A team of researchers in Japan has discovered that certain food proteins, such as those found in milk, may help prevent tumors from forming in the small intestine.

Their study, published in Frontiers in Immunology, shows how these proteins activate the immune system to prevent the growth of new tumors.

Food antigens, such as those found in milk, peanuts, eggs and other common foods, are often known to cause allergies. Even in non-allergic people, these antigens are recognized as foreign substances by the immune system.

The team led by Hiroshi Ohno of the RIKEN Center for Integrative Medical Sciences had previously found that food antigens can activate immune cells in the small intestine, but not in the large intestine.

Their latest study is exploring whether these food proteins might also help prevent tumor growth in the small intestine.

In their experiments, the researchers used mice that had a genetic mutation that made them more likely to develop intestinal tumors, similar to a condition found in humans called familial adenomatous polyposis.

They found that the number of tumors in the small intestine of mice fed the regular diet was lower than those fed the antigen-free diet. However, the number of tumors in the large intestine of both groups was the same.

For further testing, they added a protein called albumin, found in meat, to the antigen-free diet. This showed the same tumor-suppressing effects as a normal diet.

This suggests that it is not the nutritional value of food, but the presence of antigens in food that is important for preventing tumors.

The study also showed that the immune response, particularly the activity of T cells, in mice consuming food antigens was stronger than in mice consuming an antigen-free diet.

This highlights the role of dietary proteins in maintaining a healthy immune system in the small intestine.

These findings could have important implications for certain therapeutic diets, such as elemental diets, which are formulated to reduce digestive stress by eliminating proteins.

Elemental diets are special, easy-to-digest liquid diets that provide nutrients in their simplest forms, such as amino acids, sugars and fats, without complete proteins. They are typically used for people with severe digestive problems such as Crohn’s disease, to give the gut a break while still providing essential nutrients.

However, Ohno cautions that these diets should be used with caution, especially in people at high risk for small intestine tumors, such as those with familial adenomatous polyposis.