Experts have been talking about a global obesity epidemic for years. Being very overweight is associated with numerous health risks. Researchers are now reporting that fiber from certain foods could help counteract obesity.
Results from scientific studies with mice suggest that fiber from crustaceans, insects and fungi promote digestion and stimulate the immune system to counteract obesity (obesity). The study results were published in the journal “Science”.
Less weight gain
According to a statement from Washington University School of Medicine in St. Louis, researchers led by Steven Van Dyken, PhD, an assistant professor of pathology and immunology, found in mice that the digestion of chitin, an abundant fiber in insect Exoskeletons as well as fungi and crustacean shells, stimulate the immune system.
An active immune response was associated with less weight gain, less body fat and resistance to obesity.
“Obesity is an epidemic,” Van Dyken said. “What we put into our bodies has a profound impact on our physiology and how we metabolize food. We are studying ways to counteract obesity based on our understanding of how the immune system is influenced by diet.”
Activation of immune reactions
The immune system is known to protect the body from various threats, including bacteria, viruses, allergens and even cancer. The research team found that a specific arm of the immune system is also involved in chitin digestion.
Stomach distension after ingesting chitin activates an innate immune response that causes stomach cells to increase production of enzymes called chitinases that break down chitin.
Notably, chitin is insoluble – meaning it cannot be dissolved in liquid – and therefore requires enzymes and aggressive acidic conditions to digest.
Do-Hyun Kim, PhD, postdoctoral researcher and first author of the study, conducted the experiments on germ-free mice without gut bacteria. His results show that chitin activates immune responses in the absence of bacteria.
“We believe that chitin digestion relies primarily on the host’s own chitinases,” says Van Dyken.
“The stomach cells change their enzymatic production through a process we call adaptation. But it is surprising that this process occurs without microbial input, because bacteria in the gastrointestinal tract are also sources of chitinases that break down chitin.”
Van Dyken found that in mice with gut bacteria, dietary chitin changed the bacterial composition of the lower gastrointestinal tract, suggesting that gut bacteria also adapt to chitin-containing food after it leaves the stomach.
The scientists found that the greatest effect on obesity in mice occurred when chitin activated the immune system but was not digested.
Mice fed a high-fat diet were also given chitin. Some animals lacked the ability to produce chitinases to break down chitin.
The mice that ate chitin but couldn’t break it down gained the least weight, had the lowest body fat levels, and resisted obesity, compared to mice that didn’t eat chitin and those that ate chitin but were able to break it down.
When the mice were able to break down chitin, they still benefited from metabolism, but they adapted by overproducing chitinases to extract nutrients from chitin.
Follow up findings on people
Next, Van Dyken and his team plan to follow up on their findings in humans, with the goal of finding out whether chitin could be added to the human diet to help combat obesity.
“We have several options for inhibiting gastric chitinases,” explains the expert. “Combining these approaches with a diet containing chitin could have a real metabolic advantage.” (ad)