Table 2.
Multivariable adjusted mean mammographic density at baseline by level of vitamin D and calcium intake in the Women's Health Initiative Mammogram Density Study (n = 808).
| Percent Density (95% Confidence Interval) |
|||||
|---|---|---|---|---|---|
| Nutrient | n | Age-adjusted | Model 1 | Model 2 | Model 3 |
| Total Vitamin D intake (IU/day) | |||||
| < 100 | 170 | 6.3 (4.6, 7.9) | 5.4 (3.5, 7.3) | 5.6 (3.4, 7.8) | 5.8 (3.6, 8.0) |
| 100 – 199 | 262 | 9.3 (7.2, 11.3) | 9.8 (7.7, 12.0) | 10.1 (7.9, 12.4) | 10.4 (8.1, 12.6) |
| 200 – 399 | 137 | 6.9 (5.1, 8.7) | 6.2 (4.1, 8.2) | 6.1 (3.9, 8.3) | 6.2 (4.1, 8.3) |
| 400 – 599 | 147 | 4.7 (3.5, 5.8) | 4.0 (2.0, 6.1) | 3.8 (1.7, 5.9) | 3.8 (1.6, 6.0) |
| ≥ 600 | 92 | 6.9 (4.7, 9.1) | 5.7 (3.1, 8.3) | 5.2 (2.2, 8.2) | 5.1 (2.1, 8.1) |
| P = 0.28 | P = 0.96 | P = 0.66 | P = 0.67 | ||
| Vitamin D from food sources (IU/day) | |||||
| < 100 | 249 | 5.8 (4.6, 7.1) | 4.5 (3.1, 5.9) | 4.5 (3.0, 6.1) | 4.6 (3.0, 6.1) |
| 100 – 150 | 236 | 6.8 (5.2, 8.4) | 7.1 (5.5, 8.7) | 7.2 (5.6, 8.8) | 7.3 (5.6, 8.9) |
| 150 – 199 | 139 | 10.2 (7.3, 13.0) | 9.2 (6.8, 11.6) | 9.2 (6.9, 11.6) | 9.4 (7.1, 11.7) |
| ≥ 200 | 184 | 6.2 (4.8, 7.6) | 6.0 (4.4, 7.7) | 6.1 (4.3, 7.8) | 6.2 (4.5, 7.9) |
| P = 0.11 | P = 0.13 | P = 0.06 | P = 0.05 | ||
| Vitamin D from supplements only | |||||
| No | 563 | 7.8 (6.6, 9.0) | 7.7 (5.9, 9.5) | 7.7 (5.8, 9.5) | 7.5 (5.8, 9.3) |
| Yes | 285 | 5.9 (4.8, 7.0) | 5.1 (3.2, 7.0) | 5.1 (3.0, 7.1) | 5.5 (3.5, 7.5) |
| P = 0.15 | P = 0.66 | P = 0.97 | P = 0.96 | ||
| Total calcium intake (mg/day) | |||||
| < 500 | 155 | 7.0 (4.9, 9.1) | 6.9 (4.8, 9.0) | 7.2 (5.0, 9.3) | 7.3 (5.1, 9.5) |
| 500 – 749 | 235 | 5.8 (4.5, 7.1) | 5.6 (4.2, 6.9) | 4.9 (3.5, 6.4) | 4.9 (3.4, 6.4) |
| 750 – 999 | 168 | 8.4 (6.3, 10.5) | 7.8 (5.8, 9.9) | 7.4 (5.5, 9.3) | 7.3 (5.5, 9.1) |
| 1000 – 1199 | 82 | 6.8 (4.5, 9.1) | 6.1 (3.5, 8.6) | 6.5 (3.8, 9.3) | 6.9 (4.1, 9.6) |
| ≥ 1200 | 168 | 6.8 (5.2, 8.5) | 6.4 (4.7, 8.1) | 6.8 (4.9, 8.7) | 7.1 (5.2, 9.0) |
| P = 0.59 | P = 0.42 | P = 0.41 | P = 0.51 | ||
| Calcium from food sources (mg/day) | |||||
| < 500 | 210 | 6.9 (5.3, 8.4) | 6.2 (4.6, 7.9) | 6.6 (4.9, 8.2) | 6.7 (5.0, 8.3) |
| 500 – 649 | 194 | 5.8 (4.3, 7.3) | 5.4 (3.7, 7.0) | 5.0 (3.4, 6.6) | 5.0 (3.4, 6.6) |
| 650 – 799 | 140 | 7.1 (5.1, 9.1) | 6.6 (4.5, 8.7) | 6.2 (4.2, 8.2) | 6.1 (4.1, 8.1) |
| ≥ 800 | 264 | 7.7 (6.1, 9.2) | 7.3 (5.8, 8.8) | 7.4 (5.9, 9.0) | 7.6 (6.1, 9.1) |
| P = 0.60 | P = 0.85 | P = 0.85 | P = 0.72 | ||
| Calcium from supplements | |||||
| None | 512 | 7.4 (6.2, 8.7) | 7.0 (5.5, 8.5) | 6.2 (4.9, 7.6) | 6.3 (5.0, 7.6) |
| < 500 | 197 | 6.6 (5.1, 8.0) | 6.4 (4.7, 8.2) | 6.9 (5.2, 8.6) | 7.1 (5.4, 8.7) |
| ≥ 500 | 139 | 6.6 (4.8, 8.3) | 5.9 (4.0, 7.7) | 6.5 (4.6, 8.5) | 6.6 (4.7, 8.6) |
| P = 0.39 | P = 0.48 | P = 0.94 | P = 0.95 | ||
Model 1 is adjusted for age, race/ethnicity, body mass index, age at menarche, parity, oral contraceptive use and duration, previous HT use/duration, HT trial randomization assignment, family history of breast cancer, education, alcohol intake, smoking, total calorie intake, physical activity, Gail risk, and use of multivitamins.
Model 2 is adjusted for all covariates in Model 1. In addition, vitamin D is adjusted for total calcium and vice-versa, and nutrients from food sources are adjusted for nutrient from supplemental sources and vice-versa.
Model 3 is adjusted for all covariates in Model 2 plus solar irradiation and season of mammogram.