NEW YORK (Reuters Health) - Treatment with docosahexaenoic acid (DHA) slows the progression of retinitis pigmentosa, but only in patients who have not previously been treated with vitamin A, according to the findings of two studies published in the Archives of Ophthalmology for September.
In patients already receiving vitamin A, use of this omega-3 fatty acid does not slow disease progression, the research group, which conducted both studies, notes. In contrast, in patients not previously treated with vitamin A, combination therapy with this vitamin and DHA seems to slow disease progression compared with vitamin A monotherapy.
In the first study, Dr. Eliot L. Berson, from Harvard Medical School in Boston, and colleagues assessed the outcomes of 221 patients with retinitis pigmentosa who were randomized to receive vitamin A combined with DHA or control capsules.
The authors found no difference between the groups in the rate of ocular decline over a 4-year period. No significant adverse effects were seen with vitamin A monotherapy or with combined treatment.
In the second study, the researchers analyzed data from the first, this time looking for any patient subgroups that might benefit from vitamin A/DHA combination therapy.
Subjects not taking vitamin A before study entry did seem to benefit from combination therapy. In particular, they experienced a slower decline in field sensitivity (p = 0.01) and electroretinogram amplitude (p = 0.03) than their peers who just received vitamin A. However, this benefit was confined to just the first 2 years of the study.
“Together the results show that DHA supplementation shortens the interval for vitamin A to takes its full effect and supports a recommendation that most adult patients with the typical forms of retinitis pigmentosa who start vitamin A therapy at a dosage of 15,000 IU/d should also take DHA, 1200 mg/day for 2 years,” the investigators conclude.
Source: Arch Ophthalmol 2004;122:1297-1314. [ Google search on this article ]
MeSH Headings:Dietary Fats: Dietary Fats, Unsaturated: Docosahexaenoic Acids: Fats: Fish Oils: Fatty Acids, Omega-3Copyright © 2002 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content, including by framing or similar means, is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. Reuters and the Reuters sphere logo are registered trademarks and trademarks of the Reuters group of companies around the world.
