, suggesting another field for inquiry about the potential role of industrial-produced edible food products in IBD.
The study, which was a meta-analysis of four studies, found a 47% greater risk of IBD in adults who consumed high levels of ultra-processed foods, compared with adults in reference groups.
“Our data are also consistent with other observational studies that found increased consumption of junk food, along with reduced intakes of fresh fruit and vegetables, are associated with the development of IBD. Because Americans consume over 60% of their calories in the form of ultra-processed foods, reductions in this level of consumption could meaningfully decrease the incidence of IBD,” wrote authors who were led by Eric Hecht, MD, PhD, MPH, president and executive director of the nonprofit Institute of Etiological Research, Boca Raton, Fla.
The potential effect of poor diet on the gut is a critical public health question, he said. Diet may be just one possible contributor to inflammatory bowel disease. Other contributors include genetics and having a compromised immune system.
Dr. Hecht and colleagues began this study with a search on the PubMed database of published research on IBD that included details of diet. Of 10 relevant studies, 4 studies met the inclusion criteria for the analysis.
The four studies included 652,880 adults, 2,240 cases of IBD with a follow-up period ranging from 2.3 to 22.3 years. Statistically significant elevated risks for both Crohn’s disease and ulcerative colitis were documented in the studies. There was a relative risk of 1.47 (95% confidence interval, 1.29-1.66) for IBD; 1.94 (95% CI, 1.45-2.58) for Crohn’s disease, and 1.26 (95% CI, 1.10-1.45) for ulcerative colitis.
Findings from the 4 studies
Chen et al. reported, in the Journal of Crohn’s and Colitis, the results of a cross-sectional and prospective cohort study of 187,854 adults who were followed for an average of 10 years. They found that a higher intake of ultra-processed foods was associated with a higher incidence of Crohn’s disease but not ulcerative colitis. It also found that people who were already diagnosed with an IBD consumed more ultra-processed foods than did those without a diagnosis. The authors called for further studies to address the impact of UPF intake.
Vasseur et al. documented, in Inflammatory Bowel Diseases, research drawn from the NutriNet-Santé Study, a large French web-based prospective study. It did not find that ultra-processed foods were significantly associated with the risk of incident IBD. But the authors noted that certain types of food items or dietary patterns could partly explain the increase in the incidence of IBD observed in several countries, saying that further large-scale studies would be needed to support pathophysiological assumptions made about the dietary risk factors and IBD.
In September 2020 in Gastroenterology, Lo et al. used data from the Nurses’ Health Study (1984-2014), Nurses’ Health Study II (1991-2015), and Health Professionals Follow-up Study (1986-2012). The authors reported finding dietary patterns associated with high inflammatory potential to be associated with increased risk of Crohn’s disease but not ulcerative colitis.
In October 2021 in Gastroenterology, Narula et al. reported finding no significant association between certain dietary patterns and risk of ulcerative colitis. There was some signal for Crohn’s disease, in keeping with findings from earlier research. Longer term follow-up is needed to clarify whether the observed excess risk for Crohn’s disease becomes more evident as more cases accumulate.
However, in an email interview with GI & Hepatology News, Neeraj Narula, MD, MPH, of McMaster University, Hamilton, Ont., cited two of his other published works that did make a connection between diet and IBD. In July 2021 in BMJ, he and colleagues reported findings of a prospective cohort study that found that higher intake of ultra-processed food was positively associated with risk of IBD. Further studies are needed to identify the contributory factors within ultra-processed foods, they wrote. He and colleagues published a meta-analysis of 5 cohort studies which concluded that higher ultra-processed food and lower unprocessed/minimally processed food intakes were associated with higher risk of Crohn’s disease but not ulcerative colitis.
