Elderly people suffering from the early stages of a leading cause of blindness can worsen the condition by eating the fatty foods often found in processed baked goods, according to a study published on Monday.
Just as fatty foods can clog arteries and heighten the risk of heart disease, a constriction of the blood vessels feeding the eye's retina may cause a progression of the illness, called age-related macular degeneration, the study found.
Macular degeneration is an irreversible and progressive loss of vision that effects up to a quarter of people aged 75 and older in industrialized countries, where it is the leading cause of blindness.
The study surveyed patients with early signs of the illness, and examined whether diet made the problem worse but not whether a fatty diet caused the deterioration of the retina in the first place. Smoking has previously been shown to be a risk factor for macular degeneration.
The illness afflicts roughly eight million Americans with partial vision loss. About 1.3 million of these will degenerate over the next five years to where it will severely impact their quality of life, said the report published in The Archives of Ophthalmology.
In the five-year study of 261 patients with at least some vision loss, the risks that the disease would progress more than doubled among those with diets highest in fatty processed baked foods compared to those with low-fat diets.
"Specifically, higher intake of vegetable fat, and to a lesser extent animal fat, increased rates of progression," wrote study author Johanna Seddon of the Massachusetts Eye and Ear Infirmary in Boston.
Diets rich in meat and dairy also heightened the risk, but not by as much as processed baked foods. Those who plenty of fish and nuts reduced their risk of the disease progressing.