Studies financially aided by the sugary drinks industry are consistently failing to find a link between their products and problems such as obesity and diabetes, a University of California study has found.
The results of industry-funded studies were compared with independent studies as part of the research.
Dr. Dean Schillinger, professor at the University of California San Francisco and study lead author, believes that the potentially unreliable drinks industry studies are a reason why links between obesity and sugary drinks are considered to be controversial and not definitive.
“That controversy has been manufactured by the industry itself, which is harnessing the science to its own ends,” said the professor.
The research by Schillinger and his colleagues used PubMed, an online compendium of scientific research, to look at the findings of 60 experimental studies which examined how metabolic outcomes were affected by the consumption of sugary drink.
Of the findings, 34 positively associated sugary beverages with obesity, while 26 of them found no association. The 26 studies which found a negative association were all funded by the drinks industry. Only one of the 34 with a positive link had a connection to the industry.
Companies such as Nestle & PepsiCo provided funding for the studies with either direct financial support or as payments to the authors as consultants.
“It’s interesting that they looked at experimental studies,” said Jennifer Harris, a social psychologist at the University of Connecticut Rudd Center for Food Policy and Obesity, who wasn’t involved in the study. “[They are] designed to show a causation effect. If you take out the studies that were industry-funded, there is no controversy. That makes this an important study.”
Susceptibility to bias
Adela Hruby, an expert in nutritional epidemiology, who also wasn’t involved in the study, wants to know what has been omitted.
“Why only PubMed?” she asked. “And why are they limited to publications between 2001 and 2016?”
Schillinger’s research funding was provided by the National Institutes of Health. He has, however, revealed that he was previously paid by San Francisco County’s ordinance regarding billboard advertising for sugar-sweetened drinks.
Hruby concedes that Schillinger’s study is given further kudos by a study published in AIM in 2013. “I don’t think this study is hugely novel, but it does show our susceptibility to bias.”
“Susceptibility needs a closer look”, commented Schillinger, “to determine how and when biased results occur”.
“What was it about the conduct of the scientists that introduced the bias?” he asked. “We need to pay attention to conflicts of interest. And if we’re going to use science to influence consumers’ health decisions, we have to have them think more critically by asking who funded the study.”
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