The human body needs vitamin B-12 to produce genetic material, convert carbohydrates into glucose, regulate homocysteine levels and maintain a healthy nervous system, according to the University of Maryland Medical Center. Vitamin B-12 is found in eggs, organ meats, shellfish and other foods derived from animals.
Vitamin B-12 plays an important role in producing healthy DNA. Without enough B-12, folate remains in a form the body cannot use, increasing the likelihood of DNA damage. Vitamin B-12 deficiency also makes it difficult for the cells to carry out methylation, a biological reaction. Experts from the Linus Pauling Institute say this increases the risk for DNA damage and leads to an elevated risk of cancer.
Too much homocysteine, a sulfur-containing amino acid, in the blood increases the risk for cardiovascular disease, as reported by the Linus Pauling Institute. Vitamin B-12 breaks down this amino acid, helping to regulate the amount that enters the bloodstream.
Older people are susceptible to B-12 deficiency because they have less stomach acid, making it harder to absorb B-12 from foods, according to the Linus Pauling Institute. WebMD reports that people who do not have difficulty absorbing nutrients, eating foods rich in B-12 and taking B-12 supplements should be enough to prevent deficiency. However, people who have trouble absorbing nutrients sometimes need B-12 injections.