Eating ultra-processed foods regularly may raise inflammatory bowel disease (IBD) risk, a new observational study reports.
According to the researchers, participants who ate more than one serving of ultra-processed food daily had up to an 82% higher risk of developing IBD than those who ate less than one serving daily.
The study, “Association of ultra-processed food intake with risk of inflammatory bowel disease: prospective cohort study,” was published in The BMJ.
IBD, comprising Chron’s disease and ulcerative colitis, is a chronic inflammatory disorder of the gastrointestinal (gut) tract. The exact cause is unknown, but gut bacteria imbalances and activated gut immune cells are thought to be involved.
Scientists have established that diet alters gut bacteria and immunity and potentially plays a role in IBD development. Unfortunately, IBD prevalence has increased globally due to the adoption of Western diets that are typically low in fibre but high in omega-6 fatty acids, refined sugars and ultra-processed foods.
Ultra-processed foods include all types of packaged and formulated foods and beverages containing food additives, artificial flavourings, colours, or other chemical ingredients. Foods such as processed meat, cold breakfast cereal, sauces, soft drinks, refined sweetened foods (e.g., candy, chocolate, jam, jelly, brownies, pudding), chips, ice cream, commercially prepared pastries, biscuits and fruit drinks are all considered ultra-processed.
Detergents and emulsifiers added to ultra-processed foods may harm the gut barrier. Carboxymethylcellulose – a common thickener in cheese, frozen desserts and salad dressings – encourages harmful bacteria to attach to the gut and enter the small intestine. Polysorbate 80, an emulsifier used in processed foods, increases bacteria in the small intestine of people with Crohn’s disease.
Other studies have shown links between diets high in processed foods and cancer and cardiovascular diseases, but the links between ultra-processed foods and IBD risk is unclear.
To address this, a team of researchers investigated the link between ultra-processed foods and IBD by evaluating data from participants enrolled in the Prospective Urban Rural Epidemiology (PURE) study. The PURE study includes 21 low, middle and high-income countries across North America, Europe, South America, the Middle East, South Asia, China, South-East Asia and Africa.
A total of 116 037 participants with complete food frequency questionnaires (FFQs) were included in the study. Participants were followed for a median of 9.7 years, and during that period, 467 participants received an IBD diagnosis. 90 participants were diagnosed with Crohn’s disease and 377 with ulcerative colitis.
People with higher intakes of ultra-processed foods had higher risks of IBD. Compared with less than one serving daily, five or more servings of ultra-processed foods daily increased IBD risk by 82%, while up to four servings increased it by 67%. This higher risk occurred irrespective of the participant’s age and location.
Interestingly, white meat, unprocessed red meat, dairy, starchy foods, fruit, vegetables and legumes were not associated with higher IBD risk. Thus, suggesting that “it might not be the food itself that confers this risk but rather the way the food is processed or ultra-processed.”
Study limitations the researchers wrote included using food frequency questionnaires and not accounting for dietary changes over time. They also could not rule out other unmeasured (confounding) factors that may have affected their results.
“Our findings support the hypothesis that intake of ultra-processed foods could be an environmental factor that increases the risk of IBD,” they wrote.
“Further studies are needed to identify specific potential contributory factors among processed foods that might be responsible for the observed associations in our study,” they added.
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