Consistent evidence links ultra-processed food to over 30 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.

The findings, published by The BMJ today, show that diets high in ultra-processed food may be harmful to many body systems and underscore the need for urgent measures that target and 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 or heat products, undergo multiple industrial processes and often contain colours, emulsifiers, flavours, and other additives. These products also tend to be high in added sugar, fat, and/or salt, but are low in vitamins and fibre.

They can account for up to 58% of total daily energy intake in some high income countries, and have rapidly increased in many low and middle income nations in recent decades.

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, researchers carried out an umbrella review (a high-level evidence summary) 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. None were funded by companies involved in the production of ultra-processed foods.

Estimates of exposure to ultra-processed foods were obtained from a combination of food frequency questionnaires, 24 hour dietary recalls, and dietary history and were measured as higher versus lower consumption, additional servings per day, or a 10% increment.

The researchers graded the evidence as convincing, highly suggestive, suggestive, weak, or no evidence. They also assessed the quality of evidence as high, moderate, low, or very low.

Overall, the results show 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.

Evidence for the associations of ultra-processed food exposure with asthma, gastrointestinal health, some cancers and cardiometabolic risk factors, such as high blood fats and low levels of ‘good’ cholesterol, remains limited.

The researchers acknowledge that umbrella reviews can only provide high-level overviews and they can’t rule out the possibility that other unmeasured factors and variations in assessing ultra-processed food intake may have influenced their results.

However, their use of rigorous and prespecified systematic methods to evaluate the credibility and quality of the analyses suggests that the results withstand scrutiny. 

As such, they conclude: “These findings support urgent mechanistic research and public health actions that seek to target and minimise ultra-processed food consumption for improved population health.”

Ultra-processed foods damage health and shorten life, say researchers in a linked editorial. So what can be done to control and reduce their production and consumption, which is rising worldwide?

They point out that reformulation does not eliminate harm, and profitability discourages manufacturers from switching to make nutritious foods, so public policies and action on ultra-processed foods are essential. 

These include front-of-pack labels, restricting advertising and prohibiting sales in or near schools and hospitals, and fiscal and other measures that make unprocessed or minimally processed foods and freshly prepared meals as accessible and available as, and cheaper than, ultra-processed foods.  

It is now time for United Nations agencies, with member states, to develop and implement a framework convention on ultra-processed foods similar to the framework on tobacco, and promote examples of best practice, they write.

Finally, they say multidisciplinary investigations “are needed to identify the most effective ways to control and reduce ultra-processing and to quantify and track the cost-benefits and other effects of all such policies and actions on human health and welfare, society, culture, employment, and the environment.”