Association between consumption of non–cow’s milk and 25-hydroxyvitamin D levels
| Variable | Unadjusted analysis | p value‡ | Adjusted analysis* | p value‡ | ||
|---|---|---|---|---|---|---|
| % change in 25(OH)D level (95% CI) | Change in median 25(OH)D level,† nmol/L (95% CI) | % change in 25(OH)D level (95% CI) | Change in median 25(OH)D level,† nmol/L (95% CI) | |||
| Daily consumption of non–cow’s milk (per cup§) | ||||||
| Drinks cow’s milk | −4.7 (−8.4 to −0.8) | −4.7 (−6.7 to −0.6) | 0.02 | −5.1 (−8.9 to −1.4) | −4.2 (−7.1 to −1.1) | 0.008 |
| Does not drink cow’s milk | −0.3 (−3.3 to 2.8) | −0.2 (2.8 to 2.2) | 1.2 | 0.1 (−2.9 to 3.2) | 0.09 (−2.3 to 2.5) | 0.9 |
| Age (per additional year) | −0.2 (−1.1 to 0.7) | −0.2 (−0.9 to 0.5) | 0.6 | −0.8 (−1.7 to 0.1) | −0.6 (−1.3 to 0.1) | 0.09 |
| Sex (male v. female) | −0.04 (−2.6 to 2.6) | −0.03 (−2.1 to 2.1) | > 0.9 | 0.1 (−2.4 to 2.7) | 0.1 (−1.9 to 2.1) | 0.9 |
| BMI z score | −0.2 (−1.5 to 1.0) | −0.2 (−1.2 to 0.8) | 0.7 | −0.02 (−1.3 to 1.2) | −0.02 (−1.0 to 0.99) | > 0.9 |
| Cow’s milk consumption (no v. yes) | −6.4 (−9.9 to −2.7) | −5.1 (−7.9 to −2.2) | < 0.001 | −8.1 (−12.2 to −3.4) | −6.5 (−9.8 to −3.0) | < 0.001 |
| Margarine consumption (no v. yes) | −0.9 (−3.7 to 2.0) | −0.7 (−3.0 to 1.6) | 0.6 | −1.3 (−4.2 to 1.6) | −1.1 (−3.3 to 1.3) | 0.4 |
| Vitamin D supplementation (yes v. no) | 8.5 (5.7 to 11.3) | 6.8 (4.6 to 9.1) | < 0.001 | 8.9 (6.2 to 11.8) | 7.2 (4.9 to 9.4) | < 0.001 |
| Skin pigmentation (v. type III or IV) | ||||||
| Light (type I or II) | 1.8 (−0.9 to 4.6) | 1.5 (−0.7 to 3.7) | 0.2 | 1.3 (−1.4 to 4.1) | 1.0 (−1.1 to 3.3) | 0.4 |
| Dark (type V or VI) | −14.0 (−18.6 to −9.0) | −14.0 (−14.9 to 7.2) | < 0.001 | −14.0 (−18.7 to −9.2) | −14.0 (−15.0 to −7.4) | < 0.001 |
| Seasonal effect¶ | ||||||
| Sine function | 1.3 (−0.5 to 3.1) | 1.0 (−1.2 to 0.3) | 0.2 | 0.4 (−1.4 to 2.3) | 0.3 (−1.1 to 1.8) | 0.6 |
| Cosine function | −4.3 (−6.0 to −2.5) | −3.4 (−4.8 to −2.0) | < 0.001 | −4.7 (−6.6 to −2.8) | −3.8 (−5.3 to −2.3) | < 0.001 |
| Outdoor play (per additional hour) | 0.7 (0.2 to 1.3) | 0.6 (0.1 to 1.0) | 0.01 | 0.2 (−0.4 to 0.8) | 0.1 (−0.3 to 0.6) | 0.6 |
Note: 25(OH)D = 25-hydroxyvitamin D, CI = confidence interval, SD = standard deviation.
↵* Adjusted for all other variables in the table.
↵† Median level = 80.0 nmol/L.
↵‡ p values (t test) represent significance of % change in 25(OH)D level.
↵§ 1 cup = 250 mL.
↵¶ The seasonal amplitude was 10% and peaked on June 26. Seasonal effect was tested using a likelihood ratio test and was statistically significant (p < 0.001).