| NHS cases | Person-years | Age-adjusted RR (95% CI) | Multivariable RR (95% CI)† | NHSII cases | Person-years | Age-adjusted RR (95% CI) | Multivariable RR (95% CI)† | NHS & NHSII Pooled MV RR‡ | ||||
| Total vitamin D intake (IU/day)* | ||||||||||||
| Quintile 1 | 96 | 367 312 | 1.0 (Ref.) | 1.0 (Ref.) | 42 | 221 349 | 1.0 (Ref.) | 1.0 (Ref.) | 1.0 (Ref.) | |||
| Quintile 2 | 109 | 369 718 | 1.1 (0.9, 1.5) | 1.1 (0.8, 1.4) | 38 | 221 355 | 0.9 (0.6, 1.4) | 0.9 (0.6, 1.4) | 1.0 (0.8, 1.3) | |||
| Quintile 3 | 118 | 368 993 | 1.2 (0.9, 1.6) | 1.1 (0.9, 1.5) | 27 | 222 806 | 0.7 (0.4, 1.1) | 0.7 (0.4, 1.1) | 0.9 (0.6, 1.5) | |||
| Quintile 4 | 123 | 366 770 | 1.3 (1.0, 1.7) | 1.2 (0.9, 1.5) | 25 | 222 500 | 0.6 (0.4, 1.0) | 0.6 (0.4, 1.1) | 0.9 (0.5, 1.6) | |||
| Quintile 5 | 113 | 360 501 | 1.2 (0.9, 1.6) | 1.1 (0.8, 1.5) | 31 | 220 604 | 0.7 (0.5, 1.2) | 0.8 (0.5, 1.3) | 1.0 (0.8, 1.3) | |||
| p for trend¶ | 0.3 | 0.4 | 0.1 | 0.3 | 0.9 | |||||||
| Vitamin D intake from supplements only (IU/day)§ | ||||||||||||
| 0 | 275 | 873 548 | 1.0 (Ref.) | 1.0 (Ref.) | 73 | 491 260 | 1.0 (Ref.) | 1.0 (Ref.) | 1.0 (Ref.) | |||
| 1–199 | 115 | 433 721 | 0.8 (0.6, 1.0) | 0.6 (0.5, 0.8) | 34 | 225 836 | 0.9 (0.6, 1.3) | 1.1 (0.7, 1.8) | 0.8 (0.5, 1.5) | |||
| 200–399 | 98 | 326 721 | 0.9 (0.7, 1.1) | 0.7 (0.5, 1.0) | 28 | 218 858 | 0.8 (0.5, 1.3) | 1.5 (0.8, 2.8) | 1.0 (0.5, 2.0) | |||
| >400 | 71 | 326 541 | 1.0 (0.9, 1.5) | 1.0 (0.6, 1.5) | 28 | 172 659 | 1.1 (0.7, 1.8) | 2.3 (1.1, 5.1) | 1.4 (0.6, 3.3) | |||
| p for trend¶ | 0.7 | 0.5 | 0.8 | 0.04* | 0.6 | |||||||
*Cumulative average of vitamin D intake from food and supplements, in quintiles.
NHS quintile cut-offs: 1 = 2–160.3; 2 = >160.25–234.4; 3 = >234.4–333.6; 4 = >333.6–489.1; 5 = >489.1–3964.8.
NHSII quintile cut-offs: 1 = 3–187.9; 2 = >187.9–280.9; 3 = >280.9–392.0; 4 = >392.0–558.7; 5 = >558.7–5203.0.
†Multivariable model adjusted for: age at menarche, oral contraceptive use, parity, duration of breast-feeding, menopausal status, postmenopausal hormone use, cigarette smoking, latitude of residence at age 15 (north, middle or south USA), physical activity, BMI, and race.
‡Risk estimates pooled using Dersimonian and Laird random effects model. p heterogeneity for all models <0.05.
§Also adjusted for vitamin D intake from food in multivariable models.
¶p for trend is from the midpoint of the categories in both age-adjusted and multivariable models.
NHS, Nurses' Health Study; NHSII, Nurses' Health Study II.