In a recent study published in Scientific Reports, researchers examined the relationship between dietary fatty acid (FA) intake and diabetic retinopathy (DR).
Diabetic retinopathy, the leading cause of visual impairment in working adults, is a common microvascular complication of diabetes. Risk factors include prolonged duration, poor glycemic control, elevated blood pressure, and high lipid intake. Studies have shown that polyunsaturated fatty acids (PUFAs) have beneficial effects on diabetes-associated complications.
Omega-3 fatty acid supplementation has been shown to modify cardiovascular and metabolic biomarkers, glycemia, lipids, and inflammatory cytokine levels among individuals with diabetes mellitus type 2.
A randomized clinical trial (RCT) showed that omega-3 supplements delayed albuminuria progression among type 2 diabetics and those with prior coronary artery disease (CAD) history. However, studies on the relationship between FA consumption and diabetic retinopathy have reported inconsistent findings, particularly among Asians.
About the study
In the present cross-sectional ophthalmological survey-based study, researchers investigated whether fatty acid consumption impacted the risk of developing diabetic retinopathy among Japanese individuals.
Chikusei City residents, aged between 40 and 74 years, were subjected to ophthalmological and systemic screening, and diabetic individuals who participated in the Japanese Public Health Center-Prospective Study for the Next Generation (JPHC-NEXT) were analyzed.
Food consumption was evaluated using food frequency questionnaires (FFQs) and expressed as a proportion of caloric intake. Non-mydriatic fundus images of human eyes were obtained using a 45° camera.
Serum samples were obtained to measure blood glucose, glycated hemoglobin (HbA1c), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and total cholesterol (TC) levels. DR was described based on Early Treatment Diabetic Retinopathy Study (ETDRS) levels ≥ 20.0 in the right or left eye.
Multivariate logistic regression modeling was performed, and odds ratios (ORs) were calculated, adjusting for covariates such as age, body mass index (BMI), caloric intake, sex, alcohol intake, smoking status, glycated hemoglobin, dyslipidemia, systolic blood pressure (SBP), vitamin intakes (beta-carotene, ascorbic acid, vitamin D, and α-tocopherol), and creatinine.
A subgroup analysis was performed by stratifying the results by poorly controlled (HbA1c greater than or equal to 7.0%) and well-controlled (HbA1C below 7.0%) diabetes. In total, 14 individuals with missing or poor-resolution fundus images were excluded from the analysis. DR prevalence was determined by two ophthalmologists, and disagreements were resolved by a retinal specialist consultation.
Out of 647 individuals with type 2 diabetes, 100 also suffered from diabetic retinopathy. Of 7,090 individuals who participated in the survey from 2013 to 2015, 80% (n=5,691) completed the FFQs. The mean percentages for the saturated FA (SFA) and total fatty acid consumption were seven percent and 22% of TC intake (2,293 kilocalories), respectively.
The highest statistical quartiles for the total fatty acid and saturated fatty acid intakes showed positive associations with DR prevalence compared to the lowest statistical quartiles (ORs, 2.6 and 2.4, respectively).
There were no statistically significant relationships between diabetic retinopathy prevalence and the consumption of monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), omega-3 PUFA, and n-6 PUFA. In addition, the differences in total caloric consumption between individuals with and without diabetic retinopathy were non-significant. However, the consumption of total fat, saturated fatty acid, polyunsaturated fatty acid, and n-6 polyunsaturated fatty acids was significantly higher among individuals with DR compared to the intake among non-DR individuals.
DR patients had higher HbA1c values and protein consumption, lower serum triglyceride (TG) levels, less dyslipidemia, and were less likely to be current drinkers. Among well-controlled diabetic patients, an increased saturated fatty acid intake tended to be related to increased odds of developing diabetic retinopathy. Among poorly controlled diabetics, a similar tendency but a weaker association was observed.
Overall, the study findings showed that a high diet of total fat and saturated fatty acids may raise DR risk in diabetic patients, even though their total fat consumption is substantially lower than that of the Western population.
The findings are consistent with World Health Organization (WHO) recommendations that total fat should be ≤30% of total caloric and SFA intake should be below 10%, with a shift in fat consumption away from SFA and toward unsaturated fatty acid for the general population.
Although prospective long-term studies are required to corroborate this discovery, the findings could improve the understanding of the probable function of dietary fatty acid consumption in diabetes and DR management.