Dietary vitamin B1 intake and stroke risk in U.S. adults: Insights from a nationally representative health examination survey.

Stroke imposes a substantial global burden of mortality and long-term disability, and its occurrence is driven by diverse vascular risk factors. As an essential micronutrient, vitamin B1 (thiamin) has been implicated in cardiovascular protection, yet whether habitual dietary intake of this vitamin relates to stroke occurrence remains incompletely understood. The present study therefore examined the association between dietary vitamin B1 intake and stroke risk using nationally representative data from the National Health and Nutrition Examination Survey. This cross-sectional analysis included 11,750 participants aged 20 years or older drawn from the National Health and Nutrition Examination Survey cycles of 2005 to 2018. Dietary vitamin B1 intake was divided into quartiles, and stroke status was ascertained from self-reported physician diagnoses. Weighted multivariable logistic regression models, adjusted sequentially for demographic, behavioral, and clinical covariates, were fitted to estimate odds ratios for stroke across intake levels, and restricted cubic spline regression was used to characterize the dose-response pattern. Least absolute shrinkage and selection operator regression was further applied to screen predictors for a stroke risk prediction model. An inverse association was observed between dietary vitamin B1 intake and stroke. In the fully adjusted model, participants in the highest intake quartile had 44% lower odds of stroke than those in the lowest quartile (odds ratio = 0.56, 95% CI: 0.41-0.89), and this inverse gradient remained materially consistent across strata of sex, age, race/ethnicity, and major clinical conditions. Dose-response modeling revealed a nonlinear pattern in which stroke odds declined steeply until intake reached approximately 1.58 mg/d, after which the decline became more gradual. A prediction model built on least absolute shrinkage and selection operator-selected clinical variables, including vitamin B1, achieved an area under the receiver operating characteristic curve of 0.771. In this nationally representative sample of U.S. adults, greater dietary vitamin B1 intake was independently associated with lower odds of stroke, lending support to a potential cerebrovascular benefit of thiamin. Prospective cohort and interventional studies are warranted to confirm this association and to elucidate the biological pathways involved.