Edible insects are often considered a nutritious, protein-rich, environmentally sustainable alternative to traditional livestock with growing popularity among North American consumers. While the nutrient composition of several insects is characterized, all potential health impacts have not been evaluated. In addition to high protein levels, crickets contain chitin and other fibers that may influence gut health. In this study, we evaluated the effects of consuming 25 grams/day whole cricket powder on gut microbiota composition, while assessing safety and tolerability. Twenty healthy adults participated in this six-week, double-blind, crossover dietary intervention. Participants were randomized into two study arms and consumed either cricket-containing or control breakfast foods for 14 days, followed by a washout period and assignment to the opposite treatment. Blood and stool samples were collected at baseline and after each treatment period to assess liver function and microbiota changes. Results demonstrate cricket consumption is tolerable and non-toxic at the studied dose. Cricket powder supported growth of the probiotic bacterium, Bifidobacterium animalis, which increased 5.7-fold. Cricket consumption was also associated with reduced plasma TNF-α. These data suggest that eating crickets may improve gut health and reduce systemic inflammation; however, more research is needed to understand these effects and underlying mechanisms.
The human gastrointestinal tract is home to a host of bacterial cells. These cells outnumber human cells by a factor of three1 and encode at least 100 times more genes2, which influence human physiology, metabolism, and gene expression pertinent to immune function, energy, and even mood3. Extensive research demonstrates that microbiota in the gut respond to nutritional cues and generate hormone-like signals influencing normal physiology, nutritional status, metabolism, immune function, as well as disease progression and overall wellbeing2,4,5,6. Imbalances in the gut microbiota, also known as dysbiosis, and low microbial diversity are associated with metabolic and non-communicable diseases, gastrointestinal conditions, allergies, asthma, and even neuropsychiatric disorders7,8,9,10.
Diet is an especially relevant factor in defining the composition of gut microbiota11, and even small shifts have demonstrated meaningful effects5,12. Dietary diversity is linked with a more diverse, healthy microbiota that is more adept at adjusting to perturbations13. Indigestible dietary carbohydrates (dietary fibers) are the primary energy sources for gut microbiota, and thus shape microbial growth14. Not surprisingly, dietary fiber intake has been shown to contribute to the health of the gut microbiome by increasing diversity in fecal microbiota15,16, and high fiber intake has been associated with a reduced risk of breast cancer17, diverticular disease18, coronary heart disease19,20, and metabolic syndrome21,22. Edible insects are hailed as an excellent source of protein and other nutrients, but they also provide a relatively understudied fiber source, chitin, that could influence the gut microbiota. For western consumers, edible insects are a novel food that is just now gaining traction in certain areas.
Motivations to eat insects stem from their cultural and nutritional value, as well as their numerous environmental benefits. The current pressures on global food security, including climate change, population growth, and shifting dietary preferences, have ignited a search for more environmentally sustainable protein sources. Given that livestock production alone is responsible for about 14.5% of total human-induced greenhouse gas (GHG) emissions23 there is a mounting need for more efficient animal production systems. Edible insects have been touted as one such option, as they typically emit fewer GHGs24 and require less land, water, and feed to survive and thrive than traditional livestock25. The result is a significantly lower environmental impact24,25,26, and high desirability due in part to insects’ large edible body mass percentage27, high feed-conversion ratio26, and ectothermic thermoregulation, which limits energy expenditure on temperature regulation. Entomophagy, the practice of eating insects, is not new however; it has been recorded throughout human history across the globe28,29. Today, insects are regularly consumed by approximately 2 billion people25 spread across 80% of the world’s populations30 in 130 countries31. Edible insects are gaining traction in North America and Europe, in addition to regions that traditionally practice entomophagy. The commercial industry was valued at 33 million USD in 2015, with future growth estimated at more than 40% by 202332. Insects that have been eaten historically are generally considered safe for human consumption if properly processed like other animal products, although some people are allergic to insect proteins and chitin33. Generally, insects are a good source of bioavailable animal protein33,34,35,36 including all essential amino acids26, as well as B vitamins35,37, minerals37,38, and essential fatty acids39.Insects also contain relevant levels of crude fiber, most predominately in the form of chitin, derived from the exoskeleton40. A recent estimate of chitin and chitosan based on percent dry weight of whole ground crickets found values between 4.3–7.1% and 2.4–5.8%, respectively41.
Chitin (C8H13O5N)n) is a modified polysaccharide (poly-beta-1,4-N-acetylglucosamine) containing nitrogen with a structure analogous to indigestible cellulose; it is considered an insoluble fiber with potential prebiotic properties that could benefit human health by selectively promoting the growth of beneficial bacterial species in the intestines, though this relationship is not well understood. Chitin is the primary component of the exoskeleton, respiratory linings, digestive and excretory systems of arthropods42, and given the variation in insect anatomy chitin levels in common feeder insects vary widely43. Chitin has applications in health, drug delivery, agriculture, gene therapy, food technology, nano-technology, and bioenergy, among others44.