The link between diet and vision loss among older people is the focus of the Age Related Eye Disease Study, or AREDS, sponsored by the National Eye Institute, where John Paul SanGiovani is a staff scientist.

SanGiovani says the first stage of the study, called AREDS I, showed that a combination of high doses of vitamins C, E, beta-carotene and zinc significantly reduced the risk of advanced macular degeneration or AMD, the leading cause of blindness in the United States. "It was about a 25 percent reduction in the risk of progressing to this sight-threatening form of AMD."

AREDS I followed 4,500 people over a 12-year period ending in 1998. A total of 1,115 participants did not have any symptoms of AMD at the beginning of the study and were compared with those who did, including 650 who had severe AMD.

All participants reported what they ate everyday. SanGiovani says AMD risk may be lowered with a diet high in fatty fish like salmon and tuna. But he is not sure whether this is related to lifestyle among people who eat fish or simply the diet. "From what I understand about the science there is a good reason to believe that the nutrients contained in fish may act in a protective role."

AREDS II is now underway. The 5-year clinical trial will test the nutrient-vision link among 4,000 participants at 80 medical centers across the United States. SanGiovani hopes that as more is known about the dietary link to AMD, the risk can be reduced and progression slowed for the millions of people diagnosed with the disease. The research is reported in the May issue of the Archives of Ophthalmology.