Are you getting enough B12? Vegetarians may require alternate sources of B12, a vitamin available only in foods of animal origin

Better Nutrition (1989-90), March, 1989 by Eric Sessions

Are You Getting Enough B12?

Vegetarians may require alternate sources of B12, a vitamin available only in foods of animal origin.

Although vitamin B12 was the last one discovered, in 1948, it turned out to be one of the most important ones, especially to vegetarians. Because B12 is found only in foods of animal origin, vegetarians and particularly vegans depend on supplements to get adequate amounts of this vitamin.

Vitamin B12, or cobalamin, is a member of the B complex of vitamins. B vitamins serve as co-enzymes in almost all of the biochemical pathways in the body, working in conjunction with enzymes to sustain metabolism and to help carry out most of the cellular reactions.

The B complex vitamins are the only group of water-soluble vitamins, which is both good news and bad news. Any substance which readily dissolves in blood will be quickly sent throughout the body. Unfortunately, the kidneys can flush these vitamins out of the body. Although the kidneys retain most of the "good" substances like vitamins and minerals for reintroduction into the bloodstream, their filtration system is not perfect and a significant amount of B vitamins is lost each time they pass through this renal filter. Diuretics like aspirin, caffeine, nicotine, marijuana, tranquilizers, food coloring and antihistamines also increase the amount of B vitamins excreted.

B12 is the only vitamin containing the mineral cobalt as part of its complex structure. Its absorption by the body requires a highly specialized protein called intrinsic factor which seems to deteriorate in the elderly. The uptake of B12 is carried out in the stomach and a small part of the small intestine. In the stomach, the intrinsic factor finds the B12 and carries it to the site in the small intestine where the body is able to absorb it.

Many people have switched to or were raised on vegetarian diets; unfortunately, vitamin B12 is not found in any vegetables, fruits, nuts or grains. The vitamin is found in small amounts in dairy products and eggs, but for good health, other sources must be used, the most obvious of which is a supplement. The U.S. Recommended Dietary Allowance (RDA) of B12 is 3 micrograms ([Micro]g), a relatively small amount until you consider you would have to eat 100 grams of pork or 200 grams of cheese to get that amount.

Certain drugs, including anticonvulsants, antibiotics, alkaloids and oral contraceptives may induce a B12 deficiency.

While the body is able to store enough B12 to last two to three years, once the supply runs out the consequences can be severe. The areas of the body affected by a B12 deficiency are the skin, the nervous system and the blood. Because B12 is essential for the formation of healthy red blood cells, a severe lack of the vitamin can cause pernicious anemia, a condition characterized by loss of appetite, vague abdominal pains, considerable weight loss, and, if left untreated, depression, delirium and paranoia. The only treatment for pernicious anemia is vitamin B12 injections.

Further symptoms associated with B12-induced blood and nerve damage include weakness of motor function in the legs and arms, irritability, memory loss, moodiness, agitation, depression, confusion and an Alzheimer's-like dementia. Many of these symptoms develop over a long time period and cannot be reversed. Although symptoms may not be obvious, in many cases progressive damage occurs.

Two groups particularly at risk are breastfed babies of vegetarian mothers and the elderly. Babies who receive nutrition solely from mother's milk are at risk for developing a B12 deficiency if the mother herself is B12-deficient. Although the mother still may be able to rely on stored B12, it is not present in her milk.

Elderly people are at risk for a different reason. Even if they eat enough meat, they lose the ability to absorb B12 as they age. Research has shown there may be some reduction in either production of the intrinsic factor or in its functioning. For these people, it is necessary to increase the supply of B12. Many symptoms of B12 deficiency have wrongly been diagnosed as senility, so it is important to be aware of the problem.

B12 supplements have been called nature's pep pill and while they won't keep you awake at night they may help get you up in the morning. It appears that B12 blocks receptors in the brain which cause the body to remain tired for the first hour after waking. B12 also shows strong antiviral reactions; in humans, it is particularly effective in the prevention of cold stores associated with herpes simplex I.

Even if you eat foods rich in B12, be aware that cooking destroys many of the B vitamins in meat although broiling and frying tend to affect only those close to the surface. Canning and freezing food reduces the amount of B vitamins present by 30 to 60 percent.

B12 is essential for life and if you don't get an adequate supply either due to diet or age, the results can be serious, if not swift. B12 supplements are available in the form of cyanocobalamin at your health food store.