A randomized, placebo-controlled clinical trial of docosahexaenoic acid supplementation for X-linked retinitis pigmentosa

Am J Ophthalmol. 2004 Apr;137(4):704-18. doi: 10.1016/j.ajo.2003.10.045.


Purpose: Low docosahexaenoic acid (DHA) in X-linked retinitis pigmentosa (XLRP) may influence retinal function. The goals of this study were to elevate blood DHA levels and determine the effect on the rate of disease progression.

Design: In a 4-year prospective randomized clinical trial, male patients with XLRP (mean age = 16 years; range = 4-38 years) received DHA (400 mg/d; n = 23; +DHA group) or placebo (n = 21) capsules.

Methods: Red blood cell (RBC)-DHA concentrations were assessed every 6 months. Full-field cone electroretinograms (ERGs; the primary outcome measure), visual acuity, dark-adaptation, visual fields, rod ERGs, and fundus photos were recorded annually.

Results: In the +DHA group, RBC-DHA increased 2.5-fold over placebo levels (70 vs 28 mg DHA/l). Repeated measures analysis of variance for cone ERG showed a significant main effect of year (P <.0001) but not of group (P =.16). Preservation of cone ERG function correlated with RBC-DHA (P =.018), and there was less change in fundus appearance in the +DHA group (P =.04). Neither visual acuity nor visual fields were changed. In subset analysis, DHA supplementation was beneficial in reducing rod ERG functional loss in patients aged <12 years (P =.040) and preserving cone ERG function in patients > or =12 years (P =.038).

Conclusions: Although DHA-supplemented patients had significantly elevated mean RBC-DHA levels, the rate of cone ERG functional loss was not significantly different between groups. Supplemental analyses provided evidence for a DHA benefit and a direction for subsequent investigations.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Capsules
  • Child
  • Child, Preschool
  • Dark Adaptation
  • Dietary Supplements
  • Docosahexaenoic Acids / administration & dosage*
  • Docosahexaenoic Acids / metabolism
  • Electroretinography
  • Erythrocyte Membrane / metabolism
  • Genetic Diseases, X-Linked / blood
  • Genetic Diseases, X-Linked / drug therapy*
  • Genetic Diseases, X-Linked / physiopathology
  • Humans
  • Male
  • Prospective Studies
  • Retinal Cone Photoreceptor Cells / physiology
  • Retinitis Pigmentosa / blood
  • Retinitis Pigmentosa / drug therapy*
  • Retinitis Pigmentosa / genetics
  • Retinitis Pigmentosa / physiopathology
  • Visual Acuity
  • Visual Fields


  • Capsules
  • Docosahexaenoic Acids