Omega-3 Rich Diet Combined with Vitamin A Slows Visual Acuity Decline in Patients with RP
February 21, 2012
A Foundation-funded research team led by Dr. Eliot Berson found that adults with retinitis pigmentosa (RP) who, on average, ate one to two three-ounce servings of omega-3 rich fish per week while receiving a supplement of vitamin A palmitate had a 40 percent slower rate of visual acuity loss per year than those taking vitamin A alone. Results of the study were published in the February 13, 2012, online edition of the Archives of Ophthalmology.
This is the first time an effect on visual acuity for RP has been reported for vitamin A combined with an omega-3 rich diet achieved by eating salmon, tuna, herring, mackerel or sardines. In prior clinical studies, Dr. Berson and coworkers reported that supplementation with vitamin A, alone or in combination with an omega-3 rich diet, slowed the rate of decline in peripheral vision in patients with RP.
Based on the results from the new study, adding oily fish consumption to a vitamin A supplementation of 15,000 IU, or international units, per day could translate into 18 additional years of preserved central vision. The authors write, “If the rate of decline of acuity is sustained over the long-term, we estimate that a representative patient who starts receiving vitamin A by age 35 years and eats an omega-3 rich diet with an acuity of 20/30 would, on average, be expected to decline to 20/100 at age 79 years.” In comparison, the same patient “receiving vitamin A with a low dietary omega-3 intake (e.g., less than one three-ounce serving of oily fish per week) would decline to 20/100 at age 61 years.”
“To save acuity in addition to peripheral vision is a real plus for RP patients,” says Dr. Steve Rose, chief research officer, Foundation Fighting Blindness. “Acuity is critical for so many activities, including reading, driving and recognizing faces.”
Berson and his co-authors conclude that vitamin A combined with an omega-3 rich diet of one to two three-ounce servings of oily fish per week should make it possible for many patients with typical retinitis pigmentosa to retain both visual acuity and central visual field for most of their lives.
For the new study, Dr. Berson analyzed the visual acuity data of 357 people with various forms of typical RP from his three previous clinical trials. All were taking vitamin A palmitate (15,000 IU/day) for four to six years. A questionnaire was given annually to evaluate their omega-3 intake, of which docosahexaenoic acid (DHA) is a major constituent. Eyes with visual acuity of 20/100 or worse were excluded from the analysis.
In 1993, Dr. Berson and coworkers first reported the benefits of vitamin A supplementation for adults with RP. This was followed by a paper in 2004 suggesting that one to two servings of oily fish per week helped to preserve central visual field sensitivity among patients taking vitamin A with a projected benefit of 19 additional years, on average. The Foundation’s website offers complete information on Dr. Berson’s recommendations for vitamin A supplementation and DHA intake.
The Foundation is also currently funding a clinical trial of DHA for people with the X-linked form of RP. The five-year study is taking place at the Retina Foundation of the Southwest (RFSW) in Dallas, Texas. Investigators have completed enrollment and expect to report results in late 2012. Vitamin A supplementation is not part of the RFSW study.
Dr. Berson was the first retinal researcher to receive funding from the Foundation. He is now the William F. Chatlos Professor of Ophthalmology, Harvard Medical School, and the director of the Foundation-funded Berman-Gund Laboratory for the Study of Retinal Degenerations at the Massachusetts Eye and Ear Infirmary. In 1999, he received the Foundation’s Llura Liggett Gund Award for his extraordinary career achievements in retinal research.