Ultra-processed foods

Commissioning Brief 

Research question

• What are the health and health inequality impacts of interventions that affect consumption of ultra-processed foods?

There is growing interest in food processing and its effect on health. Food processing has many purposes. It can make otherwise inedible food safe to consume, preserve foods, increase shelf life, retain or modify nutrient composition (for example through micronutrient fortification), and increase food palatability and convenience. Several classification systems have been proposed to group foods according to the degree and purpose of processing. The term ‘ultra-processed foods’ (UPFs) is defined in the NOVA classification system, which classifies all foods into one of four groups. NOVA classifications range from unprocessed or minimally processed foods (e.g. fruit, vegetables, seeds, meat, eggs, milk) to ultra-processed foods (e.g. soft drinks, crisps, ice-cream, meat replacements, ready to heat products, instant soups, packaged snacks, confectionary, packaged breads, margarine). UPFs are typically industrially formulated and made from substances derived from foods and additives.

Estimates suggest that the mean proportion of UPF in the diet of the UK population is among the highest internationally. Adolescents are often found to be the most significant consumer group. Evidence reviews suggest that increased UPF consumption is associated with multiple adverse health outcomes, including obesity, non-communicable diseases such as diabetes, hypertension and cardiovascular disease, and all-cause mortality. However, the majority of available evidence is observational in nature and susceptible to confounding and bias. Additionally, some research suggests that certain UPFs (e.g. breads, cereals, plant-based alternatives) pose less risk to health than others.

Recently there have been calls for policy makers to intervene and seek to reduce consumption of UPFs across the UK population. UPFs are often more affordable, convenient, and palatable relative to other food options, and may be addictive. Relative to minimally processed foods, many UPFs have greater energy density, and contain higher amounts of fat (including saturated fat), sugar, and salt; they are also often lower in other important macronutrients such as fibre and protein. Research suggests that UPF intake varies with demographic factors including age, gender, ethnicity, and geographic region. The social determinants of health influence our access to food. The availability and affordability of different types of foods are related to our economic circumstances, our social networks, and the wider environmental, social, and cultural conditions within which we live. There is a need for research to investigate the health inequality impacts – as well as the health impacts – of interventions that affect UPF intake. 

A large proportion of existing research is observational and focuses on whether UPF consumption affects health outcomes. Evidence addressing the impact of interventions which alter (intentionally or otherwise) consumption of UPFs is limited. In keeping with the remit of the NIHR Public Health Research (PHR) Programme, which focuses on evaluative research of non-NHS interventions, we are seeking to commission research investigating the health and health inequality impacts of interventions that intentionally or unintentionally alter consumption of UPFs.

The PHR Programme recognises that terminology can vary and that classification systems may group foods in different ways. This research brief is inclusive of ‘ultra-processed’ and ‘highly-processed’ foods, or similar terms. In their recent statement on processed foods and health, the Scientific Advisory Committee on Nutrition (SACN) applied a set of screening criteria to understand which system(s) would be practical and applicable for use in the UK. The NOVA classification system met their criteria, was considered potentially suitable for use in the UK, and is the most extensively used classification system in the literature. However, NOVA does not consider the nutrient content of foods, and SACN noted some limitations of this classification system.

The PHR Programme is predominantly interested in the evaluation of interventions operating at population/group level, rather than at an individual level, and which should address health inequalities and the wider determinants of health. We recognise that interventions are likely to impact different (sub)populations in different ways and encourages researchers to explore such inequalities of impact in their study design.

Research areas of interest could include, but are not limited to:

• Evaluation of existing interventions adapted for UPF consumption (e.g. interventions relating to intake of foods high in fat, salt, or sugar (HFSS)).
• Evaluation of interventions that impact inequality aspects of UPF consumption, including effective ways to reduce inequalities, and/or ways to mitigate or prevent widening of inequalities. Potential unintended consequences of UPF-related interventions are also of interest to the PHR Programme. 
• The health and health inequality impacts of current public health messaging focused on, for example, reducing intake of HFSS foods compared with messaging about UPFs – and the dynamic that may exist between these approaches.
• Evaluation of interventions that involve advertising of UPFs.
• Evaluation of interventions that affect the (relative) cost or affordability of UPFs.
• Evaluative research of UPF-related interventions that examine sustainability and climate impacts (for example, as secondary outcomes) or sustainability/climate interventions that may impact UPF consumption. Please note the PHR Programme requires a health-related primary outcome.
• Evidence reviews (where possible and justified) of UPF-related interventions that impact health and/or health inequalities.
• Modelling studies (where possible and justified) on the health and/or health inequality impacts of UPF-related interventions.
• Evaluation of interventions that affect access to UPFs. 
• Evaluation of interventions affecting the choice architecture of the environment related to UPF purchase or consumption.
• Evaluation of interventions focused on families/households and/or children (including infants) and young people – in relation to UPF consumption.
• Evaluation of multisectoral and/or whole-system approaches related to UPF.
• Evaluation of interventions focused on food labelling (including warning labels) in the context of UPF.
• Evaluation of UPF-related interventions focused on provision of food in educational settings (e.g. schools, nurseries).

A range of study designs and outcome measures can be used. Researchers will need to clearly describe and justify their choice of outcomes and target population group, as well as the rationale for their methodological approach. Researchers will need to specify how outcomes will be measured in the short, medium, and long term. Primary outcomes must be health related. The PHR Programme will accept proxy measures for health as long as they are appropriately defined and the link to health is clearly justified. Researchers are encouraged to consider additional outcome measures including those relating to the broader determinants of health and health inequalities, which should be specified and justified.

Understanding the value of public health interventions – whether the outcomes justify their use of resources – is integral to the PHR Programme, where resources relating to different economic sectors and budgets are potentially relevant. The main outcomes for economic evaluation are expected to include health (including health-related quality of life) and the impact on health inequalities as a minimum, with consideration of broader outcomes welcomed. Different approaches to economic evaluation are encouraged as long as they assess the value and distributive impact of interventions. Applications that do not include an economic component should provide appropriate justification.

Researchers are strongly encouraged to ensure that a wide range of stakeholders, including decision-makers, commissioners, members of the public, and people with lived experience, are meaningfully involved in the design and planning of the research and throughout the work, and they might do this through involving them as costed/rewarded members of the research team.

The Programme is focused on the impact of the research it funds. Researchers are encouraged to maximise the impact of their research and should explain how they will share their findings with policy makers, public health officers, special interest groups, charities, community audiences, and other relevant stakeholders.

For further information on submitting an application to the PHR Programme, please refer to the Stage 1 guidance notes and PHR supporting information. These can be found by clicking on the relevant commissioned call on the main funding opportunities page. This also includes closing dates and details about how to apply.

In order to apply you will need to carefully review the:

• Stage 1 guidance notes
• PHR supporting information

Please consult the NIHR Specialist Centre for Public Health (SCPH) about the design of your research as soon as possible. Successful applications generally require a long time (several months) to develop.

All primary research projects are expected to establish a programme appointed Study/Trial Steering Committee and it is important that you read the Research Governance Guidelines before completing your application. Costs incurred by this committee should be included in the budget as appropriate.

You may wish to review the PHR tips for success in applying.

Webinar

We held a webinar to support applications to this funding opportunity, on 9 October 2024. A copy of the slides and recording are available on request.