Lutein, a chemical found in green vegetables, is a member of a family of substances known as carotenoids. Beta-carotene is the most famous nutrient in this class. Like beta-carotene, lutein is an antioxidant that protects our cells against damage caused by dangerous, naturally occurring chemicals known as free radicals.

Recent evidence has found that lutein may play an important role in protecting our eyes and eyesight. It may work in two ways: by acting directly as a kind of natural sunblock, and also by neutralizing free radicals that can damage the eye.

Sources

Lutein is not an essential nutrient. However, it is possible that it may be useful for optimal health.

Green vegetables are the best source of lutein, especially spinach, kale, collard greens, romaine lettuce, leeks, and peas. Unlike beta-carotene, lutein is not found in high concentrations in yellow and orange vegetables such as carrots.

Therapeutic Dosages

We don't know how much lutein is necessary for a therapeutic effect, but estimates range from 5 to 30 mg daily. (However, see Safety Issues.)

Therapeutic Uses

According to theoretical findings and two preliminary double-blind studies, it appears that use of lutein supplements might help prevent or slow the development of age-related macular degeneration (ARMD) and possibly cataracts, the two most common causes of vision loss in seniors.

Lutein has also shown a hint of promise for treatment of retinitis pigmentosa, an inherited form of eye disease that causes progressive vision loss.13

Very weak evidence hints that lutein might help prevent atherosclerosis.9

What is the Scientific Evidence for Lutein?

Most but not all observational studies suggest that people who eat foods containing lutein are less likely to develop cataracts and perhaps macular degeneration as well, the two most common causes of vision loss in adults.1-5,8 Furthermore, there are good theoretical reasons to believe that lutein may play an important role in protecting the eyes.

Lutein is the main pigment (coloring chemical) in the center of the retina, the region of maximum visual sensitivity known as the macula. Macular degeneration consists of injury to the macula and leads to a severe loss in vision. One of the main causes of macular degeneration appears to be sun damage to the sensitive tissue. Lutein appears to act as a natural eyeshade, protecting the retina against too much light.6 It is also an antioxidant, meaning that it fights dangerous, naturally occurring substances called free radicals. Free radicals may play a role in macular degeneration.

Based on this information, researchers conducted a double-blind, placebo-controlled trial of lutein.11 The study enrolled 90 people with dry-type macular degeneration and followed them for 12 months. The participants received either lutein (10 mg), lutein plus other antioxidants, and a multivitamin/mineral supplement, or placebo. At the end of the study period, participants who had taken lutein alone or lutein plus the other nutrients showed improvements in vision, while no change in vision was seen in the placebo group. A subsequent study failed to find benefit with lutein, but it used a lower dose (6 mg daily) and involved fewer people.15 Ultimately, further study will be needed to establish whether lutein is actually helpful for macular degeneration.

Besides protecting the macula, lutein might also shield the lens of the eye from light damage, slowing the development of cataracts.7 One small 2-year, double-blind, placebo-controlled trial found some evidence that lutein may improve vision in people who already have cataracts.10

A trial involving 225 adults with retinitis pigmentosa found 4 years of daily supplementation with lutein and vitamin A slowed the rate of visual loss in the mid-peripheral field.17

Safety Issues

Although lutein is a normal part of the diet, there has not been much evaluation of lutein's safety when taken as a concentrated supplement. One study found evidence that lutein is safe in doses up to the highest tested dose of 10 mg daily.14 A review of other evidence concluded that long term use of lutein should be safe when taken at a dose of up to 20 mg per day.13 A 2009 study following 77,126 adults (over age 50), however, suggests that there may be some harm in long-term supplementation with lutein. This study found that long-term use of beta-carotene, lutein or retinol supplements may increase lung cancer risk. Long-term supplement use was determined by subjects' memory of the previous 10 years, so the results of this large study should be interpreted with some caution.16

Maximum safe dosages for young children, pregnant or nursing women, or those with severe liver or kidney disease have not been established.