A review of multiple other reviews investigating links between sugar-sweetened beverages and obesity supports the suggestion that there is a 'master plan' by the industry manufacturing these drinks to instil doubt in consumers as regards their adverse effects. The review is being presented at this year's European Congress on Obesity in Liverpool, UK, and is by Dr Philippe De Wals, Laval University, Québec City, Canada, and colleagues.

"The role of sugar-sweetened beverages (SSBs) on the increasing prevalence of obesity is a matter of great interest," says Professor de Wals. "In recent years, reviews have been published on this topic with very different conclusions."

In this review, De Wals and colleagues identified the characteristics of reviews that were associated with the authors' position on evidence supporting a causal relationship between SSBs and body weight. They looked at reviews published in English in peer-reviewed journals during the 2006-2011 period. The methodological quality of these studies was assessed by two judges using two scoring systems:  A Measurement Tool to Assess Systematic Reviews (AMSTAR) and the American Dietetic Association Quality Criteria Checklist (ADA-QCC). The authors' final position was blindly assessed by 11 experts using a standard tool called the Likert scale ranging from 0='no evidence of a causal relationship' to 5='strong evidence of a causal relationship'.

The researchers identified 17 reviews in total, including 3 meta-analyses, 3 qualitative systematic reviews and 11 qualitative non-systematic reviews. Four of these reviews were funded by the food industry. Quality scores (the scientific quality of the reviews) were not correlated with the source of funding. However, reviews funded by the industry concluded that evidence supporting a causal relationship was weak (mean position score = 1.78 on the 1 to 5 scale) whereas evidence of a link was generally considered to be well founded in the other reviews (mean position score = 3.29).

Dr De Wals concludes: "Results support the hypothesis of a master plan, based on subtle intervention, that has been developed by the food industry to instil doubt regarding the adverse effects of SBB and to prevent the implementation of public health interventions and policies aiming to reduce their consumption."