Age-related macular degeneration (AMD) is the leading cause of blindness in western countries. This condition, which usually affects older adults, causes damage to the retina resulting in a loss of vision in the center of the visual field (the macula). Macular degeneration makes it difficult (or sometimes impossible) to read, and also to recognize faces, although enough peripheral vision remains to allow other activities of daily life.
Research suggests that diet could play a role in protecting against AMD. For example, when subjects were given supplements of antioxidants and zinc, they were 25% less likely to develop AMD. Since chronic inflammation may raise risk for AMD, there has also been interest in the role of certain dietary factors that might prevent inflammation. The omega-3 fats found in fatty fish have anti-inflammatory properties as well as structural roles in the retina, making them prime candidates for research on AMD. Not surprisingly, several studies have found that fish consumption is protective against ADM. Less information is known, however, about the effects of plant based omega-3 fats—the type found in soyfoods and soy oil—and their effects on risk for ADM
To gain further understanding of this issue, French researchers analyzed data from the Antioxydants Lipides Essentiels Nutrition et Maladies Occulaires (Antioxidants Essential Fats Nutrition and Ocular Diseases) Study. This is an ongoing study of nutrition and age-related eye diseases in 963 older people living in Bordeaux, France. Subjects had a first eye examination between 2006 and 2008 and then were followed for approximately 31 months. The researchers also took blood samples to assess the amount of omega-3 fats in the diets of the subjects.
Over the study period, 64 participants developed AMD in one or both eyes. After adjusting for factors known to affect risk, such as age, gender, smoking, education, and physical activity, the researchers found that higher blood levels of omega-3 fats were associated with more than a one-third reduction in risk. Furthermore, both types of omega-3 fats—the kind found in plant foods like soy as well as those found in fish—were equally protective.
Clinical trials, several of which are currently underway, should give more insight to the possible protective effect of omega-3 fats from soyfoods against AMD. For now, there is reason to think that including soyfoods in your diet, and choosing soy oil for food preparation, may help to protect eyesight. Tofu, soynuts, edamame, and soy oil are all excellent sources of omega-3 fats.
J. Nutr. 143: 505–511, 2013