London: Eating oily fish twice a week may decrease the risk of sight-threatening diabetic retinopathy in middle-aged and older individuals with type 2 diabetes, a new study has claimed.
The increasing prevalence of type 2 diabetes mellitus, coupled with an increased lifespan, has resulted in a steady rise of disability in older individuals with diabetes.
A major concern for this population group is diabetic retinopathy (DR), a leading global cause of vision loss.
The retina is rich in long-chain omega-3 polyunsaturated fatty acids (LC omega-3 PUFAs). Experimental models support dietary LC omega-3 PUFA protection against DR, but clinical data is lacking, researchers said.
Aleix Sala-Vila from Lipid Clinic in Barcelona and colleagues conducted a prospective study testing Mediterranean diets supplemented with extra virgin olive oil or nuts versus a control diet for primary cardiovascular prevention.
The trial was conducted in primary health care centres in Spain. From 2003 to 2009, 3,614 individuals aged 55 to 80 years with a previous diagnosis of type 2 diabetes were recruited.
Meeting the dietary LC omega-3 PUFA recommendation of at least 500 milligrammes per day (mg/d) for primary cardiovascular prevention was assessed by a validated food-frequency questionnaire.
Of the participants, a total of 2,611 (75 per cent) met the target LC omega-3 PUFA recommendation. During a median follow-up of 6 years, incident DR was diagnosed in 69 of the study participants.
After adjusting for age, sex, intervention group, and lifestyle and clinical variables, participants meeting the LC omega-3 PUFA recommendation at baseline (500 mg/d or greater) compared with those not fulfilling this recommendation (less than 500 mg/d) showed a 48 per cent relatively reduced risk of incident sight-threatening DR.
Researchers found that in middle-aged and older individuals with type 2 diabetes, intake of at least 500 mg/d of dietary LC omega-3 PUFA, easily achievable with 2 weekly servings of oily fish, was associated with a decreased risk of sight-threatening diabetic retinopathy.
"Our findings, which are consistent with the current model of the pathogenesis of DR and data from experimental models, add to the notion of fish-derived LC omega-3 PUFA as a healthy fat," researchers said.
The findings were published in the journal JAMA Ophthalmol.