Table 1.
Subject characteristics of study population (n = 11,983): National Health and Nutrition Examination Surveys 2007–2012 [mean ± SD or n (%)].
| Serum 25(OH)D quartiles | P-value | ||||
|---|---|---|---|---|---|
| Q1 (n = 2,995) | Q2 (n = 2,996) | Q3 (n = 2,996) | Q4 (n = 2,996) | ||
| Serum 25(OH)D, nmol/L | 32 ± 8 | 53 ± 5 | 69 ± 5 | 97 ± 19 | < 0.001 |
| Age, years | 44 ± 16 | 45 ± 16 | 48 ± 16 | 51 ± 16 | < 0.001 |
| Sex | < 0.001 | ||||
| Men, n | 1,410 (47%) | 1646 (55%) | 1625 (54%) | 1,329 (44%) | |
| Women, n | 1585 (53%) | 1,350 (45%) | 1,371 (46%) | 1667 (56%) | |
| Race-ethnicity | < 0.001 | ||||
| Non-Hispanic white, n | 541 (18%) | 1,022 (34%) | 1563 (52%) | 2099 (70%) | |
| N-Hispanic black, n | 1,250 (42%) | 600 (20%) | 377 (13%) | 271 (9%) | |
| Mexican American/Hispanic, n | 579 (19%) | 662 (22%) | 455 (15%) | 202 (7%) | |
| Others, n | 625 (21%) | 712 (24%) | 601 (20%) | 424 (14%) | |
| Smoking status | < 0.001 | ||||
| Non-smoker, n | 1903 (64%) | 2089 (70%) | 2,146 (72%) | 2,194 (73%) | |
| Smoker, n | 1,092 (37%) | 907 (30%) | 850 (28%) | 802 (27%) | |
| Alcohol consumption | < 0.001 | ||||
| No, n | 455 (15%) | 490 (16%) | 482 (16%) | 440 (15%) | |
| Yes, n | 1897 (63%) | 1923 (64%) | 2028 (68%) | 2091 (70%) | |
| Not reported, n | 643 (22%) | 583 (20%) | 486 (16%) | 465 (15%) | |
| Season of examination | < 0.001 | ||||
| Winter, n | 1826 (61%) | 1507 (50%) | 1,232 (41%) | 964 (32%) | |
| Summer, n | 1,169 (39%) | 1,489 (50%) | 1764 (59%) | 2032 (68%) | |
| BMI, kg/m | 31 ± 8 | 30 ± 7 | 29 ± 6 | 27 ± 6 | < 0.001 |
| Supplement use | < 0.001 | ||||
| No, n | 2,579 (86%) | 2,236 (75%) | 1815 (61%) | 1,275 (43%) | |
| Yes, n | 416 (14%) | 760 (25%) | 1,181 (39%) | 1721 (57%) | |
| Sedentary activity | < 0.001 | ||||
| < 3 h, n | 971 (32%) | 1,093 (37%) | 1,029 (34%) | 963 (32%) | |
| 3–6 h, n | 971 (32%) | 992 (33%) | 1,054 (35%) | 1,130 (38%) | |
| > 6 h, n | 1,053 (35%) | 911 (30%) | 913 (31%) | 903 (30%) | |
| Poverty income ratio | < 0.001 | ||||
| < 1.30, n | 1,024 (37%) | 943 (35%) | 818 (30%) | 704 (25%) | |
| 1.3–3.5, n | 1,068 (39%) | 1,019 (37%) | 982 (36%) | 930 (33%) | |
| > 3.5, n | 650 (24%) | 767 (28%) | 960 (35%) | 1,166 (42%) |