Table 1.
Factors contributing to serum 25 (OH) D in a prediction model
| Factor | Change in 25(OH)D, ng/ml |
|---|---|
| Intercept | 25.4 |
| Race | |
| White | 0 (referent) |
| Black | −11.16 |
| Dietary vitamin D | |
| < 100IU/day | 0 (referent) |
| 100–199 IU/day* | 0.47 |
| 200–299 IU/day | 1.98 |
| 300–399 IU/day | 3.36 |
| ≥ 400 IU/day | 3.87 |
| Vitamin D from supplements | |
| No | 0 (referent) |
| Yes | 2.92 |
| Season of blood draw | |
| Fall (Sept., Oct., Nov.) | 0 (referent) |
| Winter (Dec, Jan., Feb.) | −3.63 |
| Spring (March, Apr., May) | −2.79 |
| Summer (June, July, Aug.)* | 1.03 |
| UV-B flux | |
| >113 | 0 (referent) |
| 113 | −2.83 |
| <113* | −1.22 |
| Physical activity | |
| Quintile5 | 0 (referent) |
| Quintile4* | 1.51 |
| Quintile3 | −2.94 |
| Quintile2* | −1.5 |
| Quintile1 | −3.58 |
| Alcohol intake | 0.12 |
| Hormone use | |
| pre-men/ missing men | 0 (referent) |
| never/past PMH user* | −0.27 |
| current PMH user | 2 |
| Age* | 0.10 |
| Body mass index | |
| <21kg/m2 | 0 (referent) |
| 21–23, kg/m2* | 3.01 |
| 23–24.9 kg/m2* | 0.61 |
| 25–28.9 kg/m2 | −0.59 |
| >29 kg/m2 | −3.11 |
Plasma 25(OH)D prediction model developed among 1240 NHS participants who served as controls in previous nested case-control studies of breast cancer, colon polyps, and colon cancer.
*
Not statistically significant
PMH: Post Menopausal Hormone
R2= 0.32