Basically, a person may have trouble breaking down a food, perhaps because of enzyme deficiencies or because of chemicals found in the food that are difficult to process.
وبما انه لا يرتبط ايضا بالاجسام المضادة ،‏ يمكن ان نشعر بالانزعاج من اول مرة نأكل فيها طعاما معينا .‏