Investigative Analysis

The Truth About Lutein and Eye Health

April 2003

The role of antioxidants in maintaining healthy vision has long been debated by nutritionists and eye health researchers. A number of studies suggest a link between dietary antioxidants, particularly the plant pigments known as carotenoids, and decreased risk of eye diseases such as cataract and Age-related Macular Degeneration (AMD). However, the roles of specific carotenoids, such as lutein, and the potential of antioxidant supplements in treating and preventing eye diseases has yet to be determined. In other words, when it comes to lutein and other carotenoids and their relationship to eye health, more research is needed before any definite conclusions can be drawn. Nevertheless, a review of the existing research can be helpful in establishing what we do and don't know about lutein and eye health, and in illustrating some of the difficulties that scientists encounter when studying the relationships between nutrition and disease.

What the research saysÂ…and doesn't

According to the National Eye Institute (NEI), there is little scientific evidence to support claims that taking supplements containing lutein can decrease the risk of developing AMD or cataract.1 However, a number of studies suggest a link between dietary lutein and decreased risk of eye disease:

  • In 1994, an NEI-funded study indicated that consuming carotenoid-rich foods, particularly green, leafy vegetables, was associated with a reduced risk of developing AMD.
  • In 1999, a reduced likelihood of the need for cataract surgery was associated with increased intakes of lutein and zeaxanthin in the Nurses Health Study.
  • In 1999, the Health Professionals Follow-up Study found a lower risk of cataract extraction was associated with higher intakes of lutein and zeaxanthin.
  • In 1999, the Beaver Dam Study found that people with diets higher in lutein and zeaxanthin had a lower risk of developing cataract.
  • In 2001, analysis of the Third National Health and Nutrition Examination Survey found that higher intakes of lutein and zeaxanthin among people ages 40-59 was associated with reduced risk of advanced AMD.

Why the seeming discrepancy? Part of the problem stems from fundamental differences between nutrients and drugs and the ways they are studied.

Drugs and Nutrients

Drugs are tested using double-blind trials in which one study group is given the test drug and a control group is given a placebo identical in taste, smell and appearance, with neither the researchers nor the test subjects informed as to who was given the active treatment vs. the placebo. Because the only difference between the two groups is the treatment received (drug vs. placebo) outcome differences between the two groups can typically be attributed to the effects of the drug being tested. With nutrients such as lutein, this type of direct comparison is extremely difficult, if not impossible.

Unlike drugs, nutrients such as lutein are a normal part of the diet. This basic fact makes the cut-and-dried conclusions of a placebo-controlled trial virtually impossible to obtain for lutein supplements, as dietary lutein intakes could vary widely in both the test and placebo groups. For this reason, studies on lutein and eye disease have looked at trends across a population, comparing the rates of eye disease between people with high and low lutein intakes. While a number of these population-based studies suggest that diets rich in lutein may protect against cataract and AMD,2-6 they are unable to reliably determine lutein's specific effect. Foods rich in lutein also tend to contain high levels of other antioxidant carotenoids, such as zeaxanthin and beta-carotene, which could also impact eye health. The synergy of these nutrients and the fact that they are often found in the same foods make a definitive conclusion on the benefits of lutein alone very difficult to obtain.

Should You Take Lutein?

After all this discussion, many of you may still be asking "what's the bottom line on lutein?" The best answer we can give is that consumption of foods rich in lutein and zeaxanthin is associated with decreased risk of cataract and ADM. Whether lutein supplements will have the same effect has yet to be determined. It's certainly advisable to increase your intake of lutein-rich green, leafy vegetables, given the wide range of health benefits they provide. If you don't consume these foods regularly, you may want to add a lutein supplement to your diet to achieve optimum intake.

NEI Statement: Lutein and its Role in Eye Disease Prevention. National Eye Institute, National Institutes of Health, July 2002.

JAMA, 272 (18): 1413-20, 1994.

Am J Clin Nutr, 70(4): 509-16,1999.

Am J Clin Nutr, 70 (4): 517-24, 1999.

Am J Clin Nutr, 69 (2): 272-7, 1999.

Am J Epidemiol, 153 (5): 424-32, 2001.

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