A systematic scoping review of food tax-related studies, published by the University of Cambridge, exposes “a complex, limited and largely equivocal evidence base, suggesting that the public health case for using economic instruments to promote dietary and physical activity behaviour change may be less compelling than some proponents have claimed.”
The scoping review assessed 880 studies, out of which 768 studies that incorporated evidence for prices or income as correlates or determinants of target outcomes. The studies were classified and analysed in terms of key characteristics and principal findings, using a narrative, configuring synthesis focused on implications for policy and further research.
The authors revealed that few studies of economic instruments included assessment of long-term effects. Furthermore, the research found that “relationships between prices or income and target outcomes may often be non-linear, moderated by a wide range of modifiable and non-modifiable factors and mediated by complex mechanisms of action.” Ultimately, “many studies reported null associations or statistically significant associations in the opposite direction to that anticipated”.
As a general conclusion, the scoping review calls for caution when developing public health policies intended to use economic environmental stimuli to alter dietary and physical activity behaviour.
The full scoping review can be found here.