Ultra-processed foods increase the risk of inflammatory bowel disease

By James DuckerReviewed by Emily Henderson, B.Sc.Jul 16 2021

Ultra-processed foods containing high levels of added sugar, fat, and salt, but lacking in vitamins and fiber, are key contributors to the development of IBD, but further research is warranted to determine what specifically causes this.

Inflammatory Bowel Disease. Image Credit: SciePro/Shutterstock.com

Consuming 5+ servings per day of ultra-processed foods increases IBD risk by 82%

Inflammatory bowel disease (IBD) encompasses two medical conditions; Crohn's disease and ulcerative colitis, which are characterized by chronic inflammation of the gastrointestinal tract leading to fatigue, weight loss, cramps, and reduced appetite among other symptoms.

IBD is more common among industrialized nations, and past studies have provided key evidence suggesting it is linked to behaviors such as smoking, age, and inheritance. Preliminary evidence has also shown that thought that dietary factors might play a role in IBD incidence, but linking specific dietary intake to IBD is limited, particularly when considering ultra-processed food.

Ultra-processed food is packaged baked goods and snacks, fizzy drinks, sugary cereals, ready meals containing food additives, and reconstituted meat and fish products, which contain high levels of added sugar, fat, and salt, but lacking in vitamins and fiber.

To further explore this knowledge gap, an international team of researchers drew on detailed dietary information from 116,087 adults aged 35-70 years old living in 21 low-, middle-, and high-income countries participating in the Prospective Urban Rural Epidemiology (PURE) study. This study is an effort to examine how societal influences chronic diseases in different countries around the world, with data dating between 2003 and 2016, and participants reassessed after 9.7 years. During this follow-up, new diagnoses of IBD, including Crohn's disease or ulcerative colitis, were recorded.

Throughout this period, a total of 467 participants developed IBD (90 with Crohn's disease and 377 with ulcerative colitis), from which researchers corrected for confounding factors before examining the dietary choice of these patients.

Researchers found that a higher intake of ultra-processed food was associated with a higher risk of IBD. Relative to individuals that consumed less than one serving of ultra-processed food per day, the team found an 82% increased risk of IBD among those who consumed five or more servings per day, and a 67% increased risk for 1-4 servings per day.

Further evidence that dietary choice affects disease susceptibility

Dividing ultra-processed food further by category, researchers found that all components including soft drinks, refined sweetened foods, salty snacks, and processed meat, were associated with higher risks of IBD. Contrastingly, consumption of foods such as white meat, red meat, dairy, starch, and fruit, vegetables, and legumes (such as peas, beans, and lentils) were not associated with IBD.

These findings were consistent for both Crohn's disease and ulcerative colitis as well as factors including age and region, supporting the robustness of the findings.

Nonetheless, this study remains an observational analysis based on self-reported single questionnaires that cannot establish specific causality. As such, researchers cannot rule out the possibility that other factors not considered may have affected their results. Nevertheless, researchers confirm their findings "support the hypothesis that intake of ultra-processed foods could be an environmental factor that increases the risk of IBD."

Indeed, since some food items were not associated with the development of IBD, this study suggests that it might not be the food itself that confers this risk but rather the way the food is processed or ultra-processed, they explain.

Further studies are needed to identify specific potential contributory factors among processed foods that might be responsible for the observed associations in our study,"