Almost everyone knows the “Got Milk” advertisements, with celebrities like Taylor Swift, Jennifer Hudson and Harrison Ford proudly displaying a milk mustache. USA Today named the ads one of the ten best commercials of all time. So once and for all, can someone tell us how much milk can we give our children?
Milk is an important source of both calcium and vitamin D, which are key nutrients for bone growth and child development. Sounds promising. So should we be giving our kids as much milk as possible? The gut-feeling-driven-parent probably think ‘no’. Milk's many benefits include increase in calcium and vitamin D levels in the blood, but at the same time it can decrease iron levels by preventing iron absorption in the duodenum (small intestine). Iron is essential for development in children, as iron deficiency was shown to cause anemia and has been linked to delays in cognitive development. So it’s a fine balance – we want to maximize calcium and vitamin D stores without decreasing iron stores.
New research out of Toronto, Canada, by pediatrician and scientist Dr. Jonathon Maguire and his team, called TARGet Kids!, suggests that the magic number is 2 cups (500mL) of cow’s milk each day. “Children who drink a large volume of cows milk are at risk of iron deficiency, which can cause problems with brain development. But children who drink very little milk may be at risk for other nutritional deficiencies, one of which is vitamin D deficiency. So it’s a tradeoff between iron and vitamin D.” says Dr. Maguire in an interview for MedSchoolForParents.com. So how much milk is the right amount to balance those two things? It looks like it’s about 2 cups of cow’s milk per day.
The team in Toronto, Canada enrolled over a thousand healthy children 2-5 years of age and looked at samples of their blood for vitamin D levels and iron stores, and compared this to information from parents about how much milk the children drank. With about 500 millilitres of milk a day, the investigators found most children had adequate levels of vitamin D and iron.
There are two main sources of vitamin D – diet and sunlight. With darker skin pigmentation, more sunlight is needed for the skin to produce vitamin D. “Children who have darker skin pigmentation may need more milk to reach a healthy vitamin D level”, suggests Dr. Maguire. “But this would put them at risk of iron deficiency. So there are other ways of getting vitamin D, for example, through vitamin D supplementation.”
Should all children receive vitamin D supplementations?
“It depends who you ask. The American Academy of Pediatrics recommends that children who drink less than one liter of cow’s milk per day receive a vitamin D supplement. In Canada, where the study took place, Health Canada does not provide a recommendation for an additional vitamin D supplement for healthy children older than 1 year of age”, suggests Dr. Maguire.
Breastfeeding babies not receiving cow’s milk should receive vitamin D drops.
RESOURCE : Maguire et al. The Relationship Between Cow’s Milk and Stores of Vitamin D and Iron in Early Childhood. Pediatrics. 2013; 131(1): 144-151.