Why public health warnings could backfire

Premature warnings to consumers to avoid eating all ultra-processed food products have likely social costs and may harm the health of people facing food poverty—at least in the short term.

This is the clear message to policymakers in a newly published perspective article from Professors Alexandra Johnstone from the Rowett Institute of Nutrition and Health, University of Aberdeen and Eric Robinson of the University of Liverpool.

They say that until the link between ultra-processed foods (UPFs) and poor health is better understood, the focus of official public advice should remain on avoiding known threats: high fat, sugar and salt content.

Issuing formal warnings about UPFs in the U.K.—which some other countries have done—could be counter-productive, leading some people to switch to alternatives that are not classified as ultra-processed but are less nutritious than what they were consuming before, they argue.

And they highlight the potential “social cost for many people with more limited resources” of removing convenient options and the possible negative mental health impacts on “those who worry about their health or live with eating disorders, particularly if social circumstances make avoiding UPFs difficult.”

The article—published in PLOS Medicine as part of a collection on the subject of UPFs—concludes, “Based on the balance of current evidence, we do not believe it is appropriate to be advising consumers to avoid all UPFs and we await further evidence to inform consumer guidance on the need to limit consumption of specifics foods based on their degree or type of processing.

“We know with certainty that foods which are energy dense and/or high in saturated fat, salt or sugar are detrimental to health and we should continue to advise consumers to limit consumption of these foods. Likewise, we should be encouraging consumption of health-promoting foods, like fruits, vegetables and wholegrains.

“Mechanistic uncertainty over food processing and health should not prevent immediate and much needed public health policy to regulate the food industry in order to dramatically reduce the advertisement, availability and dominance of foods high in energy and/or saturated fat, salt or sugar on national diets.

“However, mechanistic uncertainty should determine how the public are communicated to and play a central role in determining public advice and emerging national dietary guidance on UPFs and food processing health risks.”

Pressure to issue guidance against eating UPFs—which account for a significant part of the national diet —has mounted in the media and elsewhere because of consistent evidence from a growing number of observational studies that they are linked to poor health outcomes.

But many UPFs are also high in fat, sugar and salt and as yet, the Food Standards Agency believe other possible causes of ill health from consuming them “have not yet been fully explained by the science,” and so specific public guidance has not been issued.

Food Standards Scotland (FSS) warned in March that “there is a risk that the emphasis on ultra-processed foods creates a distraction from the key diet issues where there is robust evidence for action, i.e., high fat, salt and sugar foods, thereby providing further impetus for FSS to provide clear consumer messaging on this issue.”

FSS has since published its organizational position on the topic, alongside consumer-facing advice, reaffirming these conclusions.

Professor Johnstone said, “We must guard against the possibility that the people in our society who are already most at risk of not being able to afford to eat healthily are not put in an even worse position as we continue to investigate the links between some ultra-processed foods and poor health.

“We need more high-quality mechanistic research in humans, using controlled diets, to tease out the effects of nutrient profile and ultra-processing per se. Diet reformulation and diet quality are two key aspects of our food environment and alongside affordability, these remain food system challenges.”

Professor Robinson said, “Foods classed as ultra-processed which are high in fat, salt and/or sugar should be avoided, but a number of ultra-processed foods are not. We should be thinking very carefully about what advice is being given to the public, as opposed to providing simplified and potentially misleading messages that grab headlines.”