Competing interests: The BMJ has judged that there are no disqualifying financial ties to commercial companies. The authors declare the following other interests: KEB’s spouse is a brewer at Steam Brewing Company, Auckland, New Zealand; SM is co-chair of the food expert group of Health Coalition Aotearoa, a non-commercial advocacy group against harmful commodities including unhealthy food; she was on the organising committee of the Nutrition Society of NZ and Australia conference in 2023; the conference received sponsorship from food companies whose products were screened for alignment with national dietary guidelines. Further details of The BMJ policy on financial interests is here: https://www.bmj.com/sites/default/files/attachments/resources/2016/03/16-current-bmj-education-coi-form.pdf."