Objective: The authors of this study sought to determine the extent to which financial conflicts of interest involving the food industry may have biased nutrition studies. To explore this question, they conducted research involving sugar-sweetened beverages (SSBs) as a test case, focusing on a period during which scientific consensus about the adverse health effects of SSB emerged from uncertainty.
Design: A PubMed search of worldwide literature was used to identify articles related to SSB and health risks published between 2001 and 2013. Financial relationships and article conclusions were classified by independent groups of co-investigators. Associations were explored by Fischer’s exact tests and regression analyses, controlling for covariates.
Results: A total of 133 articles published in English met inclusion criteria. The proportion of industry-related scientific studies decreased significantly with time, from approximately 30 % at the beginning of the study period to <5 % towards the end (P=0·003). A ‘strong’ or ‘qualified’ scientific conclusion was reached in 82 % of independent v. 7 % of industry-related SSB studies (P<0·001). Industry-related studies were overwhelmingly more likely to reach ‘weak/null’ conclusions compared with independent studies regarding the adverse effects of SSB consumption on health (OR=57·30, 95 % CI 7·12, 461·56).
Conclusion: Industry-related research during a critical period appears biased to underestimate the adverse health effects of SSB, potentially delaying corrective public health action.
Litman EA, Gortmaker SL, Ebbeling CB, Ludwig DS. Source of bias in sugar-sweetened beverage research: a systematic review. Public Health Nutr. 2018 Aug;21(12):2345-2350. doi: 10.1017/S1368980018000575. Epub 2018 Mar 26.