Monday, 21 November 2011

Spinning dairy weight loss claims

The USDA's Center for Nutrition Policy and Promotion (CNPP) provides the Nutrition Evidence Library, a clear and transparent source of systematic evidence reviews about all sorts of nutrition and health issues.

For example, here is the evidence review summary for claims about dairy consumption and weight loss:

Strong evidence demonstrates that intake of milk and milk products provide no unique role in weight control.
That seems clear enough: no unique role in weight control.

Meanwhile, the federal government's semi-public dairy checkoff program offers its own distinct review of the evidence.  Although many people do not realize it, the National Dairy Council is an arm of this checkoff program.  Its review says:
A growing body of research illustrates that enjoying three servings of milk, cheese or yogurt each day as part of a nutrient-rich, balanced diet may help maintain a healthy weight.
The first study mentioned is by Michael Zemel, the researcher who won a patent on dairy weight loss claims, which allows dairy industry organizations to collect royalties from food companies that use such claims. 

Buried deep in the subsequent studies, one finds contradictory evidence.  For example, a study by Wagner and colleagues in the Journal of the American College of Nutrition finds, "there were no significant differences in weight loss between groups.  The milk group showed significantly less reduction of body fat than the placebo group."  But you would not know that from the Dairy Council's summary statement.

The National Dairy Council -- whose messages have official status as "government speech" -- seems to be contradicting the more impartial review of USDA's scientists.  Why should the federal government be willing to play the role of "enforcer" for the National Dairy Council, collecting the millions of dollars in mandatory assessments that support the Council's industry-friendly spin on the evidence?

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