Inflammatory bowel disease, often called IBD, is a group of long-term conditions that cause inflammation in the digestive tract.
The two main forms are Crohn’s disease and ulcerative colitis.
These conditions can cause symptoms such as abdominal pain, diarrhea, fatigue, weight loss, and reduced quality of life.
While treatments have improved over the years, scientists still do not fully understand why some people develop IBD while others do not.
Researchers believe that genetics, the immune system, environmental factors, and diet all play important roles. In recent years, growing attention has focused on ultraprocessed foods, which have become a major part of modern diets around the world.
These foods are often made using industrial processing methods and may contain additives, preservatives, flavor enhancers, colorings, and refined ingredients that are rarely used in home cooking.
Now, a large international study published in the American Journal of Gastroenterology suggests that one particular category of ultraprocessed food—ultraprocessed grains—may significantly increase the risk of developing inflammatory bowel disease.
The research was led by Dr. Neeraj Narula and colleagues from McMaster University in Canada. The team analyzed data from the Prospective Urban Rural Epidemiology study, one of the largest international health studies ever conducted.
The investigation included 124,590 participants from 21 countries, making it one of the most comprehensive studies to examine the relationship between diet and IBD risk.
To understand what people were eating, researchers used validated food frequency questionnaires. Participants reported their usual intake of different foods and beverages, allowing scientists to estimate how much ultraprocessed grain they consumed on a regular basis.
Ultraprocessed grains include foods made primarily from refined grains that have undergone extensive industrial processing. Examples may include packaged pastries, sweet breakfast cereals, commercially produced crackers, instant grain products, and many packaged baked goods.
These foods often contain added sugars, unhealthy fats, emulsifiers, preservatives, and other ingredients designed to improve shelf life and taste.
After analyzing the data, researchers discovered a clear pattern. People who consumed the highest amounts of ultraprocessed grains faced a significantly greater risk of developing inflammatory bowel disease compared with those who consumed the lowest amounts.
Specifically, participants consuming 19 grams or more of ultraprocessed grains per day had an 86 percent higher risk of developing IBD compared with people consuming less than 9 grams per day. Even after researchers adjusted for many other factors that could influence health outcomes, the association remained strong.
The study also examined overall ultraprocessed food consumption. People who ate at least five servings of ultraprocessed foods per day had nearly four times the risk of developing inflammatory bowel disease compared with people who consumed less than one serving daily.
This finding suggests that ultraprocessed foods as a whole may play an important role in digestive health.
Interestingly, not all grain-based foods were associated with increased risk. Researchers found that fresh bread and rice consumption were linked with a lower risk of inflammatory bowel disease. This suggests that the degree of processing may matter more than the grain itself.
Scientists are still trying to understand exactly why ultraprocessed foods may contribute to digestive diseases. One possibility is that certain additives and processing methods may alter the balance of bacteria living in the gut.
The digestive system contains trillions of microorganisms that help regulate digestion, immune function, and overall health. Disruptions to this microbial community have been linked to inflammatory bowel disease in previous research.
Another possibility is that some ingredients commonly found in ultraprocessed foods may weaken the protective lining of the intestines. If this barrier becomes damaged, harmful substances may enter intestinal tissue more easily and trigger chronic inflammation.
The findings add to a growing body of evidence linking ultraprocessed foods to various health problems, including obesity, diabetes, heart disease, and certain cancers.
While previous studies have suggested a connection between ultraprocessed foods and digestive disorders, this large international investigation provides some of the strongest evidence so far specifically linking ultraprocessed grain consumption to IBD risk.
The study has several important strengths. Its large sample size, international representation, and long-term data collection increase confidence in the findings. However, the researchers also acknowledge limitations.
Because the study was observational, it cannot prove that ultraprocessed grains directly cause inflammatory bowel disease. Other lifestyle and environmental factors may also contribute to the relationship.
In addition, dietary habits were measured using questionnaires, which rely on participants accurately remembering and reporting what they eat. Nevertheless, the consistency of the findings across a large and diverse population strengthens the case for further investigation.
Overall, the study suggests that limiting ultraprocessed grains and reducing overall consumption of ultraprocessed foods may help support digestive health.
While more research is needed to establish cause and effect, the findings reinforce recommendations to focus on minimally processed foods such as fruits, vegetables, legumes, whole grains, and home-prepared meals whenever possible.
The study’s findings are important because inflammatory bowel disease is becoming more common worldwide, particularly in countries adopting increasingly Westernized diets.
The research cannot prove that ultraprocessed grains cause IBD, but it provides strong evidence that they may be an important risk factor. Future studies will help determine whether reducing consumption of these foods can lower disease risk and improve public health.
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