A combination of omega-3 fatty acids and vitamin A can slow the progression of retinitis pigmentosa (RP) in adults, according to a study in the February 13 online edition of Archives of Ophthalmology.
Omega-3s appear to enhance Vitamin A, which slows down retinitis pigmentosa.
In this study, the researchers evaluated 357 patients with RP who took 15,000 IU of vitamin A per day for four to six years. The researchers instructed the patients to complete dietary questionnaires, which were used to gauge the participants’ average daily omega-3 fatty acid intake.
They determined that patients who had diets rich in long-chain omega-3 fatty acids (consumption of at least 0.20g per day) experienced a 40% slower decline in distance visual acuity and a nearly 50% slower decline in central visual field sensitivity than those with diets low or deficient in omega-3s.
The researchers concluded that, with adequate vitamin A supplementation and omega-3 fatty acid intake, patients with RP should be able to retain both visual acuity and central visual field function throughout most of their lives.
“A representative patient who starts receiving vitamin A by age 35 years and eats an omega-3-rich diet (e.g., one to two 3oz servings of oily fish per week) with an Early Treatment of Diabetic Retinopathy Study (ETDRS) acuity of 50 letters would, on average, be expected to decline to an ETDRS acuity of 24 letters at age 79—whereas, this patient receiving vitamin A with a low dietary omega-3 intake (e.g., less than one 3oz serving of oily fish per week) would decline to this level at age 61,” wrote the authors.
“Patients are advised to take vitamin A to replace their rods and eat oily fish to enhance delivery of vitamin A to cones,” says lead author Eliot L. Berson, M.D., professor of ophthalmology at Harvard Medical School and the Massachusetts Eye and Ear Infirmary in Boston, explaining in shorthand why it’s beneficial for RP patients to increase their intake of both vitamin A and omega-3 fatty acid.
Dr. Berson elaborates, “With respect to vitamin A, we and others have suggested that, under daylight conditions, rods give cones vitamin A via Mueller cells. Interphotoreceptor retinoid binding protein (IRBP) transports vitamin A between these cells, and the release of vitamin A from IRBP requires DHA [which is] present in oily fish.” He adds, “Rod degeneration leads to a deficiency of vitamin A and DHA. This could explain why vitamin A plus an oily fish diet benefits patients with RP.”
Berson EL, Rosner B, Sandberg MA, et al. ω-3 intake and visual acuity in patients with retinitis pigmentosa receiving vitamin A. Arch Ophthalmol. 2012 Feb 13. [Epub ahead of print]
