People who lead overall healthy lives - exercising, eating right, and not smoking - are at significantly lower risk for age-related macular degeneration (AMD), new study findings show.
Exercise and diet each reduced the risk, but both combined, along with a lack of smoking, caused a "particularly profound lowering" of the risk - by more than 70%, study author Dr Julie Mares of the University of Wisconsin in Madison told Reuters Health.
"We don't need to be passive victims of these ravages of old age," Dr Mares said. "Relatively small things could make a difference in whether or not we develop AMD in our lifetime."
Healthy habits work together
Because healthy habits tend to work together in achieving certain health goals, Dr Mares and her colleagues reviewed information about diet, exercise, and smoking from 1,313 women between the ages of 55 and 74, collected during the 1990s. Women were revisited on average six years later, at which point they received an eye exam to check for AMD.
As the research team reported in Archives of Ophthalmology, 202 women had AMD, mostly early-stage.
Among the women who ate the healthiest (based on the modified 2005 Healthy Eating Index), 11% had an early form of AMD, compared to 19% of women with the worst diets, factoring in their intake of fruit, vegetables, whole grains, fat and sugar, among other elements.
About one in 10 women in the highest quintile of exercise developed AMD, versus one in five of those who barely got any exercise. When the researchers combined the influence of diet, exercise and no smoking, the risk of AMD decreased even further, even though smoking alone was not related to AMD.
Since previous research has linked specific dietary elements to AMD, the researchers looked at the associations of specific antioxidants with AMD risk. Women with higher levels of these antioxidants had lower risks of AMD, but not as low as women who ate well overall, Dr Mares noted. "The findings for overall healthy diets are much stronger than for single nutrients," she said.
And when it comes to exercise, even 10 hours per week of light exercise - including housework, gardening, or walking - or 8 hours of moderate exercise per week was associated with a lower risk of AMD, Dr Mares said.
The study doesn't prove that a healthy lifestyle causes the decrease in AMD, but there are many reasons why it might, Dr Mares said. Diet and exercise lower blood pressure, which can protect the eyes from degeneration. Diet and exercise also reduce free radicals and are associated with lower levels of inflammation - effects that could directly protect against AMD or help enhance the accumulation of pigments at the back of the eye, which absorb potentially damaging light.
Equal results in men and women
Even though the study only included women, Dr Mares said she suspects there will be a similar trend in men. "There's no reason I can think of to expect different results in men or women. However, these findings need to be confirmed in separate samples that include men."
"Decades of studies - basic science, retrospective and prospective clinical trials - have all established that AMD is, in part, a nutrition-responsive disease," Dr Stuart Richer of the Captain James Lovell Federal Health Care Facility told Reuters Health in an e-mail.
"Our current approach is to detect AMD at the end of the disease process and then utilise injected designer pharmaceuticals," Dr Richer said. This has helped people with advanced AMD, but there are many more people with earlier forms who have vision problems and also need help, he said. (Reuters Health/ December 2010)