PlanetRx - Learn More - Product Advice - Vitamin B-12





	Vitamins B-12 provides broad benefits Vitamin B-12 is a minimalist. Even a little bit of it ingested daily can keep your body healthy. Like other B complex vitamins, B-12 (also known as cobalamin) has multiple personalities. It keeps your red blood cells red; creates energy from fats, proteins, and carbohydrates; works with folic acid to synthesize DNA; and maintains myelin (a nerve fiber covering) to keep your neurotransmitters firing away. Unlike its B complex buddies, vitamin B-12 can't be found in plants. So even though it takes a long time to become deficient, if you're a strict vegetarian or vegan, you need to take a supplement. As a water-soluble vitamin, it must be obtained through your diet, but some is stored in your liver and kidney. Quick Facts About Vitamin B-12 (Cobalamin) RDA is 2.0 micrograms (mcg) per day for healthy adults. Some foods rich in B-12 are beef, dairy products, fish and shellfish, lean meats, organ meats, and whole eggs. Some signs of B-12 deficiency are anemia, fatigue, mental disorders, weakness.



	You May Need More B-12 if You Have (or Have Had) A history of alcohol or drug abuse Chronic malnutrition A portion of your gastrointestinal tract removed Recent injury or severe burns Recent surgery Or if You're A strict vegetarian Under excessive stress Do not produce enough stomach acid What Works Best -- and Worst -- with B-12 B vitamins work together to help to keep your body functioning. So if you increase your intake of one B vitamin you should increase the others by a proportionate amount. For example, if you're taking double the RDA of cobalamin, you should double the RDA of all other B vitamins. Tobacco decreases absorption, so smokers may require supplemental B-12. Folic acid and cobalamin work together to help keep your red blood cells healthy. Forms Available Individual supplements up to 500 mcg as tablets Extended-release capsules, injectable forms, lozenges, and a nasal gel B-complex supplements in a wide range of potencies A multivitamin supplement



	Chemical Forms Chlorocobalamin Cyanocobalamin Hydroxycobalamin Nitrocobalamin Thiocyanatocobalamin Comments on Vitamin B-12 Cobalamin contains cobalt; hence, its name. Cyanocobalamin contains cyanide at very low, non-toxic levels. But for those of you who worry, hydroxycobalami does not contain cyanide. Cobalamin is converted in the body to active forms (methylcobalamin and adenosylcobalamin). One of the many important functions of methylcobalamin is to convert homocysteine to methionine. Elevated levels of homocysteine (like those in deficiency states) may be responsible for cardiovascular and neurologic disorders. Adenosylcobalamin is needed to generate succinyl CoA, which is an intermediate essential to carbohydrate, fat, and protein metabolism. Cobalamin has a unique mechanism of absorption that involves intrinsic factor excreted from the stomach. Intrinsic factor carries cobalamin to the far end of the intestine so that it can be absorbed. Without intrinsic factor, you have vitamin B-12 deficiency.



	Known Benefits of Vitamin B-12 Supports proper growth and development Participates in formation of red blood cells Treats pernicious anemia Promotes properly functioning nervous system Helps metabolize carbohydrates, fats, and proteins Unproven Claims Helps maintain mental health Reduces fatigue May reduce precancerous lung cells in combination with folate May reduce risk of cardiovascular disease Vitamin B-12 May Prevent These Signs of Deficiency Anemia, which is characterized by: Bruising due to decreased platelet count Pallor Weakness Fatigue Faintness Ringing in ears Vertigo Rapid pulse rate Pernicious anemia, which is caused by B-12 malabsorption due to stomach abnormalities Peripheral neuropathy Memory loss Abnormal gait Recommended Dosage Range for Vitamin B-12 Our pharmacists suggest that healthy adults may take 2 to 100 mcg if needed to supplement a well-balanced diet. RDA values were set as the minimum needed to offset deficiency or disease, not as an actual value needed for optimum health. In the United States, the average consumption of B-12 is: For men, 7.84 mcg per day For women, 4.85 mcg per day For children (ages 1 to 5), 3.80 mcg per day Consult your physician before starting any high dose supplement regimen.



	Warnings Consult a physician before use or do not use vitamin B-12 if: You're about to start a high-dose supplement program. Vitamin B-12 May Have Interactions with the Following Alcohol: taken regularly lowers the level of B-12 in the body. Cholesterol-lowering drugs: Can lower B-12 levels in the body . Colchicine: Decreases the absorption of B-12. Corticosteroids: May deplete the level of B-12 in the body. Fiber: Enhances the excretion of B-12. Guanidines: Decrease the absorption of B-12. Intrinsic Factor: Taken orally with oral B-12 can successfully replace injectable B-12 in pernicious anemia. Metformin: Decreases the absorption of B-12. Neomycin: Decreases the absorption of B-12. Nitrous Oxide: Interferes with the metabolism of B-12. Para-aminosalicylic acid (PAS): Decreases the absorption of B-12. Phenformin: Decreases the absorption of B-12. Phenothiazine tranquilizers: May lower the level of B-12 in the body. Potassium Chloride: Decreases the absorption of B-12. Tobacco: Reduces the blood level of B-12. Side Effects Diarrhea Itching after injections of cobalamin (Injectable forms are only available form health professionals.) There is no known toxicity for cobalamin when taken orally. Doses of up to 100 mcg have not been reported as toxic. Signs of Overdose None anticipated.What to Do in Case of Overdose If you are concerned about cobalamin's side effects, contact your physician.



	Sources & Further Reading Books 1. Basu, TK and Dickerson, JW.Vitamins in Human Health and Disease. CAB INTL, UK 1996. 2. Bendich, A and Deckelbaum, RJ.Preventive Nutrition: The Comprehensive Guide for Health Professionals. Humana Press. Totowa, NJ 1997. 3. Groff, JL, Gropper, SS, Hunt, SM.Advanced Nutrition and Human Metabolism, Second Ed. West Pub. Co. St. Paul, MN 1995. 4. Lieberman, S and Bruning, N.The Real Vitamin & Mineral Book, Second Ed. Avery Publishing Group. Garden City, NY 1997. 5. Machlin, LJ.Handbook of Vitamins, Second Ed. Marcel Dekker, Inc. New York, NY 1991. 6. Meletis, CD and Jacobs, T.The Practitioner's Guide to Drug-Nutrient and Nutrient-Nutrient Interactions. 1996. 7. Werbach, MR.Nutritional Influences on Illness, Second Ed. Third Line Press. Tarzana, CA 1996. Find more books on health and wellness at barnesandnoble.com. Articles 1. Bottiglieri T.Folate, vitamin B12, and neuropsychiatric disorders. Nutr Rev, 1996 Dec, 54:12, 382-90. 2. Carmel R.Cobalamin, the stomach, and aging. Am J Clin Nutr, 1997 Oct, 66:4, 750-9. 3. Chatterjee A; Yapundich R; Palmer CA; Marson DC; Mitchell GW.Leukoencephalopathy associated with cobalamin deficiency. Neurology, 1996 Mar, 46:3, 832-4. 4. Chintagumpala MM; Dreyer ZA; Steuber CP; Cooley LD.Pancytopenia with chromosomal fragility: vitamin B12 deficiency. J Pediatr Hematol Oncol, 1996 May, 18:2, 166-70. 5. Delva MD.Vitamin B12 replacement. To B12 or not to B12?. Can Fam Physician, 1997 May, 43:, 917-22. 6. Donaldson D.Lessons to be learned: a case study approach. Vitamin B12 deficiency of nutritional origin. J R Soc Health, 1997 Oct, 117:5, 310-2. 7. Harriman GR; Smith PD; Horne MK; Fox CH; Koenig S; Lack EE; Lane HC; Fauci AS.Vitamin B12 malabsorption in patients with acquired immunodeficiency syndrome. Arch Intern Med 1989 Sep;149(9):2039-41. 8. Herzlich BC; Lichstein E; Schulhoff N; Weinstock M; Pagala M; Ravindran K; Namba T; Nieto FJ; Stabler SP; Allen RH; Malinow MR.Relationship among homocyst(e)ine, vitamin B-12 and cardiac disease in the elderly: association between vitamin B-12 deficiency and decreased left ventricular ejection fraction. J Nutr, 1996 Apr, 126:4 Suppl, 1249S-53S. 9. Kondo H.Haematological effects of oral cobalamin preparations on patients with megaloblastic anaemia. Acta Haematol, 1998, 99:4, 200-5. 10. Markle HV.Cobalamin. Crit Rev Clin Lab Sci, 1996, 33:4, 247-356.