Table 1.
Demographic Characteristics, Median 25(OH)D ng/ml and Vitamin Supplement Use: Study of Environment Lifestyle & Fibroids Participants 2010–2012
| N (%) | Median 25(OH)D ng/ml | Percent Using Supplementa | |
|---|---|---|---|
| Overall | 1662 (100) | 15.7 | 40 |
| Age | |||
| 23–26 | 511 (31) | 14.9 | 35 |
| 27–30 | 571 (34) | 16.0 | 41 |
| 30+ | 580 (35) | 15.9 | 44 |
| Education levelb | |||
| <HS/GED | 367 (22) | 14.1 | 28 |
| Some beyond HS | 832 (50) | 15.1 | 37 |
| Bachelors/masters/doctorate | 462 (28) | 18.1 | 56 |
| Smoking | |||
| Nonsmoker | 1219 (73) | 16.1 | 44 |
| Former | 123 (7) | 16.0 | 38 |
| Current | 320 (19) | 13.9 | 26 |
| Alcohol usec | |||
| None | 490 (29) | 15.4 | 38 |
| Moderate | 843 (51) | 16.5 | 45 |
| Heavy | 329 (20) | 14.2 | 34 |
| BMI (kg/m2)d | |||
| <25 | 329 (20) | 18.0 | 41 |
| 25–29 | 345 (21) | 16.4 | 41 |
| 30–34 | 318 (19) | 17.3 | 45 |
| 35+ | 670 (40) | 13.9 | 37 |
| Parity | |||
| Nulliparous | 651 (39) | 15.1 | 45 |
| Parous | 1011 (61) | 15.9 | 38 |
| Use of hormonal contraceptionb | |||
| None | 1193 (72) | 15.0 | 39 |
| Any estrogen | 226 (14) | 19.4 | 49 |
| Progestin alone | 241 (15) | 16.3 | 39 |
| Dietary vitamin De | |||
| 39 IU/d | 378 (23) | 13.7 | 37 |
| 78 IU/d | 383 (23) | 15.2 | 39 |
| 129 IU/d | 481 (29) | 16.1 | 43 |
| 246 IU/d | 420 (25) | 17.1 | 43 |
| Categorized melanin indexf | |||
| 1 | 430 (26) | 17.5 | 46 |
| 2 | 390 (23) | 15.3 | 45 |
| 3 | 444 (27) | 15.7 | 39 |
| 4 | 398 (24) | 14.6 | 31 |
| Sunny vacation previous winter | |||
| None | 1311 (79) | 15.6 | 40 |
| ≤7 days | 246 (15) | 15.7 | 42 |
| >7 days | 105 (6) | 16.5 | 42 |
| Time outsideb,g | |||
| Half hour/day | 326 (20) | 16.1 | 49 |
| 1 h/day | 332 (20) | 16.2 | 39 |
| 2 h/day | 349 (21) | 16.0 | 44 |
| 3 h/day | 321 (19) | 15.7 | 41 |
| 4.5 h/day | 333 (20) | 13.9 | 28 |
| Season of blood draw | |||
| Winter | 347 (21) | 13.4 | 38 |
| Spring | 388 (23) | 14.8 | 41 |
| Summer | 495 (30) | 18.9 | 41 |
| Fall | 432 (26) | 14.6 | 41 |
Abbreviations: BMI, body mass index; HS/GED, high school/general equivalency degree; 25(OH)D, 25-hydroxy-vitamin D.
Use of any supplement containing vitamin D based on self-report at clinic visit and report on food frequency questionnaire.
Missing: education (n = 1), contraception (n = 2; unable to determine hormonal or nonhormonal intrauterine device), time outside (n = 1).
Self-reported alcohol use in the past year. Heavy use meets criteria for heavy or binge use.
Calculated for measured height and weight at time of blood draw. n = 13 women with BMI <18.5 kg/m2 included with <25 kg/m2.
Within-group median dietary vitamin D intake (IU/d) from food sources alone as calculated by the Food Frequency Questionnaire.
Categorized using quartile cut points.
Time spent outdoors in warm/sunny months. Total hours per week adjusted for self-reported sun avoidance behaviors and sun screen use were used to determine quintile cut points. Rounded median unadjusted hours/day are reported for each group.