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Mediterranean Diet May Reduce Risk of AMD

People who closely follow the Mediterranean diet—especially by eating fruit—may be more than one-third less likely to develop age-related macular degeneration (AMD), a leading cause of blindness, according to a study presented at AAO 2016, the 120th annual meeting of the American Academy of Ophthalmology. The study also is the first to identify that caffeine may be especially protective against AMD.

Many studies have confirmed the health benefits of the Mediterranean diet, which emphasizes eating fruits, vegetables, whole grains, legumes, nuts, healthful fats, and fish, and limiting red meat and butter. The diet has been shown to improve heart health and reduce risk of cancer, but there's been little research on whether its benefits can extend to eye disease. To determine this, researchers studied a Portuguese population to see whether adherence to the diet impacted people's risk of AMD. Their findings revealed a significant reduction in risk in those who ate a Mediterranean diet most frequently, and particularly among those who consumed more fruit and caffeine.

Researchers at the University of Coimbra in Portugal studied 883 people age 55 or older in the central region of the country between 2013 and 2015. Of those, 449 had AMD in its early stages before vision loss, and 434 didn't have AMD. Researchers assessed their diets based on a questionnaire asking how often they ate foods associated with the Mediterranean diet. The more they ate foods associated with the diet, the higher the score, from 0 to 9. Those who closely followed the diet scored a 6 or greater.

Higher diet adherence scores meant lower AMD risk. Of those who didn't closely follow the diet (scored below a 6), 50% had AMD. Of those who did closely follow the diet (scored 6 or above), only 39% had AMD. This represents a 35% lower risk compared with those who didn't adhere to the diet.

Fruits were especially beneficial. Researchers analyzed consumption of foods and found that people who consumed higher levels of fruit were significantly less likely to have AMD. Of those who consumed 150 g (about 5 oz) or more of fruit a day, 54.5% didn't have AMD, and 45.5% had AMD. Overall, people who ate that much fruit or more each day were almost 15% less likely to have AMD, based on an odds ratio calculation.

Caffeine and antioxidants also were protective. Researchers used a computer program to analyze the participants' consumption of micronutrients according to their answers on the questionnaire. They found higher consumption of antioxidants such as caffeine, beta-carotene, and vitamins C and E was protective against AMD. Of those who consumed high levels of caffeine (about 78 mg a day, or the equivalent of one shot of espresso), 54.4% didn't have AMD, and 45.1% had AMD.

While caffeine isn't considered part of the Mediterranean diet per se, consumption of caffeine-containing foods such as coffee and tea is common in Mediterranean countries. The researchers opted to look at caffeine because it's a powerful antioxidant that's known to be protective against other conditions, such as Alzheimer's disease.

"This research adds to the evidence that a healthy, fruit-rich diet is important to health, including helping to protect against macular degeneration," says Rufino Silva, MD, PhD, lead author of the study and a professor of ophthalmology at the University of Coimbra in Portugal, ophthalmologist at the Centro Hospitalar e Universitário de Coimbra, and investigator at the Association for Innovation and Biomedical Research on Light and Image. "We also think this work is a stepping stone towards effective preventive medicine in AMD."

— Source: American Academy of Ophthalmology

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