Summary

A review of research suggests that omega-3 fatty acid consumption can help reduce the risk of age-related macular degeneration (AMD). Eating fish twice a week was linked to an overall lowered risk, and those with a high dietary intake of omega-3s had a 38 percent reduced risk of advanced AMD.

Introduction

Age-related macular degeneration is the leading cause of vision loss among older people. The condition involves loss of cells from the retina, affecting the central field of vision. There are some new treatments for AMD around, but these are for people with the so-called 'wet' form of AMD. Primary prevention, through diet or giving up smoking, is therefore important to avoid the disability and loss of quality of life associated with AMD. Elaine Wong of the University of Melbourne, Australia, and colleagues have reviewed the potential role of omega-3 fatty acids, found in fish and fish oils, in the prevention of AMD.

What was done

The researchers carried out a systematic review of studies carried out before May 2007 to evaluate fish consumption and overall omega-3 fatty acid intake and the prevention of AMD. They focused upon nine studies in total, involving nearly 89,000 participants, of whom 3,203 had AMD. These included prospective studies, such as the Nurses' Health Study and the Blue Mountain Eye Study, Australia. In a prospective study, researchers look forward, following a population with respect to some factor (here, omega-3 or fish consumption) to see what influence it has on their future health. Some of the studies were case control studies, where those with and without AMD were compared for their omega-3 or fish consumption.

What was found

The highest intakes of omega-3 fatty acids were linked to a 38 percent reduction in the risk of late AMD, which is the advanced form of the disease. Fish consumption at least twice a week was associated with a 24 percent reduction on the risk of early AMD and a 33 percent reduced risk of late AMD.

What this study means

Long chain omega-3 fatty acids, and DHA (docosahexaenoic acid) in particular, form an integral part of the retina. They also reduce oxidative stress and inflammation, both of which may be potent factors in AMD. A diet high in omega-3s and fish may, therefore, keep the retina healthy and ward off AMD. However, the researchers feel there is not quite enough evidence in their review to justify the recommendation of omega-3s or fish to prevent AMD. More research, in the form of randomized clinical trials, is needed to clarify the role of these nutrients in eye health. However, fish has other health benefits - such as improving the health of the heart - so should be eaten once or twice a week anyway. Any help in reducing AMD risk as well would be an added bonus. Tuna, sardines, salmon and trout are especially good sources of omega-3s. This study did not focus on fish oil supplements or supplement sources of omega-3 but they too many turn out to be a useful aid.