Report Warns Of Biases in Drink Studies

Can the source of a study's funding affect its conclusions?

Maybe, according to a paper looking at beverage studies in the online journal PLoS Medicine, published by the Public Library of Science.

The paper looked specifically at research about milk, soft drinks and juice. Not only are all three beverages popular, but "they're all highly controversial, highly profitable and heavily marketed to children," notes the study's lead author, David Ludwig, director of the Optimal Weight for Life Program at Children's Hospital in Boston.

At the National Library of Medicine's Medline database, Ludwig and his colleagues culled through more than 500 papers on the beverages published between 1999 and 2003. Studies that were done only in animals or that did not look at health outcomes were eliminated. So was research that didn't cite funding sources. That left 111 studies to examine closely.

To reduce any potential bias, the team members did their analysis in separate steps. One researcher chose the studies that met the project's standards for inclusion. Two others reviewed each study's findings after the paper's title, authors and sponsors and had been removed from the text. These two researchers also classified the study's conclusions as favorable, neutral or unfavorable to the beverage under investigation. A fourth scientist, who was blinded to the other team members' conclusions, then estimated whether the findings would benefit, disadvantage or be neutral to the funder's financial interests.

The team found that studies funded by industry were four to eight times more likely to show bias in favor of sponsors' products than studies that did not receive industry funding.

"That suggests that financial conflict could provide fundamental bias in the scientific literature," notes Ludwig, whose research was sponsored by the Charles H. Hood Foundation and the Department of Medicine at Children's Hospital.

Since the U.S. Dietary Guidelines and other nutrition advice are based on the scientific literature, the team notes that its findings have "potentially significant implications for public health."

Courtesy of Washington Post

Steve - what a shock! We have said this all along, especially in the case of milk.