TABLE 3.
Multiple regression model for serum 25(OH)D3 and 3-epi-25(OH)D3 in adults aged 18–84 y (National Adult Nutrition Survey participants, n = 1082)1
| Serum 25(OH)D3 |
Serum 3-epi-25(OH)D3 |
|||
| B (95% CI) | P | B (95% CI) | P | |
| Age group (vs. aged 18–35 y) (y) | ||||
| 36–50 | 4.32 (0.86, 7.78) | 0.014 | 0.13 (−0.08, 0.36) | 0.22 |
| 51–64 | 6.62 (2.38, 10.8) | 0.002 | 0.46 (0.19, 0.73) | 0.001 |
| ≥65 | 5.41 (0.37, 10.4) | 0.036 | 0.54 (0.22, 0.86) | 0.001 |
| Sex (F vs. M) | 2.18 (−1.21, 5.58) | 0.21 | −0.15 (−0.37, 0.06) | 0.16 |
| Waist circumference (cm) | −0.22 (−0.33, −0.10) | <0.0001 | −0.009 (−0.016, −0.001) | 0.019 |
| Serum creatinine (mmol/L) | −0.03 (−0.12, 0.06) | 0.47 | −0.002 (−0.007, 0.004) | 0.60 |
| Serum 25(OH)D2 (nmol/L) | −1.01 (−1.53, −0.49) | <0.0001 | −0.05 (−0.08, −0.02) | 0.002 |
| Using a vitamin D supplement | 8.89 (4.61, 13.2) | <0.0001 | 0.36 (0.09, 0.64) | 0.009 |
| Dietary vitamin D intake (μg/d) | 1.49 (0.93, 2.05) | <0.0001 | 0.04 (0.004, 0.076) | 0.027 |
| Using a calcium supplement | 1.46 (−3.58, 6.50) | 0.57 | 0.23 (−0.09, 0.56) | 0.115 |
| Dietary calcium intake (mg/d) | −0.001 (−0.006, 0.004) | 0.58 | 0.00 (0.000, 0.000) | 0.84 |
| Dietary magnesium intake (mg/d) | 0.009 (−0.008, 0.027) | 0.28 | 0.000 (−0.001, 0.001) | 0.57 |
| Total ethanol intake (g/d) | 0.020 (−0.002, 0.041) | 0.07 | 0.001 (0.000, 0.003) | 0.10 |
| Meat intake (g/d) | 0.009 (−0.006, 0.024) | 0.24 | 0.001 (0.000, 0.002) | 0.032 |
| Season of blood sampling (vs. winter) | ||||
| Spring | 0.91 (−3.05, 4.86) | 0.65 | 0.26 (0.003, 0.509) | 0.047 |
| Summer | 20.8 (16.6, 25.1) | <0.0001 | 1.75 (1.48, 2.02) | <0.0001 |
| Autumn | 14.1 (10.3, 18.0) | <0.0001 | 0.77 (0.53, 1.02) | <0.0001 |
| Sun habits (vs. avoids sunshine exposure) | ||||
| Sometimes in the sun | 1.53 (−2.11, 5.17) | 0.41 | 0.24 (0.01, 0.48) | 0.040 |
| Prefers sunshine exposure | 8.53 (4.47, 12.6) | <0.0001 | 0.73 (0.47, 0.99) | <0.0001 |
| Frequency of sunscreen use (vs. never) | ||||
| Rarely | −0.68 (−6.24, 6.11) | 0.98 | 0.08 (−0.32, 0.47) | 0.69 |
| Sometimes | 3.36 (−2.27, 8.99) | 0.24 | 0.24 (−0.12, 0.60) | 0.20 |
| Always | 2.32 (−3.66, 8.30) | 0.45 | 0.29 (−0.09, 0.67) | 0.13 |
| Smoking status (vs. smoker) | ||||
| Ex-smoker | 5.65 (1.46, 9.84) | 0.008 | 0.26 (−0.003, 0.532) | 0.053 |
| Non-smoker | 7.05 (3.43, 10.7) | <0.0001 | 0.28 (0.05, 0.51) | 0.017 |
| R2 for model, % | 30.7 | 29.9 | ||
1
Values are unstandardized coefficients (B) (95% CIs) unless otherwise indicated. 25(OH)D2, 25-hydroxyergocalciferol; 25(OH)D3, 25-hydroxycholecalciferol; 3-epi-25(OH)D3, 3 epimer of 25-hydroxycholecalciferol.