TABLE 2.
HRs (95% CIs) for early menopause by cumulatively averaged vitamin D intake: NHS2 (1991–2011)1
| HR (95% CI) |
||||
| Vitamin D | Median, IU/d | Cases, n | Age-adjusted | Multivariable 12 |
| Total, quintile | ||||
| 1 | 145 | 438 | 1 | 1 |
| 2 | 241 | 392 | 0.86 (0.75, 0.99) | 0.89 (0.78, 1.02) |
| 3 | 341 | 419 | 0.90 (0.79, 1.03) | 0.95 (0.83, 1.08) |
| 4 | 474 | 399 | 0.89 (0.77, 1.02) | 0.94 (0.82, 1.07) |
| 5 | 695 | 393 | 0.95 (0.83, 1.09) | 0.99 (0.86, 1.13) |
| P-trend | — | — | 0.80 | 0.76 |
| RDA, IU/d | ||||
| <600 | 301 | 1711 | 1 | 1 |
| ≥600 | 721 | 330 | 1.02 (0.90, 1.15) | 1.02 (0.91, 1.15) |
| Dietary, quintile | ||||
| 1 | 148 | 441 | 1 | 1 |
| 2 | 232 | 424 | 0.94 (0.82, 1.07) | 0.97 (0.85, 1.11) |
| 3 | 301 | 375 | 0.81 (0.71, 0.93) | 0.85 (0.74, 0.98) |
| 4 | 383 | 441 | 0.96 (0.84, 1.09) | 1.01 (0.88, 1.15) |
| 5 | 528 | 360 | 0.79 (0.69, 0.91) | 0.83 (0.72, 0.95) |
| P-trend | — | — | <0.01 | 0.03 |
| From dairy sources | ||||
| 1 | 25 | 436 | 1 | 1 |
| 2 | 62 | 403 | 0.88 (0.77, 1.01) | 0.90 (0.79, 1.03) |
| 3 | 101 | 399 | 0.86 (0.75, 0.99) | 0.90 (0.78, 1.03) |
| 4 | 153 | 419 | 0.88 (0.77, 1.01) | 0.92 (0.80, 1.05) |
| 5 | 254 | 384 | 0.82 (0.71, 0.94) | 0.85 (0.74, 0.98) |
| P-trend | — | — | 0.02 | 0.06 |
| Nondairy dietary, quintile | ||||
| 1 | 46 | 436 | 1 | 1 |
| 2 | 75 | 421 | 0.96 (0.84, 1.10) | 1.02 (0.89, 1.16) |
| 3 | 101 | 401 | 0.93 (0.81, 1.07) | 0.99 (0.86, 1.14) |
| 4 | 135 | 397 | 0.93 (0.81, 1.06) | 0.98 (0.86, 1.13) |
| 5 | 196 | 386 | 0.94 (0.81, 1.07) | 0.97 (0.84, 1.12) |
| P-trend | — | — | 0.32 | 0.55 |
| Supplemental, IU/d | ||||
| 0 | 0 | 899 | 1 | 1 |
| 1–599 | 209 | 1102 | 1.01 (0.92, 1.11) | 1.04 (0.95, 1.15) |
| ≥600 | 800 | 40 | 1.30 (0.94, 1.78) | 1.29 (0.94, 1.77) |
| P-trend | — | — | 0.23 | 0.10 |
1
NHS2, Nurses’ Health Study II; RDA, Recommended Daily Allowance.
2
Multivariable Cox proportional hazards model adjusted for age, pack-years of smoking (0–10, 11–20, or ≥21), BMI (in kg/m2; <18.5, 18.5 to <25, 25 to <30, or ≥30), age at menarche (continuous), parity (nulliparous, 1–2, or ≥3), breastfeeding duration (months; continuous), physical activity (continuous metabolic equivalent task-hours per week), percentage of total calories from vegetable protein (quintiles 1–3 or 4 + 5), and alcohol intake (<10 or ≥10 g/d).