Here are some studies demonstrating sex differences in vitamin D status:
Heritability and Environmental Factors Affecting Vitamin D Status in Rural Chinese Adolescent Twins (2009)
Conclusion: This study of Chinese adolescents found that males had slightly higher vitamin D levels than females, those who engaged in lots of physical activity had higher vitamin D levels, and that vitamin D levels increased in the summertime. “25(OH)D level was influenced by gender, season, and physical activity level.”
Conclusion: 269 elderly people living in retirement homes were evaluated for their vitamin D levels their physical performance in isometric strength tests and a 6-minute walking test. The rate of vitamin D-deficiency was significantly higher in the women than in the men and vitamin D status was significantly correlated with physical performance in the female subjects. Among the women, those with the lower vitamin D levels demonstrated lower arm and leg muscle strength and reported more disability than those with higher vitamin D levels. The study also found that vitamin D levels were significantly lower in the winter for everyone.