Put Down Those Chips -- While You Can Still See Them

Aug. 14, 2001 -- Your favorite snack foods -- French fries, chocolate, potato chips, cookies -- are taking another hit.

Doctors have long known that some fats in processed foods can cause heart disease. But now a new study warns that fat in your diet can also lead to age-related macular degeneration, the leading cause of blindness in people age 65 and over.

"This is a significant finding," says study Johanna M. Seddon, MD, associate professor of ophthalmology at Harvard Medical School and Massachusetts Eye and Ear Infirmary in Boston. "[Fats in such snacks] caused a twofold increased risk of age-related macular degeneration."

Just as dietary fat can accumulate in blood vessels and lead to heart disease, it can also clog up the vessels going to the eyes, leading to loss of vision. It's a serious situation, as there is no proven treatment for early and moderate forms of macular degeneration, and therapies for the advanced stages are limited, says Seddon, whose study appears in this month's issue of Archives of Ophthalmology.

Seddon's multisite study -- the largest thus far to look at the connection between dietary fat and this eye disease -- involved more than 300 patients at five of the country's biggest ophthalmology centers. All were between ages 55 and 80, and all had advanced macular degeneration.

Each person was sent a checklist of foods, both healthy and high-fat foods, and was asked to indicate how often he or she consumed each food or beverage during the past year. Among items on the list were margarine, chocolate, commercially prepared pie, cake, cookies, peanut butter, potato chips, French fries, and nuts.

"We found that not all fat is bad, and that some types of fats are, in fact, good for you," Seddon says.

People who ate more processed foods of any type on a daily basis -- foods high in vegetable, monounsaturated, and polyunsaturated fats -- were at higher risk for the eye disease, she says. Those foods that were highest in a type of fat called linoleic acid -- found primarily in snack foods like potato chips -- seemed to put people at even higher risk.

However, people who ate fish high in omega-3 fatty acids -- like salmon, halibut, swordfish, and tuna -- were less likely to have the eye disease, says Seddon, but only if they also ate very little linoleic acid-containing snack food.

Saturated fats from animal meat did not seem to increase risk of macular degeneration, she says.

Seddon's previous studies on macular degeneration "have shown that it does run in families," suggesting a genetic component. "But part of it could be environmental as well," she says. "People in families share common eating habits."

Bottom line, she says: "Eat fish, not fat. Eat fish two or more times a week."

And start doing it now, rather than later, says Thomas Aaberg Sr., MD, director of the Emory Eye Center in Atlanta.

Macular degeneration is a 30- to 40-year process, and any dietary and lifestyle changes have to be made at an early age, says Aaberg. "People need to be eating leafy vegetables like spinach," he says. "If you're eating a lot of junk food, it's probably hurting you in many ways that [you] won't see effects of for many years."

And if you have a family history of macular degeneration, he adds, get checked early for the disease, especially if you have other known risk factors such as smoking. "The biggest risk factor of all is smoking," he says.