Drinking milk produced from sources other than cows may increase the risk for low levels of serum vitamin D in young children compared with drinking cow's milk, according to a study published online October 20 in the Canadian Medical Association Journal.
Although fortification of cow's milk with vitamin D is required in the United States and Canada, fortification of non-cow's milk is voluntary.
Grace J. Lee, BASc, from the University of Toronto, Ontario, Canada, and colleagues conducted a cross-sectional study of children between 1 and 6 years old recruited from seven pediatric or family medicine primary care practices during well-child visits between December 2008 and September 2013. The practices are in the network collaboration of the Faculty of Medicine, the Department of Paediatrics, and the Department of Family and Community Medicine at the University of Toronto.
The researchers compared levels of serum 25-hydroxyvitamin D in 2468 children who drink cow's milk with levels in 363 children who drink goat's milk or plant-based milk. Researchers collected data through physical measurements, blood samples, and interviews with parents.
Mean age of participants was 2.9 years, and the children were split almost equally between boys and girls.
The median vitamin D level was 80 nmol/L in the entire study population, 81 nmol/L in those drinking just cow's milk (n = 1950), and 78 nmol/L in those drinking only non-cow's milk (n = 146).
However, the vitamin D level was below 50 nmol/L in 4.7% of those who drank only cow's milk and in 11.0% of those who drank only non-cow's milk. Using logistic regression analysis, the researchers found that children who drank only non-cow's milk were almost three times as likely as children who drank cow's milk to have vitamin D levels lower than 50 nmol/L (odds ratio, 2.7; 95% confidence interval, 1.6 - 4.7).
Overall, in an unadjusted analysis, researchers found that a 3.1% decrease (P = .005) in vitamin D level occurred for each 250-mL cup of non-cow's milk consumed.
"Among children who drank both types of milk, each additional cup of non–cow's milk beverage consumed was associated with a 5% decrease in 25-hydroxyvitamin D level," the researchers write. The estimated was adjusted for clinically relevant variables, the authors note.
They conclude, "Our findings may be helpful for health care providers caring for children who drink non–cow's milk beverages because of an allergy to cow's milk, lactose intolerance or a dietary preference."