Lutein: The Eyes Have It

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:    Frankp@chiro.org

From The November 2000 Issue of Nutrition Science News

by Dena Nishek

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Lutein is an eye-opening carotenoid you'll be seeing more of in antioxidant formulas. Some major national multivitamin brands now include this antioxidant because research indicates lutein may help maintain eye health. Lutein appears to prevent free radical damage in the macula and retina, two lutein-rich [1] and highly oxidant-sensitive areas susceptible to age-related macular degeneration (ARMD) and cataracts.

ARMD is the leading cause of irreversible blindness in people older than 65. More than 10 million Americans have impaired vision caused by ARMD, according to the American Macular Degeneration Foundation in Northampton, Mass.

ARMD has no known cause or cure. It occurs when cells of the macula are destroyed, causing sight loss in the central field of vision but leaving intact peripheral vision. Oxidation and light damage may cause this macular deterioration. It seems lutein acts as a natural sunshade, protecting the eye from too much light. [2]Because eyes gradually lose lutein with age, [3] some researchers theorize that lutein loss leads to retinal sun damage and ultimately to a degeneration in macular thickness.

Epidemiologic data indicate that people with low plasma levels of carotenoids and antioxidants such as vitamins C and E may increase their risk of ARMD. [4]Carotenoids--particularly lutein and zeaxanthin--and antioxidant vitamin E help protect the retina from oxidative damage caused in part by light absorption. [5]

Blue light, which has the shortest wavelength on the visible spectrum, is especially damaging to the eye and can cause photo-oxidation in the macula. This can lead to lipid peroxidation, which is toxic to the retina. In a small study at Florida International University in Miami, researchers examined the effects of lutein supplementation on macular density. Two subjects took 30 mg lutein daily for 140 days. Their macular pigment optical density was measured before, during and after the supplementation period. Researchers also measured serum-lutein concentration. Twenty to 40 days after lutein supplementation began, the subjects showed increased macular pigment density and serum-lutein concentration. At the end of the study, one subject increased macular pigment density by 39 percent, the other by 21 percent. Researchers concluded that the modest period of supplementation resulted in a 30 to 40 percent reduction in blue light reaching the photoreceptors and other optical tissues vulnerable to ARMD. [6]

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Popeye Had It Right

A pilot study done at the DVA Medical Hospital of North Chicago indicates that lutein may improve vision. Researchers demonstrated short-term positive effects in visual function after patients incorporated more lutein into their diets. Fourteen male patients between ages 61 and 79 with early symptoms of ARMD such as blurred vision or loss of central vision ate four to seven servings of spinach weekly. Researchers saw improvements ranging from 60 to 92 percent on several visual function tests in all patients. [7]

In a study sponsored by the National Institutes of Health, based in Bethesda, Md., researchers found that a higher dietary intake of carotenoids was associated with a lower risk for ARMD. They adjusted for risk factors such as smoking and found that, of 876 patients, those with the highest carotenoid intake had a 43 percent lower risk of developing ARMD. Lutein and zeaxanthin were most strongly associated with the reduced risk. The right nutritional program, including kale, collard greens and spinach (the three foods richest in lutein), may help people maintain their vision. [4]

Another common age-related vision problem is cataracts. Lens protein oxidation plays a central role in cataract formation. Researchers at the University of Massachusetts, Amherst, examined the association between carotenoid and vitamin A intakes and cataract extraction in 77,466 women aged 45 to 71 as part of the now-famous Nurses' Health Study. During the study, 1,471 cataracts were extracted. Researchers controlled for age, smoking and other potential risk factors and found that those with the highest intake of lutein and zeaxanthin, as reported in food frequency questionnaires, had a 22 percent decreased cataract extraction risk. Neither vitamin A, retinol, nor other carotenoids such as alpha- and beta-carotene, lycopene and beta-cryptoxanthin were associated with reducing cataracts. [8]

Researchers have made the connection between lutein levels in the eye and age-related eye diseases. They have also shown that increasing consumption of lutein-rich foods increases carotenoid levels in the eyes, thereby helping to protect them from disease. There is no established therapeutic dose of lutein, but research points to 6 mg per day. It is a good idea to recommend lutein-rich foods to your customers, but remind them that it is difficult to get a therapeutic amount every day from food alone. Although a serving of spinach does the trick, for anyone other than Popeye, a supplement may be in order.

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Dena Nishek, former managing editor of NSN, is a freelance writer and editor in Boulder, Colo.

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References

1. Handelman GJ, et al. Carotenoids in the human macula and whole retina. Invest Ophthalmol Vis Sci 1988 Jun; 29(6):850-5.

2. Schalch W. Carotenoids in the retina--a review of their possible role in preventing or limiting damage caused by light and oxygen. EXS 1992;62:280-98.

3. Hammond BR, et al. Density of the human crystalline lens is related to the macular pigment carotenoids, lutein and zeaxanthin. Optom Vis Sci 1997;74:499-504.

4. Seddon JM, et al. Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. Eye Disease Case-Control Study Group. JAMA 1994 Nov 9;272(18):1413-20.

5. Snodderly DM. Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Am J Clin Nutr 1995 Dec;62(6 Suppl):1448S-61S.

6. Landrum JT, et al. A one-year study of the macular pigment: the effect of 140 days of a lutein supplement. Exp Eye Res 1997 Jul;65(1):57-62.

7. Richer S. ARMD--pilot (case series) environmental intervention data. J Am Optom Assoc 1999 Jan;70(1):24-36.

8. Chasan-Taber L, et al. A prospective study of carotenoid and vitamin A intakes and risk of cataract extraction in U.S. women. Am J Clin Nutr 1999 Oct;70(4):509-16

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