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New research points to a link between ultra-processed foods and inflammatory bowel disease. BanksPhotos/Getty Images
  • A spike in inflammatory bowel disease (IBD) prevalence worldwide parallels an uptick in Western dietary patterns.
  • Clinicians have long conjectured that ultra-processed foods may compromise gastrointestinal (GI) tract health, but they lacked the evidence to confirm this link.
  • A recent multinational study provides good evidence that regularly consuming highly processed foods and beverages is associated with inflammation and IBD.

IBD is more prevalent in affluent countries than in those with lower median incomes. However, cases are rising in developing nations where ultra-processed foods are increasingly available and popular.

For years, gastroenterologists have suspected that ultra-processed foods may contribute to inflammation and IBD. However, few clinical studies have evaluated this hypothesis on a large scale.

A recent multinational prospective cohort study explored the relationship between the consumption of ultra-processed food and the risk of developing IBD.

Neeraj Narula, M.D., an assistant professor of medicine at McMaster University in Hamilton, Canada, led the study. The results appear in the British Medical Journal.

IBD is a group of diseases that cause chronic inflammation in the GI tract. Crohn’s disease and ulcerative colitis are in this category.

About 3 million people in the United States live with IBD.

Some studies point to genetic risk factors for the condition, but mounting evidence links dietary patterns to its development.

Ashkan Farhadi, M.D., MS, FACP, a gastroenterologist and author, describes IBD as “a disease of wealthy nations.”

As societies progress economically, he says, they forgo traditional ways of growing, preparing, and preserving foods in favor of grabbing conveniently packaged products.

In a recent interview with Medical News Today, he hailed the current study as the first cohort work pinpointing processed foods as the culprit driving IBD development.

Before this, Dr. Farhadi noted, “there was no actual research demonstrating what happens [to gut health] as a nation becomes better off economically.”

Dr. Farhadi also commended the researchers for having included ultra-processed drinks, unlike most other research.

The NOVA food classification system defines four categories of foods: unprocessed and minimally processed foods, processed ingredients, processed foods, and ultra-processed foods.

Ultra-processed foods include most mass-produced foods and beverages. These items contain food additives, such as emulsifiers, preservatives, added sweeteners and flavorings, trans fats, and colorings.

Prof. Tim Spector, an author and epidemiologist at the King’s College London in the United Kingdom and co-founder of the ZOE personalized nutrition program, shared his insights on ultra-processed foods with MNT.

Prof. Spector asserted that adults in the U.S. eat more highly processed foods than those living in any other country in the world. He stated that ultra-processed foods make up more than 60% of the caloric intake there.

Narula and his team assessed the medical data of more than 116,000 adults aged 35–70 years. The participants came from 21 low, middle, and high income nations across North America, South America, Europe, Africa, Middle East, South Asia, Southeast Asia, and China.

The participants completed a food frequency questionnaire at least every 3 years from 2003 to 2016.

They reported their consumption of “all types of packaged and formulated foods and beverages that contain food additives, artificial flavorings, colors, or other chemical ingredients.”

The study’s primary outcome was diagnoses of IBD following completion of the baseline questionnaire.

Participants in North America, South America, and Europe reported higher consumption of ultra-processed food than those in the other regions. The occurrence of IBD was greater in these three areas, as well.

Earlier research suggests that certain foods increase the risk of developing IBD.

For instance, the popular low FODMAP diet encourages people with IBD to avoid foods with high levels of specific sugars.

Narula’s team did conclude that higher consumption of ultra-processed foods and drinks increases the likelihood of developing IBD.

The study, however, could not confirm a causal link between ultra-processed foods and IBD development.

Although high consumption of ultra-processed foods was associated with a higher incidence of IBD, consumption of the same foods in unprocessed form did not carry the same risks. Therefore, the researchers conclude that the risk of IBD is associated with the processing of the foods.

The study authors mentioned several limitations that could have affected their findings.

Firstly, they acknowledge that food questionnaires may not assess absolute intake. However, they note that these can capture relative — high vs. low — intake of the food categories in question.

Also, the researchers are uncertain whether their findings, which came from participants aged at least 35 years, can apply to children or young adults who develop IBD.

The age range of the study’s participants may have limited the ability to determine risk factors for Crohn’s disease, too.

Although the study does not account for dietary modifications over time, the reported dietary patterns seemed to remain stable.

However, the observational nature of the study may have left some residual bias due to unmeasured variables, such as antibiotic use during childhood and unknown confounders.

Narula and his team hope that further research will clarify just how ultra-processed foods might trigger IBD.

According to Spector, “most clinicians and gastroenterologists believe the quality of the diet is really important for health.”

He feels that the consumption of “low quality” food disturbs the gut microbes, weakens the immune system, and causes the inflammatory overreactions behind many common diseases.

The professor hopes that the current study and his own work in personalized nutrition, which he is carrying out as part of the ZOE project, will encourage a more mindful, proactive approach to food choices. He also wants physicians to advise patients on how to assess the quality of food. He said:

“[We’re] trying to educate people to what’s in the food, [to] start thinking about food a different way […] — not just as calories, fats, or proteins, but actually, what are all these chemicals doing to your body?”