April 12, 2010
BOSTONProviding retinitis pigmentosa patients with lutein plus vitamin A palmitate slowed the loss of midperipheral vision, according to a study out of the Massachusetts Eye and Ear Infirmary, Harvard Medical School (Arch Ophthalmol. 2010;128(4):403-11). Retinitis pigmentosa is characterized by progressive loss of peripheral and central vision, which is caused by a number of genetic defects, and affects approximately 1 in 4,000 Americans.
Researchers randomized 225 nonsmoking patients, aged 18 to 60 years, for the controlled, double-masked four-year trial. Patients received 12 mg/d of lutein or a control tablet, in addition to standard treatment with 15,000 IU/d of vitamin A palmitate. Primary outcome was total point score for the Humphrey Field Analyzer (HFA) 30-2 program; prespecified secondary outcomes were total point scores for the 60-4 program and 30-2/60-4 programs combined. While no significant difference in rate of decline was found in the primary outcome, added lutein did decrease mean rate of sensitivity loss in the 60-4 program. Mean decline in the 60-4 program was slower among those with highest serum lutein levels or highest increase in macular pigment optical density (MPOD) at studys end. The patients with the highest increases in MPOD also had the slowest decline in the combined field sensitivity.
While the results led the research team to conclude that clinicians would do well to add lutein to the vitamin A supplements taken by nonsmoking adults with retinitis pigmentosa, an editorial in the same issue of the journal (2010;128(4):493-95) questioned whether the evidence supports the recommendation. Robert W. Massof, Ph.D., from the Lions Vision Center, Baltimore, and Gerald A. Fishman, M.D., from the Eye and Ear Infirmary, University of Illinois, Chicago, noted this is the third clinical trial from this research group showing positive results of nutritional intervention to address retinitis pigmentosa; previous studies have examined the impact of vitamin E, docosahexaenoic acid (DHA), lutein and vitamin A in various combinations. While Fishman and Massof call the results of the trials intriguing, they ultimately conclude that none justify a change to clinical recommendations because of possible confounders in the data analysis and challenges in comparing loss of functional measures in a diseases that progresses slowly and possibly non-linearly. Further, they argue that simply because there is no other viable treatment for retinitis pigmentosa is not a reason to recommend any of the nutritional supplements investigated because the data is not convincingthe primary outcome measures in the studies did not show a difference, only secondary measures found a possibilityand there are possible safety concerns about the high nutrient levels used in the studies, particularly levels of vitamin A.
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