New Clues to Dietary Defenses Against Vision Loss with Aging
Want to protect your eyes against the leading cause of blindness in older Americans? Eat more fish high in omega-3s. That’s the conclusion of a new study of 38,022 participants in the Women’s Health Study, linking regular consumption of fish and the omega-3 fatty acids found in fish (DHA and EPA) to reduced risk of age-related macular degeneration (AMD).
Over 10 years of follow-up, 235 of the women were diagnosed with AMD. Based on food questionnaires at the start of the study, those eating fish at least once a week were 42% less likely to develop AMD than women eating fish less than once a month. “This lower risk appeared to be due primarily to consumption of canned tuna fish and dark-meat fish,” according to researchers William Christen, ScD, of Harvard University, and colleagues. Consumption of dietary omega-3s was also specifically associated with lower risk, with the highest intake of DHA, for example, linked to a 38% lower likelihood of AMD. Similar results were observed for higher intake of EPA and for higher consumption of both omega-3s together.
Christen and colleagues characterized their results as the “strongest observational evidence to date in support of a possible role for intake of omega-3 long-chain fatty acids and fish in the primary prevention of AMD.”
“This is a finding that seems to be holding up in several studies,” comments Allen Taylor, PhD, director of Tufts’ HNRCA Laboratory for Nutrition and Vision Research. “I think we can safely recommend eating more dark fish (and less of other higher caloric or fatty foods) to promote health.”
Taylor is less enthusiastic, however, about the practical benefits of another new study on AMD—this one linking vitamin D to reduced risk. Amy E. Millen, PhD, of the University at Buffalo, and colleagues analyzed data on 1,313 women from the Carotenoids in Age-Related Eye Disease Study (CAREDS). They found that among women younger than age 75, high blood levels of vitamin D were associated with a significantly lower incidence of AMD. Women who consumed the most vitamin D from food and supplements were 59% less likely to develop AMD than those with the lowest intake; no such link was observed for self-reported sunlight exposure, which causes the body to make vitamin D. The results back up earlier findings using the NHANES national nutrition survey, which also found a strong connection between higher vitamin D and lower AMD risk.
The association between vitamin D and lower AMD risk was reversed for women over age 75, however, who actually saw a borderline significant higher risk with more vitamin D. Says Tufts’ Taylor, “I would not make any recommendation based upon the data, and certainly not for those over 75.”
TO LEARN MORE: Archives of Ophthalmology, online before print, abstract at