Articles

Vitamin B12

Introduction

Cobalamin is the common name of vitamin B12 because it contains the heavy metal cobalt, which gives this water-soluble vitamin its red color. Vitamin B12 is essential for growth and plays a role in metabolism within cells, especially those of the gastrointestinal tract, bone marrow and nervous tissue.

Vitamin B12 is not found in plants, but it is produced by bacteria in the digestive tract of animals, which explains why animal protein products are the only dietary source of this nutrient. Organ meats are the best source of vitamin B12, followed by clams, oysters, beef, eggs, milk, chicken and cheese.

Dosage Info

Dosage Range

Maintenance 1-25mcg daily.
Deficiency doses can be 250mcg daily, doses as high as 2,000mcg daily have been used in chronic renal insufficiency. (1)

Most Common Dosage

100mcg daily.

Dosage Forms

Tablets, capsules, liquids, liposomal sprays, effervescent tablets, sublingual lozenges, intranasal sprays, gels, and injectable (Rx only).

Interactions and Depletions

Depletions

Reported Uses

On the cellular level, Vitamin B12 plays an important role in the replication of DNA while supporting growth of the body’s cells. The vitamin is also vital for the function and maintenance of the nervous system and red blood cells. Vitamin B12 is instrumental in the body’s metabolism of protein, fat and carbohydrates.

One of the most important long-term benefits of vitamin B12 is the role it plays in preventing elevated levels of homocysteine from building up in the body even when the levels are increased by lipid lowering drugs known as fibrates. (2) , (3) , (4) Homocysteine is actually a toxic substance that is formed during the metabolism of the amino acid methionine. Vitamin B12 is one of the vitamins that is required to convert homocysteine into a non-toxic compound. Elevated homocysteine increases the risk of developing atherosclerosis. (5) Also, vitamin B12 deficiency may occur in strict vegetarians which could increase the risk of hyperhomocysteinaemia. (6)

Studies involving hundreds of patients who had undergone successful coronary angioplasty have evaluated these individuals following six months of therapy on vitamin B6, vitamin B12 and folic acid, comparing the results to patients on placebo. After one year, the patients on the vitamin therapy had lower rates of related cardiovascular events including heart attacks and repeated angioplasty. (7) , (8)

Dietary supplementation with the B-vitamins prevented hyperhomocysteinemia but did not prevent the development of vascular dysfunction or atherosclerotic lesions. (9)

Studies have shown cognitive skills such as knowing, thinking, learning and judging can be impaired in older adults with low levels of certain B vitamins. Supplementation with folate, vitamin B12 and vitamin B6 has been effective in enhancing cognitive performance in older adults. (10) In fact, one study in older adults noted that subjects with low levels of vitamin B12 or folate had twice the risk of developing Alzheimer's disease. (11) In another study, researchers found there was a correlation between vitamin B12 deficiency, hallucinations and diurnal rhythm disturbances in dementia patients. (12)

Vitamin B12 deficiency has also been associated with depression in the elderly, and it may treat certain symptoms of Crohn’s disease. (13) , (14) Vitamin B12 has been used experimentally to suppress the AIDS virus and to support health in AIDS patients, who are commonly deficient. (15) Vitamin B12 may ease symptoms for people with bronchial asthma while possibly supporting healthy brain function in diabetics. (16) , (17) Vitamin B12 may also enhance sperm count and sperm activity in cases of male infertility. (18) Also of note is the fact that vitamin B12 can prevent allergic reaction to sulfite. (19)

One study found that older women with lower levels of serum vitamin B12 had a greater risk of bone loss. (20)

The vitamin B12 deficiency condition known as pernicious anemia can be effectively treated by supplementation with vitamin B12 under the supervision of a health care professional. (21)

Toxicities & Precautions

Introduction

[span class=alert]Be sure to tell your pharmacist, doctor, or other health care providers about any dietary supplements you are taking. There may be a potential for interactions or side effects.[/span]

General

This dietary supplement is considered safe when used in accordance with proper dosing guidelines.

Pregnancy / Breast Feeding

To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Proper nutrition is essential during pregnancy for the healthy development of the fetus. Numerous vitamins and minerals are a vital part of proper nutrition. If you are pregnant, think you might be pregnant, trying to get pregnant, or breast-feeding an infant, talk to your healthcare professional about supplementing your diet with appropriate vitamins and minerals.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Vitamins and minerals are an essential part of proper growth and development. Talk to your healthcare professional about the appropriate use of vitamins and minerals in children. Do not use any vitamin or mineral in children under 2 years of age unless first discussed with your healthcare professional.

References

  1. View Abstract: Sperschneider H, Stein G, Lauterbach K, Gunther K. Diagnosis of vitamin B12 deficiency in chronic kidney insufficiency. Z Urol Nephrol. May1984;77(5):301-9.
  2. View Abstract: Siri PW, et al. Vitamins B6, B12, and Folate: Association with Plasma Total Homocysteine and Risk of Coronary Atherosclerosis. J Am Coll Nutr. Oct1998;17(5):435-41.
  3. View Abstract: Dierkes J, Westphal S, Kunstmann S, Banditt P, Lossner A, Luley C. Vitamin supplementation can markedly reduce the homocysteine elevation induced by fenofibrate. Atherosclerosis. Sep2001;158(1):161-4.
  4. View Abstract: Woodside JV, Yarnell JW, McMaster D, Young IS, Harmon DL, McCrum EE, et al. Effect of B-group vitamins and antioxidant vitamins on hyperhomocysteinemia: a double-blind, randomized, factorial-design, controlled trial. Am J Clin Nutr. May1998;67(5):858-66.
  5. View Abstract: Lindeman RD, Romero LJ, Yau CL, Koehler KM, Baumgartner RN, Garry PJ. Serum homocysteine concentrations and their relation to serum folate and vitamin B12 concentrations and coronary artery disease prevalence in an urban, bi-ethnic community. Ethn Dis. 2003;13(2):178-85.
  6. View Abstract: Waldmann A, Koschizke JW, Leitzmann C, Hahn A. Homocysteine and cobalamin status in German vegans. Public Health Nutr. May2004;7(3):467-72.
  7. View Abstract: Schnyder G, Roffi M, Pin R, Flammer Y, Lange H, Eberli FR, et al. Decreased rate of coronary restenosis after lowering of plasma homocysteine levels. N Engl J Med. Nov2001:345(22):1593-600.
  8. View Abstract: Schnyder G, Roffi M, Flammer Y, Pin R, Hess OM. Effect of homocysteine-lowering therapy with folic Acid, vitamin B12, and vitamin b6 on clinical outcome after percutaneous coronary intervention: the swiss heart study: a randomized controlled trial. JAMA. Aug2002;288(8):973-9.
  9. View Abstract: Lentz SR, Piegors DJ, Malinow MR, Heistad DD. Supplementation of atherogenic diet with B vitamins does not prevent atherosclerosis or vascular dysfunction in monkeys. Circulation. Feb2001;103(7):1006-11.
  10. View Abstract: Calvaresi E, Bryan J. B vitamins, cognition, and aging: a review. J Gerontol B Psychol Sci Soc Sci. Nov2001;56(6):P327-39.
  11. View Abstract: Wang HX, Wahlin A, Basun H, Fastbom J, Winblad B, Fratiglioni L. Vitamin B(12) and folate in relation to the development of Alzheimer's disease. Neurology. May2001;56(9):1188-94.
  12. View Abstract: Engelborghs S, Vloeberghs E, Maertens K, et al. Correlations between cognitive, behavioural and psychological findings and levels of vitamin B12 and folate in patients with dementia. Int J Geriatr Psychiatry. Apr2004;19(4):365-70.
  13. View Abstract: Joosten E, et al. Metabolic Evidence that Deficiencies of Vitamin B12 (cobalamin), Folate, and Vitamin B6 Occur Commonly in Elderly People. Am J Clin Nutr. Oct1993;58(4):468-76.
  14. View Abstract: Imes S, et al. Iron, Folate, Vitamin B12, Zinc, and Copper Status in Outpatients with Crohn's Disease: Effect of Diet Counseling. J Am Diet Assoc. Jul1987;87(7):928-30.
  15. View Abstract: Weinberg JB, et al. Cobalamin Inhibition of HIV-1 Integrase and Integration of HIV-1 DNA into Cellular DNA. Biochem Biophys Res Commun. May1998;246(2):393-97.
  16. Simon SW. Vitamin B12 Therapy in Allergy and Chronic Dermatoses. J Allergy. 1951;22:183-85.
  17. Khan MA, et al. Vitamin-B12 Deficiency and Diabetic Neuropathy. Lancet. Oct1969;2(7624):768-70.
  18. View Abstract: Nagai N, et al. Treatment in Male Infertile Clinic of Kaizuka Municipal Hospital. Hinyokika Kiyo. May1988;34(5):839-46.
  19. View Abstract: Anibarro B, et al. Asthma with Sulfite Intolerance in Children: A Blocking Study with Cyanocobalamin. J Allergy Clin Immunol. Jul1992;90(1):103-09.
  20. View Abstract: Stone KL, et al. Low Serum Vitamin B-12 Levels Are Associated with Increased Hip Bone Loss in Older Women: A Prospective Study. J Clin Endocrinol Metab. Mar2004;89(3):1217-1221.
  21. View Abstract: Lederle FA. Oral Cobalamin for Pernicious Anemia: Back From the Verge of Extinction. J Am Geriatr Soc. Sep1998;46(9):1125-27.