Industry Sponsorship of Nutritional Studies - is a bias revealed?

JAMA Internal Medicine presented a paper entitled Association of Industry Sponsorship with Outcomes of Nutrition Studies – A systematic review and meta-analysis by Nicholas Chartres et. al. Culling 775 reports, the authors chose 12 that met inclusion criteria and was primarily a meta-analysis of 12 meta-analysis papers. Here is a summary of their findings:

•    The 2 reports that assessed the association of sponsorship and the statistical significance of research results found no association.

•    In studies of sugar-sweetened beverages, industry studies demonstrate smaller amounts of harmful outcomes on calories and body weight, but they were not statistically different from non-industry sponsored studies.

•    Although industry-sponsored studies were more likely to have favorable conclusions than non-industry sponsored studies, the difference was not significant.

•    Our review found that industry-sponsored studies were of equal or better quality than those with other funding sources.

And here are the conclusions:

•    Although industry-sponsored studies were more likely to have conclusions favorable to industry than non-industry sponsored studies, the difference was not significant.

•    There was also insufficient evidence to assess the quantitative effect of industry sponsorship on the results and quality of nutrition research.

And now wait for it……

•    These findings suggest but do not establish that industry sponsorship of nutrition studies is associated with conclusions that favor the sponsors, and further investigation of differences in study results and quality is needed. 

Am I missing a key point because I am very unclear how this study supports this conclusion? Perhaps the authors have a bias not captured in their conflict of interest disclosures. Conflicts of interest are not solely financial. I thought I was the only one to believe that these conclusions had only a passing relationship to their findings. But Aaron Carroll of the Incidental Economist came through, perhaps a bit more politely.