USA Today (2/24, Marcus) reports that, according to a study published Feb. 23 in the Archives of Internal Medicine, “taking B vitamins could lower the risk for” age-related macular degeneration (AMD), “a leading cause of blindness in older Americans.” For the study, William Christen, Sc.D., of Brigham and Women’s Hospital, and colleagues “collected data from a cardiovascular disease trial involving more than 5,200 women over 40 who reported they did not have” AMD at the start of the study. The “women had been randomly assigned to take either a daily combination of folic acid, B-6, and B-12 supplements, or a placebo.” Over seven years, “55 cases of” AMD “were confirmed in the vitamin group,” compared to 82 cases “confirmed in the placebo group.” In other words, women “who took the supplements had a 41 percent lower risk of being diagnosed with” AMD.
AMD “is the leading cause of blindness in people 65 and older, with nearly two million Americans in the advanced stage of the condition,” the Wall Street Journal/AP (2/24, D3, Johnson) points out. AMD “causes a layer of the eye to deteriorate, blurring the center of the field of vision and making it difficult to recognize faces, read, and drive. There’s no cure, but treatment…can slow it down.” Despite the study’s finding, however, Christen explained that there “were too few cases of the most advanced AMD to make claims about vitamins’ potential benefits.” He emphasized that “it’s too soon to recommend B vitamins to people who want to prevent age-related vision loss.” Instead, he “recommended food sources of B vitamins and folic acid, such as meat, poultry, fortified cereals, beans, nuts, leafy vegetables, spinach, and peas.”
Bloomberg News (2/24, Ostrow) explains that AMD “is caused by damage to the arteries that carry blood to the retina. Folic acid and vitamins B6 and B12 may lower the risk for the disease, Christen said, because they reduce blood levels of homocysteine, an amino acid that contributes to plaque buildup in the arteries.” Study participants “who received the supplements had about an 18 percent lower level of homocysteine than those given the placebo, Christen said.”
The UK’s Telegraph (2/24, Smith) quotes Christen as saying, “From a public health perspective, this [finding] is particularly important, because persons with early AMD are at increased risk of developing advanced AMD, the leading cause of severe, irreversible vision loss.” Currently, “the only way to reduce the risk of AMD…is not to smoke.” The study authors theorized that “supplements reduce levels of…homocysteine which can damage the lining of blood vessels and make blood more likely to clot.” In addition, “the vitamins may also have an antioxidant effect to improve the blood vessel functioning in the eye.”
Writing in the Boston Globe (2/23) White Coat Notes blog, Elizabeth Cooney observed, “The study’s results stand in contrast to other findings from [a] cardiovascular study, which was designed to test whether the folic acid-vitamin B6 and B12 combination could prevent heart attacks or stroke in women who had a history of cardiovascular events or risk factors.” The study “showed no benefit for women taking folic acid and vitamins B6 and B12 in reducing their risk for cardiovascular events.”
MedPage Today (2/23, Smith) noted that the study authors “concluded that their findings could be due to chance and need confirmation, but ‘it may be worthwhile to consider whether the discordant findings for AMD and” cardiovascular disease “reflect important differences between the choroidal and systemic vasculature with respect to responsiveness to the lowering of homocysteine levels.”
CBC News (2/24), Canada’s CTV (2/23), and WebMD (2/23, Warner) also covered the story. HealthDay (2/23, Edelson) also mentioned the study.