A varied diet and exposure to new foods from childhood helps educate the immune system and thus prevent allergies.
Dietary diversification would limit the development of allergies, suggests a study published at the end of January in the prestigious magazine Science. American researchers from the La Jolla Institute for Research in Immunology and Allergology (United States) have indeed shown that a varied diet from childhood helps to educate the immune system so that it tolerates unfamiliar foods.
“Our immune system protects us from elements foreign to our body, such as viruses and pathogens,” explains Professor Charles Surth, responsible for this study. Our work shows that food tolerance is acquired and involves a specific population of T lymphocytes which develops according to our diet. Without these cells, our body would react very strongly to unfamiliar foods ”.
To better understand the usefulness of these T lymphocytes called Treg cells, the researchers studied “naive” mice. These laboratory animals are raised in a sterile environment and are fed a very specific diet that cannot trigger food intolerance. Their immune system has therefore never been confronted with viruses or an allergen. By feeding them eggs, the scientists found that this new food induced the production of Treg cell in their stomachs and helped block the allergic reaction. These cells are therefore immunosuppressants.
Different populations of Treg cell
The researchers therefore wanted to know if this phenomenon took place in normal mice. For this, they used mice fed with proteins but lacking intestinal flora. By analyzing their stomachs, they discovered that these mice naturally had Treg cells while the first naive mice did not.
For the researchers, this only difference between guinea pigs suggests that a protein diet stimulates the production of Treg cell. And therefore, this means that these cells are naturally present in normal mice.
Using these two mouse models, scientists also demonstrated that food and gut bacteria do not generate the same Treg cells. However, mice without microbiota only have food-induced Treg cells, and are known to be more susceptible to allergies. Also, the researchers deduced that it is necessary to have different populations of Treg cell to prevent allergies.
A system that is not infallible
Based on their observations, the authors speculate that one would become tolerant over time by expanding the repertoire of these T cells to recognize unfamiliar foods as “safe”. In other words, the more varied our diet, the more our alert system will understand that a foreign food is not a danger.
In their next work, researchers will focus on molecular and cellular details that could explain why our immune system sometimes goes off the rails and triggers an allergic reaction. “We will pay particular attention to foods known to be allergenic such as peanuts, eggs or even milk” conclude the authors.
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