Study finds industry funding could lead to bias in artificial sweetener research

Studies funded by artificial sweetener companies were 17 times more likely to find that artificial sweeteners have beneficial effects.

Researchers analyzed 31 review studies from 1978 to 2014 and established that research funding from both the sugar industry and artificial sweetener companies was more likely to lead to biased conclusions on sweetener's effects on weight loss. This research comes after documents released earlier this month revealed the sugar industry paid off scientists in the 1960s and 70s to downplay sugars role in obesity and focus on saturated fat instead.

 We speak with Lisa Bero from the University of Sydney, who studied industry impact in artificial sweetener and sugar research. She told us why conflict of interest is one reason the safety of artificial sweeteners is still so controversial.

ResearchGate: Could you briefly outline the findings of your study and their significance?

Lisa Bero: We examined reviews of studies on the beneficial effects of artificial sweeteners on weight loss and reviews that looked at potentially harmful effects, such as diabetes. We identified 31 relevant reviews and found that reviews funded by artificial sweetener companies were about 17 times more likely to have results that favor artificial sweeteners. This is significant as the data found in these studies is used to develop dietary guidelines. These studies were also likely to have more favorable conclusions than those that were independently funded.

Four reviews we looked at were funded by “competitor companies” that marketed sugary drinks or water, with all four of these reviews having conclusions that did not favor artificial sweeteners. This demonstrates that it is important to be critical of reviews that are funded by any food or beverage related industry, not just the artificial sweetener or sugar industry. Additionally, about one third of the reviews did not even disclose their funding sources, so transparency around author conflict of interest and research funding sources for this area of nutrition research is lagging behind other fields.

When we assessed the quality of the reviews, we found that there was no difference in quality related to funding source. This means that the differences in conclusions and results cannot be captured by the standard tools used to assess quality of reviews, but are likely due to subtle differences in inclusion of data or the interpretation of results.

RG: Is your sample size representative? How did you go about choosing which studies to include?

Bero: We have a comprehensive sample, not a representative sample. We used systematic review methods, so we attempted to identify all reviews of artificial sweeteners and their effects on obesity, not a sample of them. In our study, we looked at published reviews that included human research studies comparing one or more artificially sweetened beverages to water, sugar sweetened beverages or mixed comparisons where the effects on weight were evaluated as a primary or secondary outcome through BMI score or other measures of overweight and obesity.

RG: There has been a great deal of controversy surrounding the sugar industry funding studies to downplay the role sugar plays in coronary heart disease. Would you say conflicts of interest in research funding is a widespread problem in science today?

Bero: Yes, in addition to our most recent study on artificial sweeteners, our research group at the Charles Perkins Center has conducted a number of empirical studies demonstrating bias in drug industry, tobacco industry and chemical industry funded studies.

RG: What are the benefits of industry funding for studies?

Bero: Industry can provide financial support for research, but this is a benefit only if the sponsor cannot influence the design, conduct or publication of the research. One way to minimize the influence of any individual sponsor is to put all industry funding into a common fund that is then administered by an independent group that does not involve any of the funders.

Feature image: Amy van der Hiel on Flickr