Vitamin B12

Vitamin B12- Deficiency produces two clinical syndromes. B12 is essential for DNA synthesis. When it is deficient the result is rapidly proliferating incomplete cells. Megaloblastic anemia: profound weakness, pallor and fatigue. The anemia of folic acid and B12 deficiency look alike, therefore it is imperative to use diagnostic tests to distinguish the two.

B12 is also linked to folic acid and B6 by their common suppression of homocysteine levels. By keeping this amino acid at bay the vitamins together help to prevent clogged arteries and heart disease.

A neurologic syndrome is secondary to B12 deficiency. It consists of numbness, tingling and burning of the feet as well as stiffness and generalized weakness of the legs. Psychiatric manifestations such as impaired mentation and depression may be present. Treatment may reverse neuropsychiatric abnormalities, this may not occur especially when symptoms have been present for a long time.

Gastrointestinal disorders can predispose to B12 deficiency. Achlorhydria is the absence of hydrochloric acid, natural stomach juice. This happens in the elderly and it happens as part of HIV disease, it can also be due to excessive use of antacids. Without this natural juice there is likely to be a deficiency of "intrinsic factor", a component of stomach juice that is needed to absorb vitamin B12 from the diet.

Vitamin B12 is one of those vitamins that is made in the gut by "friendly" bacteria. This is the most bountiful source of the vitamin. Antibiotics taken for bacterial infections are usually non-selective and tend to kill off all bacteria. During periods of antibacterial therapy multiple B vitamin therapy may be more important than ever.

Best food sources of B12 are organ meats and bivalve seafood such as clams. Egg yolks, meat and fish are good sources. Not all soy products, but tempeh, contains appreciable B12 too. Dairy has a little of the vitamin, but is not a good source.

In the healthy person B12 is carefully recycled and very little is lost over time. It may be decades before a vegan (strict vegetarian) becomes B12 deficient. But in HIV, other chronic illness and the elderly a deficiency could precipitate much more rapidly. Research suggests supplementation in these populations.

Vitamin B12 is not toxic. We suggest that you take B12 as part of your B complex available in "B 50" and "B 100". If you have special needs, peripheral neuropathy being one, you can ask your doctor for B12 injections weekly or you can safely take single oral supplements of B12 at 1000mcg.

Donna Tinnerello, MS, RD, CD/N.

Donna Tinnerello MS, RD,, CD/N is registered dietician with more than 10 years experience in HIV and nutrition. She works at Cabrini Medical Center in lower Manhattan,in private practice and the community.Her subspecialties are cardiovascular, renal, and gastrointestinal disease, diabetes and weight loss. Donna is available for private consultation by referral only.