Industry-sponsored studies that report extraordinary health effects from ordinary beverages should be viewed with skepticism, suggests a team of Boston researchers that found biases in research involving milk, juices and soft drinks.

Writing in the journal Public Library of Science, David Ludwig and colleagues evaluated 111 beverage studies published between Jan. 1, 1999, and Dec. 31, 2003. They said soft drinks, milk and juices were up to eight times more likely to show results favorable to the sponsoring industry than in studies that did not have a corporate link.

"It's widely recognized when drug companies sponsor research the results are likely to be favorable to the company," said Ludwig, a director of the Optimal Weight for Life program at Children's Hospital in Boston. "But this had never been studied with respect to nutrition."

New York University nutritionist Marion Nestle lauded the new analysis, saying many studies with corporate ties had wrongly influenced how people thought about drinks and foods.

"These kinds of studies are designed to be used in advertising," Nestle, a professor of nutrition and author of the book What to Eat, said recently.

Ludwig said his aim was not to single out companies in his research. But of the 22 studies that were entirely funded by an industry organization or company, only three found unfavorable results for the beverage under study, he said. Yet 38 percent of independent beverage studies found negative results.

Industry groups say their sponsorship of studies is forthright. Susan K. Neely, chief executive of the American Beverage Association, said Ludwig failed to examine the merits of the science in the studies.

"This is yet another attack on industry by activists who demonstrate their own biases," she said in a statement.

Brenda Beltram, spokeswoman for the American Dairy Association and Dairy Council, said the dairy industry sponsored research only after a positive link between dairy consumption and a health effect was found.

In recent years, industry research has produced a flurry of papers suggesting tomato juice can prevent cancer, milk can cut blood pressure, and orange juice can bolster the immune system.