A new study, published in the journal Circulation, adds to growing doubts about the benefits of skim or low-fat milk, NPR reports this morning: 

“People who had the most dairy fat in their diet had about a 50 percent lower risk of diabetes” compared with people who consumed the least dairy fat, says Dariush Mozaffarian, dean of the Friedman School of Nutrition Science and Policy at Tufts University, who is also an author of the study.

NPR reporter Allison Aubrey notes other recent studies on the possible benefits of dairy fat and then reports:

With all the new evidence that challenges the low-fat-is-best orthodoxy, Mozaffarian says it may be time to reconsider the National School Lunch Program rules, which allow only skim and low-fat milk.

“Our research indicates that the national policy should be neutral about dairy fat, until we learn more,” says Mozaffarian.

And there’s the problem for public policy. Why do we need a national policy on dairy fat? Why do we need national rules on what local schools can serve for lunch? And most specifically, since our understanding of nutrition science is always changing, why should we codify today’s understandings in law and regulation?

As I wrote a few months ago in response to a Washington Post story on the possibility that decades of government warnings about whole milk may have been in error,

It’s understandable that some scientific studies turn out to be wrong. Science is a process of trial and error, hypothesis and testing. Some studies are bad, some turn out to have missed complicating factors, some just point in the wrong direction. I have no criticism of scientists’ efforts to find evidence about good nutrition and to report what they (think they) have learned. My concern is that we not use government coercion to tip the scales either in research or in actual bans and mandates and Official Science. Let scientists conduct research, let other scientists examine it, let journalists report it, let doctors give us advice. But let’s keep nutrition – and much else – in the realm of persuasion, not force. First, because it’s wrong to use force against peaceful people, and second, because we might be wrong….

Today’s scientific hypotheses may be wrong. Better, then, not to make them law.