Health and Well-Being-Internet study shows RP improvement
A six-month study of individuals with retinitis pigmentosa (RP), recruited and monitored via the Internet, concludes that diet supplementation with the nutrient lutein may improve vision, at least over the short term, according to an article in the March issue of Optometry: Journal of the American Optometric Association.
Retinitis pigmentosa is actually a group of diseases that cause degeneration of the retina, the thin layer of tissue that lines the inside of the back of the eye. The damage begins with the light-sensitive rod cells, causing loss of night vision. As the disease progresses over several decades, peripheral vision gradually disappears, but most patients retain a small island of central vision; patients with severe RP eventually lose all their sight. Approximately 100,000 Americans have RP and closely related retinal diseases. In most cases, the disease is caused by an inherited genetic defect, and there is currently no cure.
The study, by principal author Gislin Dagnelie, PhD, assistant professor of ophthalmology at the Johns Hopkins University School of Medicine in Baltimore, and two co-authors afflicted with RP looked at the effects of lutein supplementation on visual acuity and central visual field area in an international population recruited via an Internet mailing list. Lutein, a carotenoid found in the human retina, is derived from the diet, primarily from dark green leafy vegetables and egg yolk.
All 16 participants in the study took lutein at breakfast, 40 mg daily for two months, and 20 mg daily for the remaining four months. The results indicate that most participants registered a significant improvement in both visual acuity and central visual field, as early as three to four weeks after starting the supplementation. "There appeared to be no difference between the two supplement regimens, but in addition to the overall benefit we did find two puzzling relationships: Blue-eyed participants had substantially higher gains in visual acuity than dark-eyed participants, and those already taking other supplements prior to the study — notably vitamin A and/or beta-carotene — had substantially greater visual field benefits," notes Dagnelie, who added that larger, placebo-controlled studies will be needed to confirm the effects reported.
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