Vitamin A and Eye Health
“Eat your carrots. They’re good for your eyesight.” Sound familiar? Most of us have probably heard this once or twice. But is it really true?
Beta carotene, which gives color to carrots and other yellow and orange vegetables, is a form of vitamin A. This fat soluble vitamin, which is stored in the liver, plays an essential role in vision, but consuming large amounts will not improve poor eyesight.
Interestingly, this widespread belief is the result of British propaganda during World War II. The Royal Air Force told the world that they were feeding their pilots carrots so they could see the German Luftwaffe during night air raids to disguise the fact that they were using radar to detect the approaching enemy aircraft.
Vitamin A also has a hand in normal bone and tooth development, reproduction, and the health of skin and mucous membranes. It helps regulate the immune system, is involved in formation of red blood cells and may have antioxidant properties. A diet rich in beta-carotene and vitamin A has been thought to have some protective effect against certain types of cancers.
Vitamin A is actually a group of compounds, including retinoids and provitamins.
The retinoids are the active form of vitamin A and are found in animal sources such as liver, milk, margarine and eggs.
Provitamins are found in fruits and vegetables with yellow, orange and dark green pigments. These are known as carotenoids and are converted to the active form of vitamin A by the body. The most common of these pigments is beta carotene, found in foods such as sweet potatoes, carrots, collard greens, kale, pumpkin, spinach, sweet peppers, winter squash, apricots, cantaloupe, mango and broccoli.
Vitamin A is expressed in International Units on food and supplement labels. This measure takes into account the different forms of vitamin A and their varying levels of biological activity. The recommended dietary allowance (RDA) for men ages 14 years and older is 3000IU; for women ages 14 years and older it is 2310 IU.
These levels can usually be met by eating a healthy diet that includes a variety of foods from each food group with five or more servings of foods with beta-carotene each day. Additional or supplemental sources of vitamin A are not typically necessary or advisable for the general population and in some cases may be detrimental. Vitamin A deficiency is largely unseen in the US, and healthy adults usually have adequate vitamin A stores in their liver.
There are, however, some conditions which raise the potential of a deficiency. This includes zinc and iron deficiency, excess alcohol intake, diseases of the pancreas or liver, and conditions that interfere with fat absorption (i.e., Celiac disease, Crohn’s disease). Some populations, including vegetarians who do not consume eggs or dairy foods and children with inadequate health care or immunizations, especially if they are living at or below the poverty level may also be at higher risk of vitamin A deficiency.
While eye diseases such as diabetic retinopathy, macular degeneration and glaucoma are 25 times more common among people with diabetes than in the general population, vitamin A deficiency is not. Of course the goal is to prevent all of these problems. Some ways to protect your eyes and vision overall are to:
- Include at least five servings of good vitamin A food sources daily
- Make lutein-rich foods (dark green leafy vegetables) part of your regular diet.
- Add Omega 3 Fatty Acids (Fatty fish, fish oils, Flax seed, Chia seeds) to your eating plan
- Don’t smoke
- Lose excess weight
- Keep blood sugar and blood pressure under control
- Wear sunglasses
- Have a dilated eye exam every one to two years
In addition, you can talk with your healthcare provider to determine if you are receiving the proper balance of vitamins and minerals in your diet and if there is a need to meet with a Registered Dietitian. If so, she or he will tell you to eat your carrots because they taste good and are a great part of a healthy diet, not to improve your eyesight!