Conflict of Interest in Systematic Reviews

There is a recent systematic review of systematic reviews in PLOS Medicine examining the effect of industry funding on conclusions. The authors found that industry sponsored systematic reviews are 5 times more likely to support a conclusion of no positive association between sugar-sweetened beverages and obesity or weight gain as compared to studies that did not report industry funding. The authors do not give suggestions for the mechanism by which bias may have entered the systematic reviews other than the heterogeneity of literature selection. Examine systematic reviews carefully!