In the U.S., the leading cause of blindness in those over 55 is a condition called age-related macular degeneration (AMD), which affects 11 million Americans. The macula, located in the retina, directly behind the pupil, is responsible for central vision.
AMD occurs in two forms: wet (exudative) in which blood vessels leak blood and fluid into the macula damaging photoreceptor cells, and dry (atrophic) in which waste products from photoreceptor cells accumulate in the tissue beneath the macula (90 percent of cases).
Since 1984, multiple major studies revealed that foods such as spinach, kale and other dark, leafy greens were associated with a decreased risk from AMD. While these foods are rich in beta-carotene, they are also loaded with the carotenoids lutein and zeaxanthin. These carotenoids, which accumulate in the macula, are the ones most strongly associated with protection from AMD.
Since the tissues of the eyes are subject to oxidative stress from pollution, smoking, sunlight and even normal metabolic processes, a diet rich in antioxidants like carotenoids may prevent or at least slow the progression of AMD.
The National Eye Institute's 1990 Age-Related Eye Disease Study (AREDS) -- a randomized, controlled clinical trial evaluating the effect of dietary supplements on eye health among 5,000 patients across 11 U.S. cities -- found supplementation with a variety of antioxidants, vitamin C (500mg), vitamin E (400 IU), beta-carotene (15 mg) and zinc oxide (80 mg) with cupric oxide (2mg) resulted in 25 percent reduction in advanced AMD risk over 5 years.
Carotenoids in Action
With 8 million Americans at risk of developing advanced AMD, this was a significant find, leading researchers to speculate that 300,000 persons could be saved from vision loss over a 5-year period if they all took AREDS-type supplements.
Next to dark green vegetables and eggs, enhanced beverages are the best sources of eye-protecting lutein.www.nakedjuice.com, Azusa, Calif., provides a selection of minimally processed fresh fruit and vegetable juices loaded with natural antioxidants. Boasting "a pound of fruit in every bottle" and sporting colorful names such as "Berry Blast," "Mighty Mango" and Green Machine." These juice drink formulations also include added antioxidants in the form of beta-carotene and selenium.
Odwalla Inc, (www.odwalla.com), Santa Cruz, Calif., has several offerings laced with extra antioxidants and beta-carotene, including Mo'Beta, a combination of orange, peach, mango, plum and pineapple juices plus vitamins C and E and green tea extract in addition to the beta-carotene. Both Odwalla and Naked helped make carrot juice mainstream in the U.S. Pure carrot juice contains about 500 percent of the Daily Values for vitamin A as beta-carotene per cup.
Glaceau's vitamin water (www.glaceau.com), Whitestone, N.Y., adds vitamin A and lutein to "focus," its kiwi and strawberry-flavored enhanced water. The company describes the low-calorie beverage as "a natural and powerful antioxidant that acts as an internal pair of sunglasses for the eyes and skin, providing a natural defense from damaging ultraviolet rays."
Another way to take in beneficial carotenoids is to feed a healthy diet to the animals we depend on for food. "Our eggs gets zeaxanthine and lutein from corn, marigold and alfalfa meal in the diet we feed our hens," says Bart Slaw, Ph.D., director of quality assurance for Eggland's Best Inc. (www.egglandsbest.com), King of Prussia, Pa. While most eggs are good sources of zeaxanthin, Eggland's Best eggs also boast 200mcg of lutein each.
But it's not so much the quantity of carotenoids in eggs that's impressive as it is the bioavailability. According to a recent Tufts University (Boston) study, lutein from eggs is absorbed into the bloodstream more readily than lutein from other dietary sources. Carotenoids are fat soluble, and eggs are rich in lecithin, which acts as a fat emulsifier.
Formulating with Lutein and Zeaxanthin
"Supplementation with lutein in foods is relatively new. Lutein is still not approved in some markets for food or as a natural colorant," says Zohar Nir, Ph.D., vice-president of new product development and scientific affairs for LycoRed Corp. (www.lycored.com), Orange, N.J. LycoRed makes Lyc-o-lutein for food and beverage applications.
Eggs from specially fed hens provide one of the most bioavailable sources of lutein.
Regulatory hurdles for adding lutein continue due to the complicated process of approving new ingredients for both food and as a natural colorant. "The market growth may come through the functional-food and new market segments within the food industry; such as foods that target seniors," says Nir. "These may create new opportunities for all natural carotenoids."
"Adding lutein and zeaxanthin to food and beverage products adds value and differentiates those products from those without added nutrients," says Bob Berman, senior marketing manager for DSM Nutritional Products Inc. (www.nutraaccess.com), Parsippany, N.J. "GRAS levels for lutein vary between 0.3 and 3.0mg per serving, based on the kind of food," continues Berman. "The most likely uses for lutein and zeaxanthin will be bars, beverages and egg substitutes."