Do Fatty Acids Lower Diabetic Retinopathy Risk?

Greater intake of dietary omega-3 fatty acids can lower the risk of diabetic retinopathy among patients with type 2 diabetes mellitus (DM), according to a new study.¹

In middle-aged and older individuals with T2DM, intake of at least 500 mg per day of dietary long-chain ω3 polyunsaturated fatty acids, easily achievable with 2 weekly servings of oily fish, is associated with a decreased risk of sight-threatening diabetic retinopathy, state the researchers, led by Aleix Sala-Vila, DPharm, PhD, of the Lipid Clinic, Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.

Diabetic retinopathy is a common complication of T2DM. The researchers note that the retina is rich in long-chain ω-3 polyunsaturated fatty acids. Experimental models show these fatty acids protect against diabetic retinopathy, but clinical data are lacking.

The researchers conducted a prospective study within the randomized clinical trial Prevencion con Dieta Mediterranea (PREDIMED), testing Mediterranean diets supplemented with extra virgin olive oil or nuts against a control diet for primary cardiovascular prevention.

The study was conducted in primary health care centers in Spain and included 3,614 individuals age 55 to 80 years with a previous diagnosis of T2DM; full data were available for 3,482 participants, average age 67 years.

A validated food-frequency questionnaire assessed whether the participants met the recommendation of at least 500 mg per day of long-chain ω-3 polyunsaturated fatty acids for primary cardiovascular prevention. The main outcome was incident diabetic retinopathy requiring laser photocoagulation, vitrectomy, and/or antiangiogenic therapy confirmed by an external adjudication committee.

The results show that a total of 2,611 (75%) of the participants met the target dietary intake recommendation. During a median follow-up of 6 years, the researchers diagnosed 69 cases of diabetic retinopathy.

After adjusting for age, sex, intervention group, and lifestyle and clinical variables, those who met the dietary recommendation at baseline showed a 48% relatively reduced risk of incident sight-threatening diabetic retinopathy compared with those who did not fulfill this recommendation.

“Higher risk reductions were observed in participants with hypertension, those with diabetes of greater than 5 years' duration, and those treated with insulin at baseline,” according to the researchers.

The findings are consistent with the current model of the pathogenesis of diabetic retinopathy and data from experimental models, and add to the notion of fish-derived long-chain ω-3 polyunsaturated fatty acids as a healthy fat, the researchers state.

They add that the findings “support the view that regular consumption of oily fish might be beneficial to delay the onset or progression of vascular diseases in arterial beds other than the coronary and cerebrovascular ones.”

In an accompanying editorial, Michael Larsen, MD, DMSc, department of ophthalmology, Rigshospitalet-Glostrup and University of Copenhagen in Glostrup, Denmark, notes that the study was conducted in Spain, primarily in large urban centers where fish is a staple.²

“Fish and nuts are already part of the food culture, available in every supermarket, cafeteria, and restaurant and in most households. The potential value of a large-scale switch to a diet rich in [omega-3] fatty acids merits serious attention.”

References:

1. Sala-Vila A, et al. Dietary marine ω-3 fatty acids and incident sight-threatening retinopathy in middle-aged and older individuals with type 2 diabetes: prospective investigation from the PREDIMED trial. JAMA Ophthalmol. 2016 Aug 18.

2. Larsen M. Eat your fish or go for nuts. JAMA Ophthalmol. 2016 Aug 18.