self-renew or differentiate into progenitor cells, which themselves undergo several rounds of proliferation before differentiating into one of several intestinal cell types: secretory Paneth cells (the only differentiated cell type that travels downwards into the crypt), Goblet cells, enteroendocrine cells, Tuft cells, or the absorptive enterocytes which make up the majority of the intestinal lining .–67.65–67and mice –72, althand mice . Lammingand mice –79. Geneand mice , indicatC. elegans via inhibition of AMPK activity [C. elegans are in part dependent upon AMPK activity [Like the mTOR complexes, the AMPK signaling pathway monitors nutrient status and regulates subsequent cell growth and differentiation processes by responding to changes in ATP, ADP, and AMP levels. In times of nutrient depletion, AMP and ADP concentrations rise, and AMPK is activated by phosphorylation of LKB1 at Thr172. This phosphorylation event is made possible through a conformational change induced by AMP/ADP binding at the regulatory γ subunit of AMPK. In turn, AMPK can directly and indirectly inhibit mTOR activity to reduce anabolic processes and promote autophagy . Targetsactivity , whereasactivity . The benactivity , 87. Conactivity . Severalactivity , 88.Within the stem cell, changes in metabolism are able to direct various cellular phenomena such as senescence, proliferation, stemness, differentiation, apoptosis, and resistance to cancer treatment. HSCs remain in a largely quiescent state, with estimations of less than 10% to be actively dividing. Aging in the hematopoietic system is characterized by loss of self-renewal capacity of HSCs, expansion of HSC numbers, myeloid lineage skewing, and clonal hematopoiesis . On the Hematopoietic stem cells must also maintain a balance of mTOR signaling over time. The activity of this pathway is linked to progenitor proliferation, yet inhibition of its activity with rapamycin in aged HSCs leads to improved stem cell function and renewal , 96. Tho+ progenitor cells in the lymph glands of Drosophila use FAO as their primary metabolic state, unlike pre-progenitors and intermediate progenitors [Stem and progenitor cell function has also been shown to be regulated by mitochondrial metabolism and fatty acid oxidation . Dome+ pgenitors . Kratchmgenitors . Similargenitors . Regardigenitors . Inhibitgenitors , but it genitors .Drosophila have informed how nutrient sensing and aging in the gut can regulate intestinal stem cells, tissue homeostasis, and longevity [Drosophila [Numerous studies in ongevity ••. Aminoosophila , and furosophila . Early sosophila ••, 108.Apc [We and others have hypothesized that the beneficial effects of caloric restriction may be due to prolonged periods of fasting. To test this hypothesis, we recently asked how short-term, 24 hour fasting affects ISC function and numbers, especially in the context of aging. Interestingly, this short-term fasting led to a significant boost of both young and aged stem cell function and protected the intestine from radiation-induced damage. Unbiased RNAseq analysis of ISCs revealed fasting induced transcriptional upregulation of PPAR targets and subsequent metabolic switch to fatty acid oxidation. Pharmacological or genetic ablation of the rate-limiting enzyme for mitochondrial fatty acid import, CPT1A, blunted the effects of fasting in cultured organoids and reduced stem cell numbers in vivo, but treatment with PPARδ agonist GW501516 increased stem cell numbers, boosted stem cell function, and increased FAO rates in intestinal crypts from aged animals. Collectively, this suggests that FAO promotes stem cell self-renewal and that its disruption compromises ISC function ••. Long-Apc .Cheng and colleagues recently showed that intestinal stem cells are highly enriched for HMGCS2, the rate-limiting enzyme in ketone body production, and that deletion of HMGCS2 in the intestine decreases beta-hydroxybutyrate (BOHB) levels in crypts, reduces stemness, and skews differentiation to a secretory lineage phenotype ••. Conve+ stem cells leads to increased stem cell proliferation, and a similar hyperproliferative phenotype was observed with the loss of Drosophila MPC [Even within the small intestine, there appears to be metabolic variability among stem cells in the intestinal crypt. Stine et al. found that both PRDM16 and PPAR expressions were highest in the duodenal crypts and decreased distally, suggesting duodenal stem cells rely more on fatty acid oxidation . This wahila MPC . Along thila MPC .+ to cyclic ADP ribose (cADPR) to induce stem cell renewal [With regards to mTOR signaling, in the aging mouse intestinal crypt, Pentinmikko et al. found that old Paneth cells exhibit increased mTORC1 activity, as evidenced by increased phosphorylation of the S6 ribosomal protein ••. Conve renewal . Simulta renewal . The int renewal . As a reCurrent studies are examining combination treatments that target pathways in addition to mTOR such as the Sirtuins, in order to account for these mixed responses across cell types and tissues. It is worth noting, too, that while rapamycin treatment alone can induce boosts in stem cell function and self-renewal that are generally seen with CR , treatmeIn a similar fashion, AMPK phosphorylation is elevated in the intestinal crypts of calorie-restricted mice, and in the intestinal stem cells in particular . As withLike intestinal stem cells, neural stem cells exhibit marked decline in function with age and become less able to counteract neuron loss or damage with regeneration over time •. ProlifKnobloch et al. found that compared to proliferating neural stem and progenitor cells (NSPCs), quiescent NSPCs have higher expression levels of CPT1A. Inducing quiescence upregulates Spot14, a negative regulator of malonyl-CoA, suggesting that high levels of Spot14 along with low levels of malonyl-CoA help promote fatty acid oxidation. A massive die-off of quiescent NSPCs occurred after etomoxir treatment, while treatment of proliferative NSPCs led to a reduction of proliferation, indicating that FAO is much more crucial to quiescent NSPCs than proliferative ones, further supported through the upregulated expression of PPARα and its targets in quiescent NSPCs . As an oIn muscle, mTOR signaling is associated with muscle size, where its increased activity can contribute to hypertrophy but can also lead to muscle degeneration as a result of oxidative damage . ConsequPPARα, PPARγ, ACOX, LPL, FABP4, and CPT1, suggesting that unsaturated fatty acids like linoleic or oleic acids could promote FAO in muscle satellite cells [Satellite cells isolated from irradiated mice are more likely to have incomplete oxidation of 14C-palmitate and reduced levels of insulin-stimulated glucose uptake, regardless of whether mice were on a regular chow or high fat diet . After ote cells .Somatic stem cells integrate critical environmental inputs that inform decisions on self-renewal, differentiation, and subsequent tissue turnover. Aging is a risk factor for many diseases, and recent studies are starting to uncover the molecular mechanisms of how environmental factors, such as diet, can influence stem cell behavior over time. With aging, many adult stem cell populations accumulate damage and become impaired in their function, which leads to inefficient tissue repair and may predispose to age-associated diseases such as cancer. Although numerous studies have shown that dietary restriction confers beneficial effects on overall organismal lifespan, we are just starting to uncover the complexities of metabolic dependencies in stem cells and how the availability of specific nutrients are sensed within a heterogeneous population of stem, progenitor, and niche cells and communicated between each other. The advent of new single cell technologies has already begun to enhance our ability to resolve the complex metabolic heterogeneity and interactions that exist in certain niches, such as in the gut crypt and bone marrow.Recent studies using single cells technologies have also revealed that seemingly uniform, terminally differentiated cells in the liver and intestinal villus have specific transcriptional metabolic profiles that are driving cell function. These differences among hepatocytes and enterocytes were largely influenced by location, proximity to nutrients, and oxygen supply within their respective tissues , 138. In