The findings, presented last year at the annual meeting of Arvo but published in a peer-reviewed journal this week, were the first to show actual improvement in several key visual functions among patients with AMD.
The disease is the leading cause of blindness in the western world, affecting an estimated 30 million people worldwide. This number is expected to double by 2030.
Before the LAST study (Lutein Antioxidant Supplementation Trial), the carotenoid lutein and other antioxidants were widely believed to be purely a preventive measure in reducing risk in the onset of AMD among high-risk patients.
The trial showed however that patients who took the lutein supplements experienced improvements in several symptoms, including glare recovery, contrast sensitivity and visual acuity, compared with patients taking the placebo. Patients also experienced a 50 per cent increase in macular pigment density relative to those on placebo.
Lead investigator Stuart Richer, chief of optometry at the North Chicago VA Medical Center and associate professor at the Illinois College of Optometry, said: "Our findings show that AMD symptoms may be reversed through purified lutein supplementation or a supplement mix of lutein and other antioxidants such as vitamin A, vitamin C, vitamin E, and beta carotene. By no means a cure for AMD, the study does show improvement among several disease symptoms in AMD patients."
The charity AMD Alliance says the results, published in this month's issue of Optometry - Journal of the American Optometric Association (vol 75, no 4) indicate the need for larger studies involving more participants over a longer period to ascertain more definitive findings.
In the LAST study, 90 AMD patients were supplemented daily with a capsule containing 10mg of crystalline FloraGLO lutein, an OcuPower supplement of 10mg crystalline lutein plus a mixed antioxidant formula, or placebo for 12 months.
"However, we encourage people with AMD to discuss nutrition strategies with their doctor now and consider whether taking a vitamin supplement containing lutein might be right for them," said Gerrard Grace, chair of the organisation.
He explained that we already know from the Age Related Eye Disease Study (AREDS) that there is a beneficial effect of supplementation with vitamins C, E, beta-carotene and zinc - all combined in one pill. "This study demonstrated a 25 per cent reduction in progression of AMD over five years," he added.
Lutein is a naturally occurring molecule found in dark green leafy vegetables such as spinach, kale and collard greens but the average American ingests only 1-2 mg of lutein daily.
Previous research has suggested lutein intake fortifies the macula of the eye. The macula filters out blue wavelength light from the sun and artificial light, suppressing the oxidation of retinal cells that can otherwise cause degenerative eye disease.
Several brands of lutein supplements are available in North America and Wyeth, maker of leading multivitamin brand Centrum, last month announced that it was to include lutein in its Centrum formula for the German market (the first European market for the modified formula).