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Vitamin E and Minerals:
Eye Nutrition from Nuts

By Gina White; review and contributions by Gary Heiting, OD

Nuts and seeds are tasty snacks. They also are excellent sources of vitamin E and minerals such as zinc that help keep your eyes healthy and may decrease your risk of cataracts and age-related macular degeneration.

What Is Vitamin E?

Vitamin E is a powerful antioxidant that helps protect membranes of cells throughout the body against damage caused by metabolic by-products called free radicals. Harmful free radicals in the body also can result from exposure to environmental pollutants, including cigarette smoke.

The term "vitamin E" describes not just one substance, but a group of eight compounds called tocopherols and tocotrienols. Alpha-tocopherol is the most active form of vitamin E.

Natural forms of vitamin E are designated with a "d-" prefix (d-alpha-tocopherol, for example); synthetic vitamin E has a "dl-" prefix (dl-alpha-tocopherol). Natural vitamin E (the "d" forms) is more beneficial for your eyes and body than synthetic ("dl") vitamin E.

Eye Benefits of Vitamin E

Some studies suggest that E helps to possibly prevent cataracts, and it might be yet another factor in preventing macular degeneration (AMD).

In the Age-Related Eye Disease Study (AREDS) involving nearly 5,000 people, researchers found a 25 percent lower risk of developing advanced stages of AMD when a nutritional formula including vitamin E was taken. The AREDS supplement included 400 International Units (IU) of vitamin E, as well as high levels of vitamin A (as beta-carotene), vitamin C and zinc.

Almonds and other nuts are excellent sources of natural vitamin E.

Based on AREDS and other nutritional studies, many eye doctors recommend that their patients supplement their diet with a daily multivitamin that contains up to 400 IU of vitamin E in combination with other antioxidants as part of their preventative eye care.

Some studies suggest vitamin E also may play a role in preventing cataracts:

• In a large, long-term study of more than 3,000 adults (ages 43 to 86) in Wisconsin, five-year risk for cataracts was 60 percent lower among people who reported using multivitamins or any supplement containing vitamin E or vitamin C for more than 10 years, compared with nonusers.
• In a 2008 study that evaluated the dietary intake of more than 35,000 female health professionals, women whose diets (including supplements) had the highest levels of lutein and vitamin E had a lower relative risk of cataracts than women whose diets were in the lowest 20 percent for levels of these nutrients.

However, other studies provide conflicting findings and some eye doctors say more research is required before a clear conclusion can be reached.

Vitamin E Foods

How much vitamin E do you need? The U.S. Recommended Daily Allowance (RDA) for adults and children of ages 14 or older is 15 mg per day — the equivalent of 22.5 IU. For women who are breastfeeding, the RDA is 19 mg (28.5 IU). As is true with vitamins A and C, if you smoke, you should plan to consume extra vitamin E.

Sunflower seeds and nuts are among your best sources of vitamin E. Here's a sampling of foods that are high in E:

Vitamin E Side Effects

Because vitamin E is a fat-soluble vitamin, it can accumulate in the body and potentially cause unwanted side effects if ingested in high quantities.

For safety, the tolerable upper intake level of natural vitamin E (d-alpha-tocopherol) for adults is 1,500 IU. (The tolerable upper intake level for vitamins is established by the Institute of Medicine within the U.S. National Academy of Sciences.)

If ingested in very high doses, vitamin E can interfere with the body's blood clotting ability, posing a risk to people taking blood thinners for certain health conditions.

Minerals That Help Your Body Absorb Antioxidants

Your eyes can use some minerals as well. Important minerals for your eyes include zinc and selenium.

Zinc helps your body absorb vitamin A and also helps many antioxidant enzymes in your body reduce the number of free radicals. Zinc has been shown to protect against macular degeneration and night blindness.

The selenium and zinc in oysters are good for your eyes.

Good food sources of zinc include oysters and other seafood, beef, eggs, black-eyed peas, tofu and wheat germ.

However, avoid taking high doses of zinc (beyond 100 mg daily) without first consulting a physician. While zinc is vital to our health in moderation, higher doses have been associated with adverse effects such as reduced immune function.

Selenium is a mineral that helps your body to absorb vitamin E. Good food sources of selenium include Brazil nuts, oysters and other seafood.

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Resources:

Vitamin supplement use and incident cataracts in a population-based study. Archives of Ophthalmology. November 2000.

Dietary carotenoids, vitamins C and E, and risk of cataract in women. Archives of Ophthalmology. January 2008.

[Page updated December 2010]