Lutein is concentrated in the retinas of your eyes, so it's a necessary component of normal vision. It also works as an antioxidant to reduce the damage done by free radicals.
Eating a diet with lots of colorful fruits and vegetables that contain lutein may also decrease your risk of cardiovascular disease. One study found that people who had higher levels of lutein and other antioxidants in their blood also had healthier blood vessels. Of course, there are other healthy lifestyle factors that go along with eating a lutein-rich diet, so it's difficult to know how much (if any) of the effect was due to lutein alone.
Plant sources of lutein include kale, spinach, carrots, corn, squash and other deep green, orange and yellow fruits and vegetables. There is one animal source of lutein available -- you'll find lutein in egg yolks.
If you eat a diet with a sufficient amount of colorful fruits and vegetables, you should get ample amounts of lutein.
You can buy lutein supplements in supermarkets, health foods stores, pharmacies, and online -- but there probably isn't any benefit for your heart or blood vessels. You're better off getting your lutein from fruits and vegetables, at least for prevention of cardiovascular disease. Lutein supplements may, however, protect your vision.
Researchers studied lutein as part of the supplement formula used in the The Age Related Eye Disease study, using Twin Lab's Ocuvite. They found that large doses of lutein, combined with the dietary mineral zinc, vitamin C, vitamin E, beta-carotene, and copper may help slow down the progression of macular degeneration (MD) and preserve vision in people who have early MD.
Unfortunately, lutein doesn't appear to have any effect on prevention or progression of cataracts, which is a condition where the lens of one or both eyes becomes cloudy.
National Institutes of Health, National Eye institute. "Facts About Cataract." Accessed February 3, 2012. http://www.nei.nih.gov/health/cataract/cataract_facts.asp.
National Institutes of Health, National Eye Institute. "Age-Related Eye Disease Study--Results." Accessed May 17, 2011. http://www.nei.nih.gov/amd/.
Dwyer JH, Paul-Labrador MJ, Fan J, Shircore AM, Merz CN, Dwyer KM. "Progression of carotid intima-media thickness and plasma antioxidants: the Los Angeles Atherosclerosis Study." Arterioscler Thromb Vasc Biol. 2004 Feb;24(2):313-9.