Consumption of non-cow's milk beverages and serum vitamin D levels in early childhood

Abstract

Background: Vitamin D fortification of non-cow's milk beverages is voluntary in North America. The effect of consuming non-cow's milk beverages on serum 25-hydroxyvitamin D levels in children is unclear. We studied the association between non-cow's milk consumption and 25-hydroxyvitamin D levels in healthy preschool-aged children. We also explored whether cow's milk consumption modified this association and analyzed the association between daily non-cow's milk and cow's milk consumption.

Methods: In this cross-sectional study, we recruited children 1-6 years of age attending routinely scheduled well-child visits. Survey responses, and anthropometric and laboratory measurements were collected. The association between non-cow's milk consumption and 25-hydroxyvitamin D levels was tested using multiple linear regression and logistic regression. Cow's milk consumption was explored as an effect modifier using an interaction term. The association between daily intake of non-cow's milk and cow's milk was explored using multiple linear regression.

Results: A total of 2831 children were included. The interaction between non-cow's milk and cow's milk consumption was statistically significant (p = 0.03). Drinking non-cow's milk beverages was associated with a 4.2-nmol/L decrease in 25-hydroxyvitamin D level per 250-mL cup consumed among children who also drank cow's milk (p = 0.008). Children who drank only non-cow's milk were at higher risk of having a 25-hydroxyvitamin D level below 50 nmol/L than children who drank only cow's milk (odds ratio 2.7, 95% confidence interval 1.6 to 4.7).

Interpretation: Consumption of non-cow's milk beverages was associated with decreased serum 25-hydroxyvitamin D levels in early childhood. This association was modified by cow's milk consumption, which suggests a trade-off between consumption of cow's milk fortified with higher levels of vitamin D and non-cow's milk with lower vitamin D content.

Figure 1:

Selection of patients for the study.

Figure 2:

Unadjusted association between consumption of non–cow’s milk beverages and serum 25-hydroxyvitamin D (25[OH]D) levels among children 1 to 6 years of age.

Figure 3:

Adjusted* association between total consumption of non–cow’s milk beverages and serum 25(OH)D (25-hydroxyvitamin D) levels among children drinking only non–cow’s milk and among those drinking both non–cow’s milk and cow’s milk products. *Adjusted for age, sex, body mass index z score, vitamin D supplementation, margarine consumption, level of skin pigmentation, outdoor play time, season, and cow’s milk consumption as an effect modifier. Screened areas = 95% confidence intervals.

Figure 4:

Adjusted* association between daily consumption of non–cow’s milk beverages and daily consumption of cow’s milk. *Adjusted for age and sex.