TABLE 1.
Baseline characteristics of the participants
| Characteristic | Overall (n = 2495) | Placebo arm (n = 830) | Vitamin D3 1600 IU/d arm (n = 832) | Vitamin D3 3200 IU/d arm (n = 833) |
|---|---|---|---|---|
| Female sex, n (%) | 1069 (42.8) | 372 (44.8) | 349 (41.9) | 348 (41.8) |
| Age, mean (SD), years | 68.2 (4.5) | 68.2 (4.5) | 68.1 (4.5) | 68.3 (4.4) |
| Age group, n (%) | ||||
| 60–64 years1 | 620 (24.8) | 202 (24.3) | 209 (25.1) | 209 (25.1) |
| 65–69 years | 1089 (43.6) | 373 (44.9) | 358 (43.0) | 358 (43.0) |
| 70–74 years | 589 (23.6) | 186 (22.4) | 203 (24.4) | 200 (24.0) |
| ≥75 years | 197 (7.9) | 69 (8.3) | 62 (7.5) | 66 (7.9) |
| Employment status, n (%) | n = 2469 | n = 823 | n = 824 | n = 822 |
| Full-time work | 201 (8.1) | 76 (9.2) | 61 (7.4) | 64 (7.8) |
| Part-time work | 95 (3.8) | 27 (3.3) | 38 (4.6) | 30 (3.6) |
| Unemployed | 61 (2.5) | 14 (1.7) | 25 (3.0) | 22 (2.7) |
| Retired | 2097 (84.9) | 703 (85.4) | 692 (84.0) | 702 (85.4) |
| Not working for other reasons | 15 (0.6) | 3 (0.4) | 8 (1.0) | 4 (0.5) |
| Leisure-time physical activity,2 mean (SD), h/week | ||||
| Light | 13.1 (10.8) (n = 2172) | 13.1 (10.9) (n = 712) | 13.3 (11.2) (n = 721) | 12.8 (10.5) (n = 739) |
| Heavy | 5.7 (6.5) (n = 1601) | 5.6 (6.3) (n = 525) | 5.8 (6.6) (n = 532) | 5.9 (6.5) (n = 544) |
| Smoking regularly,3n (%) | 885 (35.7) (n = 2477) | 292 (35.4) (n = 825) | 300 (36.5) (n = 823) | 293 (35.3) (n = 829) |
| At least high school diploma, n (%) | 417 (16.8) (n = 2483) | 135 (16.3) (n = 827) | 149 (18.0) (n = 827) | 133 (16.0) (n = 829) |
| Married, n (%) | 1849 (74.7) (n = 2476) | 620 (75.2) (n = 824) | 606 (73.5) (n = 825) | 623 (75.3 (n = 827) |
| BMI, mean (SD), kg/m2 | 27.1 (4.3) (n = 2491) | 27.2 (4.3) (n = 828) | 27.1 (4.3) (n = 832) | 26.9 (4.3) (n = 831) |
| Alcohol intake, mean (SD), g/day | 7 (13) (n = 2464) | 8 (16) (n = 824) | 7 (11) (n = 818) | 7 (11) (n = 822) |
| Vitamin D intake from diet, mean (SD), IU/d | 428 (312) (n = 2464) | 416 (260) (n = 824) | 456 (384) (n = 818) | 420 (280) (n = 822) |
| The major vitamin D sources in diet | ||||
| Liquid dairy products, mean (SD), g/d | 488 (409) | 473 (387) | 518 (413) | 474 (426) |
| Fish, mean (SD), g/d | 76 (96) | 71 (74) | 83 (132) | 72 (71) |
| Vegetable fat spreads, mean (SD), g/d | 13 (9) | 12 (9) | 13 (9) | 13 (9) |
| Use of own vitamin D supplements, n (%) | ||||
| Not at all | 1670 (66.9) | 535 (64.5) | 566 (68.0) | 569 (68.3) |
| 200–400 IU/day | 361 (14.5) | 133 (16.0) | 104 (12.5) | 124 (14.9) |
| >400 to <800 IU/day | 74 (3.0) | 27 (3.3) | 26 (3.1) | 21 (2.5) |
| 800 IU/day | 390 (15.6) | 135 (16.3) | 136 (16.3) | 119 (14.3) |
| Calcium intake from diet, mean (SD), mg/d | 1369 (739) (n = 2463) | 1344 (708) (n = 824) | 1413 (735) (n = 817) | 1350 (772) (n = 822) |
| Daily calcium supplement use, n (%) | 381 (16.0) (n = 2387) | 143 (18.1) (n = 792) | 112 (14.1) (n = 792) | 126 (15.7) (n = 803) |
| Daily medication use, n (%) | 1736 (70.1) (n = 2476) | 597 (72.3) (n = 826) | 559 (67.9) (n = 823) | 580 (70.1) (n = 827) |
| Hypertension medication, n (%) | 1047 (42.3) (n = 2476) | 353 (42.7) (n = 826) | 344 (41.8) (n = 823) | 350 (42.3) (n = 827) |
| Antiarrhythmic medication, n (%) | 122 (4.9) (n = 2476) | 45 (5.4) (n = 826) | 48 (5.8) (n = 823) | 29 (3.5) (n = 827) |
| Statin medication, n (%) | 717 (29.0) (n = 2476) | 255 (30.9) (n = 826) | 218 (26.5) (n = 823) | 244 (29.5) (n = 827) |
| Diabetes medication, n (%) | 222 (9.0) (n = 2476) | 68 (8.2) (n = 826) | 89 (10.8) (n = 823) | 65 (7.9) (n = 827) |
| Self-rated health good or excellent, n (%) | 1460 (59.2) (n = 2467) | 460 (56.0) (n = 822) | 493 (60.3) (n = 818) | 507 (61.3) (n = 827) |
| Vacation in a sunny place during previous 12 months, n (%) | 663 (26.6) (n = 2490) | 210 (25.4) (n = 828) | 225 (27.1) (n = 830) | 228 (n = 27.4) (n = 832) |
| Use of sunscreen in the summertime, n (%) | 581 (23.4) (n = 2488) | 183 (22.1) (n = 828) | 199 (24.0) (n = 828) | 199 (23.9) (n = 832) |
1
All participants in this age group are men.
2
Light activity was defined as gardening and other light outdoor activities, while heavy activity was defined as physical exercise that causes sweating or heavy breathing.
3
Smoking regularly was defined as smoking almost every day during the last year.