Vitamin B12 Health Article

Deficiency

Cobalamin deficiency may be manifested as a variety of symptoms since cobalamin is so widely used in the body. Severe fatigue may occur initially. Effects on the nervous system can be wide-ranging, and include weakness, numbness and tingling of the limbs, memory loss, confusion, delusion, poor balance and reflexes, hearing difficulties, and even dementia. Severe deficiency may appear similar to multiple sclerosis. Nausea and diarrhea are possible gastrointestinal signs. The anemia that results from prolonged deficiency may also be seen as a pallor, especially in mucous membranes such as the gums and the lining of the inner surface of the eye.

Megaloblastic anemia is a common result of inadequate cobalamin. This condition can also result if a person stops secreting enough intrinsic factor in the stomach, a substance essential for the absorption of cobalamin. Inadequate intrinsic factor leads to pernicious anemia, so called because it persists despite iron supplementation. Long-term deficiencies of cobalamin also allow homocysteine levels to build up. Negative effects of large amounts of circulating homocysteine include heart disease, and possibly brain toxicity. Taking high levels of folic acid supplements can mask cobalamin deficiency and prevent the development of megaloblastic anemia, but neurological damage can still occur. This damage may become permanent if the cobalamin deficiency persists for a long period of time.

Risk factors for deficiency

The primary groups at risk for cobalamin deficiency are vegans who are not taking supplements, and the elderly. Older adults are more likely to have both insufficient intrinsic factor secreted by the stomach and low levels of stomach acid, causing cobalamin to be poorly absorbed. Malabsorptive diseases and stomach surgery can also predispose to a deficiency.

Precautions

People who are sensitive to cobalamin or cobalt should not take cobalamin supplements. Symptoms of hypersensitivity may include swelling, itching, and shock. Adverse effects resulting from B₁₂ supplementation are rare. Cobalamin should also be avoided by those who have a type of hereditary optic nerve atrophy known as Leber's disease.

Side effects

Very high doses of cobalamin may sometimes cause acne.

Interactions

Large amounts of vitamin C taken within an hour of vitamin B supplements will destroy the cobalamin component. Absorption of cobalamin is also impaired by deficiencies of folic acid, iron, or vitamin E. Improved absorption occurs when it is taken with other B vitamins or calcium. Some medications may also cause an increased use or decreased absorption of this vitamin. Those on colchicine, corticosteroids, methotrexate, metformin, phenformin, oral contraceptives, cholestyramine, colestipol, clofibrate, epoetin, neomycin, or supplemental potassium may need extra cobalamin. Use of nicotine products or excessive alcohol can deplete B₁₂.

BOOKS

Bratman, Steven, and David Kroll. Natural Health Bible. CA: Prima Publishing, 1999.

Feinstein, Alice. Prevention's Healing with Vitamins. PA: Rodale Press, 1996.

Griffith, H. Winter. Vitamins, Herbs, Minerals & Supplements: The Complete Guide. AZ: Fisher Books, 1998.

Jellin, Jeff, Forrest Batz, and Kathy Hitchens. Pharmacist's Letter/Prescriber's Letter Natural Medicines Comprehensive Database. CA: Therapeutic Research Faculty, 1999.

Pressman, Alan H. and Sheila Buff. The Complete Idiot's Guide to Vitamins and Minerals. New York: Alpha Books, 1997.

Judith Turner