Lutein and Zeaxanthin: A Primer

The carotenoids are a large family of over 600 pigments that include alpha and beta-carotene, beta-cryptoxanthin, lycopene, lutein and zeaxanthin - the most common carotenoids in the American diet. Many people are most familiar with beta-carotene. This carotenoid nutrient, found in produce such as carrots and sweet potatoes, is best known as a source of vitamin A and for its ability to act as an antioxidant. However the importance of lutein and its structural look-alike zeaxanthin has emerged in recent years.

Why are Lutein and Zeaxanthin Important in our Diet?
Lutein (pronounced LOO-teen) and zeaxanthin (zee-a-ZANTH-in) are found in dark green leafy vegetables such as spinach, kale, collard, mustard and turnip greens. Egg yolks, corn and various fruit are also sources of lutein.

Once absorbed from food, lutein is transported through the blood stream where it is taken up and concentrated in various tissues. Tissues containing high levels of these two carotenoids are the eye and skin. In these tissues lutein filters potentially damaging ultraviolet (UV) light and acts as a free radical-scavenging antioxidant. Simply put, free radicals can damage the proteins, fats and genetic material in cells if they're not neutralized or inactivated by antioxidants. Free radical damage over time has been implicated in a number of chronic disorders.

Lutein and zeaxanthin belong to the xanthophylls (ZAN-tho-fills), a subgroup of the carotenoid family that is distinct from other carotenoids such as beta-carotene. Unlike beta-carotene, the xanthophylls aren't converted to vitamin A in the body. In addition the xanthophylls, but not beta-carotene, are present in the lens and macula of the eye.

The Role of Lutein and Zeaxanthin in the Eyes and Skin
The eye's retina contains cells that sense light (photoreceptors) and the blood vessels that nourish them. The most sensitive part of the retina is a small area called the macula where the sharpest central vision occurs. The macula can deteriorate as we get older resulting in age related macular degeneration or AMD, and cumulative damage from UV light contributes to this process.

Lutein, zeaxanthin and the metabolite meso-zeaxanthin, make up the yellow pigment of the macula. These yellow carotenoids act as a "filter", absorbing high-energy blue light, which generates free radicals that can damage sensitive photoreceptor cells. Reducing the amount of blue light that reaches the photoreceptor cells helps protect them from UV light-induced damage. Since the body cannot make its own supply of lutein, we rely solely on our diet to provide these necessary carotenoids that make up the macular pigment.

Scientists have theorized that the blue light filtering ability of lutein allows it to play a similar protective function in our skin. Research findings are beginning to bolster this theory, with reports that dietary carotenoids accumulate in the skin and offer a measurable photo-protective benefit that's directly linked to their concentration in this tissue [insert link to Staying Healthy Feb. '05].

Lutein and Zeaxanthin Research
A number of studies have linked higher intakes of lutein with a better chance of retaining macular, lens and skin health. Researchers are now studying lutein and zeaxanthin to clarify their role in eye health, to better understand their metabolism, and to determine who might benefit from greater intake. Read or listen to an interview with researcher, Paul S. Bernstein, MD, PhD on the role of lutein in macular health.

While we await these findings, many scientists are urging Americans to eat more lutein and zeaxanthin rich foods to help close the lutein dietary gap. Our diets typically provide about 1-2 mg of lutein daily, while the available research suggests that much higher levels - closer to 6 mg or more per day - are needed to realize its potential health benefits.