BackgroundAbnormalities in lipid metabolism are common among adult asthmatics. However, the precise directionality linking asthma to blood lipid levels remains controversial. Our study aimed to evaluate the association between the Non-HDL to HDL Ratio (NHHR), a lipid composite index, and asthma prevalence among the adult population in the United States.MethodsUtilizing adult participants’ data from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2009 to 2018, the study employed a multivariable logistic regression model, adjusting for covariables, to establish the relationship between NHHR levels and the prevalence of asthma. Furthermore, smoothing curve fitting and subgroup analyses were conducted to investigate the robustness of this association.ResultsThis study included 26,023 adult individuals (mean age = 49.63 ± 17.66). In the fully adjusted model, a significant inverse association was observed between log-transformed NHHR values and asthma prevalence (OR = 0.85, 95% CI: 0.79–0.93). Subgroup analysis revealed that gender served as a modulator, altering the association between NHHR levels and asthma prevalence. A more pronounced negative association between lnNHHR and asthma prevalence was noted among male participants [(Male: OR = 0.78, 95% CI: 0.69–0.88) vs. (Female: OR = 0.92, 95% CI: 0.83–1.03), P for interaction = 0.0313].ConclusionsOur study revealed an inverse association between NHHR levels and the prevalence of asthma in the US adult population, which is influenced by gender. NHHR measurement may be a potential tool for early identification and prediction of adult asthmatics in specific populations.