The research, led by Dr Lisa Bero at the University of Sydney, sought to determine whether food industry sponsorship was associated with findings that are favourable to the sponsor.
Dr Bero and the team assessed reports that evaluated primary research studies or reviews, and that quantitatively compared food industry–sponsored studies with those that had none or other sources of sponsorship.
Two reviewers independently extracted data from each report and rated its quality using the ratings of the Oxford Centre for Evidence-Based Medicine, ranging from a highest quality rating of 1 to a lowest of 5.
Writing in JAMA Internal Medicine, they stated: “Although industry-sponsored studies were more likely to have conclusions favourable to industry than non–industry-sponsored studies, the difference was not significant. There was also insufficient evidence to assess the quantitative effect of industry sponsorship on the results and quality of nutrition research.”
Of 775 reports reviewed, 12, with quality ratings ranging from 1 to 4, met the inclusion criteria.
Notably two reports, with data that could not be combined, assessed the association of food industry sponsorship and the statistical significance of research results, but neither found an association.
Another report, however, examined effect sizes and found that studies sponsored by the food industry reported significantly smaller harmful effects for the association of soft drink consumption with energy intake and body weight than those not sponsored by the food industry.
They added: “Eight reports, including 340 studies, assessed the association of industry sponsorship with authors’ conclusions. Although industry-sponsored studies were more likely to have favourable conclusions than non–industry-sponsored studies, the difference was not significant (risk ratio, 1.31 [95%CI, 0.99-1.72]). Five reports assessed methodological quality; none found an association with industry sponsorship.”
They wrote that their findings “suggest, but do not establish, that industry sponsorship of nutrition studies is associated with conclusions that favour the sponsors.”
Further research is now needed, they added, to investigate the differences in study results and quality to subject nutrition data to the same standards as other sectors.
“Previous research documenting the influence of industry sponsorship on research in other health-related fields has led to international reforms to make data more accessible, conflicts of interest and funding more transparent, and to calls for stricter standards and policies for managing conflicts of interest, critiquing and reporting evidence, and conducting systematic reviews.
“Similar research is needed to help refine methods for evaluating studies used in systematic reviews that form the basis of dietary guidelines,” they added.
In August, Dr bero was among researchers from the University of Sydney who claimed widespread bias in industry-funded research into artificial sweeteners, arguing those funded by industry were 17 times more likely to have favourable results.
Source: JAMA Internal Medicine
Published online ahead of print. doi:10.1001/jamainternmed.2016.6721
“Association of Industry Sponsorship With Outcomes of Nutrition Studies. A Systematic Review and Meta-analysis”.
Authors: Lisa Bero, et al.