Association between dietary inflammatory index and adolescent myopia based on the National Health and Nutrition Examination Survey

The prevalence of adolescent myopia is remarkably increasing. Previous studies have indicated that an unhealthy diet is a risk factor for myopia. However, the link between diet-related inflammation and myopia is unclear. To explore their correlation, we used dietary inflammation index (DII) that is a parameter to quantify the inflammatory potential of diet, to reveal the relationship between DII and myopia in adolescents. We extracted sociodemographic data, information of diets and eye refractive status of adolescents from National Health and Nutrition Examination Survey (NHANES) for period 1999–2008. Dietary intake data was used to calculate DII scores, which were then categorized into quartiles. Multivariable regression models and subgroup analyses were conducted to investigate the association between DII and myopia. Subsequently, smoothed curve analyses were conducted to discern the trend of correlation between DII and myopia across diverse population. A total of 7191 juveniles aged at 12 to 18 years with complete information were included in our study, consisting 3367 participants with diagnosis of myopia. Among these participants, a trend towards an increasing prevalence of myopia was observed with a higher DII. After adjusting for all covariates, stratified logistic regression analyses showed that among the population aged in 16 to 18 years old or with 9-11th grade educational level, the prevalence of myopia was significantly increased with higher DII score (OR = 1.06, 95% CI = 1.01, 1.11, P = 0.006; OR = 1.06, 95% CI = 1.01, 1.11, P = 0.010). In the two subgroups, participants in the highest quartile of DII had a 31.00% higher risk of myopia and a higher 27.00% risk of myopia respectively, compared to those in the lowest quartile of DII. Our results revealed an increasing trend in the prevalence of myopia with increased DII score in adolescents. Particularly, DII was positively associated with the risk of myopia among the population aged in 16 to 18 years old and with 9-11th grade educational level.