Ultra-processed foods linked to 32 damaging health outcomes

Consistent evidence shows that higher exposure to ultra-processed foods is associated with an increased risk of 32 damaging health outcomes, including cancer, major heart and lung conditions, mental health disorders and early death. These findings, published in The BMJ, underscore the need for urgent measures that aim to reduce dietary exposure to these products and better understand the mechanisms linking them to poor health.

Ultra-processed foods, including packaged baked goods and snacks, fizzy drinks, sugary cereals and ready-to-eat products, undergo multiple industrial processes and often contain colours, emulsifiers, flavours and other additives. They also tend to be high in added sugar, fat and/or salt, but are low in vitamins and fibre. Many previous studies and meta-analyses have linked highly processed food to poor health, but no comprehensive review has yet provided a broad assessment of the evidence in this area.

To bridge this gap, international researchers carried out an umbrella review of 45 distinct pooled meta-analyses from 14 review articles associating ultra-processed foods with adverse health outcomes. The review articles were all published in the past three years and involved almost 10 million participants, with the researchers grading the evidence as convincing, highly suggestive, suggestive, weak or no evidence. Overall, the results showed that higher exposure to ultra-processed foods was consistently associated with an increased risk of 32 adverse health outcomes.

Convincing evidence showed that higher ultra-processed food intake was associated with around a 50% increased risk of cardiovascular disease-related death, a 48–53% higher risk of anxiety and common mental disorders, and a 12% greater risk of type 2 diabetes. Highly suggestive evidence also indicated that higher ultra-processed food intake was associated with a 21% greater risk of death from any cause, a 40–66% increased risk of heart disease-related death, obesity, type 2 diabetes and sleep problems, and a 22% increased risk of depression.

The researchers acknowledged that umbrella reviews can only provide high-level overviews and they can’t rule out the possibility that other unmeasured factors in assessing ultra-processed food intake may have influenced their results. However, they say their use of rigorous and pre-specified systematic methods to evaluate the credibility and quality of the analyses suggests that the results withstand scrutiny.

“These findings support urgent mechanistic research and public health actions that seek to target and minimise ultra-processed food consumption for improved population health,” the researchers said, stating that public policies on ultra-processed foods are essential. These include front-of-pack labels, restricting advertising and prohibiting sales near schools and hospitals, and fiscal and other measures that make unprocessed or minimally processed foods as accessible as, and cheaper than, ultra-processed foods.

Commentating on the findings, some experts — including Professor Helen Truby from The University of Queensland — have noted that the studies were all observational, and so cannot prove causality, and that the evidence was not always strong. The authors themselves have acknowledged this, Truby said, calling for “much-needed research to provide direct cause-and-effect evidence: for example, can symptoms of anxiety be reduced or improved by swapping ultra-processed foods with unprocessed food?”

Truby concluded, “The volume of evidence in this review would suggest that it would do no harm to swap out the pop tart for a piece of wholegrain toast.”

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