Diet, Physical Activity, and UV Protection Comprehensively Influenced Vitamin D Status: A Cross-Section Study of Chinese College Students

Abstract Background: Vitamin D deficiency is a major public health problem in China while there are seldom reports about vitamin D nutrition status in Chinese college students. The purpose of this study is to explore the vitamin D status of the college freshmen who came from different provinces of China and to comprehensive analyze the effects of diet, physical activity, and UV protection on serum vitamin D levels. Methods: Totally 1,667 freshmen who came from 26 provinces, autonomous districts or municipalities, were recruited into this study. An online questionnaire was used to collect the information including demographic status, diet habit, physical activity, and UV protection of the participants. Serum 25(OH)D3 concentrations were measured using a liquid chromatograph mass spectrometer. Multivariate linear regression analyses were used to explore the comprehensive influence of diet, physical activity, and UV protection on serum 25(OH)D3 levels. Results: The average age of the subjects was18.55±0.90 years, with 23.0% male and 77.0% female. The mean serum 25(OH)D3 was 18.06±6.34ng/mL and the proportion of vitamin D deficiency and insufficiency was 67.5% and 27.8%, respectively. Multivariate linear regression indicated that milk and yogurt intake≥200mL/d, calcium or vitamin D supplements and average time of outdoor activity ≥60 min/day were positively linked to higher serum vitamin D while sweets intake ≥10g/d and higher UV protection index were negatively influenced serum vitamin D after adjusted for age, gender, students’ original residence, latitudes and longitude. Conclusions: Vitamin D deficiency is an important health problem in Chinese college students. Milk and yogurt intake and outdoor activity should be encouraged while sweets intake should be limited for preventing vitamin D deficiency. Public health policies should consider well-balanced guidelines on UV protection and vitamin D food fortification or supplementation.