Geographic location and ethnicity comprehensively influenced vitamin D status in college students: a cross-section study from China.

Background: Vitamin D plays an important role in the health of adolescents, whereas vitamin D status of Chinese college students was seldom studied in China. To explore the vitamin D status and its relationship with ethnicity and geographic location in Chinese college students.

Methods: The freshmen were taken a physical examination by trained medical personnel after they reported to university. Demographic information including age, gender, ethnicity, region of original residence was collected using a questionnaire survey. Serum 25(OH)D concentrations were measured using a liquid chromatograph mass spectrometer. Multiple regression analyses were used to explore the factors that influence serum 25(OH)D levels.

Results: Totally 3220 freshmen who came from 26 provinces, autonomous districts or municipalities were recruited, with a mean age of 18.75 ± 1.18 years and 70.2% of them were female. The mean serum 25(OH)D levels were 18.51 ± 6.54 ng/mL, and the proportion of vitamin D deficiency (< 20 ng/mL) and insufficiency (20 ~  < 30 ng/mL) was 64.4% and 30.2%, respectively. The combined proportion of vitamin D deficiency and insufficiency was increased with the latitude increased. Miao had the highest serum 25(OH)D levels, whereas Kazak ethnic had the lowest (22.51 ng/mL vs. 13.94 ng/mL) among different ethnic groups. Female students, students from city, Uighur and Kazak ethnic, residing in high latitude was significantly associated with lower serum 25(OH)D levels (P < 0.05).

Conclusions: Vitamin D deficiency is an important health problem in Chinese college students. Sunlight activities, dietary and life-style intervention for college students according to geographic location and ethnicities should be considered.