(dailyRx News) Gradual vision loss as a result of macular degeneration is primarily determined by genetics. Lifestyle and diet changes may slow the progression of the chronic eye disease or reduce the severity, according to a new study of identical twins.
Tufts Medical Center researchers studied identical twins from the U.S. World War II Twin Registry and found that eating a diet high in vitamin D and avoiding smoking might reduce the risk of developing the chronic eye disease that causes vision loss in the center of the eye.
Macular degeneration occurs when cells in the macula, the part of the eye responsible for clear central vision, slowly die. It is one of the leading causes of vision loss in older Americans.
The study was published in the journal Ophthalmology, and is the first to look at identical twins in which one had early age-related macular degeneration, and the other had late-stage, age-related macular degeneration.
Lead researcher Johanna M. Seddon, M.D., director of the Epidemiology and Genetics Service at Tufts Medical Center and professor of ophthalmology at Tufts University School of Medicine, said the goal was to look at why each twin had different stages of the disease if they carried the same genes.
She noted that eating a healthy diet full of fruits and vegetables and avoiding smoking can make a difference for those with a genetic susceptibility to the chronic eye disease.
Each twin completed a questionnaire about their diet and it was found that twins whose macular degeneration was at the early stages tended to consume more vitamin D from dietary sources, such as fish or milk, than their sibling.
Vitamin D may cut the risk of disease because it has anti-inflammatory properties, and because it may block the formation of new blood vessels that can grow under the macula, leaking blood and causing vision loss in the more severe stages of the disease.
It was also discovered that higher intakes of betaine and methionine were linked to a slower progression of the condition. Betaine is found in fish, grains and spinach, while methionine is found in poultry, fish and dairy foods. Twins who were heavier smokers also tended to have more severe cases of the disease.
The study evaluated pairs of elderly male twins and used a survey of personal dietary and health habits to determine variations.