Vitamin B12 status in women of childbearing age in the UK and its relationship with national nutrient intake guidelines: results from two National Diet and Nutrition Surveys.
OBJECTIVE
To assess serum B12, folate and the associated homocysteine (Hcy) levels among women of childbearing age in the UK and examine their association with dietary intake in relation to the UK Recommended Nutrient Intakes (RNIs) for B12 and folate.


DESIGN
Cross-sectional study.


SETTING
Data from two publicly available National Diet and Nutrition Surveys (NDNS 2000/2001 and 2008/2012) were used. These were population-based surveys of randomly selected samples of adults which were carried out in their households.


PARTICIPANTS
Women of childbearing age (aged 19-39 years), representative of the UK population. Those who were pregnant or breastfeeding were excluded.


OUTCOME MEASURES
The associations between micronutrient intakes and blood levels of B12, folate and Hcy were assessed by correlation and stepwise linear regression. B12 intake was divided into quintiles and plotted against blood B12 and Hcy concentrations to determine the threshold of any associations.


RESULTS
299 women from the first NDNS cohort had complete intake and biomarker data. The prevalence of serum vitamin B12 (≤150 pmol/L) and serum folate (≤10 nmol/L) deficiency and hyperhomocysteinemia (≥12 µmol/L) was 12.4%, 6.4% and 21.2%, respectively, despite seemingly adequate B12 intakes (median 3.8 μg/day, 96% consumed more than the UK RNI of 1.5 μg/day). B12 concentrations increased across all quintiles of intake with serum levels in quintiles 4 and 5 (median intake 4.9 and 7.1 μg/day, respectively) significantly higher than quintile 1. However, Hcy concentrations levelled off between quintiles 4 and 5. Comparison of micronutrient intake between the two surveys found that folate intake has reduced in the more recent cohort.


CONCLUSIONS
The UK RNI for B12 intake should be increased for women of childbearing age with intakes of around 5-7 μg/day likely to be associated with stable biomarker levels. B12 levels should also be measured in women preconceptionally or in early pregnancy given the high rates of deficiency.
['Sukumar|Nithya|N|0000-0002-8549-2061', 'Adaikalakoteswari|Antonysunil|A|', 'Venkataraman|Hema|H|', 'Maheswaran|Hendramoorthy|H|', 'Saravanan|Ponnusamy|P|']
D000328:Adult D003430:Cross-Sectional Studies D004032:Diet D005260:Female D005492:Folic Acid D006710:Homocysteine D006801:Humans D020138:Hyperhomocysteinemia D044342:Malnutrition D018673:Nutrition Policy D009749:Nutrition Surveys D015995:Prevalence D006113:United Kingdom D014805:Vitamin B 12 D014806:Vitamin B 12 Deficiency D055815:Young Adult
NUTRITION & DIETETICS