Media reports poured in this week about a new study from researchers at the University of Toronto touting the benefits of cow milk—and the potential harms of non-cow milk, such as soy, rice, and almond milk.
Based on diet surveys and physical measurements of 5,034 children aged two to six, researchers found that that the 643 kids who drank cow milk alternatives tended to be shorter than their cow milk-drinking counterparts. The study even went so far as to suggest a dose-dependent response: the more non-cow milk, the shorter the child. Every daily cup of non-cow milk linked to a 0.4 cm drop in height, the researchers reported in The American Journal of Clinical Nutrition. At age 3, kids who drank three cups of non-cow milk a day were 1.5 cm shorter than those who drank 3 cups of cow milk per day.
The study has several weaknesses. Most notably, it doesn’t account for the children’s overall diet or the height of both parents. (Height is determined not just by nutrition, but environmental factors and genetics.) It’s also simply a correlative study, not able to determine causation even in the best of cases. Further, even if there is a link between various milks and height, the significance is questionable. The study makes no claim that such slight differences in stature at a young age have any bearings on current or future health or adult height. None of the kids were malnourished or suffering from stunted growth.