According to a new study from the Icahn Mount Sinai School of Medicine, fasting can be detrimental to fighting infection and may lead to an increased risk of heart disease.
The study, which focused on mouse models, was one of the first to show that skipping meals triggers a response in the brain that negatively affects immune cells. The breakfast results may help better understand how chronic fasting can affect the body in the long run, writes News Medical .
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“There is a growing awareness that fasting is good for health, and indeed there is a lot of evidence for the benefits of fasting. Our study comes with a caveat because it suggests that fasting may be associated with health risks. This is a mechanistic study focusing on some of the fundamental biological aspects of fasting. The study shows that there is a dialogue between the nervous and immune systems,” says Philip Swirsky, Ph.D., lead author, director of the Icahn Mount Sinai Institute for Cardiovascular Research.
The researchers sought to better understand how fasting (from relatively short fasts of just a few hours to more severe fasts of 24 hours) affects the immune system. They analyzed two groups of mice. One group ate breakfast right after waking up (breakfast is their biggest meal of the day), while the other group didn’t eat breakfast. The researchers collected blood samples from both groups: when the mice woke up, then four hours later, and eight hours later.
Studying the work of the blood, the researchers noticed a distinct difference in the group on an empty stomach. In particular, the researchers saw a difference in the number of monocytes, which are white blood cells that are produced in the bone marrow and travel throughout the body, where they play many important roles, from fighting infections to heart disease and cancer.
Initially, all mice had the same number of monocytes. But after four hours, the monocytes in mice from the starvation group suffered sharply. The researchers found that 90 percent of these cells had disappeared from the bloodstream, and after eight hours their number had decreased even further. At the same time, monocytes in the group that did not eat on an empty stomach were not affected.
In fasting mice, the researchers found that monocytes return to the bone marrow to hibernate. At the same time, the production of new cells in the bone marrow decreased. Monocytes in the bone marrow, which usually have a short lifespan, have changed significantly. They survived longer because they remained in the bone marrow and aged differently than monocytes, which remained in the blood.
The researchers continued to starve the mice for up to 24 hours and then reintroduced the food. Cells hidden in the bone marrow re-entered the bloodstream a few hours later. This surge led to increased levels of inflammation. Instead of protecting against infection, these altered monocytes were more inflammatory, making the body less resistant to fighting infection.