It's a refrain heard in kitchens and dining rooms across North America: "Finish your milk." But is it sound advice? Opinions on the benefits and risks of milk tend to boil over, so here is what I hope is a brief and sane review on an often frothy subject.
To start with, let's explore what milk is. Looking at 2 percent milk, it's a beverage that, drop per drop, contains 27 percent more calories than Coca-Cola along with just over 3 teaspoons of sugar. The sugar is in the form of lactose, which, in folks who aren't lactose intolerant, is cleaved into glucose and galactose by the enzyme lactase. Of course, milk also contains calcium – 290 milligrams of the stuff per glass, and it's a good source of vitamins B12 and B2, phosphorus and protein. Most milk these days is also fortified with vitamin D.
The milk industry has been working hard for decades to convince us that it's absolutely essential for everyone to drink milk. The U.S. Department of Agriculture has agreed, and MyPlate explicitly encourages the consumption of two to three glasses of milk a day for kids (and 3 cups for everyone over the age of 9). Putting this degree of milk consumption in the caloric perspective of Coca-Cola, drinking 3 cups a day of plain, unflavored, 2 percent milk packs the caloric punch of more than a liter of the sugared soda and translates to as much as 43 pounds worth of milk calories a year!
Proponents of milk's health-promoting properties are so enamored with the white stuff that they'll even recommend children drink flavored milk, where "flavor" tends to come from obscene amounts of added sugar. Never mind that chocolate milk in some cases packs double the calories and 20 percent more sugar than Coca-Cola, milk's defenders would still want you to make sure your kid drinks two to three glasses a day (by that logic, I suppose we should be serving pies to the kids who don't love fruit).
Milk supporters – and the milk industry – tend to focus their marketing on bone health and the prevention of osteoporosis to sell their cupfuls. And while intuition may tell you that the consumption of calcium must, in turn, do a body good, the medical literature isn't so sure.
In a recent commentary for JAMA Pediatrics, Harvard's David Ludwig and Walter Willett argue that the daily calcium recommendations in the United States were based predominantly on studies that were three weeks in duration or less and that they likely grossly overestimate actual requirements. Moreover, they point out the somewhat disconcerting association that bone fracture risks tend to be lowest in those countries consuming the least milk and that meta-analyses report that milk consumption does not protect against fractures in adults.
Interestingly and importantly, given the rapidly rising rates of childhood obesity, current associations would suggest that low-fat milk may paradoxically be linked with increased weight, with the potential reason being that whole milk is more filling. Consequently, if weight's a concern for your children, you might, in fact, be better off serving them whole milk. Though I'd argue, if weight's a concern, you're almost certainly better off looking for non-liquid sources of calcium; despite the fact that whole milk may be more filling than reduced-fat milk, solid foods are always more filling than liquids.
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And what of the milk haters? They often tend to point out a few truths: We're the only animal on the planet to drink milk beyond early childhood; cow milk is designed for calves and not people; and drinking milk is a very recent phenomenon in the grand evolutionary scheme of things. And while all of those statements are true, none of them carry with them any actual weight in that just because milk drinking is a recent development and it's made by cows for cows does not automatically relegate milk to the evil pile.
My take on milk is rather straightforward. From an evidence-based perspective, milk does not appear to be a magic fairy food whose consumption leads to bones of steel or eternal health. It also does not appear to be a dietary demon that's poisoning the nation. I think that milk is a liquid source of calcium, that there are many alternative sources of calcium and that, if bone strength and general health is your concern, you're much better off ensuring you and your children do plenty of weight-bearing exercise.
In my home, my kids all drink some milk, but we definitely don't go out of our way to encourage its consumption. We always offer ice-cold water, and if they don't want to finish their milk, that's just fine by us. We also give our children a daily 400 IU supplement of vitamin D. And it probably goes without saying, but chocolate milk isn't part of our kids' daily lives, though occasionally they'll have some as a treat.
I think it's time to put an end to milk's finish-your-cup club. What about you?
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Yoni Freedhoff, MD, is an assistant professor of family medicine at the University of Ottawa, where he's the founder and medical director of the Bariatric Medical Institute—dedicated to non-surgical weight management since 2004. Dr. Freedhoff sounds off daily on his award-winning blog, Weighty Matters, and you can follow him on Twitter. Dr. Freedhoff's latest book, The Diet Fix: Why Everything You've Been Taught About Dieting is Wrong and the 10-Day Plan to Fix It, will be published by Random House's Crown/Harmony in 2014.