The findings, published by The BMJ, 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.
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.
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.”
