Vitamin B-12, also known as cobalamin, is a water-soluble vitamin needed by the body for the production of healthy red blood cells, DNA synthesis and for the maintenance of healthy nerve cells. Taking vitamin B-12 together with other B vitamins such as vitamin B-6 and folic acid is essential for promoting good eye health may help prevent an eye disease known as age-related macular degeneration, according to MedlinePlus.
Age-Related Macular Degeneration and Vitamin B-12
Age-related macular degeneration affects the macula, the part of the eye that enables people to see fine details of objects. Patients with macular degeneration lose their sharp, central vision. MedlinePlus asserts that age-related macular degeneration is the leading cause of blindness in Americans over 60 years of age, which makes it a compelling issue for researchers and aging Americans. A research team at Harvard-affiliated Brigham and Women's Hospital in Boston found that women in their study who took a combination of B vitamins --- B-6, folic acid and B-12 --- reduced their risk of macular degeneration by more than one-third after seven years compared to women taking dummy pills. The researchers postulate that the eye's small blood vessels respond well to B vitamins' effect on homocysteine, keeping them -- and therefore eye tissue -- healthy.
Glaucoma and Vitamin B-12
Glaucoma is loss of peripheral vision resulting from optic nerve damage caused by elevated fluid pressure in the eye or toxins that damage the optic nerve. Vitamin B-12 has been shown to be beneficial to nerve health, and it may be protective against developing glaucoma. In the journal "Glaucoma" Japanese researchers describe how they prescribed 28 glaucoma patients 1,500 micrograms/day vitamin B-12 for five years. The patients receiving B-12 experienced less measurable loss of peripheral vision, more stable visual acuity, and better control of eye fluid pressure compared to a group that did not take B-12. The effects of vitamin B12 are attributed to the preservation of myelin, which insulates nerve cells. Results of this study were achieved with methylcobalamin, a readily absorbable form of vitamin B12.
Food Sources of Vitamin B-12
Foods containing vitamin B-12 include eggs, fish, milk, dairy products and poultry. Vitamin B-12 is generally not present in plant foods, but some breakfast cereals are fortified with vitamin B-12. Fortified foods vary in the amount of B-12 they contain, so it is important to read product labels to determine how much they contain. The Recommended Dietary Allowance for vitamin B-12 is 2.4 micrograms per day for adult men and women.
Warning
Vitamin B-12 should not be taken by patients with early Leber's disease, which is an inherited condition that causes optic nerve atrophy, according to the Mayo Clinic. Taking vitamin B-12 may cause irreversible optic nerve damage and lead to blindness in patients with Leber's disease.
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