While fiber often brings to mind grains, fruits, and vegetables, it's noteworthy that crustacean shells, insects, and mushrooms are also rich sources, despite their less appealing reputation.
A recent mouse study, titled "A Type 2 Immune Circuit in the Stomach Controls Mammalian Adaptation To Dietary Chitin" published in Science, from Washington University School of Medicine, suggests that consuming the exoskeleton of crunchy creatures may have metabolic benefits.
Dietary Fiber Chitin in Crustaceans, Insects, and Mushrooms Promotes Digestion
The study, led by Dr. Steven Van Dyken, discovered that digesting chitin, a dietary fiber found in insect exoskeletons, mushrooms, and crustacean shells, triggers the immune system in mice. An active immune response was associated with reduced weight gain, lower body fat, and resistance to obesity, motivating research into obesity prevention through diet-immune system interactions.
The findings highlight a previously less-known role of the immune system in digestion, specifically in breaking down chitin, a challenging dietary fiber found in insect exoskeletons, mushrooms, and crustacean shells.
When chitin is consumed, stomach distention activates an innate immune response that prompts stomach cells to increase the production of enzymes called chitinases, responsible for chitin breakdown.
Remarkably, chitin is insoluble and necessitates both enzymes and acidic conditions for digestion. The research, conducted in germ-free mice without intestinal bacteria, showed that chitin activates immune responses independently of bacteria, suggesting that the host's chitinases play a significant role in digestion.
Interestingly, in mice with intestinal bacteria, chitin-containing food altered the bacterial composition in the lower gastrointestinal tract, indicating that gut bacteria also adapt to chitin-containing food once it leaves the stomach.
The research demonstrated that in mice the most significant impact on obesity occurred when chitin activated the immune system but remained undigested. Mice on a high-fat diet were supplemented with chitin, and some were unable to produce chitinases for chitin digestion.
On the other hand, the mice that consumed chitin but could not digest it gained the least weight, had lower body fat, and resisted obesity compared to mice that did not eat chitin or those that could digest it.
Don't Just Consume Exoskeletons for Their Chitin, Researchers Warn
The team intends to further investigate these findings in humans to explore the potential of incorporating chitin into diets for obesity control. Van Dyken noted that there are multiple methods available to inhibit stomach chitinases, potentially leading to significant metabolic benefits when combined with chitin-rich foods.
However, the team also warns of consuming insects and crustaceans for their chitin content. They explained that the consumption of insects and crustaceans for chitin can pose risks, including the presence of harmful bacteria, viruses, and fungi, as well as documented cases of botulism associated with insect consumption. Additionally, ingesting chitin from these sources may trigger reactions akin to shellfish allergies.
As the study was conducted on mice rather than humans, further research is essential to assess the safety of chitin and chitin-containing organisms for human consumption.
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