Proteins in meat and milk can help suppress gut tumours

A new study highlights the role of food proteins in maintaining a healthy immune system in the small intestines.

In Short

• The presence of food antigens, not the nutritional value, is key to preventing tumours
• Study highlights the role of food proteins in maintaining a healthy immune system

A team of researchers in Japan has discovered that certain food proteins, like those found in milk, can help prevent tumours from forming in the small intestines.

Their study, published in Frontiers in Immunology, shows how these proteins activate the immune system to stop the development of new tumours.

Food antigens, such as those in milk, peanuts, eggs, and other common foods, are often known for causing allergic reactions. Even in non-allergic people, these antigens are recognised by the immune system as foreign substances.

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

Their latest study explores whether these food proteins can also help stop tumour growth in the small intestines.

In their experiments, the researchers used mice with a genetic mutation that makes them prone to developing tumours in the intestines, similar to a condition in humans called familial adenomatous polyposis.

They found that mice fed a regular diet had fewer tumours in their small intestines compared to those fed an antigen-free diet. However, both groups had the same number of tumours in the large intestines.

To test further, they introduced a protein called albumin, commonly found in meat, into the antigen-free diet. This led to the same tumour-suppressing effects as seen with a normal diet.

This suggests that the presence of food antigens, not the nutritional value of the food, is key to preventing tumours.

The study also showed that the immune response, particularly the activity of T cells, was much stronger in mice that consumed food antigens compared to those on an antigen-free diet.

This highlights the role of food proteins in maintaining a healthy immune system in the small intestines.

These findings could have important implications for certain medical diets, such as elemental diets, which are designed to reduce digestive strain by eliminating proteins.

Elemental diets are specialised, easily digestible liquid diets that provide nutrients in their simplest forms, such as amino acids, sugars, and fats, without whole proteins. They are typically used for people with severe digestive issues like Crohn's disease, allowing the gut to rest while still receiving essential nutrients.

However, Ohno warns that these diets should be used cautiously, especially in people at higher risk for small intestinal tumours, such as those with familial adenomatous polyposis.