Vitamin B12 is present in foods of animal origin, including dairy products and eggs. Thus, vegetarians are more susceptible to a dietary deficiency of this important nutrient. Likewise, vitamin B12 serum concentrations are reported to be significantly lower in elderly population groups compared to younger groups. It is estimated that 10% to 30% of individuals over the age of 50 have low stomach acid secretion217,218 which results in decreased bioavailability of vitamin B12 from food. To overcome food-bound vitamin B12 malabsorption problems, the Institute of Medicine recommends that vitamin B12-fortified foods (such as fortified ready-to-eat breakfast cereals) or supplements containing vitamin B12 be used to meet much of the requirement. Vitamin B12, or cobalamin, works synergistically with vitamin B6 and folate to regenerate (methylate) the amino acid methionine, which helps to maintain already healthy homocysteine levels already within normal range, which is important for heart health.