Sugar-Sweetened Beverages and Obesity Risk in Children and Adolescents: A Systematic Analysis on How Methodological Quality May Influence Conclusions

Background In the context of a worldwide high prevalence of childhood obesity, the role of sugar-sweetened beverage (SSB) consumption as a cause of excess weight gain remains controversial. Conflicting results may be due to methodological issues in original studies and in reviews. Objective The aim of this review was to systematically analyze the methodology of studies investigating the influence of SSB consumption on risk of obesity and obesity among children and adolescents, and the studies' ability to answer this research question. Methods A systematic review of cohort and experimental studies published until December 2013 in peer-reviewed journals was performed on Medline, CINAHL, Web of Knowledge, and ClinicalTrials.gov. Studies investigating the influence of SSB consumption on risk of obesity and obesity among children and adolescents were included, and methodological quality to answer this question was assessed independently by two investigators using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Results Among the 32 identified studies, nine had positive quality ratings and 23 studies had at least one major methodological issue. Main methodological issues included SSB definition and inadequate measurement of exposure. Studies with positive quality ratings found an association between SSB consumption and risk of obesity or obesity (n=5) (ie, when SSB consumption increased so did obesity) or mixed results (n=4). Studies with a neutral quality rating found a positive association (n=7), mixed results (n=9), or no association (n=7). Conclusions The present review shows that the majority of studies with strong methodology indicated a positive association between SSB consumption and risk of obesity or obesity, especially among overweight children. In addition, study findings highlight the need for the careful and precise measurement of the consumption of SSBs and of important confounders.