Do you consume cow's milk or provide it to your children if you're a parent? Turns out many people are making a switch from cow's milk to other 'milk' alternatives such as almond milk, soy milk, or coconut milk, or to milk from another animal source such as goats. When queried on the switch parents in particular cite allergy concerns and antibiotic exposure as motivational factors, but, as Rick and I discuss on PodMed this week, such a strategy may have a much greater negative impact on children’s' health than any upside. That's based on a study of vitamin D levels and milk consumption in the Canadian Medical Association Journal (greetings Tom, our Canadian colleague ).
Researchers gleaned data from an ongoing Canadian study known by the acronym TARGet Kids!, described as a partnership between child health researchers in the departments of medicine, pediatrics, and family and community medicine at the University of Toronto. The current study recruited children from 1 to 6 years of age and who did not have chronic illness or a medical condition impacting growth. Almost 3000 children were enrolled and serum 25-hydroxyvitamin D measurements were obtained from each child, as well as extensive information from parents on type of milk consumed and how much. Additional data, including age, sex, body mass index, daily vitamin D supplementation, consumption of margarine, skin pigmentation, and outdoor play time were also obtained.
Turns out that "each 250-mL cup of non–cow’s milk consumed was associated with a 3.1% decrease in 25-hydroxyvitamin D level. " Furthermore, the authors report, "We identified a dose-dependent association between consumption of non–cow’s milk beverages in early childhood and decreased serum levels of 25-hydroxyvitamin D. This association was modified by cow’s milk consumption, which suggests a trade-off between the consumption of cow’s milk fortified with higher levels of vitamin D and non–cow’s milk beverages with lower vitamin D content." Children of darker skin pigmentation who did not consume cow's milk were at higher risk for lower vitamin D levels in the absence of supplementation.
Okay, I query Rick in the podcast, what about outdoor playtime? He opines that exposure to sunlight is inadequate to overcome a loss of dietary vitamin D such as is seen when cow's milk is eliminated from the diets of children. Indeed, the authors of this paper point out that in the US and Canada, cow's milk is required to contain about 40 IU of vitamin D per 100ml, and is the major source of vitamin D for kids. Seems prudent therefore, for parents to supplement their kids with vitamin D if they choose an alternative to cow's milk. Does this also mean they should ask their child's pediatrician to measure their serum vitamin D? Rick's opinion is that if they supplement to the level supplied in cow's milk that may not be necessary. In any case mentioning this dietary choice to your child's pediatrician seems like the right thing to do.
Other topics this week include the persistence of banned substances in dietary supplements in JAMA, knowledge of the presence of central venous catheters in Annals of Internal Medicine, and the cost impact of MD versus hospital ownership of medical practices in JAMA also. Until next week, y'all live well.