Researchers in Japan have uncovered a surprising link between food antigens, like milk proteins, and the suppression of tumor growth in the small intestine.

Their study highlights the potential risks of antigen-free diets and underscores the importance of medical oversight when considering such dietary changes.

A team from the RIKEN Center for Integrative Medical Sciences (IMS), led by Hiroshi Ohno, discovered that food antigens, particularly those found in milk, help activate immune cells in the intestines, which in turn prevent tumor growth.

Their research, recently published in Frontiers in Immunology, suggests that far from being harmful, as often thought in the context of food allergies, certain antigens play a protective role against intestinal tumors.

Food antigens, typically associated with allergic reactions to items like peanuts, shellfish, and milk, are recognized as foreign by the immune system. Even when they don’t provoke an allergic response, the body still monitors them closely.

Ohno's team previously found that food antigens specifically stimulate immune activity in the small intestine, whereas immune cells influenced by gut bacteria are more active in the large intestine.

This new research merges these insights, exploring whether food antigens can also curb tumor growth in the small intestines.

Experimental Findings

The researchers conducted their experiments using a special strain of mice with a genetic mutation similar to that seen in humans with familial adenomatous polyposis—a condition where tumors develop throughout the intestines.

The team divided the mice into two groups: one fed a normal diet, and the other an antigen-free diet. The results were clear: mice on a normal diet had significantly fewer tumors in the small intestine compared to those on the antigen-free diet.

However, the number of tumors in the large intestine remained unchanged, suggesting the effect was specific to the small intestine.

In a second experiment, the researchers introduced a common antigen—albumin, found in meat—into the antigen-free diet. Remarkably, this addition restored the tumor-suppressing effect in the small intestine, further confirming that the presence of food antigens, rather than the nutritional content of the food, was responsible for the anti-tumor activity.

The study also examined the role of T cells, key players in the immune system. Mice on the antigen-free diet had far fewer T cells in their small intestines compared to those on normal food or antigen-free food supplemented with milk protein. This indicated that antigens stimulate a specific immune response crucial for tumor suppression.

Clinical Implications and Risks

These findings carry significant clinical implications. Elemental diets, which are often prescribed to patients with severe gastrointestinal conditions like Crohn’s disease or irritable bowel syndrome (IBS), consist of simple amino acids rather than whole proteins, reducing the digestive load.

However, as Ohno notes, “Small intestinal tumors are much rarer than those in the colon, but the risk is higher in cases of familial adenomatous polyposis.” He emphasizes that the use of elemental diets in such high-risk individuals should be approached with caution.

Beyond clinical settings, some people without severe digestive issues adopt antigen-free or elemental diets to manage weight, bloating, or inflammation. This new research suggests that doing so without medical supervision could carry unforeseen risks, including a heightened susceptibility to tumors in the small intestine.

In light of these findings, it's clear that antigen-free diets, while beneficial in certain medical scenarios, may pose risks when used improperly. As with any significant dietary change, particularly one that limits essential immune-activating components, consulting with a healthcare provider is crucial.

Study:

Published 30 July 2024, Frontiers in Immunology; “Food antigens suppress small intestinal tumorigenesis” DOI: 10.3389/fimmu.2024.1373766

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