Got (just the right amount, not too much, but not too little) milk?
PROBLEM: Still in the throes of "Got Milk?" inundation, disagreement is rife over whether drinking cow's milk is as good for us as we've been led to believe. After all, critics argue, it's estimated that up to 75 percent of people experience a reduction in their ability to digest milk after infancy, and the beverage has also been associated with iron deficiency -- not only because it's low in iron itself, but because it also hinders the body's ability to absorb iron from other sources. Milk remains, on the other hand, an important source of vitamin D, which among other things, has been shown to protect against both diabetes and the common cold in children. So, should you be giving your kids milk? And if so, how much?
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METHODOLOGY: Canadian researchers tracked the milk drinking habits of 1,300 "healthy urban preschoolers" over the course of two years. The children also submitted blood samples (probably reluctantly) from which their iron and vitamin D levels could be analyzed. Skin pigmentation, whether or not they were breast fed, use of vitamin D supplements, and variations in season (which affects how much sunlight they get) were all taken into account.
RESULTS: As children consumed more cow's milk, their blood levels of vitamin D increased, but their iron levels proportionately decreased. At two glasses per day, however, children were able to get a healthy level amount of vitamin D without losing too much iron.
CONCLUSION: While there is a trade-off between the health benefits -- increased vitamin D -- and negative effects -- depleted iron -- of drinking milk, two cups a day seems to strike the ideal balance for young children.
IMPLICATIONS: Vitamin D is important, but milk is only a good source of it in moderation. During the winter months, and especially for children with darker skin pigmentation, the researchers suggest that children be given vitamin D supplements rather than extra milk.
The full study, "The Relationship Between Cow's Milk and Stores of Vitamin D and Iron in Early Childhood," is published in the journal Pediatrics.
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