Vitamin B and Folic Acid May Lower Risk of AMD

B & Folic Acid | B6, B12 & Folic Acid | Homocysteine

Vitamin B & Folic Acid

A team of Harvard researchers found that women who took a combination of folic acid and vitamins B6 and B12 had a 35% to 40% lower risk of developing age related macular degeneration (AMD) than women who took a placebo.

A group of 5442 female health care professionals 40 years or older (of whom 5205 did not have a diagnosis of AMD at the beginning of the study) received either a combination of folic acid/B6/B12 or a placebo.

After more than seven years of treatment and follow-up, 137 women were diagnosed with AMD.  Of these 137:

  • 55 had been taking the supplements; 82 had been taking the placebo.
  • 70 had ‘visually significant AMD’, including 26 who had been taking the supplements and 44 who had been taking the placebo.

Researchers concluded that daily supplementation with folic acid, pyridoxine (vitamin B6), and cyanocobalamin (vitamin B12) may reduce the risk of AMD.

Published:  “Folic Acid, Pyridoxine, and Cyanocobalamin Combination Treatment and Age-Related Macular Degeneration in Women”, Christen et al, Arch Intern Med. 2009;169(4):335-341.

Folic Acid, Vitamins B6 & B12

Researchers reviewed data from the “Women’s Antioxidant and Folic Acid Cardiovascular Study,” looking specifically at vision information. They found that supplementation with a combindation of folic acid, vitamin B6 and vitamin B12 lowered the risk of age related macular degeneration in women who also have cardiovascular disease.

Scientists have known that these 3 B family vitamins reduce high homocysteine levels, a risk factor for conditions of the vascular system, including advanced macular degeneration.

The study looked at data for over 8,000 age 40 or older female medical professionals  who had been diagnosed with cardiovasular disease or who had a minimum of 3 risk factors for development of macular degeneration.  In a secondary trial they randomly received vitamin C daily, vitamin E every other day, and beta-carotene (every other day) or a placebo.

About 5,400 of these women were part of a later trial in which they received a placebo or a combination of folic acid, vitamins B6 and B12 or a placebo daily.  About 200 of these women had previously been diagnosed with macular degeneration.  Results were both self-reported, confirmed by medical records, and diagnosed as macular degeneration with vision reduced to 20/30 or lower due to the condition.

The researchers determined that 137 macular degeneration cases occurred over approximately 7 years of treatment and followup. There were 55 incidences in the group receiving treatment and 82 occurences in the placebo group.  The results for patients with macular degeneration and 20/30 or worse vision loss, there were 26 incidences in the B vitamins sub-group, and 43 cases in the placebo sub-group.

The researchers determined that women who take supplement B vitamins are 34 percent less likely to experience macular degeneration, and 40 percent less likely to experience vision loss as a result.

The researchers noted that although high doses of  B vitamins were tested, lower doses may well have been effective.  Another study looking at cardivascular disease found that homocysteine decrease if proportional to the dose of folic acid only up to 800 mcg daily while excessive amounts of folic acid have been tied to colorectoral tumors.

Researchers: Brigham and Women’s Hospital and the National Eye Institute

References :
Christen WG, et al. Folic acid plus B-vitamins and age-related macular degeneration in a randomized trial in women. Investigative Ophthalmology & Visual Science 48:E-abstract 1152, ARVO, 2007.
Wald DS, et al. Randomized trial of folic acid supplementation and serum homocysteine levels. Archives of Internal Medicine 161:695-700, 2001.

Homocysteine

Homocysteine, an amino acid believed to contribute to heart attack, stroke and dementia, may also play a role in retinal damage and vision loss.  Homocysteine levels rise when folic acid levels drop, a common problem for Americans whose diets are often poor in folate-rich fruits, tomatoes, vegetables and grains.

Researchers are looking at homocysteine levels upon the retina to find out exactly what happens in this vast and delicate network.  Looking at retina photos, one can see that the structure of the retina is damaged significantly in patients with high levels of homocysteine.

Folic acid and vitamin B12 convert homocysteine to methionine, an amino acid essential to protein synthesis.  People need only about 1 mcg  of vitamin B12 daily.  The source of B12 is microorganisms that are common in the gastrointestinal system of animals. Strict vegetarians are typically the only Americans who have problems with B12 deficiency, he says. People need about 400 micrograms of folic acid daily. Pregnant women as well as those trying to become pregnant need at least double that.

Researchers are investigating several mice models and will control their diets to raise and lower folic acid levels to see what happens to homocysteine and the retina:

  • a model  with slightly raised homocysteine levels that behave like a human diet deficient in folic acid –  this model that also has diabetes, which goes along with cardiovascular disease and diabetic retinopathy;
  • a model of the rare genetic defect that results in extraordinarily high homocysteine levels.

The scientists believe that continual raised homocysteine levels will damage the normal functioning of the retina and degrade the retinal tissue, a situation that is worsened by diabetes.

Researchers: Dr. Sylvia Smith, cell biologist, and Dr. Vadivel Ganapathy, Chair, Department of Biochemistry and Molecular Biology, Medical College of Georgia

Published:  Medical College of Georgia, “Impact of elevated homocysteine levels on vision under study,” Oct. 15, 2007.

B & Folic Acid | B6, B12 & Folic Acid | Homocysteine