September 2009 Issue

Eating for Eye Health
By Lindsey Getz
Today’s Dietitian
Vol. 11 No. 9 P. 12
You likely give your clients many reasons for eating healthier—weight loss, heart health, preventing or managing chronic illness. But how often do you emphasize the importance of maintaining a healthy diet for eye health? While clients may take the health of their eyes for granted when they are young, if they eat healthy today, they may be able to prevent problems down the road.

“The eye as an organ depends on all of the other systems in the body,” says Robert Abel, Jr, MD, a former clinical professor of ophthalmology at Thomas Jefferson University in Philadelphia; the founder of the Eye Advisory, Inc; and the author of The Eye Care Revolution: Prevent and Reverse Common Vision Problems. That makes overall good health and nutrition critical for maintaining a set of healthy eyes. “In fact,” continues Abel, “[of all normal tissues], the retina has the highest rate of metabolism in the body, which means you need to resupply it with nutrients on a regular basis.”

“The retina is extremely vulnerable,” adds Cynthia Sass, MPH, MA, RD, CSSD, a Manhattan-based dietitian and author. “Because the tissue has a higher metabolic rate, it consumes more oxygen. Plus, it is exposed to so much light. We know that certain nutrients can help protect the eyes, offsetting the effects of eye stress and even staving off age-related vision loss.”

Clients should be taught to start protecting their eyes as early as possible. Too many people wait until their eyesight deteriorates to start making necessary changes. But adding vital nutrients to the diet in advance can help prevent problems. “Nutrition is a powerful form of preventative medicine, so it’s never too early to start,” says Sass. “An adequate amount of key nutrients can fight the effects of aging and oxidations on every part of the body, including the eyes.”

Erin Dummert, RD, CD, owner of Madam Nutrition in Whitefish Bay, Wis., says a good place for people to start building up their nutrient supply is by simply fulfilling their daily fruit and vegetable requirements. “We already recommend that clients eat five to nine servings of fruits and vegetables per day, but they should know that doing so is linked to better eye health,” she says. “It’s a matter of giving clients yet another reason to be eating well.”

Research shows that leafy greens are particularly beneficial for the eyes, as they are packed with the antioxidant carotenoids lutein and zeaxanthin. A study published in the Archives of Ophthalmology found that a high intake of these two carotenoids reduced the risk of cataracts by 18%. Foods rich in lutein and zeaxanthin include spinach, kale, turnip greens, collards, broccoli, pumpkin, and corn.

Dummert adds that vegetables don’t have to be the only source of lutein. “We all know that leafy green vegetables are high in lutein, but eggs are another good source,” she says. “While they comparatively have a smaller amount [than leafy greens], a new study shows that they are more bioavailable. That means that even though there is a smaller amount of lutein in eggs, it goes directly into the bloodstream.”

Another egg-related study, published in the Journal of Nutrition, found that eating one egg per day can increase levels of both lutein and zeaxanthin in the bloodstream. Researchers found that lutein levels were increased by 26% and zeaxanthin levels by 38% during the weeks that study participants consumed one egg per day. The research team also made note that adding a daily egg to participants’ diets did not increase total, LDL, or HDL cholesterol or triglycerides—an important fact for those who are still wary of eating eggs.

“I think there are still a lot of people out there who are afraid of eating eggs after so many years of talking about them in terms of cholesterol concerns,” says Dummert. “So sharing this research gives them another healthy reason to start eating more eggs.”

Vitamin C has also been shown to help keep eyes healthy by providing protection against the damage that UV light causes. Most of your clients are probably already aware that citrus fruits are packed with vitamin C, but many don’t realize that the vitamin also shows up in red bell peppers, strawberries, raspberries, broccoli, and Brussels sprouts. Vitamin E may also help prevent cataracts and even age-related macular degeneration. Some of the best sources of this vitamin are sunflower oil, peanut butter, wheat germ, and almonds.

In general, maintaining a healthy weight is also important for protecting the eyes from disease, adds Dummert. “Research indicates that obesity and diabetes can both be linked to eye health,” she says.

The American Diabetes Association reports that people with diabetes have a higher risk of blindness than those without the disease. While anyone is at risk for developing cataracts as they age, patients with diabetes are 60% more likely to develop the condition. In addition, people with diabetes are 40% more likely to develop glaucoma. If left untreated, glaucoma can lead to complete and permanent blindness.

More Omega-3s
Many dietitians already suggest a Mediterranean-style diet to their clients for its proven heart-health benefits. But now studies have shown that adults who follow a Mediterranean-style diet high in omega-3 fatty acids also have a much lower risk of developing macular degeneration.

Age-related macular degeneration is the leading cause of blindness among older adults in the developed world. At this time, the only known risk factors are genetic markers, older age, and smoking, making it even more important that people do what they can to protect their eyes while they’re young. “Americans are vastly undernourished in omega-3s,” says Abel. “Omega-3 essentially comes from the sea, and the greatest amount is found in algae. Therefore, fish that eat algae, like free-range fish, are highest in omega-3 and need to be recommended as a core dietary item, not only for eye patients but also for maintaining general health.”

Results from a study performed by researchers at the University of Sydney in Australia showed that people who ate one serving of fish per week had a 31% lower risk of early signs of age-related macular degeneration. In addition, those who ate one to two servings of nuts rich in omega-3 fatty acids had a 35% lower risk of developing the disease. Researchers believe that omega-3 fatty acids may have a protective effect on the eyes by preventing the buildup of plaque in the arteries or reducing inflammation in the retina.

“It’s important to recommend that clients are eating fatty fish at least twice a week,” says Dummert. “Again, this is a recommendation that dietitians are already making, but when you’re able to link it to something as scary as macular degeneration, clients are more likely to realize the importance of making changes to their diet. These are very simple recommendations, but they can help prevent some very serious diseases.”

A second study, performed by researchers at the Centre for Eye Research Australia, found that people who ate higher levels of trans fats were more likely to develop late-stage age-related macular degeneration. Conversely, the study also found that those who ate the most omega-3 fatty acids were less likely to have the disease. While researchers already knew that trans fats can increase the risk of heart disease by increasing cholesterol levels, they now believe these fats may also have a similar effect on the eye’s blood vessels. It’s yet another good reason to encourage your clients to cut trans fats from their diet.

The Eyes Have It
Since vision is such a crucial part of a person’s well-being, Abel says it is wise for dietitians to encourage their clients to have periodic eye examinations. He also says that dietitians may want to educate their clients on other ways to protect their eye health, besides healthy eating. “In addition to diet, two other major factors in vision are sunlight and stress in general,” says Abel. “Appropriate UV-blocking sunwear is worth a lifetime of vision. And developing stress-reducing techniques is important, too, as it reduces the epinephrine and cortisol release that creates greater nutritional demands.”

But in your role as a dietitian, the main thing you can do is educate your clients about all of the benefits of maintaining a healthy diet. Sass says the best way to get clients to eat more of these eye-healthy foods is to make sure they understand the direct effects they can have on protecting vision. “It’s important to explain the relationship,” she says. “Today more than ever, consumers are looking for natural approaches to wellness and disease prevention. Dietitians are in a unique position. Because we have the knowledge of both food and the human body, plus the skills to explain science-based concepts in terms consumers can understand, we are able to empower our clients.”

Encouraging your clients to eat nutritiously for good eye health will likely not have any effect on the recommendations you’re already making. The difference is that giving them information on how healthy eating can help protect their eyes is just more motivation for your clients to stick to a prescribed plan. “The bottom line,” says Abel, “is that those items that are good for the body are also good for the eyes. Filtered water, nuts, fruits, vegetables, whole grains, and other sources of fiber are all important for overall good health.”

— Lindsey Getz is a freelance writer based in Royersford, Pa.