By Margarita Nahapetyan
Women who take vitamin B and folic acid supplements are less likely to develop common type of vision loss, called age-related macular degeneration (AMD), a new study reports.
"This is the first randomized trial to indicate a possible benefit of folic acid, B-6 and B-12 vitamin supplements in reducing the risks of age-related macular degeneration," said William Christen, an associate professor of medicine at Brigham and Women's Hospital in Boston, and a lead author of the study.
Age-related macular degeneration is a progressive disease which leads to a permanent damage of the retina inside the eye, making it difficult to read, drive and perform everyday chores. The condition is a leading cause of vision loss in people older than 60 years of age, the majority of them being women. Certain factors such as obesity, smoking and a family history of the irreversible condition are contributing into the risk of developing AMD. Treatment options exist for patients with severe cases of the disease, but the only known prevention method is not to smoke.
For their study, Christen and his colleagues collected data from a cardiovascular disease trial involving more than 5,000 middle-aged women who did not have macular degeneration at the beginning of the study.
The women then had been randomly assigned to receive either a daily placebo or a daily combination of 2.5 mg of folic acid, 50 mg of vitamin B-6, and 1 mg of vitamin B-12. The participants were also asked to answer annual questionnaires for nearly 7 years, about their adherence to the pill regimen and the development of any new diseases.
At the end of the study, seven years later, 137 women were found to develop age-related macular degeneration - 55 such cases were confirmed in the group who took the folic acid, vitamin B-6, and vitamin B-12 combination compared to 82 cases in the placebo group. Examining only those whose macular degeneration had progressed to a very poor vision, the researchers found that 26 women were in the vitamin group compared with 44 in the placebo group.
The researchers speculated that folic acid and vitamins B-6 and B-12 may help reduce the risk for the disease by lowering levels of homocysteine, an amino acid that can damage the lining of blood vessels by building up a plaque in the arteries. "It is fairly well-established that folic acid, B-6 and B-12 can reduce blood levels of homocysteine, so there is a reason to suspect a possible benefit," said Christen.
It is also believed that the small blood vessels in the eyes respond better to the effects of B vitamins on homocysteine than larger vessels located in other parts of the body, according to the researchers. The vitamins could also work through the effects of antioxidants.
Christen said that it is yet too soon to recommend taking B vitamins for the prevention of vision loss in the elderly. He suggested that people who already are battling macular degeneration could talk to their doctors about taking over-the-counter supplements that are known as vision protectors. Such supplements include vitamins C, E and zinc, which research suggests have also been associated with slowing the progression of the disease.
In addition, foods such as meat, poultry, beans, fortified cereals, nuts, green leafy vegetables, spinach and peas are known as proven natural sources of B vitamins and folic acid that have been shown to help slow macular degeneration.
The research, funded by the U.S. National Institutes of Health, was published in the latest issue of Archives of Internal Medicine.