Background The UK front of package labelling (FOPL) multiple traffic light (MTL) system is used to inform consumers on the nutrient content of purchases. However, FOPL does not include information on food processing, which is associated with a range of adverse health outcomes, including obesity and cardiovascular disease. The objective of this study was to compare food and drink in the National Diet and Nutrition Survey (NDNS) database based on FOPL MTL scoring, nutrient content and NOVA classification. Methods and findings Food and drink items were obtained from Intake24, the electronic dietary assessment method used in NDNS Year 12. Items were coded into minimally processed food (MPF), processed culinary ingredients (PCI), processed food (PF) and ultra-processed food (UPF) according to the NOVA classification, and coded into green, amber and red FOPL traffic lights according to Food Standards Agency guidance for fat, saturated fat, total sugar and salt per 100g. Nutrient content, FOPL MTL and NOVA classifications were then analysed. Of the 2,980 items in the analysis, 55.4% were UPF, 33.1% were MPF, 9.5% were PF, and 2.0% were PCI. UPFs contained greater fat, saturated fat, total sugar, and salt per 100g than MPFs, and had a higher energy density and proportion of hyper-palatable items (p<0.001). PFs contained more fat, saturated fat, salt and energy per 100g than MPFs (all p<0.001), but similar total sugar. UPFs had a higher odds of containing red FOPL (odds ratio (OR): 4.59 [95%CI: 3.79, 5.57]), lower odds of containing green FOPL (OR: 0.05 [95%CI: 0.03, 0.10]), and higher odds of an unhealthier overall FOPL MTL score (OR: 7.0 [95%CI: 6.1, 8.2], compared with MPFs. When considering items without any red traffic lights, UPFs still contained more fat, saturated fat, total sugar and salt than MPF, and had a higher energy density and proportion of hyper-palatable items (p < 0.001). However, a number of UPFs have healthier FOPL MTL scores. Conclusions Most items in the are UPF. UPFs have an unhealthier nutritional profile than MPFs, are more likely to have an unhealthier FOPL MTL score and be more energy-dense and hyper-palatable. When considering items without any red FOPL, UPFs still have a poorer nutritional profile than MPFs, with a higher energy density and hyper-palatability. But, not all UPFs were unhealthy according to FOPL. The results have important implications for understanding how consumers may interpret the healthiness of UPFs or FOPL MTLs, and updating UK food and drink labelling.

All authors have completed the ICMJE uniform disclosure form at http://www.icmje.org/disclosure-of-interest/ and declare: S.J.D receives royalties from Amazon for a self-published book that mentions ultra-processed food, and payments from Red Pen Reviews. R.L.B reports honoraria from Novo Nordisk, Eli Lilly, Medscape, ViiV Healthcare Ltd and International Medical P and advisory board and consultancy work for Novo Nordisk, Eli Lilly, Pfizer, Gila Therapeutics Ltd, Epitomee Medical Ltd and ViiV Healthcare Ltd. A.B. reports honoraria from Novo Nordisk, Office of Health Improvement and Disparity, Johnson and Johnson and Obesity UK outside the submitted work and is on the Medical Advisory Board and shareholder of Reset Health Clinics Ltd.

S.J.D. is funded by a Medical Research Council grant (MR/N013867/1). R.L.B. is funded by the National Institute for Health and Care Research, Sir Jules Thorn Charitable Trust and Rosetrees Trust. A.B is funded by Rosetrees Trust.

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I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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Data can be made available upon request to the authors. For access to Intake24 datasets, please contact the Intake24 team directly: [email protected]; https://intake24.co.uk.

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