Vitamin B12 is present in foods of animal origin, such as dairy products and eggs. Thus, vegetarians are more prone to a dietary deficiency of this important nutrient. Likewise, low vitamin B12 seems to happen more in elderly individuals than younger groups. It is estimated that 10% to 30% of individuals over the age of 50 cannot properly metabolise vitamin B12. To overcome it, the Institute of Medicine recommends that sources fortified with vitamin B12 (food and supplements) be used to increase the ingested amount. Vitamin B12 works synergistically with vitamin B6 and folate to regenerate the amino acid methionine, necessary to maintain healthy homocysteine levels and thus a healthy heart..