Knowledge, attitudes, and practices regarding vitamin D among university students in Quzhou, China: a cross-sectional study

BACKGROUND: Vitamin D deficiency remains common in China, yet recent evidence on university students is limited. METHODS: We conducted a cross-sectional online survey among 397 undergraduates at Quzhou University from November to December 2025 using convenience sampling. A validated questionnaire assessed vitamin D knowledge, attitudes, and practices (KAP) with pre-specified adequacy thresholds (knowledge ≥6/11; attitude ≥3/5; practice ≥4/7). Associations with good practice were examined using logistic regression; item-level subgroup contrasts were explored by sex, attitude, and monthly pocket money. RESULTS: Awareness of vitamin D, defined as prior recognition of vitamin D, was universal (100%). Only 58.4% (232/397) had adequate knowledge; 66.8% (265/397) had a positive attitude; and 69.5% (276/397) achieved good practice. In multivariable models, women had lower odds of good practice than men (OR 0.57, 95% CI 0.35-0.90); monthly pocket money ≥2000 RMB was associated with higher odds of good practice (OR 3.74, 95% CI 1.70-8.24); and a positive attitude was independently associated with good practice (OR 3.02, 95% CI 1.91-4.79). Knowledge adequacy was not independently associated with practice. Item-level gaps clustered in sun-related behaviors (less daily outdoor walking, <15 min/day exposure, and sun-protection factor use), particularly among women, students with non-positive attitudes, and those with lower pocket money. CONCLUSION: Vitamin D KAP was suboptimal in this single-university sample in China. Practice was associated with sex, attitude, and economic means, but not knowledge adequacy alone. Future practice-oriented strategies may prioritize safe sun exposure, affordable supplementation, and on-campus testing for women, economically disadvantaged students, and students with non-positive attitudes.