A new study involving researchers from Wroclaw Medical University suggests that not only the amount of grain products we eat, but also the degree to which they are processed, may influence the risk of developing inflammatory bowel disease.
Inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis, is becoming increasingly common worldwide. Although its development is influenced by genetic, immunological, and environmental factors, growing evidence suggests that diet also plays an important role.
Researchers from the PURE study previously showed that people who consume more ultra-processed foods are at greater risk of developing inflammatory bowel disease. In their latest analysis, they examined grain products to determine whether the degree of processing also affects disease risk.
The analysis included more than 140,000 adults from 27 countries who were followed for many years. During the study period, 467 participants developed inflammatory bowel disease. The researchers adjusted their analyses for factors including age, sex, physical activity, smoking, place of residence, and overall diet quality to better assess the relationship between grain products and disease risk.
The problem may not be grains, but how they are processed
The findings showed that higher consumption of ultra-processed grain products was associated with an increased risk of developing inflammatory bowel disease. No such association was observed for less processed grain products.
“Diet is one of the most important modifiable risk factors for inflammatory bowel disease. Our findings suggest that ultra-processed grain products may be particularly relevant, making these results important for both dietary recommendations and prevention strategies,” says Dr Alicja Basiak-Rasała from the Department of Population Health and Civilization Diseases Prevention at Wroclaw Medical University.
The products included in the analysis comprised industrially packaged bread, cakes, cookies, and instant noodle-based meals. However, the authors stress that these findings should not be interpreted as evidence that all grain products are harmful.
“This study specifically focused on grain products and identified a particularly strong association with ultra-processed foods. At the same time, consumption of high-quality bread with a lower degree of processing or rice was not associated with an increased risk of inflammatory bowel disease,” explains Dr Alicja Basiak-Rasała.
What may explain the increased risk?
The authors emphasize that the study does not identify a single ingredient responsible for the observed association. Interestingly, no similar relationship was found for many other food groups, including unprocessed red meat, poultry, dairy products, starchy foods, vegetables, fruit, or legumes. Likewise, sodium intake was not associated with disease risk.
According to the researchers, the findings suggest that the increased risk may be related primarily to industrial food processing. Potential contributors include food additives such as emulsifiers, preservatives, and maltodextrins. Experimental studies indicate that these compounds may alter the gut microbiota, weaken the intestinal barrier, and promote inflammatory responses.
“This is not the first analysis based on PURE data in the context of inflammatory bowel disease. A 2021 publication demonstrated an association between overall consumption of ultra-processed foods and the risk of inflammatory bowel disease (https://doi.org/10.1136/bmj.n1554). The current study provides more specific evidence that ultra-processed grain products may play a particularly important role. It is estimated that up to 40% of dietary emulsifiers are consumed through processed grain products,” adds the researcher.
The authors conclude that reducing the intake of ultra-processed foods should remain an important dietary goal.
“Completely eliminating ultra-processed foods from the diet is difficult in today’s world. However, it is worth choosing fresh, minimally processed foods whenever possible and following a diet rich in fiber, whole grains, vegetables, fruit, and legumes. The Mediterranean diet remains one of the best-supported dietary patterns and has been associated with a lower risk of inflammatory bowel disease in previous studies,” summarizes Dr Alicja Basiak-Rasała.
Polish contribution to one of the world’s largest epidemiological studies
The publication is based on data from the international PURE (Prospective Urban Rural Epidemiology) study, one of the world’s largest epidemiological projects investigating how social, environmental and lifestyle factors influence chronic diseases. The study is currently conducted in 27 countries and was initiated by Prof. Salim Yusuf from McMaster University in Canada.
The Polish PURE cohort has been coordinated at Wroclaw Medical University since 2007 by Prof. Katarzyna Zatońska and Prof. Andrzej Szuba. It is one of the largest and longest-running population studies in Poland, with findings regularly published in leading international journals that contribute to a better understanding of how modifiable lifestyle factors affect health.
This article is based on the publication:
Ultraprocessed grains and risk of inflammatory bowel disease: Results from the Prospective Urban Rural Epidemiology study.
Authors: Neeraj Narula, Emily C.L. Wong, Andrew Mente, Sumathy Rangarajan, Xinyue Lang, Qi Li, Mengxi Chen, Indu Mohan, Nafiza Mat-Nasir, Maria Luz Diaz, Patricio Lopez-Jaramillo, Ahmad Bahonar, Alvaro Avezum, Kubilay Karsidag, Annika Rosengren, Marc Evans M. Abat, Fernando Lanas, Elizabeth C. Swart, Rita Yusuf, Khalid F. Alhabib, Romaina Iqbal, Alicja Basiak-Rasała, Rasha Khatib, Afzalhussein Yusufali, Karen Yeates, Jephat Chifamba, John K. Marshall, Paul Moayyedi, Walter Reinisch, Salim Yusuf.