Fasting yes or no? They warn that doing so can also compromise the immune system.

Skipping meals triggers a response in the brain that negatively affects immune cells, according to a study in mice, which finds fasting can be bad for fighting infection and lead to an increased risk of heart disease.

The research, focused on breakfast and conducted by the Icahn School of Medicine in Mount Sinai (United States), is published in the Immunity magazine and it might help to better understand how it can affect the body long-term chronic fastingthe authors point out.

“There is growing awareness that fasting is healthy, and indeed there is abundant evidence of its benefits. Our study offers a caveat, as it suggests that fasting can also come at a cost that carries a health risk“, says lead author Filip Swirski.

The work shows that there is “a conversation between the nervous and immune systems,” it adds in a statement.

The goal was to better understand how fasting, from a relatively short fast of a few hours to a more severe 24-hour fast, affects the immune system.

To do this, the scientists analyzed two groups of mice. One group ate breakfast soon after waking up (breakfast in this experiment was the largest meal of the day) and the other group did not.

The researchers collected blood samples from both groups when the mice woke up, four hours later, and eight hours later. examining them, observed a distinct difference in the fasted group.

Specifically, they found a difference in the number of monocytes, white blood cells that are produced in the bone marrow and travel throughout the body, where they perform many critical functions, from fighting infection to heart disease and cancer.

At first, all the mice had the same number of monocytes, but after four hours, these white blood cells of the mice in the fasting group were drastically affected.

The researchers found that 90 percent of these cells disappeared from the bloodstream, and the numbers were still declining after eight hours; Instead, monocytes in the non-fasting group were not affected.

In fasted mice, the researchers found that the monocytes returned to the bone marrow to hibernate; there they survived longer and aged differently than the monocytes left in the blood.

Additionally, they found that the production of new blood cells in the bone marrow decreased.

The experiment continued with the mice fasting for 24 hours and then with the introduction of food.

The cells hidden in the bone marrow then returned to the bloodstream within hours, an increase that led to further inflammation.

Instead of protecting against infection, these altered monocytes were more inflammatory made in body less resistant to fighting infections.

This study is one of the first to establish the connection between the brain and these immune cells during fasting, say the authors, who found that specific brain regions control monocyte response during fasting.

The investigation proved it fasting causes a stress response in the brain (it’s what makes people feel hungry and angry), which triggers instantly a large-scale migration of these white blood cells into the bone marrowand then back into the bloodstream shortly after the food was reintroduced.

“Although there is also evidence for the metabolic benefits of fasting, this new study represents a useful advance in fully understanding the mechanisms of the body,” concludes Swirski.

EFE extension