B-Vitamins and the Prevention of Macular Degeneration

by | Mar 16, 2009 | Folic Acid & Folate, Macular Degeneration, Vitamin B12, Vitamin B6, Vitamins

Written by Marcia J.Egles MD.  Women treated with B-vitamins had a 34% lower risk of macular degeneration. Smoking doubled this risk.

The leading cause of severe, permanent loss of vision in older Americans is age-related macular degeneration (AMD). The macula is the specialized, central part of the retina of the eye.  It allows a person to see fine detail in the center of the field of vision (1).  New research from a study at Harvard Medical School finds that treatment with vitamins B6 (pyridoxine), vitamin B12 (cyanocobalamine), and folic acid (also known as folate or B9), used in combination, reduced the risk of AMD in women.

Cigarette smoking has been established to be a risk factor for the development of AMD.  Smokers take on over twice the risk of AMD as compared to non-smokers (2,3).  Past studies have found that anti-oxidants such as vitamins C and E, beta caroteneand zinc may slow the progression of AMD (4). This recent study is the first to show a means , other than by not smoking, of preventing the development of AMD.

High levels of an amino acid known as homocysteine have been found in previous studies to be associated with higher risks of AMD (5). Treatment with folic acid, and vitamins B6 and B12, has been shown effective in reducing homocysteine levels(6).

The study is part of the Women’s Antioxidant and Folic Acid Cardiovascular Study which started in 1998 and finished in 2005. This clinical trial involved 5,442 women aged 40 and older who either already had heart disease or who had three or more risk factors for heart disease. At the beginning of the study 5,205 did not have AMD.  The women who did not have known AMD were randomly assigned, in equal numbers, to either a placebo group or a treatment group. The treatment group received a daily oral dose in one combined pill of 2.5 milligrams of folic acid, 50 milligrams of pyridoxine and 1 milligram of cyanocobalamin.

The occurrence of AMD, as well as the numbers of dosages taken, was reported back to the researchers by means of an annual questionnaire. Cases of AMD were reviewed. Approximately 84% of the women in both the treatment and placebo groups reported taking at least two-thirds of their pills.

During an average of 7.3 years of treatment and follow-up, a total of 137 cases of AMD were documented. In the treatment group, 55 cases of AMD occurred. In the placebo group, 82 cases of AMD occurred. For the women treated with the B- vitamins, this is a 34% lower (p= .02) risk of AMD. For the most severe AMD, there were 26 cases in the treatment group and 44 in the placebo group. The risk of more severe AMD was 41% lower (p=.03) in the treatment group.

The findings of this clinical trial, that daily supplementation of folic acid, pyridoxine, and cyanocobalamin, reduced the risk of age-related macular degeneration in women at high risk for cardiac disease, could be quite important. The results need to be verified by further studies.

Source: Christen, William G., et al. “Folic acid, pyridoxine, and cyanocobalamin combination treatment and age-related macular degeneration in women: the Women’s Antioxidant and Folic Acid Cardiovascular Study.” Archives of internal medicine 169.4 (2009): 335-341.

©2009 American Medical Association. All rights reserved.

Posted March 16, 2009.

References:

  1. National Eye Institute
  2. Christen WG, Glynn RJ, Manson JE, Ajani UA, Buring JE. A prospective study of cigarette smoking and risk of age-related macular degeneration in men. JAMA. 1996;276(14):1147-1151.
  3. Seddon JM, Willett WC, Speizer FE, Hankinson SE. A prospective study of cigarette smoking and age-related macular degeneration in women. JAMA. 1996;276(14):1141-1146.
  4. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report No. 8. Arch Ophthalmol. 2001;119(10):1417-1436.
  5. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report No. 8. Arch Ophthalmol. 2001;119(10):1417-1436.
  6. Homocysteine Lowering Trialists’ Collaboration. Dose-dependent effects of folic acid on blood concentrations of homocysteine: a meta-analysis of the randomized trials. Am J Clin Nutr. 2005;82(4):806-812.