Do dietary long-chain ω-3 fatty acids protect against diabetic retinopathy?
A substudy of the PREDIMED randomized clinical trial analyzed as an observational longitudinal cohort, considering only participants with type 2 diabetes at baseline, showed after median follow-up of 6 years that those reporting intake of at least 500 mg/d of long-chain ω-3 fatty acids at baseline had a 46% decreased risk of sight-threatening diabetic retinopathy compared to those not meeting this target.
Results suggest fish-derived long-chain ω-3 fatty acids are a healthy fat in this cohort.
Diabetic retinopathy (DR) is a devastating complication of individuals with type 2 diabetes mellitus. The retina is rich in long-chain ω-3 polyunsaturated fatty acids (LCω3PUFAs), which are substrate for oxylipins with anti-inflammatory and antiangiogenic properties. Experimental models support dietary LCω3PUFA protection against DR, but clinical data are lacking.
To determine whether LCω3PUFA intake relates to a decreased incidence of sight-threatening DR in individuals with type 2 diabetes older than 55 years.
Design, Setting, and Participants
In late 2015, we conceived a prospective study within the randomized clinical trial Prevención con Dieta Mediterránea (PREDIMED), testing Mediterranean diets supplemented with extra virgin olive oil or nuts vs a control diet for primary cardiovascular prevention. The trial was conducted in primary health care centers in Spain. From 2003 to 2009, 3614 individuals aged 55 to 80 years with a previous diagnosis of type 2 diabetes were recruited. Full data were available for 3482 participants (48% men; mean age 67 years).
Meeting the dietary LCω3PUFA recommendation of at least 500 mg/d for primary cardiovascular prevention, as assessed by a validated food-frequency questionnaire.
Main Outcomes and Measures
The main outcome was incident DR requiring laser photocoagulation, vitrectomy, and/or antiangiogenic therapy confirmed by an external adjudication committee.
Of the 3482 participants, 48% were men and the mean age was 67 years. A total of 2611 participants (75%) met target LCω3PUFA recommendation. During a median follow-up of 6 years, we documented 69 new events. After adjusting for age, sex, intervention group, and lifestyle and clinical variables, participants meeting the LCω3PUFA recommendation at baseline (≥500 mg/d) compared with those not fulfilling this recommendation (<500 mg/d) showed a 48% relatively reduced risk of incident sight-threatening DR, with a hazard ratio of 0.52 (95% CI, 0.31-0.88; P = .001). This association was slightly stronger for yearly updated LCω3PUFA intake (relative risk, 0.48; 95% CI, 0.28-0.82; P = .007).
Conclusions and Relevance
In middle-aged and older individuals with type 2 diabetes, intake of at least 500 mg/d of dietary LCω3PUFA, easily achievable with 2 weekly servings of oily fish, is associated with a decreased risk of sight-threatening DR. Our results concur with findings from experimental models and the current model of DR pathogenesis.
clinicaltrials.gov Identifier: http://www.controlled-trials.com/ISRCTN35739639
Sala-Vila A, Díaz-López A, Valls-Pedret C, Cofán M, García-Layana A, Lamuela-Raventós R, Castañer O, Zanon-Moreno V, Martinez-Gonzalez MA, Toledo E, Basora J, Salas-Salvadó J, Corella D, Gómez-Gracia E, Fiol M, Estruch R, Lapetra J, Fitó M, Arós F, Serra-Majem L, Pintó X, Ros E, for the Prevención con Dieta Mediterránea (PREDIMED) Investigators. Dietary Marine ω-3 Fatty Acids and Incident Sight-Threatening Retinopathy in Middle-Aged and Older Individuals With Type 2 DiabetesProspective Investigation From the PREDIMED Trial. JAMA Ophthalmol. 2016;134(10):1142-1149. doi:10.1001/jamaophthalmol.2016.2906