Table 4 Mean plasma 25-hydroxyvitamin D concentrations and standard deviations (SDs) by sex, age group, and season in 8497 participants providing blood samples

 Men

3710

56.5

18.4

< 0.0001

 Women

4787

45.4

16.5

 < 49

1489

42.9

17.6

Reference

 50–59

2345

47.7

17.7

< 0.0001

 60–69

3400

53.7

17.9

< 0.0001

 ≥ 70

1263

54.5

17.0

< 0.0001

 Spring (Mar–May)

1905

44.9

17.4

Reference

 Summer (Jun–Aug)

3890

50.8

17.6

< 0.0001

 Autumn (Sep–Nov)

2375

53.9

18.6

< 0.0001

 Winter (Dec–Feb)

327

48.8

19.5

0.0047