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Diet and Macular Degeneration: Some Good News on Delaying the Onset of Disease

  • Science News
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A variety of fruits and vegetables displayed on forks.

Funded in part by BrightFocus’ Macular Degeneration Research program, Allen Taylor, MD, and his colleagues at Tufts University are studying how dietary patterns can affect the eyes and one’s risk of macular degeneration. 

Their findings so far show that the more one consumes what Taylor calls a “prudent diet” (also called the Mediterranean diet), with lots of fresh fruits, vegetables, and fish, the less chance one has of getting macular degeneration—either the advanced or the early form. The more one eats an unhealthy diet of high sugars and fats (the so-called Western diet), the greater the chance of advanced macular degeneration.

“We don’t have a lot of data, but the data that we do have around does support the idea that consuming diets rich in fruits, vegetables, and fish, and less rich in sweets and high fats, is better for your eyes,” says Taylor, who is a professor of nutrition, development, molecular and chemical biology, and ophthalmology at the Tufts School of Medicine.

Taylor spoke about the potential effects of diet at a recent BrightFocus Chat teleforum.  “If we can delay the progress of macular degeneration from very early stages to middle or late stages, where it compromises vision, we virtually have developed a cure without any drugs.”

Put another way, “to the extent that you can arrest or delay the progress of the early disease, you preserve vision for that many more years,” he says.

Studying the Glycemic Index

One area of study involves dietary glycemia, which refers to the amount of sugar your body processes when you consume a food item containing carbohydrates.  People who consume diets that deliver sugar rapidly to the bloodstream, called a high glycemic index diet, have a greater risk for macular degeneration at all stages, when compared to people who consumer lower glycemic index diets.

Taylor notes that drastic changes to one’s diet are not necessary to reduce a high glycemic index diet. He gives one startling example.

“If people could just change their diet from five slices of white bread to whole grain bread, you could save 100,000 people from macular degeneration over several years.  That is profound.”

Americans could certainly use a reduction of sugar in the average diet. By some estimates, the average American drinks 50 gallons of soda per year.  “In my mind, that is absolutely mind-boggling,” says Taylor.  He also notes that an estimated 50% of all packaged foods at supermarkets may be sweetened.

“We are not asking people to not eat bread, or not eat pasta, or not eat potatoes or corn, but rather to replace a little bit of that with something that is more whole grain or something that liberates the sugar more slowly.”

In mice studies the situation is very clear.  Mice fed a low glycemic index diet did not get damage to the retina. In addition, if mice are switched from a high glycemic index to a low one, “we seem to arrest the damage at very early stages.” If that same information plays out in human studies, Taylor thinks “we can delay the onset of age-related macular degeneration.”

People who consume lower glycemic diets are also protected against cardiovascular disease and getting type 2 diabetes.  Says Taylor, “It isn’t just protecting your eye; you’re really protecting your whole body.

In fact, Taylor and colleagues have recently found that the diet also affects the microbiota, which  are the bacteria in one’s gut.  It turns out that the gut makes some compounds that are absorbed into the bloodstream.  Those compounds may affect the vitality and function of one’s eyes, adds Taylor. 

The Hurdles – and Promise – of Human Studies

Taylor acknowledges that more human studies are needed to confirm the relationship of diet and gut bacteria to eye health.  Clinical studies are expensive, and scientists sometimes have difficulty recruiting people for participation.  But for persons wanting to participate, Taylor offers this information on getting started:

  • Inquire through your academic ophthalmology departments, or your own academic ophthalmologist, if there are any eye studies recruiting participants.
  • You might be asked to fill out a health questionnaire to tell study officials about your health. They will ask you for permission to contact your doctor to validate information.
  • You may need to come in for an ophthalmological exam, and to give a blood sample.
  • Officials might ask questions about glaucoma pressure in the eye, or your dietary history.

When it comes to participation in clinical studies, “the earlier in your life you can get started, the better,” says Taylor.  “What we want to do is delay the onset of disease.”

From Optimism to Optimal Aging

Taylor is optimistic about future progress on vision disease, due in large part to the research done over the last 50 years, “whether it is research to enhance surgical techniques, how to modify the biochemistry within the eye, or even simple things with nutrition that can have the most profound effects in terms of delaying diseases. 

“I think we can look forward to what I call “optimal aging”—that is, to live longer and healthier, with the goal of getting through the older years without as many debilitating disabilities as our parents had.”