Table 1.
Baseline characteristics according to randomized assignment to vitamin D3 vs placebo groups
| Characteristic | Total (N = 771) | Vitamin D3 Group (N = 388) | Placebo Group (N = 383) | P-value |
|---|---|---|---|---|
| Female sex, n (%) | 360 (46.7%) | 179 (46.1%) | 181 (47.3%) | 0.76 |
| Age, mean (SD) | 63.8 (6.1) | 63.7 (6.0) | 63.9 (6.3) | 0.53 |
| Race or ethnic group,a n (%) | ||||
| Non-Hispanic white | 630 (83.4%) | 317 (82.8%) | 313 (84.1%) | 0.49 |
| Black | 67 (8.9%) | 35 (9.1%) | 32 (8.6%) | |
| Nonblack Hispanic | 26 (3.4%) | 11 (2.9%) | 15 (4.0%) | |
| Asian | 15 (2.0%) | 9 (2.3%) | 6 (1.6%) | |
| Native American or Alaskan native | 5 (0.7%) | 2 (0.5%) | 3 (0.8%) | |
| Other or unknown | 12 (1.6%) | 9 (2.3%) | 3 (0.8%) | |
| Body mass index, mean (SD) kg/m2 | 28.3 (5.1) | 28.3 (5.2) | 28.3 (5.1) | 0.93 |
| Fat mass index, mean (SD) kg/m2 | 10.3 (3.89) | 10.3 (4.04) | 10.3 (3.74) | 0.94 |
| Lean mass index, mean (SD) kg/m2 | 16.5 (2.4) | 16.5 (2.3) | 16.5 (2.5) | 0.97 |
| ALM/BMI, mean (SD) kg/m2 | 0.73 (0.18) | 0.74 (0.18) | 0.72 (0.18) | 0.14 |
| Leisure time physical activity, median (interquartile range) MET, h/week | 21.5 (7.9-37.1) | 21.6 (7.9-37.8) | 21.0 (8.0-36.0) | 0.62 |
| Diabetes history, n (%) | 84 (10.9%) | 44 (11.4%) | 40 (10.4%) | 0.68 |
| Hypertension history, n (%) | 338 (44.0%) | 161 (41.6%) | 177 (46.5%) | 0.18 |
| Use of cholesterol-lowering medications, n (%) | 262 (34.3%) | 132 (34.5%) | 130 (34.2%) | 0.94 |
| Current smoking, n (%) | 48 (6.3%) | 26 (6.8%) | 22 (5.8%) | 0.56 |
| Baseline calcium supplement use,b n (%) | 132 (17.1%) | 69 (17.8%) | 63 (16.4%) | 0.62 |
| Baseline vitamin D supplement use,b n (%) | 326 (42.3%) | 157 (40.5%) | 169 (44.1%) | 0.30 |
| Baseline total 25(OH)D,c mean (SD) nmol/L | 69.1 (22.7) | 67.4 (22.0) | 71.1 (23.2) | 0.03 |
| Baseline free 25(OH)D, mean (SD) pmol/L | 14.6 (4.7) | 14.4 (4.5) | 14.8 (4.8) | 0.21 |
a Race and ethnic groups self-reported by participants.
b Personal calcium supplement intake limited to ≤1200 mg/day, vitamin D intake ≤800 IU/day.
c To convert values of 25(OH)D to ng/mL, multiple by 0.4.