by Dan Roberts
(Updated July 2008)
Progress is being made in the study of both lutein and zeaxanthin as potentially effective nutritional supplements for macular degeneration patients.
According to a 1995 study, increasing the consumption of dark green, leafy vegetables appears to offer some protection against macular degeneration. Because nutritional factors may play a role in AMD, researchers decided to correlate the disease with dietary antioxidant intake in subjects participating in the NIH Eye Disease Case-Control Study (Seddon JM et al. JAMA. 1994; 272: 1413-1420).
The investigators found that higher intakes of carotenoids were associated with a reduced risk of wet (exudative neovascular) macular degeneration.
The carotenoids lutein and zeaxanthin were the most strongly associated with reduced risk of MD. These are obtained primarily from dark green, leafy vegetables such as spinach, collard greens, kale, mustard greens, and turnip greens. Eating spinach and collard greens five or more times a week was found to noticeably reduce the risk of MD. Other conclusions from the study were:
- The intake of retinol (preformed vitamin A) supplements showed no effect on MD.
- Vitamin C from food intake had little effect.
- Vitamin E actually showed negative effects.
In addition to their antioxidant mechanism, lutein and zeaxanthin may help to protect the retina for any or all of the following reasons:
- They may protect against photodamage of the retina by filtering out blue light, which is not stopped by the cornea and lens, and which can damage the retina over time.
- They may protect against peroxidation of fatty acids in the photoreceptor membrane.
- They may protect the blood vessels that supply the macular region.
Daily amounts of lutein and zeaxanthin are generally recommended at 20 mg of lutein and 6-10 mg of zeaxanthin. Lutein is easily available on the market in the recommended amount, either alone or as part of several brands of multi-supplements. Zeaxanthin is available in a single pill containing the recommended amount by only one company, ZeaVision (www.zeavision.com), which owns the patent. Other companies, however, offer zeaxanthin in pills containing up to 4 mg each, either alone (see www.swansonvitamins.com) or in combination with 30 mg of Vitamin C to assist in absorption (see www.biosyntrx.com). These 4 mg dosages can be safely doubled or tripled to obtain recommended amounts.
On April 7, 2004 the North Chicago VA Medical Center issued a press release announcing that lutein has been shown to not only help prevent, but to actually reverse symptoms of ARMD. According to the release, “The LAST study (Lutein Antioxidant Supplementation Trial) is the first trial to record actual improvement in several key visual functions among patients with AMD.” The data was published in the April issue of Optometry Ð The Journal of the American Optometric Association. Stuart Richer, O.D., Ph.D., chief of optometry at the North Chicago VA Medical Center and associate professor at the Illinois College of Optometry, was the LAST lead investigator. He was quoted as saying that lutein is “by no means a cure for AMD, [but] the study does show improvement among several disease symptoms in AMD patients.”
The press release went on to say that, “in the study, 90 AMD patients were supplemented daily with an OcuPower supplement capsule containing 10 mg of crystalline FloraGLO lutein, 10 mg lutein plus a mixed antioxidant formula, or placebo for 12 months. The average American ingests one to two mg of lutein daily. . . Patients ingesting the lutein supplement experienced significant improvements in several objective measurements of visual function including glare recovery, contrast sensitivity, and visual acuity vs. placebo. Patients also experienced a 50% increase in macular pigment density relative to those on placebo.”
Other research examining the effectiveness of lutein and zeaxanthin on ARMD is being conducted by the National Eye Institute (NEI) in a study called the “Carotenoids and Age-Related Eye Disease in Women’s Health Study.” For further information, see the National Eye Institute web site.
Elsewhere, in an overview of the research, the Roche Company concludes that lutein and zeaxanthin “possess physical and chemical properties that are biologically well suited to protect the macula and lens. Based on typical intake in the general population and reported intakes of lutein and zeaxanthin associated with reduced risk, people may need to increase consumption of these carotenoids to cover a potential dietary gap of at least 2 to 4 mg/day.”
See also: “Study Demonstrates Essential Role of Zeaxanthin in Eye Health” on this site.
Effects on Cataract Formation
In January 2008, it was reported in Archives of Ophthalmology that “prospective data from a large cohort of female health professionals indicate that higher intakes of lutein/zeaxanthin and vitamin E are associated with decreased risk of cataract.” This conclusion was reached after William G. Christen, Sc.D., of Brigham & WomenÕs Hospital and Harvard Medical School, Boston, and colleagues analyzed dietary information from 35,551 female health professionals who enrolled in the WomenÕs Health Study in 1993. The women were then followed for an average of 10 years, and the diets of those who developed cataracts were compared with the diets of those who did not.
According to an article published on Ophthalmology Web (January 14, 2008), A total of 2,031 women developed cataracts during the study. When the participants were split into five groups based on the amount of lutein and zeaxanthin they consumed, those in the group who consumed the most (about 6,716 micrograms per day) had an 18 percent lower chance of developing cataracts than those who consumed the least (1,177 micrograms per day). The one-fifth who consumed the most vitamin E from food and supplementsÑabout 262.4 milligrams per dayÑwere 14 percent less likely than the one-fifth who got the least (4.4 milligrams per day).
The authors concluded by saying, “Although reliable data from randomized trials are accumulating for vitamin E and other antioxidant vitamins, randomized trial data for lutein/zeaxanthin are lacking,” and further study is needed to determine if vitamin supplementation will help to prevent cataract formation.
Method of Transport Discovered
The August 2008 issue of Journal of Lipid Research reported that the protein SR-B1, or scavenger receptor class B, type 1, plays a central role in transporting lutein and zeaxanthin from the bloodstream to cells in the eye.
Led by senior study author Earl Harrison (Dean’s Distinguished Professor and chair of human nutrition, Ohio State University), introduced the xanthophylls lutein and zeaxanthin, along with beta carotene, to human retinal pigment epithelial (RPE) cells. The cells absorbed much more of the xanthophylls than the beta carotene, which was predicted from previous experiments. Most notably, absorption of the two xanthophylls was reduced by 41 to 87 percent when the SR-B1 protein was blocked. This, Harrison concluded, helps to explain the process by which these nutrients are transported to the retina–findings which may lead to methods for slowing the progression of macular degeneration.
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Biologic mechanisms of the protective role of lutein and zeaxanthin in the eye. Krinsky NI, Landrum JT, Bone RA, Annu Rev Nutr. 2003;23:171-201. Feb 27, 2003
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