Association between dietary thiamin, riboflavin and niacin intake and hypertension and increased pulse pressure: A cross-sectional study of the National Health and Nutrition Examination Survey 1999-2023.

This cross-sectional study aimed to examine the associations between total intake of 3 B vitamins (thiamin, riboflavin, niacin) and hypertension and increased pulse pressure in U.S. adults, and to explore potential nonlinear relationships.Data from the U.S. National Health and Nutrition Examination Survey (NHANES) 1999-2023 were analyzed. A total of 17,484 participants aged ≥ 20 years were included. Total vitamin intake (diet plus supplements) was categorized into quartiles. Hypertension was defined as SBP ≥ 140 mm Hg or DBP ≥ 90 mm Hg; increased pulse pressure as PP ≥ 60 mm Hg. Multivariable logistic regression and restricted cubic spline (RCS) models were used, adjusting for demographic, socioeconomic, and clinical factors.In fully adjusted models, the highest quartile of total thiamin (OR 1.17, 95% CI 1.04-1.31), riboflavin (OR 1.23, 95% CI 1.10-1.39), and niacin (OR 1.16, 95% CI 1.03-1.30) intake was positively associated with hypertension (P-trend < 0.05 for all). Conversely, only riboflavin was inversely associated with increased pulse pressure (OR 0.84, 95% CI 0.75-0.94). RCS analysis revealed a J-shaped nonlinear association between niacin intake and hypertension (P-nonlinear = 0.041), with the lowest risk observed at 30-40 mg/day. A suggestive inflection point was identified at 46.163 mg/day (P = .087). No clear thresholds were found for thiamin or riboflavin. Subgroup analyses showed largely consistent associations.This study suggests that high total intake of B vitamins may be associated with higher odds of hypertension, while riboflavin may be inversely associated with pulse pressure. The findings highlight the importance of considering total nutrient intake and caution against excessive supplementation. However, as a cross-sectional analysis, causality cannot be inferred, and residual confounding cannot be ruled out.