There has been much interest in the role of nutrition in eye health, and hundreds of observational studies have linked various aspects of diet to various eye outcomes—but such studies can only suggest associations, not establish causality. Most also rely on individuals' recall of what they've eaten, which can be faulty. The bottom line of almost all such studies is that people concerned about eye health should eat the same sort of foods shown to be healthy for the heart.
For practical reasons, most clinical trials studying nutrition and eye health use supplements. So far, however, there's no evidence any dietary supplement will protect vision, with the exception of the AREDS formula for those with intermediate age–related macular degeneration (AMD).
Vitamins and vision
Still, it is clear that malnutrition can harm vision. A significant deficiency of vitamin A, for example, causes night blindness and other problems. Thus, carrots really are good for your eyes if you're not getting enough vitamin A, since they're rich in beta carotene, which the body converts into vitamin A.
Other nutrients and plant compounds may help protect vision, perhaps by acting as antioxidants and reducing inflammation. These include two other carotenoids, lutein and zeaxanthin, which are antioxidant pigments found in many vegetables and fruits. Lutein and zeaxanthin are also found in the retina of the healthy eye, where they act as a filter against ultraviolet radiation and other harmful components of sunlight—sort of like built-in sunglasses. Most (but not all) observational studies have found that people with high dietary intakes or high blood levels of these carotenoids have a reduced risk of AMD and cataracts. More research is needed, however.
Similarly, some studies have found that people who consume plant foods rich in other antioxidants, such as vitamins C and E and selenium, are at reduced risk for cataracts and AMD. For instance, a 2011 British study in the American Journal of Clinical Nutrition found that older vegetarians are 30 to 40 percent less likely to develop cataracts, compared to high meat eaters (more than 3.5 ounces of meat a day).
Zinc is found in the retina, and it may protect eye tissue from the damaging effects of light and inflammation. Unless you have AMD, get zinc from food; supplemental zinc has never been found to be beneficial to healthy eyes, and high doses can have adverse effects. Meat, seafood (especially oysters), and liver are the richest sources. Brewer's yeast, milk and other dairy products, beans, wheat germ, and whole grains also supply some zinc.
Focus on the pattern
Some research, including data from the well-known Women's Health Initiative, suggests that a heart-healthy diet (as opposed to individual nutrients in supplement form) can protect against eye disorders.
Colorful fruits and vegetables may benefit your eyes. In particular, leafy greens such as kale and spinach are rich in carotenoids and may protect against AMD and cataracts. Blueberries, blackberries, beets, broccoli, and carrots are also excellent choices. Colorful foods-deep green, orange, yellow, purple, red, blue-contain the most carotenoids and other healthy pigments, as well as other nutrients.
As part of a healthy dietary pattern, the unsaturated fats in fish and nuts may also benefit the retina.
Eat like a Mediterranean
If you're familiar with the Mediterranean diet, which studies have associated with cardiovascular benefits, the preceding nutrition advice may sound familiar. The Mediterranean diet abounds in fruits, vegetables, whole grains, nuts, legumes, and fish, with only modest amounts of red and processed meats. In addition to boosting heart health, findings published in 2015 in the American Journal of Clinical Nutrition offer encouraging evidence that following a Mediterranean eating plan may also have eye benefits.
Researchers analyzed the dietary patterns of 2,525 participants in the original AREDS study, who already had intermediate AMD. Those who most closely adhered to a Mediterranean-style diet were about 25 percent less likely to progress to advanced AMD over a 13-year period compared to those who veered farthest from this eating pattern.
Fish and Your Eyes
In addition to having heart benefits, fish may be good for your eyes. Here are some study findings.
Also see Should You Take Vision Supplements?
Published February 22, 2018