Table 1. Baseline characteristicsa.
| Characteristic |
Vitamin D3 dose assignment (IU per day) |
P-valueb | |||
|---|---|---|---|---|---|
| Placebo | 1000 | 2000 | 4000 | ||
| (n=81) | (n=81) | (n=83) | (n=83) | ||
| Age, years, median (IQR) | 50.7 (44.1–58.0) | 51.1 (43.4–60.1) | 50.3 (43.5–58.3) | 51.3 (44.1–59.7) | 0.98 |
| Sex, No. (%) | 0.72 | ||||
| Male | 27 (33.3) | 22 (27.2) | 28 (33.7) | 29 (34.9) | |
| Female | 54 (66.7) | 59 (72.8) | 55 (66.3) | 54 (65.1) | |
| BMI, kgm−2, median (IQR) | 31.2 (26.5–35.9) | 30.5 (27.0–37.5) | 31.9 (26.2–36.9) | 31.4 (27.4–35.7) | 0.82 |
| BMI <25 kgm−2, mean (s.d.) | 20.8 (2.2) | 23.3 (1.4) | 22.9 (1.4) | 21.9 (3.1) | |
| No. (%) | 11 (13.5) | 11 (13.5) | 16 (19.2) | 10 (8.3) | |
| BMI 25–29.9 kgm−2, mean (s.d.) | 27.0 (1.1) | 27.9 (1.5) | 27.6 (1.5) | 27.6 (1.5) | |
| No. (%) | 25 (30.8) | 24 (29.6) | 21 (25.3) | 25 (30.1) | |
| BMI >30 kgm−2, mean (s.d.) | 37.1 (5.9) | 37.6 (5.8) | 38.4 (6.2) | 36.6 (5.6) | |
| 25(OH)D <20 ng ml−1, No. (%) | 53 (65) | 50 (62) | 59 (71) | 53 (64) | 0.46 |
| 25(OHD) ng ml−1, median (IQR) | 15.1 (10.4–23.6) | 16.2 (11.0–22.7) | 13.9 (9.5–22.3) | 15.7 (11.0–23.3) | 0.63 |
| Smoking status, No. (%) | 0.26 | ||||
| Never | 33 (40.7) | 36 (44.4) | 33 (39.8) | 44 (53.0) | |
| Past | 20 (24.7) | 16 (19.8) | 27 (32.5) | 20 (24.1) | |
| Current | 28 (34.6) | 29 (35.8) | 23 (27.7) | 19 (22.9) | |
| Frequency of exercise,c days per week, median (IQR) | 3.0 (0.5–5.0) | 3.0 (1.0–5.0) | 3.0 (0–5.0) | 3.0 (0–5.0) | 0.99 |
| Dietary vitamin D intake, median (IQR) | 147.3 (71.4–262.8) | 162.5 (92.6–295.5) | 144.0 (58.0–265.1) | 198.1 (83.2–306.4) | 0.41 |
| Dietary calcium intake, median (IQR) | 264.6 (177.7–600.8) | 419.4 (233.5–820.3) | 314.4 (178.2–632.0) | 425 (203.4–829.0) | 0.11 |
| Regular multivitamin use,d No. (%) | 10(12) | 18(22) | 15(18) | 22(27) | 0.16 |
| Regular vitamin D supplement use,d No. (%) | 8(10) | 6(8) | 2(2) | 8(10) | 0.45 |
| Food, servings per week (median (IQR)) | |||||
| Milk | 0.1 (0.1–0.3) | 0.1 (0.1–0.6) | 0.3 (0.1–0.6) | 0.3 (0.1–0.6) | 0.9 |
| Soy milk | 0 | 0 | 0 | 0 | 0.41 |
| Cheese | 0.3 (0.1–0.3) | 0.3 (0.1–0.3) | 0.3 (0.1–0.6) | 0.4 (0.1–0.6) | 0.58 |
| Ice cream | 0.1 (0–0.1) | 0 (0–0.1) | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.64 |
| Yogurt | 0 (0–0.1) | 0.1 (0–0.3) | 0 (0–0.3) | 0.1 (0–0.3) | 0.03 |
| Green leafy vegetables | 0.3 (0.1–0.6) | 0.3 (0.3–0.6) | 0.3 (0.1–0.6) | 0.3 (0.3–0.6) | 0.71 |
| Dark fish | 0.1 (0–0.3) | 0.1 (0–0.1) | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.52 |
| Orange juice | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.1 (0–0.6) | 0.29 |
| Cold cereal | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.1 (0–0.3) | 0.78 |
| Post-menopausal hormone use, No. (%) | |||||
| Yes | 0 | 0 | 0 | 1 (0.5) | 0.72 |
| Regular calcium supplement use,d No. (%) | 7 (8.7) | 9 (11.1) | 7 (8.4) | 9(10.8) | 0.49 |
| Regular aspirin use,e No. (%) | 4 (4.9) | 10 (12.3) | 5 (6.0) | 8 (9.6) | 0.23 |
| Regular NSAID use,f No. (%) | 6 (7.4) | 10(12.3) | 10 (12.0) | 7 (8.4) | 0.73 |
| Regular acetaminophen use, No. (%)e | 6 (7.4) | 6 (7.4) | 5 (6.0) | 5 (6.0) | 0.96 |
| Marital status, married, No. (%) | 23 (28.4) | 30 (37.0) | 23 (27.7) | 24 (28.9) | 0.58 |
| History of cancer, No. (%)g | 6 (7.4) | 0 | 3 (3.6) | 15 (4.6) | 0.032 |
Abbreviations: IU, international units; IQR, interquartile range; No., number; NSAID, non-steroidal anti-inflammatory drug.
Data are No. (%) unless otherwise indicated. The numbers do not always sum to group totals owing to missing information for some variables. 25(OH)D conversion to nmol l−1 is 2.49 nmol l−1 for each ng ml−1.
The Kruskal–Wallis test was used to calculate P-values for continuous variables. All statistical tests are two-sided.
Exercise defined as moderate to vigorous physical activity for at least 30 minutes, resulting in a faster-than-normal heart rate, sweating and deep breathing.
Defined as supplement use for 7 days per week during preceding month.
Defined as three or more pills per week during the past week.
Defined as three or more pills per week during the past week. Types of NSAIDs included salsalate, diflunisal, ibuprofen, ketoprofen, nabumetone, piroxicam, naproxen, diclofenac, indomethacin, sulindac, tolmetin, etodolac, ketorolac and oxaprozin.
Reported cancers include breast cancer, cervical cancer, uterine cancer, lung cancer, prostate cancer and sarcoma.