Fish Oil (2004) Retinitis Pigmentosa Treatment with fish oils & DHA

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Researchers wanted to find out whether DHA (docosahexaenoic acid) will slow the course of retinal degeneration in patients with retinitis pigmentosa who are receiving vitamin A.

208 patients with retinitis pigmentosa, 18 to 55 years old, were randomly assigned to DHA plus vitamin A given as retinyl palmitate (DHA + A group) or control fatty acid plus 15 000 IU/d of vitamin A (control + A group) and followed up over 4 years. Seventy percent of the patients in each group were taking vitamin A, 15 000 IU/d, prior to entry. We compared rates of decline in ocular function in the DHA + A vs control + A groups among the subgroups defined by use or nonuse of vitamin A prior to entry. We also determined whether decline in ocular function was related to red blood cell phosphatidylethanolamine docosahexaenoic acid level, dietary omega-3 fatty acid intake, or duration of vitamin A use. Main outcome measures were Humphrey Field Analyzer visual field sensitivity, 30-Hz electroretinogram amplitude, and visual acuity. RESULTS: Among patients not taking vitamin A prior to entry, those in the DHA + A group had a slower decline in field sensitivity and electroretinogram amplitude than those in the control + A group over the first 2 years (P =.01 and P =.03, respectively); these differences were not observed in years 3 and 4 of follow-up or among patients taking vitamin A prior to entry. In the entire cohort, red blood cell phosphatidylethanolamine docosahexaenoic acid level was inversely related to rate of decline in total field sensitivity over 4 years (test for trend, P =.05). This was particularly evident over the first 2 years among those not on vitamin A prior to entry (test for trend, P =.003). In the entire control + A group, dietary omega-3 fatty acid intake was inversely related to loss of total field sensitivity over 4 years (intake, <0.20 vs > or =0.20 g/d; P =.02). The duration of vitamin A supplementation prior to entry was inversely related to rate of decline in electroretinogram amplitude (P =.008).

CONCLUSIONS: For patients with retinitis pigmentosa beginning vitamin A therapy, addition of docosahexaenoic acid, 1200 mg/d, slowed the course of disease for 2 years. Among patients on vitamin A for at least 2 years, a diet rich in omega-3 fatty acids slowed the decline in visual field sensitivity.

Published: Further evaluation of docosahexaenoic acid in patients with retinitis pigmentosa receiving vitamin A treatment: subgroup analyses. Arch Ophthalmol. 2004 Sep;122(9):1306-14.

Researchers: Berson EL, Rosner B, Sandberg MA, Weigel-DiFranco C, Moser A, Brockhurst RJ, Hayes KC, Johnson CA, Anderson EJ, Gaudio AR, Willett WC, Schaefer EJ. Berman-Gund Laboratory for the Study of Retinal Degenerations, Harvard Medical School, 243 Charles Street, Boston, MA