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SCOTT JAGOW: Word today that the price of soft drinks is going up. That's because of the higher costs for aluminum, corn syrup and concentrate. Yum. Analysts say we're looking at a four percent increase this year. A lot of nutrition studies are done by the beverage and food industry. Allan Coukell tells us those studies could be a little biased.

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ALLAN COUKELL: Researchers at children's hospital in Boston reviewed five years of studies on the nutritional effects of milk, juice or soda.

Industry-funded studies were almost eight times more likely to be favorable to their products, compared with studies from independent sponsors.

David Ludwig authored this study of studies. He's worried about a systematic bias.

DAVID LUDWIG: It could affect the advice that doctors and dieticians give to their patients. And it could also affect FDA regulation of food advertisements.

Ludwig's study is published today in the journal PLoS Medicine.

Soda and dairy companies defend their work, saying the real test is whether the results are published in a scientific journal.

In Boston, I'm Allan Coukell for Marketplace.