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Ultraprocessed foods: Large study finds link with Crohn’s disease

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‘Valuable evidence’ for diet’s impact

Because consumption of industrially manufactured foods has risen in parallel with the incidence of autoimmune diseases, modern diets are hypothesized to contribute to the development of inflammatory bowel disease. In this study, Lo and colleagues conducted a retrospective cohort study to determine if individuals who reported higher levels of ultraprocessed food intake had higher rates of developing IBD. In their adjusted analysis, the authors report that the rate of developing Crohn’s disease was 70% higher for individuals who consumed the highest quartile of ultraprocessed foods; there was no association seen with ulcerative colitis.

Ravy K. Vajravelu, MD, MSCE, is an assistant professor of medicine in the division of gastroenterology, hepatology and nutrition at the University of Pittsburgh Center for Health Equity Research and Promotion and the VA Pittsburgh Healthcare System.

Dr. Ravy K. Vajravelu

This carefully conducted study utilizing data from a large, long-term cohort with validated exposures and diagnoses adds valuable evidence for the role of diet in the development of Crohn’s disease. Future studies should aim to identify specific ingredients that mediate the association, such as emulsifiers. For example, the authors report that the heterogeneous category of breads and breakfast foods were the most strongly associated subgroup of ultraprocessed foods. Distinguishing what components of these is responsible for the association between diet and Crohn’s disease is paramount for clinicians to appropriately counsel patients on dietary choices.

While we await clarification about which ingredients are responsible, we should continue to encourage our patients to incorporate whole foods into their diets for both gastrointestinal and cardiometabolic health. At the same time, we must remain empathetic to systemic barriers to accessing and preparing high-quality, minimally processed foods. As such, we should advocate for policies and programs that mitigate food deserts. If food policy remains status quo, this study illustrates a frightening possibility of how disparities in gastrointestinal health equity could worsen in the future.

Ravy K. Vajravelu, MD, MSCE, is an assistant professor of medicine in the division of gastroenterology, hepatology, and nutrition at the University of Pittsburgh Center for Health Equity Research and Promotion and the VA Pittsburgh Healthcare System. This commentary does not represent the views of the U.S. Department of Veterans Affairs or the United States Government. Dr. Vajravelu reports no relevant disclosures.



Higher consumption of ultraprocessed foods was linked with a significantly higher risk of Crohn’s disease (CD), but not ulcerative colitis, in a large prospective cohort study published online in Clinical Gastroenterology and Hepatology.

Researchers, led by Chun-Han Lo, MD, of Massachusetts General Hospital, Boston, defined ultraprocessed foods “as ready-to-consume formulations of ingredients, typically created by [a] series industrial techniques and processes. They frequently involve the incorporation of additives, such as sweeteners, preservatives, emulsifiers, thickeners, and flavors, which aid in food preservation and produce hyperpalatable products.”

The rising global incidence of inflammatory bowel disease (IBD) in regions undergoing Westernization has overlapped with rising increase in consumption of ultraprocessed food (UPF) over the past few decades, according to the authors. Previous studies have focused on links with individual nutrients and IBD, but this study focuses on the processing role itself. This study comprised 245,112 participants (203,516 women and 41,596 men) and more than 5,468,444 person-years of follow-up, taken from three cohorts: Nurses’ Health Study, Nurses’ Health Study II, and Health Professionals Follow-up Study.

In the highest quartile, UPFs made up on average nearly half (46.4%) of participants’ total energy consumption, compared with 21% in the lowest quartile.

The researchers found that compared with participants in the lowest quartile of simple updated UPF consumption, those in the highest quartile had a significantly increased risk of CD (adjusted hazard ratio, 1.70; 95% confidence interval, 1.23-2.35).

In addition, “a secondary analysis across different CD locations demonstrated that participants in the highest quartile of simple updated UPF intake had the highest risk of ileal, colonic, and ileocolonic CD,” the authors wrote.

Three groups of processed foods driving risk increase

Three groups of UPFs appeared to drive the increased risk of CD: ultraprocessed breads and breakfast foods; frozen or shelf-stable ready-to-eat/heat meals; and sauces, cheeses, spreads, and gravies.

Just as with overall consumption, researchers did not find an association between any of those three subgroups and UC risk.

The authors suggested several reasons for the link with Crohn’s disease. Among them were that higher UPF consumption may mean those foods are taking the place of unprocessed or minimally processed foods, such as those rich in fiber. Second, UPFs contain additives, such as salt, that may promote intestinal inflammation. Third, artificial sweeteners in UPFs may predispose the gut to inflammation, as supported by supplementing sucralose/maltodextrins in mice models of spontaneous ileitis.

As for why CD, but not UC, the authors said diet may be more relevant and have a stronger effect biologically in CD compared with UC. Another potential reason, they said, is that results “may reflect the greater specificity of dietary ligands and metabolites on the small intestine compared with the colon.”

Data from three large, prospective cohorts

Researchers used data from three ongoing, prospective nationwide cohorts of health professionals in the United States – the Nurses’ Health Study (1986-2014); the Nurses’ Health Study II (1991-2017); and the Health Professionals Follow-up Study (1986-2012).

In all three cohorts, participants filled in questionnaires at enrollment and every 2 years thereafter with information such as medical history and lifestyle factors. Diet was assessed via validated semi-quantitative food frequency questionnaires.

They used Cox proportional hazards models, adjusting for confounders to estimate the hazard ratios (HRs) and 95% confidence intervals for Crohn’s disease and ulcerative colitis, according to participants’ self-reports of their consumption of ultraprocessed foods.

Further studies could help determine which UPF components are driving the higher risk for Crohn’s disease and whether risk differs by length of exposure to UPFs.

“By avoiding UPF consumption, individuals might substantially lower their risk of developing CD in addition to gaining other health benefits,” the authors wrote.

A coauthor, James M. Richter, MD, is a consultant for Policy Analysis Inc and Takeda Pharmaceuticals. Andrew T. Chan, MD, serves as a consultant for Janssen Pharmaceuticals, Pfizer Inc, and Bayer Pharma AG. Ashwin N. Ananthakrishnan, MD, has served as a scientific advisory board member for Abbvie, Gilead, and Kyn Therapeutics, and received research grants from Pfizer and Merck. The remaining authors disclosed no conflicts. This work was supported by the National Institutes of Health; the Beker Foundation, the Chleck Family Foundation, and the Crohn’s and Colitis Foundation.

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