Conflicts of Interest in Artificial Sweetener Studies

A new systematic review published in the Public Library of Science examines the relationship between research outcomes and risk of bias, study sponsorship, and author financial conflicts of interest in reviews of the effects of artificially sweetened beverages on weight.

Highlights:

• “The food and beverage industry frequently sponsors research on the health effects of added sugars consumption and has produced reviews for policy purposes. For example, the cane and beet sugar industry has lobbied public health organizations, such as the World Health Organization, and produced reviews critical of the role of sugar in dental caries, overweight and obesity, and atherosclerotic vascular disease.”

• “The replacement of added sugars with artificial sweeteners to prevent and control obesity is controversial, due to safety concerns [18–20] and conflicting evidence on their effect on weight. Some studies have shown that artificial sweeteners may negatively affect the gut microbiome and pathways associated with diabetes mellitus or obesity in both rodents and humans.”

• “Another possible explanation for the conflicting results of studies of artificially sweetened beverages may be bias related to funding source. The observed bias related to funding is not explained by other risks of bias in the studies (for example sequence generation, concealment of allocation, or loss to follow-up).”

• “We performed a systematic review of reviews of the effects of artificially sweetened beverages on weight. Two assessors independently screened articles for inclusion, extracted data, and assessed risks of bias. We compared risk of bias, results and conclusions of reviews by different industry sponsors, authors’ financial conflict of interest and journal sponsor.”

• “According to the US Agency for Healthcare Research and Quality and the US National Toxicology Program, funding source is recommended as a factor to consider when evaluating risk of bias of individual studies for selective reporting and then again for evaluating the body of evidence for publication bias.”

• “Our findings show that review sponsorship, financial conflicts of interests of authors and journal funding are all associated with favorable outcomes related to the effects of artificially sweetened beverages on weight outcomes. Reviews sponsored by the artificial sweetener industry were more likely to report results and conclusions that favored artificially sweetened beverages than non-industry sponsored reviews. We also found that reviews performed by authors with a conflict of interest with the food industry were more likely to have results and conclusions that favored artificially sweetened beverages than reviews performed by authors without financial conflicts of interest.”

• “Artificial sweetener industry sponsored reviews were more likely to have favorable results (3/4) than non-industry sponsored reviews (1/23), as well as favorable conclusions (4/4 vs. 15/23).”

• All reviews funded by competitor industries reported unfavorable conclusions (4/4). In 42% of the reviews (13/31), authors’ financial conflicts of interest were not disclosed. Reviews performed by authors that had a financial conflict of interest with the food industry (disclosed in the article or not) were more likely to have favorable conclusions (18/22) than reviews performed by authors without conflicts of interest (4/9).”