麻豆传媒

CHICAGO -- Certain dietary components, some of which are found in the Mediterranean diet, are associated with a lower incidence of age-related macular degeneration (AMD).

In an extension of the Joãão Figueїra, MD, from the University of Coimbra, Portugal, and colleagues discovered through dietary survey and software analysis of nutritional composition that adherence to a diet high in fruit, dietary fiber, beta carotene, vitamin C and vitamin E, as well as caffeine, afforded protection against AMD.

The protective effect of caffeine has not been found previously, said Figueїra, who reported the findings at the 2016 meeting of the

Supplementation with high doses of minerals and antioxidants compared with placebo is well-established as being protective against progression of early AMD to advanced AMD. "One problem with supplementation is the patients' low adhesion to this treatment," he said. Also, in Europe, available formulations of supplements do not always follow the protective dosages established in landmark studies.

Dietary nutrients are a possible modifiable risk factor for AMD. "I'm not saying that we can substitute for the supplementation but we should look at it very rigorously," Figueїra added. The Mediterranean diet has been proposed as the prototype of a healthy diet, showing value in multiple non-ophthalmological diseases.

He and co-investigators wanted to find out the effect of high adherence to a Mediterranean diet on development of AMD. They also looked at the potential protective effect of dietary patterns by food groups and the impact of dietary micronutrient consumption.

To accomplish this, they studied 833 subjects older than 55 years who lived in Lousã, Portugal, and who participated in the Coimbra Eye Study, a cross-sectional, observational study of 833 subjects. Of the 833 participants, 449 (50.8%) had early AMD and 434 (49.2%) did not have AMD.

All study subjects answered food frequency questionnaires organized individually by food groups. They were scored on a 0-to-9 scale for adherence to a Mediterranean diet in the previous year, earning 1 point each for consumption above the sex-specific median of vegetables, legumes, fruits, cereals, fish and monounsaturated fatty acids relative to saturated fatty acids.

They also earned 1 point each for consumption of meat and dairy products below the sex-specific median and for consumption of 10 to 50 g/day of alcohol for men and 5 to 25 g/day for women. High adherence was defined as a total score of 6 to 9. This model of adherence to the Mediterranean has been validated for a Greek population, and is already used to measure the effect of adherence to the diet on non-ophthalmological diseases, Figueїra noted. The investigators used specialized software that converted ingested food into micronutrient composition.

The mean age in the AMD and no AMD groups was approximately 69 years. Body mass index was slightly greater than 28 in each group. About one fourth of the subjects in each group were current or former smokers. More people in the group without AMD reported engaging in daily physical activity than in the AMD group (32.3% versus 24.7%, HR 0.69, P=0.012).

Sixty percent of the group without AMD had a Mediterranean diet score ≥6 compared with <40% in the AMD group. High adherence to the diet seemed to be associated with a lower frequency of AMD compared with medium or low adherence (frequency rates 39.3% versus 50.2%), which just missed statistical significance (P=0.057).

When adherence to the aforementioned food groups were examined, high consumption of fruit was more common in the no-AMD group compared with the AMD group (54.5% veruss 45.5%, P=0.029).

On micronutrient analysis, high consumption of caffeine was found in the group without AMD relative to the AMD group (54.5% versus 45.1%, P=0.029). As well, high consumption of fiber (P=0.023), beta carotene (P=0.009), vitamin C (P=0.037), vitamin E (P=0.019) and the total of vitamin C plus vitamin E (P=0.009) was more frequent in the no AMD group. No significant differences were found between groups in the consumption of monounsaturated fats, omega-3 fatty acids, omega-6 fatty acids, zinc, or alcohol.