Table 2.
VDBP, total, non-bioavailable, bioavailable, and free 25(OH)D concentrations by selected characteristics.
| Characteristics | Group | N | VDBP (µg/mL) | Total 25(OH)D (nmol/L) | Non-Bioavailable 25(OH)D (nmol/L) | Bioavailable 25(OH)D (ng/mL) | Free 25(OH)D (pg/mL) |
|---|---|---|---|---|---|---|---|
| Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | Mean (SE) | |||
| All participants | 323.6 (0.85) | 49.8 (0.29) | 43.4 (0.26) | 2.5 (0.02) | 5.7 (0.04) | ||
| Age | <60 years | 2229 | 329.5 (1.43) | 51.3 (0.52) | 44.8 (0.46) | 2.6 (0.03) | 5.7 (0.07) |
| 60–64 years | 1664 | 324.6 (1.57) | 51.2 (0.57) | 44.6 (0.50) | 2.6 (0.03) | 5.8 (0.07) | |
| 65–69 years | 1267 | 320.1 (1.72) | 48.4 (0.56) | 42.2 (0.49) | 2.5 (0.04) | 5.6 (0.08) | |
| ≥70 years | 739 | 314.8 (2.33) | 46.4 (0.72) | 40.3 (0.62) | 2.4 (0.05) | 5.5 (0.11) | |
| Sex | Females | 3310 | 332.0 (1.16) | 46.1 (0.30) | 40.3 (0.26) | 2.3 (0.02) | 5.1 (0.04) |
| Males | 2589 | 312.9 (1.20) | 54.6 (0.53) | 47.3 (0.46) | 2.9 (0.03) | 6.4 (0.07) | |
| School education | ≤ 9 years | 4429 | 324.2 (1.00) | 49.1 (0.33) | 42.7 (0.29) | 2.5 (0.02) | 5.6 (0.05) |
| 10–11 years | 816 | 322.9 (2.03) | 51.4 (0.79) | 44.9 (0.69) | 2.6 (0.05) | 5.8 (0.10) | |
| ≥12 years | 654 | 320.3 (2.44) | 52.8 (1.00) | 45.9 (0.88) | 2.8 (0.06) | 6.1 (0.13) | |
| Smoking status | Never smokers | 3005 | 325.1 (1.19) | 48.7 (0.37) | 42.6 (0.33) | 2.5 (0.02) | 5.5 (0.05) |
| Former smokers | 1918 | 319.5 (1.52) | 53.4 (0.56) | 46.4 (0.49) | 2.8 (0.04) | 6.1 (0.08) | |
| Current smokers | 976 | 326.9 (1.94) | 46.1 (0.72) | 40.1 (0.64) | 2.3 (0.04) | 5.2 (0.10) | |
| Physical activity | Low | 4013 | 323.5 (0.99) | 47.8 (0.34) | 41.7 (0.30) | 2.4 (0.02) | 5.4 (0.05) |
| Moderate/high | 1886 | 323.8 (1.60) | 54.0 (0.56) | 47.0 (0.49) | 2.8 (0.04) | 6.2 (0.08) | |
| Regular multivitamin intake | No | 5043 | 322.4 (0.88) | 49.4 (0.32) | 43.0 (0.28) | 2.5 (0.02) | 5.6 (0.04) |
| Yes | 856 | 330.9 (2.66) | 52.3 (0.77) | 45.8 (0.68) | 2.6 (0.05) | 5.8 (0.10) | |
| Fish consumption | <1 time/week | 1955 | 322.2 (1.37) | 49.4 (0.53) | 43.1 (0.46) | 2.5 (0.03) | 5.6 (0.07) |
| ≥1 time/week | 3944 | 324.3 (1.07) | 50.0 (0.35) | 43.5 (0.31) | 2.6 (0.02) | 5.7 (0.05) | |
| Hypertension | No | 3355 | 324.9 (1.18) | 50.6 (0.40) | 44.1 (0.35) | 2.6 (0.03) | 5.8 (0.06) |
| Yes | 2544 | 321.8 (1.20) | 48.7 (0.43) | 42.5 (0.37) | 2.5 (0.03) | 5.5 (0.06) | |
| Diabetes | No | 5044 | 326.0 (0.93) | 50.3 (0.32) | 43.9 (0.28) | 2.6 (0.02) | 5.7 (0.04) |
| Yes | 855 | 309.3 (1.96) | 46.7 (0.69) | 40.7 (0.61) | 2.4 (0.04) | 5.5 (0.09) | |
| Cardiovascular disease | No | 4739 | 325.5 (0.95) | 50.0 (0.32) | 43.6 (0.28) | 2.5 (0.02) | 5.7 (0.05) |
| Yes | 1160 | 316.0 (1.85) | 48.9 (0.68) | 42.6 (0.60) | 2.5 (0.04) | 5.7 (0.09) | |
| Cancer | No | 5447 | 323.4 (0.89) | 49.8 (0.30) | 43.4 (0.27) | 2.6 (0.02) | 5.7 (0.04) |
| Yes | 452 | 325.4 (2.69) | 49.3 (1.04) | 43.1 (0.92) | 2.5 (0.06) | 5.5 (0.14) | |
| Chronic kidney disease | No | 5405 | 323.7 (0.88) | 49.9 (0.30) | 43.5 (0.26) | 2.6 (0.02) | 5.7 (0.04) |
| Yes | 494 | 322.2 (3.12) | 48.5 (1.18) | 42.2 (1.01) | 2.5 (0.08) | 5.6 (0.18) | |
| Body mass index | <25 kg/m2 | 1619 | 331.3 (1.68) | 51.5 (0.58) | 45.0 (0.52) | 2.6 (0.03) | 5.8 (0.08) |
| 25–29.9 kg/m2 | 2750 | 322.4 (1.23) | 50.8 (0.44) | 44.2 (0.39) | 2.6 (0.03) | 5.8 (0.06) | |
| 30–34.9 kg/m2 | 1188 | 319.3 (1.86) | 47.2 (0.57) | 41.2 (0.50) | 2.4 (0.04) | 5.4 (0.08) | |
| ≥35 kg/m2 | 342 | 311.6 (2.84) | 42.6 (0.85) | 37.2 (0.75) | 2.1 (0.06) | 4.9 (0.13) | |
| Total cholesterol | <200 mg/dL | 1345 | 310.5 (1.68) | 51.8 (0.65) | 45.0 (0.57) | 2.7 (0.04) | 6.1 (0.09) |
| ≥200 mg/dL | 4554 | 327.5 (0.97) | 49.2 (0.33) | 42.9 (0.29) | 2.5 (0.02) | 5.5 (0.05) | |
| C-reactive protein | <3 mg/L | 3619 | 317.7 (1.03) | 50.6 (0.37) | 44.0 (0.33) | 2.6 (0.02) | 5.8 (0.05) |
| ≥3 mg/L | 2280 | 332.9 (1.43) | 48.5 (0.47) | 42.5 (0.42) | 2.4 (0.03) | 5.4 (0.07) |
Bold print indicates p < 0.05. Abbreviations: SE: standard error; VDBP: vitamin D binding protein.