VITAMIN B-12

 Chapter: Vitamins, Minerals, and Related Nutrients

AKA: Acti-B-12, Alphamin, Alpha Redisol, Anocobin, Bedoc, Berubigen, Betalin 12, Cobalamin, Codroxomin, Cyanabin, cyanocobalamin, Droxomin, hydroxocobalamin, Kaybovite, Kaybo-vite-1000, Redisol, Rubion, Rubramin, Rubramin-PC.

The only B vitamin that can be stored by the body (the liver can store three to five years worth).

Food Sources: Beef, brewer's yeast, cheese, dairy products, egg yolk, fish, kidney, liver, milk, pork, seaweed, soybeans and soy products, yeast, yogurt.

Effects: Encourages RNA and DNA synthesis in nerve cells, is needed for the transportation and storage of folic acid, helps stabilize the brain's metabolism of carbohydrates and proteins and its synthesis of myelin in the nerves, plays an indirect role in making choline available for the synthesis of neurotransmitters, protects against stress and fatigue (promotes the release of energy in foods), and is an essential growth factor needed for healthy brain and nerve function. Lab rats experience an increase in their rate of learning, and it has been used to treat depression, insomnia, and memory loss. Preliminary studies have shown that supplementation of B-12 and folic acid may prevent or delay the onset of Alzheimer's. According to Pearson and Shaw, a dose of approximately 1000 micrograms taken immediately before sleep has about a 50% chance of creating dreams in color. Combined with folic acid and methionine, it can help manufacture choline in the body.

Because the body can recycle the vitamin, deficiency is rare, and years of chronic inadequate intake may precede the onset of symptoms. Those at risk include smokers, heavy drinkers, pregnant women, vegans, those who do not produce enough intrinsic factor in the stomach to help utilize it, those with chronic malabsorption problems, those who have undergone stomach surgery, and those taking estrogen, potassium supplements, sleeping pills, and anticoagulant drugs. A deficiency is known as pernicious anemia, and symptoms include poor appetite, a tingling in the hands and feet, depression, nervousness, nerve disorders, fatigue, weakness, digestive disorders, memory loss, moodiness, difficulty walking and maintaining balance. The effects of pernicious anemia may include nerve transmission problems, severe psychosis, brain damage, and death. Deficiency symptoms of B-12 can be masked by taking more than 1000 meg/day of folic acid.

Precautions: It should not be taken by those with Leber's disease (optic nerve atrophy). Those with gout should consult a physician before taking supplements. The RDA for adults is 3 micrograms, yet no toxicity was observed in tests where individuals took 500 to 1000 micrograms (0.5 to 1 mg) for up to five years, or took 100,000 micrograms in a single dose. Allergies to this vitamin are rare, and reactions (the symptoms for which include acne, eczema, and a swelling or crusting of skin around the lips) usually occur with injections, rather than tablets. Rare side effects consist of itchy skin, wheezing, and diarrhea. Life-threatening symptoms, usually resulting from overdose, consist of faintness (from anaphylaxis), hives, itching, and rash.

Dilantin can deplete the body's stores of B-12, and an underactive thyroid gland can interfere with the absorption of this vitamin. It can also be destroyed or have absorption interfered with by acids and alkalies, alcohol, anticonvulsants, chloramphenicol, cholestyramine, cimetidine, coffee, colchicine, estrogen, famotidine, laxatives, neomycin, nizatidine, oral contraceptives, potassium (extended-release forms), ranitidine, sleeping pills, stomach medications (such as Prevacid, Prilosec, Pepcid, Tagamet, and Zantac), sunlight, tobacco, vitamin C (if taken within two hours of each other), and water. As it is only found in meat and dairy products, strict vegetarians may not get enough, though lack of deficiency in nonmeat eaters leads some to speculate that some vegetables may contain bacteria that produce B-12. The vitamin needs to be taken with calcium to be properly absorbed and utilized by the body.

Dosage: 3 meg/day. It is absorbed best when taken with meals that contain calcium. It is recommended that those age 51 and over take 4 meg/day; however, recent evidence suggests that some older people who have less stomach acid and more digestive bacteria may need to take as much as 25 meg/day. Some tablets sold contain the B-12 intrinsic factor, a mucoprotein secreted in the stomach which aids in the absorption of this vitamin, overcoming deficiency. Vitamin B-12 injections are generally regarded as worthless.

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