Lutein and Zeaxanthin are in a group of carotenoids called xanthophylls. Since they have such a similar structure and are found in the same foods, these often grouped together by researchers. These xanthophylls have the same long hydrocarbon chain as other carotenoids, but have a hydroxyl group (containing oxygen) which makes them different from carotenes. The two phytochemicals are extremely similar, with the only difference between them being the location of one double bond on one end of the chain. This double bond location makes them behave differently in the body though, particularly in the eye where they tend to accumulate in different areas. See the Alternative Medicine Review link below to see their chemical structures.
Luteus means yellow in Latin, and lutein is one of the pigments that gives plants and some animal products a bright yellow color. Zeaxanthin takes its name from Xanthophyll, which is derived from the Greek word for yellow. These are two of over 600 carotenoids found in nature. Unlike alpha and beta carotene and beta-cryptoxanthin, lutein and zeaxanthin are NOT Vitamin A precursors, meaning our bodies cannot turn them into Vitamin A. However they still have several important functions.
These compounds are strong antioxidants that may help protect those parts of our body that are exposed to sunlight, the skin and the eyes. Lutein and zeaxanthin are the only carotenoids found in the retina and lens of the eye. Blue light is thought to contribute to age related macular degeneration of the eye, and lutein, found in the macula, absorbs this blue light and prevents it from passing through. Numerous epidemiological studies such as this one published in June 2003 in Investigative Ophthalmology and Visual Science suggest that lutein can protect against AMD. Another study published in January of 2007 in Experimental Eye Research showed that risk factors for AMD are related to lower levels of these pigments in the macula. In 2004 a study published in Optometry Journal recorded an improvement in visual function of AMD patients when they recieved lutein supplements. Most of the research in this area has been done with diet, however, and the recommendation is to get plenty of xanthophylls in your diet rather than taking supplements.
A clinical study presented in September 2006 at the "Beyond Beauty Paris" conference in France demonstrated that lutein can significantly increase hydration, elasticity and superficial lipids of the skin, and decrease the effects of oxidation. In April of 2007, Skin Pharmacology and Physiology published a study reporting that oral supplements of lutein and zeaxanthin provided a four-fold increase in protection from UV radiation-induced skin damage. This study was co-funded by Kemin Health, the company which makes the lutein supplements used in the study. However it was a scientifically sound randomised, double-blind placebo-controlled study.
The antioxidant properties of these xanthophylls may also have a protective effect against cardiovascular disease. Reasearch has shown that in the lab they can inhibit the adhesive effects of molecules in the arteries, and also prevent thickening of the walls of the carotid arteries. Studies have found an inverse relationship between a high intake of lutein and zeaxanthin and lung cancer rates, among populations that traditionally eat a lot of dark green leafy vegetables.
Dark green leafy vegetables like spinach, kale, turnip greens, collards, dandelion greens and mustard greens are the best sources of lutein and zeaxanthin. The yellow color of lutein in these vegetables is covered up by the large amount of green chlorophyll. Squash, peas, pumpkin, brussel sprouts, broccoli and yellow corn are also good sources. Egg yolks provide them in a way that is very easily absorbed. Like other carotenoids, lutein and zeaxanthin are fat soluble, so are absorbed more easily when eaten with at least a small amount of fat and when the cell structure of the plant has been broken up already by cooking, chopping, or pureeing.