Association between dietary folic acid intake and diabetic retinopathy among patients with diabetes: An analysis of 2005-2008 NHANES data.

OBJECTIVES

Dietary folic acid (FA) intake may reduce homocysteine levels and alleviate oxidative stress, both of which are closely associated with the development and progression of diabetic retinopathy (DR). This study aims to investigate the association between dietary FA intake and DR among patients with diabetes aged ≥40 years in the United States.

METHODS

Data from the 2005-2008 National Health and Nutrition Examination Survey (NHANES) were used. The study population comprised 3 220 patients previously diagnosed with type 2 diabetes mellitus, after excluding patients with diabetes who had missing data on dietary FA intake or DR. Multivariable logistic regression was used to evaluate the association between dietary FA intake and the prevalence of DR, with subgroup analyses and interaction tests performed. Smooth curve fitting was used to explore the potential nonlinear relationship between dietary FA intake and DR.

RESULTS

After adjustment for potential confounders, higher dietary FA intake was significantly associated with a lower prevalence of DR (OR=0.394, 95% CI 0.193 to 0.804, P=0.011). Smooth curve fitting revealed a predominantly linear, inverse dose-response relationship between dietary FA intake and the odds of DR, with no significant non-linearity detected (P value for non-linearity=0.6535). Subgroup analyses demonstrated that the inverse association remained consistent across subgroups stratified by sex, age, body mass index (BMI), education level, smoking status, alcohol consumption, hypertension, and hypercholesterolemia (all P values for interaction >0.05).

CONCLUSIONS

Among adults with diabetes aged ≥40 years in the United States who were diagnosed clinically or based on biochemical testing, higher dietary FA intake is significantly associated with a lower prevalence of DR. Future prospective studies are needed to clarify the causal relationship and underlying mechanisms.