Blog | Thursday, August 23, 2012

Poor science writing leads to bunk nutritional advice

Journalist Virginia Hughes pointed me (and all her twitter followers) toward an interesting piece in the New York Times. In it, "opinionator" Mark Bittman makes some rather provocative statement about cow's milk.

According to Bittman, we drink too much of it. In the U.S., where obesity is becoming the norm, there's some truth to this. Milk is rich in calories and should be consumed by adults in moderation. In kids it is an important staple. What are his arguments against milk, and where do they come from? Are they convincing?

First he tries to shock us with large numbers, and by converting volume into weight:

"Until not long ago, Americans were encouraged not only by the lobbying group called the American Dairy Association but by parents, doctors and teachers to drink four 8-ounce glasses of milk, "nature's perfect food," every day. That's two pounds! We don't consume two pounds a day of anything else; even our per capita soda consumption is "only" a pound a day."

First of all, "until recently" renders the rest of the sentence moot. "Until recently" barbers performed surgery. "Until recently" beta blockers weren't recommended in heart failure. And the fact that it was recommended by a milk producers lobbying group shouldn't surprise us. I don't know of any of my colleagues who recommends that our adult patients drink 32 oz. of milk daily.

In fact the real recommendations are more subtle. The U.S. Department of Health and Human Services recommends three cups per day of low fat or fat free milk products which can include milk, yogurt, cheese, or soy milk.

So far, his arguments against milk are simply "it seems like a lot". Perhaps he's saving his better arguments.

Or not. His next argument is that many Americans are lactose-intolerant. So what? If you are lactose intolerant and want to drink milk, you can by lactose-free milk. You can eat yogurt. If you still don't want milk, no one is making you. Most people, after linking their abdominal distress to milk, will use their brains and substitute something like soy milk for cow's milk. This does not invalidate dairy recommendations.

He then goes on to state that water is "nature's perfect beverage." By what measure? If we are speaking simply of hydration, then milk and water are about equivalent. If we are talking about other nutrients such as vitamins and minerals, water is empty. Of course, it's also empty of sugar, which may be a good thing. Right?

"But, says Neal Barnard, president of the Physicians Committee for Responsible Medicine, "Sugar--in the form of lactose--contributes about 55 percent of skim milk's calories, giving it ounce for ounce the same calorie load as soda.'"

That's a deceptive statistic from an unreliable source. First of all, the Physicians Committee for Responsible Medicine is an animal rights front that advocates vegetarian and vegan diets for just about everyone. Their interest is not in nutrition, but in how our eating habits affect animals.

The statement is also very deceptive. An 8 oz. glass of milk has about 122 calories. An 8 oz. coke has about 100. So Coke is better, right? Well, no. about 100 % of Coke's calories comes from sugar (26 g per serving). The same glass of milk contains only 12 g of sugar. About one third of milk's calories comes from sugars, the other two thirds of fats and proteins. Coke and milk are comparable only in calories, perhaps the most misleading of facts.

Next argument, some people have bad milk allergies. OK, true. And some people are allergic to walnuts. If you're allergic to it, it's pretty clear that no one would recommend 32 oz. per day of milk. Foolish argument.

He goes on to give an anecdote from his past on how dairy seemed to give him heartburn, but he made changes suggested by a doctor who wrote a book on "detoxification." This same doctor writes about the supposed auto-immune basis to all disease, and appears to be into some deeply flawed autism work.

So far, Bittman has quoted a deceptive animal rights front and a doctor who has no special knowledge of dairy and nutrition but does have some questionable associations.

Bittman's ideas about milk are largely wrong, are based on opinions not of experts but of non-experts with an ax to grind, and are on their face based more on ideology and anecdotes than science. As a science writer, he has some explaining to do.

Before you pull some sort of "Milk Shill Gambit", I don't work for anyone who would benefit from milk sales. I don't personally drink milk since I'm lactose intolerant. I do love yogurt though.

Apparently he's not a "science writer". I would call the piece an attempt at science writing based on its content. As either food, nutrition or science writing, it fails.

Peter A. Lipson, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. After graduating from Rush Medical College in Chicago, he completed his internal medicine residency at Northwestern Memorial Hospital. This post first appeared at his blog, White Coat Underground. The blog, which has been around in various forms since 2007, offers "musings on the intersection of science, medicine, and culture." His writing focuses on the difference between science-based medicine and "everything else," but also speaks to the day-to-day practice of medicine, fatherhood, and whatever else migrates from his head to his keyboard.