The authors wrote:
Adopting these healthy habits may markedly lower the prevalence of early AMD, the number of people who develop advanced AMD in their lifetime, and healthcare costs associated with treatment for this condition.
Participants in the study previously gave researchers a detailed dietary and lifestyle history about six years before AMD was assessed, making them ideal to look at to examine links between behavioral factors and AMD, a leading cause of vision loss among U.S. adults ages 60 and older.
Self-reported diets at baseline were scored according to the content of relatively healthy foods, such as whole grains, vegetables and fruits, and milk, as well as unhealthy foods including saturated fats, sodium, and added sugar.
Responses to questionnaire items on recreational and household physical activity were translated into estimated energy expenditures, expressed as metabolic energy task-hours (MET-hours) per week.
Lowered associations with AMD risk were found to be statistically significant for both diet and exercise. Interestingly, smoking by itself was not a particularly strong risk factor for AMD in this study. Compared with participants who never smoked.
But all three factors combined were a powerful indicator of AMD risk ompared to women who practiced good diet and exercise habits.
The observational study provided no hard evidence for a causal mechanism, but the researchers suggested that healthy lifestyles may keep blood pressure down, which, in turn, could reduce AMD risk.
Behavioral factors can also affect the composition of macular pigment which potentially makes the macula more or less vulnerable to various pathologies such as oxidative damage – which causes AMD.