Both vitamin B-12, or cobalamin, and folate, known as vitamin B-9, help the body convert carbohydrates into glucose. B-12 and B-9 work together to maintain the health of the nervous and immune systems, produce DNA and RNA, and control blood levels of homocysteine, an amino acid associated with heart disease.
Vitamin B-12 occurs naturally in meats, eggs, dairy products, and fish and shellfish. Manufacturers also add it to fortified cereals. Because the body's ability to absorb B-12 declines with age, elderly people may need to increase their intake of foods containing B-12 or take a B-12 supplement. Vegans also need B-12 supplements to meet the recommended intake of 2.4 micrograms a day for most adults, 2.6 micrograms daily for pregnant women and 2.8 micrograms for breastfeeding women. Vitamin B-12 deficiency can cause nerve damage.
Healthy adults need 400 micrograms of folate daily, and a pregnant woman needs 600 micrograms daily to reduce the risk of neural tube defects for her unborn children; the requirement drops to 500 micrograms per day for breastfeeding women. Dietary sources of folate include dark leafy greens, beans, asparagus, salmon and root vegetables. In the United States, food manufacturers fortify all grain and cereal products with folic acid, the synthetic form of folate. Folic acid supplements are available, but a patient should consult with her health care provider before taking large doses, as high levels of folic acid can mask vitamin B-12 deficiency.