The foods people eat every day may have a bigger impact on digestive health than many realize.
A large international study has found that eating high amounts of ultraprocessed grain products may increase the risk of developing inflammatory bowel disease, a serious condition that affects millions of people worldwide.
The findings were published in the American Journal of Gastroenterology and add to a growing body of evidence linking highly processed foods to chronic health problems. Researchers say the results could help shape future dietary recommendations aimed at preventing digestive diseases.
Inflammatory bowel disease is a term used to describe long-lasting conditions that cause inflammation in the digestive tract. The two most common forms are Crohn’s disease and ulcerative colitis. Symptoms can include stomach pain, diarrhea, bleeding, fatigue, weight loss, and nutritional deficiencies. In severe cases, surgery may be required.
The exact causes of inflammatory bowel disease remain unclear. Scientists believe that genetics, immune system activity, environmental exposures, and lifestyle factors all contribute. Among these factors, diet has become one of the most actively studied areas.
Modern diets are very different from those consumed by previous generations. Many people now rely heavily on packaged foods because they are convenient, affordable, and widely available. These products often contain numerous ingredients added during manufacturing to improve taste, texture, appearance, or shelf life.
Researchers refer to these products as ultraprocessed foods. Examples may include packaged snack foods, sweetened breakfast cereals, commercial baked goods, processed breads, crackers, and other grain-based products that have undergone extensive industrial processing.
To investigate whether these foods affect digestive health, scientists analyzed information from the Prospective Urban Rural Epidemiology study. This massive international research project includes participants from a wide range of countries, cultures, and economic backgrounds.
The study examined dietary information from 124,590 adults living in 21 countries. Participants completed validated food questionnaires that allowed researchers to estimate their consumption of various foods, including ultraprocessed grain products.
Researchers then followed participants over time and recorded cases of inflammatory bowel disease. By comparing dietary patterns with health outcomes, they were able to identify associations between food consumption and disease risk.
The results showed that people who consumed larger amounts of ultraprocessed grains were significantly more likely to develop inflammatory bowel disease. Participants consuming at least 19 grams of ultraprocessed grains per day had substantially higher risk than those consuming less than 9 grams per day.
Researchers also looked at total ultraprocessed food consumption. Here, they found an even stronger relationship. Individuals consuming five or more servings of ultraprocessed foods each day had almost four times the risk of developing inflammatory bowel disease compared with those who consumed less than one serving daily.
One particularly interesting finding involved foods that were not heavily processed. Fresh bread and rice were associated with lower risk of inflammatory bowel disease. This suggests that grains themselves may not be the problem. Instead, the way foods are processed could play a critical role.
Scientists believe several biological mechanisms may help explain these findings. One possibility involves the trillions of microorganisms living in the digestive tract. Together, these microorganisms form the gut microbiome, which plays a vital role in digestion, immunity, and overall health.
Research has shown that certain food additives and processing methods can alter the gut microbiome. Changes in these microbial communities may increase inflammation and disrupt the protective barrier lining the intestines. Over time, this may contribute to the development of inflammatory bowel disease.
Another possibility is that highly processed foods may promote chronic low-grade inflammation throughout the body. This type of inflammation has already been linked to conditions such as obesity, diabetes, cardiovascular disease, and certain cancers.
The study’s findings are important because inflammatory bowel disease has become increasingly common worldwide. Rising rates have been observed not only in Western countries but also in many developing nations undergoing rapid dietary changes.
Despite the strong results, researchers caution that the study does not prove ultraprocessed grains directly cause inflammatory bowel disease. Observational studies can identify relationships but cannot establish cause and effect. Other lifestyle factors may contribute to the observed associations.
In addition, some authors disclosed relationships with pharmaceutical and nutrition companies. Such disclosures are standard practice in scientific publishing and help readers evaluate potential conflicts of interest.
From a scientific standpoint, the study is impressive because of its large sample size, international scope, and long follow-up period. The consistency of the findings strengthens the evidence linking ultraprocessed foods to digestive disease.
However, additional research will be needed to understand exactly how these foods influence the gut and whether reducing consumption can directly lower disease risk. For now, the results support public health advice encouraging people to eat more minimally processed foods and fewer heavily processed products as part of a healthy diet.
If you care about gut health, please read studies about how junk food harms your gut health, and how probiotics can protect gut health.
For more information about health, please see recent studies about how fiber affects weight loss and your overall health, and results showing why a glass of red wine is good for your gut.
Source: McMaster University
