Background Intake of added sugar among adolescents is generally above recommended levels. Added sugar intake has been associated with weight gain and cardiometabolic risk factors during adolescence. Dietary habits developed during this period may persist into adulthood, increasing chronic disease risk in later life. A better understanding of the underlying trajectories of sugar consumption across adolescence and early adulthood will help inform appropriate interventions for this age group. This systematic review investigated changes in intake of added sugars and sugary foods and drinks, and determinants of such changes, between the ages of 13 and 30 years.

Methods In accordance with the registered protocol (PROSPERO: CRD42015030126), 7 electronic databases were searched in January 2016 for longitudinal studies of diet during adolescence or early adulthood. The papers retrieved were screened for studies including multiple measures of intake of sugars or sugary foods or drinks in cohort participants between the ages of 13 and 30 years. Data from included studies were extracted and analysed using random-effects meta-analysis, by the three main nutrient and food group categories identified.

Results We identified 23 papers reporting longitudinal data on intake of added sugar or sucrose (n=5), sugar-sweetened beverages (SSBs) (n=20) and/or confectionery (n=9). Eight papers reported data from the US, with Norway, Sweden and Australia also contributing several papers. On average, we found a per-year of age decrease in added sugar or sucrose intake (−0.28% total energy intake (95% CI −0.44; −0.12)), a decrease in confectionery consumption (−0.20 servings/week (95% CI −0.41; −0.001)) and a non-significant decrease in SSB consumption (−0.15 servings/week (95% CI −0.32; 0.02)). A small number of studies reported associations between behavioural determinants (e.g. screen time and fast food consumption) and change in intake of added sugar. Only three papers reported data beyond the age of 21 which weakens applicability of these findings to the early adulthood years.

Conclusion This review demonstrates a decrease in added sugar intake from adolescence to early adulthood, which may suggest an opportunity to capitalise on such changing preferences with interventions to further improve dietary choices within this age range. Improved longitudinal data is needed to further develop our understanding of changes in added sugar consumption into early adulthood and determinants of these changes.