Vitamins, Your Diet and Your Eyes
Like the rest of the body, a healthy lifestyle helps maintain and preserve your vision. In addition to regular physical exercise, and abstaining from the use of tobacco and controlled substances, a well balanced diet is necessary to ensure your eyes' longevity. Smoking has been associated with an increased risk of cataract formation and age related macular degeneration (a disease that causes severe central vision loss in older adults).
Although there is still much to be learned about the relationship between the eyes and nutrients, medical studies have consistently demonstrated the need for a select group of vitamins and minerals, both as a preventative to eye disease, and a means of therapy. Vitamins are not a substitute for a healthy diet. Nutritional supplements are not intended to replace a healthy diet, but merely enhance it, and should only be taken after research and consultation with a medical doctor.
Vitamin A, perhaps more than any other substance, is vital for eye health. Derived from carotenoids (or plant pigment-typically yellow and red), vitamin A is necessary to prevent many of the ailments that can afflict the eye. Vitamin A deficiency has been linked to dry eye, corneal ulcers, swollen eyelids, and even total blindness, as has happened frequently in third world countries. There is also evidence to indicate that Vitamin A can prevent the formation of cataracts and macular degeneration.
Those who smoke or drink alcohol have decreased ability to absorb vitamin A. However, smokers should avoid high dose Vitamin A supplementation due to an studies indicating an increased occurrence of lung cancer in smokers. Lutein may be a better supplement for smokers.
In addition to supplements, vitamin A can also be found in liver, carrots, sweet potatoes, kale, squash, red peppers, mangos, cantaloupes, and butter. If it is taken through supplements, the recommended daily dose for men and women is 1000 and 800 RE, respectively.
Vitamin C has also been linked to the prevention of cataracts and macular degeneration. Studies have also suggested that Vitamin C plays a role preventing and alleviating the symptoms of glaucoma through its ability to reduce the pressure within the eye.
It is recommended that men and women take at least 60mg per day, every day, because of the body's inherent inability to store this vitamin for extended periods of time. High dose Vitamin C, 500 mg, was used in the Age Related Eye Disease Study.
Vitamin C can be found in red peppers, potatoes, broccoli, leafy green vegetables, and any citrus fruits. If possible, these foods should be bought fresh and eaten raw, as Vitamin C tends to be degraded through the rigors of processing and cooking. Also, be sure to buy orange juice (rich in vitamin C) in opaque containers, as sunlight can also degrade its nutritional value.
Like Vitamins A and C, studies have shown vitamin E to play a role in the prevention of cataracts and macular degeneration. It also has been shown to aid in the development of the retina in growing children. However, controversy has arisen over the possibility of dangerous side effects when taking the vitamin in supplement form.
A recent study published in The Annals of Internal Medicine suggested that those who take mega doses (400 IU or more) have had a higher incidence of internal bleeding and an overall higher mortality rate. The results came from a pooling of data from nineteen previous experimental trials. The results of these studies may or may not apply to you. Consult with your physician before taking high does (400 IU or higher) of Vitamin E.
Of all the trace elements and minerals within the eye, zinc is by far the most abundant, although its importance to ocular health is still uncertain. A study conducted in 1988 indicated that twice daily supplements of zinc sulfate slowed the progression, and possibly the onset of Adult Macular Degeneration.
Additionally, intake of high doses of zinc can impair the body's ability to absorb important minerals such as copper and iron, which can lead to anemia and hardening of the arterial walls. Most zinc supplements try to compensate by also containing trace amounts of copper, but no study has tested to determine whether this action represents an effective compromise.
In addition to zinc and copper, selenium is also an important mineral, both for its powers as an antioxidant, but also for its ability to aid in the absorption of vitamin E and the body's ability to produce its own anti-oxidizing agents. It too may have adverse side effects, and all these substances should be taken only upon consultation with a physician.
Herbal remedies have become increasingly popular, and one of the most popular of the herbal remedies, is ginkgo biloba. It has been advertised in magazines, and on radio and TV, but what are the benefits for eye health? A French study determined that ginkgo biloba extract (50:1 ratio) was beneficial to individuals who suffered from AMD. Researchers believe its health benefits are due to its ability to inhibit the body's inflammatory response, yielding increased blood circulation to, among others, the brain and eyes. However, like zinc supplements, ginkgo biloba has yet to be studied on a large scale. Ginkgo biloba poses a health risk to those with weakened ability to clot (such as hemophiliacs) and to those currently taking the blood thinner coumadin. Therefore, if you are interested in taking ginkgo biloba, you should first consult with your physician.
You can learn more about ocular nutrition at the All About Vision webpage.