Purpose This study aims to reveal the presence of products with negatively correlated nutrients in the marketplace and their implications for consumer choices. It also investigates the role of an overall simplified nutrition scoring system (SNSS) – health star rating (HSR), in improving the healthiness of consumer choices. Design/methodology/approach Three (lab, online and eye-tracking) experiments investigate the effects of negatively correlated nutrients and the mitigating role of an overall SNSS for consumers’ food choices. A final panel-data study analyzes the changes in actual food purchases after the introduction of HSRs (an SNSS) in Australia. Findings Experimental results show that consumers use a decision strategy based on a dominant nutrient to choose food products, which creates health halos and leads to less healthy choices when products have negatively correlated nutrients. The presence of an overall SNSS leads to more accurate healthiness perception and healthier choices. Panel data analysis shows that the healthiness of consumer food purchases increased after the introduction of HSRs. Research limitations/implications The study investigated the effect of an overall SNSS on specific categories, but not on the overall shopping basket. Practical implications For policymakers, this paper shows that overall SNSS helps consumers choose healthier options. Food manufacturers and retailers could be motivated to formulate healthier products when consumers choose healthier options. Originality/value This is the first study to document the presence of products with negatively correlated nutrients and their implications for consumer choices. It highlights the unique role of an overall SNSS, in helping consumers identify healthier options when products have negatively correlated nutrients.