Eating a well-balanced diet is important to maintaining a normal weight, preventing disease, having good eyes and maintaining overall health. A balanced diet with foods from each of the food groups provides the body with nutrients critical to eye health. Selenium, an often overlooked mineral, is one of the many nutrients involved in preserving eyesight. Consuming selenium-rich foods can help delay the onset of eye-related diseases and improve vision.
Function
Selenium is a trace element, meaning it is needed by the body in very small amounts, and is toxic at higher levels. Selenium functions as an antioxidant, along with vitamin E, by scavenging particles in the body known as free radicals. Free radicals are unstable compounds that cause oxidative damage to cell membranes and DNA, contributing to aging and chronic disease. Selenium neutralizes free radicals by donating an electron, thus reducing and preventing the damage they can cause. According to the Linus Pauling Institute at Oregon State University, the body uses selenium to produce selenoproteins, which then form a functional protein. These proteins help regulate thyroid function and immunity.
Recommended Dietary Allowance
The Food and Nutrition Board of the Institute of Medicine revised the daily recommended intake for selenium in 2000. The current selenium recommendations are based on the amount necessary to maximize its antioxidant activity. From birth to 6 months, children require 15 micrograms selenium per day; from 6 months to 3 years, 20 micrograms; from ages 4 to 8 years, 30 micrograms; and from 9 to 14 years, 40 micrograms. Adolescents and people ages 15 and older require 55 micrograms per day; pregnant women need 60 micrograms, while lactating females require 70 micrograms. Doses of 200 micrograms per day over a long period of time have been associated with an increased risk of developing diabetes.
Food Sources
On average, your body contains only 14 milligrams of selenium, but this small amount plays an important part in nutrition for the eyes in addition to the function and growth of cells. The richest sources of selenium include organ meats and poultry like liver and chicken; seafood such as scallops, lobster and oysters; and fish including mackerel, tuna, halibut, flounder and herring. Other good sources of selenium are walnuts and Brazil nuts; sunflower seeds; wheat germ; brewer’s yeast; milk and butter; garlic; and whole grains such as brown rice, whole wheat pasta and rye bread. The amount of selenium in plant foods varies widely according to the level of selenium in the soil where the food is grown. Fruits and vegetables tend to be relatively poor sources of selenium in the United States. Additionally, selenium is destroyed when foods are processed or refined.
Selenium and Eye Health
The primary cause of eye-related diseases such as cataracts and macular degeneration is lipid peroxidation in the eye. The term lipid peroxidation refers to the degradation of lipids -- a process by which free radicals steal electrons from lipids within cell membranes, resulting in cellular damage. Blood tests of individuals suffering from macular degeneration show low levels of selenium in addition to other nutrients, indicating the value of adequate selenium concentrations in the treatment and prevention of eye-related disorders. If you are concerned about protecting your eyes, eat plenty of nuts, shellfish, oatmeal, brown rice, brewer’s yeast and eggs, all of which are good food sources of this trace mineral.
References
- University of Maryland Medical Center; Selenium; Steven D. Ehrlich, NMD
- Linus Pauling Institute; Selenium; Jane Higdon, Ph.D.; October 2003
- Your-Eye-Sight.org: Vitamin E and Mineral Nutrition for Eyes: Go Nuts for Eye Health
- Antioxidants-for-Health-and-Longevity.com: Benefits of Selenium: Boost Your Antioxidant Defense System
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