The amount of nutrients your body requires can increase greatly during pregnancy. Many women turn to supplements to meet these increased needs. The amount of vitamin B-12 needed during pregnancy only increases slightly, and it is rare for women of childbearing age to be deficient in this vitamin.
Role of B-12
Vitamin B-12 is necessary for the formation of red blood cells and the metabolism of fatty acids and amino acids. It also helps protect and promote the growth of nerve cells. Vitamin B-12 can also help lower the risk of heart disease by decreasing the amino acid homocysteine. High levels of homocysteine in the blood are associated with heart disease. Vitamin B-12 also plays a role in the development of neurological chemicals that can affect brain function and mood.
Toxicity
The RDA for vitamin B-12 for adults is 2.4 mcg per day. This recommendation increases to 2.6 mcg of vitamin B-12 per day in pregnancy. Large amounts of vitamin B-12 do not appear to be toxic. There is no tolerable upper limit for B-12, a measure set by the Food and Nutrition Board to indicate the highest safe level for intake of a nutrient. Because research is limited on the subject of too much vitamin B-12, it's best not to take large doses on a regular basis.
Supplements
Vitamin B-12 supplements come as pills, sublingual tablets and injections. Vitamin B-12 injections may be the most beneficial for individuals that have difficulty absorbing vitamin B-12, a condition that occurs due to insufficient intrinsic factor, a protein produced in the stomach lining that is necessary for vitamin B-12 absorption. Absorption of vitamin B-12 from supplements is limited, depending on the presence of intrinsic factor. In healthy people, approximately 10 mcg of a 500 mcg oral B-12 supplement is absorbed, according to the Office of Dietary Supplements.
Food Sources
Vitamin B-12 is almost solely available from animal-based foods. Eggs, dairy, fish, meat and poultry are good sources of B-12. There are very few plant sources of vitamin B-12. Nutritional yeast and fortified cereals may contain small amounts of B-12. The American Dietetic Association recommends vegans and lacto-ovo vegetarians take vitamin B-12 supplements during pregnancy to meet maternal and fetal needs.
References
- "Krause's Food, Nutrition, and Diet Therapy"; L. Kathleen Mahan, et al.; 2004.
- Institute of Medicine: Dietary Reference Intakes: Vitamins
- Linus Pauling Institute: Micronutrient Information Center: Vitamin B12; Jane Higdon, March 2003.
- Office of Dietary Supplements: Dietary Supplement Fact Sheet: Vitamin B-12
