Studies have shown that foods high in omega-3 fatty acids can protect against heart disease and rheumatoid arthritis. Now a new study has concluded that omega-3 also appears to lower the risk of age-related macular degeneration. The American Optometric Association says AMD is the No. 1 cause of severe vision loss in people 50 and older.

Researchers from Harvard Medical School and Brigham and Women's Hospital evaluated data on 38,000 women who had not been diagnosed with AMD when the study began. Over a 10-year period, those who ate at least one serving of fish a week had a 42 percent lower risk of AMD than women who ate fish less than once a month. Researchers said the lower risk "appeared to be due primarily to consumption of canned tuna fish." Other good sources of omega-3 besides tuna are salmon, walnuts, flaxseeds and soybeans.

The study was published in the Archives of Ophthalmology's online edition in March.