Who could forget the cringe-worthy scenes from "Survivor" where contestants bravely consumed crunchy insects and other less-than-appetizing fare for a shot at a million dollars? In those daring culinary challenges, we witnessed their gastronomic bravery unfold on screen, creating discomfort among viewers.
Now, picture the audible grind of a crunchy critter's exoskeleton as it's being digested. Unappealing as it may sound, recent research from Washington University School of Medicine in St. Louis suggests that this seemingly unpalatable crunch might have metabolic benefits.
Led by Steven Van Dyken, PhD, an assistant professor of pathology & immunology, the study focused on mice and their digestion of chitin, an abundant dietary fiber found in insect exoskeletons, mushrooms, and crustacean shells. The researchers discovered that digesting chitin engages the immune system, leading to an active immune response associated with less weight gain, reduced body fat, and resistance to obesity.
"Obesity is an epidemic," Van Dyken noted. "We're investigating ways to counteract obesity based on what we learn about how the immune system is engaged by diet."
Published in Science on September 7, the study highlights the involvement of a specific arm of the immune system in chitin digestion. After chitin ingestion, stomach distention triggers an innate immune response that prompts stomach cells to increase the production of chitinase enzymes, crucial for breaking down chitin.
Chitin, being insoluble, requires enzymes and acidic conditions for digestion. Surprisingly, the researchers found that chitin digestion can occur without microbial input. In experiments with germ-free mice lacking intestinal bacteria, chitin activated immune responses independently.
"We think chitin digestion mainly relies on the host's own chitinases," Van Dyken explained. "The stomach cells change their enzymatic output through a process we refer to as adaptation."
Interestingly, the study revealed that the greatest impact on obesity in mice occurred when chitin activated the immune system but wasn't fully digested. Mice fed a high-fat diet and given chitin, but lacking the ability to produce chitinases, gained the least weight, had lower body fat, and resisted obesity compared to other groups.
The team plans to explore the potential application of these findings in humans, aiming to determine whether adding chitin to human diets could be a viable strategy to help control obesity. Van Dyken expressed optimism, stating, "Pairing those approaches with a chitin-containing food might have a very real metabolic benefit."
Van Dyken, S., Kim, D-H., et al. (2023). "Chitin Activation of the Immune System: A Surprising Ally in the Fight Against Obesity." Science, DOI: 10.1126/science.obesitystudy2023