Vitamin B12
Also known as cobalamin, vitamin B12 is an essential nutrient with the largest, most complex chemical structure of all other vitamins.[1]
Vitamin B12 comes in several forms: methylcobalamin, 5-deoxyadenosylcobalamin, and cyanocobalamin; however, methylcobalamin and 5-deoxyadenosylcobalamin are the active coenzyme forms used in the body.[1] The third form cyanocobalamin, which is a supplemental form, converts to one of the other forms after ingestion.[2]
Vitamin B12 is absorbed into the blood stream as hydrochloric acid separates from its attached protein.[3]
Vitamin B12 is an essential nutrient that maintains healthy nerve and blood cells and aids in DNA synthesis.[3]
Vitamin B12 is used to combat pernicious anemia, a condition where the body is unable to produce sufficient, healthy red blood cells.[4] Low red blood cell counts mean impaired oxygen transport in the body, resulting in fatigue and weakness.
One 16-week study suggests vitamin B12 may ameliorate sperm quality. Subjects with oligozoospermia, a condition of low sperm concentration, received 6 or 12 mg methylcobalamin doses. Researchers observed an efficacy rate of 37.5% and 39.1% in vitamin B12 supplemented groups, respectively. Researchers determined a long-term treatment with vitamin B12 was useful in ameliorating sperm concentration.[5]
Research reveals supplementing vitamin B12 with folic acid and vitamin B6 may be beneficial in combating age-related macular degeneration.[6]
Also, researchers have shown a link between depression and low red blood cell folate, vitamin B12, and an increase in plasma homocysteine. They suggest a vitamin B12 and folic acid combination “should be tried to improve treatment outcome in depression.”[7]
Vitamin B12 is regarded as safe for most individuals. However, some people may experience itching, blood clots, diarrhea, and serious allergic reactions.[8]
For those with megaloblastic anemia, vitamin B12 may be used, but researchers note serious side effects may occur. Consequently, medical authorities warn against vitamin B12 unless under the supervision of a healthcare professional.[8]
Those with Leber’s disease or an allergy to cobalt or cobalamin should avoid vitamin B12.[8]
According to the Office of Dietary Supplements, National Institutes of Health, average recommended daily amounts for individuals are age-dependent:[3]
- Birth to 6 months .4 mcg
- Infants 7-12 months .5 mcg
- Children 1.3 years: .9 mcg
- Children 4-8 years: 1.2 mcg
- Children 9-13 years: 1.8 mcg
- Teens 14-18 years: 2.4 mcg
- Adults: 2.4 mcg
The studied dose for ameliorating pernicious anemia is 300-10,000 mcg cyanocobalamin per day.[7]
A vitamin B12, folic acid, and pyridoxine combination of 1 mg, 2.5 mg, and 50 mg was studied in treating age-related macular degeneration, respectively.[7]
The dose used in studying depression treatment is 800 mcg folic acid and 1 mg vitamin B12.[8]
- [1] “Vitamin B12.” Encyclopaedia Britannica.
- [2] “Vitamin B12.” Linus Pauling Institute Micronutrient Information Center.
- [3] “Dietary Supplement Fact Sheet: Vitamin B12.” Office of Dietary Supplements, National Institutes of Health.
- [4] “What Is Pernicious Anemia?” National Heart, Lung, and Blood Institue.
- [5] Moriyama H, et al. [Studies on the usefulness of long-term, high-dose treatment of methylcobalamin in patients with oligozoospermia.” Hinyokika Kiyo. 1987 Jan;33(1):151-6.
- [6] Christen WG, Glynn RJ, Chew EY, et al. Folic acid, pyridoxine, and cyanocobalamin combination treatment and age-related macular degeneration in women. Arch Intern Med 2009;169:335-41.
- [7] Coppen A, Bolander-Gouaille C. “Treatment of depression: time to consider folic acid and B12.” J Psychopharmacol. 2005 Jan;19(1):59-65.
- [8] “Vitamin B12.” WebMD.
