Table 3 Relative risk of MS according to updated cumulative average intake of vitamin D for NHS (1980–1998) and NHS II (1991–1999)

ParametersNHS*NHS II*Pooled*Pooled
Median IU/dCases/person-yRR (95% CI)Median IU/dCases/person-yRR (95% CI)RR (95% CI)RR (95% CI)
* Adjusted for age in 5-y groups.
† Further adjusted for smoking (never, <10 packs/y, 10–24 packs/y, 25+ packs/y) and latitude at birth.
MS = multiple sclerosis; NHS = Nurses’ Health Study; RR = relative risk.
Total vitamin D
    Quintile 18719/316,294Ref.13518/149,943Ref.Ref.Ref.
216715/322,4090.78 (0.40–1.54)22630/149,3091.68 (0.94–3.02)1.22 (0.79–1.88)1.23 (0.79–1.90)
325013/320,8970.70 (0.35–1.41)32618/150,5151.01 (0.52–1.94)0.85 (0.53–1.37)0.84 (0.52–1.35)
437322/321,2751.20 (0.65–2.19)46816/150,5780.92 (0.47–1.80)1.06 (0.68–1.66)1.03 (0.65–1.63)
55997/318,4060.41 (0.18–0.94)71415/149,7300.83 (0.41–1.67)0.61 (0.36–1.04)0.63 (0.37–1.07)
76/1,599,28197/750,075
    p trend0.160.130.040.05
    p heterogeneity0.92
    Vitamin D from food
    Quintile 17112/315,641Ref.11219/149,785Ref.Ref.Ref.
212324/322,0652.00 (1.00–3.99)17617/149,4430.90 (0.47–1.73)1.33 (0.83–2.11)1.33 (0.83–2.12)
316517/320,9881.46 (0.70–3.05)23031/150,8431.62 (0.92–2.87)1.56 (0.99–2.45)1.57 (1.00–2.47)
421410/321,8640.89 (0.39–2.03)29417/150,3090.89 (0.46–1.72)0.89 (0.53–1.49)0.89 (0.53–1.49)
529813/318,7231.15 (0.52–2.53)39913/149,6950.68 (0.33–1.39)0.86 (0.51–1.45)0.87 (0.52–1.47)
76/1,599,28197/750,075
    p trend0.530.290.220.22
    p heterogeneity0.75
Vitamin D from supplements, IU/d
    0043/784,669Ref.056/381,710Ref.Ref.Ref.
    < 40015229/600,0891.12 (0.69–1.81)20027/232,1360.81 (0.51–1.29)0.94 (0.68–1.32)0.99 (0.70–1.40)
    ≥ 4004004/214,5320.35 (0.13–0.98)40014/136,2290.70 (0.39–1.26)0.57 (0.34–0.94)0.58 (0.35–0.96)
76/1,599,28197/750,075
    p trend0.100.180.040.06
    p heterogeneity0.47