Table 2 Multivariate linear regression analysis of factors affecting vitamin D levels in Chinese college students (n = 3220)

Age

0.279

0.050

0.003

Gender

 Male

–

–

–

 Female

− 3.950

− 0.276

< 0.001

Students originally from

 City

–

–

–

 Town

1.150

0.059

0.002

 Countryside

1.744

0.115

< 0.001

Ethnicity

 The Han Ethnic

–

–

–

 The Hui Ethnic

− 0.226

− 0.003

0.854

 The Manchu Ethnic

− 0.138

− 0.001

0.930

 The Miao Ethnic

1.782

0.020

0.227

 The Uighur Ethnic

− 5.818

− 0.102

< 0.001

 The Zhuang Ethnic

− 2.776

− 0.024

0.159

 The Kazak Ethnic

− 5.824

− 0.035

0.045

 Other minorities

− 0.552

− 0.011

0.535

Latitude (northern hemisphere)

− 0.114

− 0.060

0.001

Longitude (eastern hemisphere)

− 0.073

− 0.081

0.003