Inner Vision: Nutrition and Supplements that Protect Your Eyes

Of all my senses -- taste, touch, hearing, sight, and smell -- there's one I hope to never lose. That's my sight. And so preserving the health of my eyes and my vision is always of paramount importance.

Unfortunately, we're more likely to develop some degree of impaired vision compared with a loss of any of our other senses. Day in and day out, whether the skies are sunny or cloudy, our eyes are exposed to the damaging ultraviolet (UV) rays in sunlight. Prediabetes and diabetes -- conditions that affect 100 million Americans -- also increase the risk of eye diseases. In fact, aging itself boosts the risk of serious eye diseases, including night blindness, macular degeneration, cataracts, glaucoma, and retinitis pigmentosa.

The good news is that healthy eating habits and nutritional supplements can reduce your risk of developing these eye disorders.

Night Blindness

The Problem. Night blindness is the eyes' inability to quickly adjust to changes in light intensity. You have night blindness if your eyes have difficulty adjusting to the darkness of a movie theater, or if you are blinded by the glare of headlights at night. Most people with serious eye diseases also suffer from night blindness.

Stats. Vitamin A deficiency is common in the United States. According to data from the U.S. Department of Agriculture, only 45 percent of Americans consume the recommended daily amounts of vitamin A.

The Research. Night blindness is a sign of vitamin A deficiency. The vitamin forms part of the light-sensitive pigment rhodopsin, found in the retina's light-sensing cells called rods. Research linking vitamin A deficiency and night blindness dates back almost a century, but most recent scientific studies on night blindness have focused on malnourished people in developing nations. In one collaborative study, researchers gave vitamin A or beta-carotene supplements to several thousand pregnant women suffering from night blindness. Vitamin A supplements reduced the incidence of night blindness by 67 percent. Betacarotene, which the body can convert to vitamin A, was not as effective as the vitamin itself.

Not everyone efficiently converts beta-carotene to vitamin A, so 5,000 IU of beta-carotene does not equal 5,000 IU of vitamin A. The conversion depends on bacteria in the gut, and so gut health can have a strong bearing on vitamin A levels.

My Recommendations. For night blindness, I suggest taking 25,000 IU of vitamin A daily for one month, then decreasing the amount to 10,000 IU daily. Most vitamin A supplements are either from fish liver oil or synthetic sources. If there is a chance that you may become pregnant, do not exceed 5,000 IU of vitamin A daily because of a slight risk of birth defects. Beta-carotene is nontoxic at high doses, and it is available from natural (D. salina algae) or synthetic sources.

Macular Degeneration

The Problem. The macula is a yellowish spot in the center of the retina, and it is responsible for seeing details, such as when you are reading.

In age-related macular degeneration (AMD), the macula becomes abnormally thin and shows signs of oxidative damage.

Stats. Macular degeneration is the leading cause of nonreversible blindness among seniors. It affects an estimated 1.75 million Americans, but a partial loss of vision from AMD may impact another 10 million people.

The Research. Several nutritional supplements can reduce the risk of AMD. The macula is composed largely of lutein and zeaxanthin, both antioxidant carotenoids found in leafy green vegetables. Studies have found that eating high-lutein diets or taking lutein supplements increases the thickness of the macular pigment within several months. Two forms of lutein are sold as supplements: free (unbound) lutein and lutein esters. Both are derived from marigold flower petals and are absorbed well. The body converts some lutein to zeaxanthin.

Last year researchers reported in the American Journal of Clinical Nutrition that supplements of either lutein or docosahexaenoic acid (DHA, an omega-3 fat) increased the thickness of the macular pigment. The subjects took either 12 mg of lutein or 800 mg of DHA daily for four months. DHA led to an increase in thickness of the center of the macular pigment, whereas lutein increased the thickness of the outer regions of the macular pigment.

Another recent study, conducted at the Harvard Medical School, asked 5,205 women to take a combination of three B vitamins or placebos daily for an average of seven years. The supplements contained 2,500 mcg (2.5 mg) of folic acid, 50 mg of vitamin B6, and 1,000 mcg (1 mg) of vitamin B12. The protective effect of these B vitamins started to appear after two years.

Women taking the vitamin supplements had a 34 percent lower risk of developing any form of AMD and a 41 percent lower risk of severe AMD.

My Recommendations. To reduce the risk or slow the progression of AMD, I recommend taking 10 mg of lutein, at least 1 gram of omega-3 fish oils, and a high-potency B-complex or multivitamin daily.

Cataracts

The Problem. Cataracts are cloudiness in the lens, the part of the eye that helps focus images on the retina. Cataracts are a result of protein damage in the lens and are virtually impossible to reverse. Living at a high altitude, significant lifetime sun exposure, flying frequently in aircraft, and smoking tobacco increase the risk of cataracts.

Stats. Worldwide, cataracts are the leading cause of blindness. In the United States, more than 1 million cataract surgeries are performed each year. About 20 million Americans over the age of 40 have at least one cataract, and another 20 million people have undergone cataract surgery.

The Research. Researchers at Tufts University, Boston, reported that women taking 400 mg or more of supplemental vitamin C—for at least 10 years—had an 83 percent lower risk of developing cataracts. However, high dietary vitamin C intake was not protective. Several studies have found that lutein supplements can improve visual acuity in people with cataracts and other eye disorders, even though it doesnt affect the cataract itself.

My Recommendations. Reduce your risk of cataracts by wearing polarizing sunglasses and a wide-brimmed hat and taking at least 400 mg of vitamin C daily. If you have cataracts, you can likely improve your visual acuity by taking at least 15 mg of lutein ester supplements.

Glaucoma

The Problem. Glaucoma is caused by an increase in fluid pressure inside the eye. The higher pressure damages the optic nerve and narrows the field of vision.

Stats. Glaucoma affects an estimated 3 million Americans over age 65. It is the second most common cause of blindness (after AMD) in the United States. Conventional treatments include surgery and drugs.

The Research. A small study found that alphalipoic acid, an antioxidant involved in regulating blood sugar issues, can improve vision in people with glaucoma. The researchers gave 150 mg of alpha-lipoic acid daily to 19 patients for one month. Half of the patients improved. According to a report of two case histories, large amounts of alpha-lipoic acid (380 mg daily) and a high-protein, high-vegetable, low-carbohydrate diet can lower eye pressure levels, most likely by improving glucose tolerance.

Still other research has found that magnesium supplements can lead to improved blood flow and vision in glaucoma patients. Another supplement, L-carnosine, might also protect against glaucoma, according to an animal study conducted by Russian researchers.

My Recommendations. To improve glucose tolerance and likely reduce intraocular eye pressure, cut back on carbs and emphasize quality protein in your diet. Consider taking these supplements: alpha-lipoic acid, 300-400 mg; magnesium, 200 mg; and L-carnosine, 50 mg daily.

Retinitis Pigmentosa

The Problem. Retinitis pigmentosa is a genetic disease in which the retina slowly degenerates. Night blindness is an early sign, followed by a narrowing of the visual field -- the effect being similar to looking through a tunnel.

Stats. An estimated 100,000 Americans suffer from retinitis pigmentosa. In later stages, it causes blindness.

The Research. Several nutritional supplements show promise in slowing the progression of retinitis pigmentosa. Taking 15,000 IU of pure vitamin A daily may extend useful vision among people with retinitis pigmentosa, according to a study at the Harvard Medical School. Eating a diet high in omega-3 fish oils, or taking 1,200 mg of DHA daily, seems to enhance the benefits of vitamin A. A study of three patients suggested that supplemental coenzyme Q10, a vitamin-like nutrient, might also be of value in retinitis pigmentosa.

My Recommendations. Vitamin A, 15,000 IU daily -- perhaps more under the care of an ophthalmologist; beta-carotene, 25,000 IU daily; coenzyme Q10, 100-200 mg daily.

Visual Acuity

The Problem. Poor sensitivity to contrast, difficulty seeing in low-light situations, and glare (such as from a computer monitor) are common vision problems.

Stats. No statistics are available on the prevalence of poor visual acuity. However, the use of artificial lights and computer monitors likely contributes to the problem.

The Research. Several studies have found that lutein supplements can reduce glare and improve visual acuity in both healthy people and those with eye diseases. However, lutein will have no effect on myopia, hyperopia, or astigmatism. Lutein appears to work somewhat like polarizing lenses in that it helps organize light ways entering this central region of the retina. In a recent study, researchers gave lutein supplements to 37 long-term computer users. The subjects had improvements in visual sensitivity, particularly when taking 12 mg of lutein daily.

One study found that supplemental gamma-linolenic acid (GLA), which has anti-inflammatory benefits, reduced glare and improved healing after laser eye surgery. It is likely that the benefits will be enhanced by combining GLA supplements with omega-3 fish oils.

My Recommendations. Take 10-20 mg of lutein supplements daily. The improvement should be noticeable after a couple of months.

References available on request.