Vitamin B12 is an essential nutrient important for body functions such as DNA synthesis, neurologic function and red blood cell formation. The amount of vitamin B12 you require on a daily basis depends on your age and gender. If you're deficient in vitamin B12, you'll require much more vitamin B12 than individuals who are not deficient.
Background
Vitamin B12 is found in foods such as milk; yogurt; cheese; meat, especially fish; clams; eggs and some fortified breakfast cereals. Vitamin B12 is also obtained by oral B12 supplements, some multivitamin supplements or vitamin B12 injections given intramuscularly. People at risk for developing a vitamin B12 deficiency include vegetarians, especially vegans, elderly individuals, people with gastrointestinal problems and people with pernicious anemia who cannot absorb vitamin B12 properly.
IOM Recommendations
The Institute of Medicine established minimum recommended dosages for all essential nutrients including vitamin B12, called recommended dietary allowances, or RDAs. The vitamin B12 RDA for adult men and women is 2.4 mcg, 2.6 mcg for pregnant women and 2.8 mcg for women who are nursing.
Deficiency
A form of anemia called megaloblastic anemia can result from vitamin B12 deficiency, and can cause fatigue, weakness and weight loss. Although vitamin B12 deficiency is commonly treated with intramuscular vitamin B12 injections, high oral dosages of vitamin B12 might be just as effective. According to the Office of Dietary Supplements, taking 2,000 mcg of vitamin B12 orally each day followed by dosages of 1,000 mcg per day, 1,000 mcg per week and finally 1,000 mcg per month might be as effective as intramuscular B12 injections.
Research
Researchers leading a 2011 study published in "Clinical Therapeutics" studied the effectiveness of taking oral vitamin B12 supplements compared with B12 injections in people with low levels of vitamin B12. Researchers in the study found that both oral B12 and B12 injections were effective in correcting low levels of vitamin B12. Dosages used in the study were 1,000 mcg of oral vitamin B12, or 1,000 mcg of vitamin B12 injections over a period of three months.
Review Research
According to a 2011 review article published in "American Family Physician," oral vitamin B12 administration was as effective as administering B12 injections for correcting vitamin B12 deficiencies. Oral dosages of vitamin B12 used in this study were 1 to 2 mg per day, which is equivalent to 1,000 to 2,000 mcg of B12 each day.
References
- Office of Dietary Supplements; Vitamin B12; June 2011
- Institute of Medicine Food and Nutrition Board: Dietary Reference Intakes (DRIs): Recommended Dietary Allowances and Adequate Intakes for Vitamins and Elements
- "American Family Physician"; Update on Vitamin B12 Deficiency; R.C. Langan, et al.; June 2011
- "Clinical Therapeutics"; Comparing the Efficacy and Tolerability of a New Daily Oral Vitamin B12 ...; M.C. Castelli et al.; March 2011
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