Food Science and TechnologyVolume 36, Issue 2 p. 24-28 FeaturesFree Access Making a meal out of bugs First published: 09 June 2022 https://doi.org/10.1002/fsat.3602_5.xAboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Valerie J. Stull of the University of Wisconsin-Madison and John Wilson and Tiffany Weir of Colorado State University discuss the benefits and risks of eating insects. Introduction Pressured on all sides, global food security remains tenuous given inequitable distribution, excessive food waste, climate change, a growing population and mounting environmental degradation. Concurrently, food production itself contributes more than a quarter of all human-caused greenhouse gas (GHG) emissions, with a significant portion from livestock production. Although staple crop yields have reached historic highs, an estimated 768m people remained undernourished as of 2020. Novel and sustainable systems of food production and distribution, as well as changes in dietary behaviours, will all be needed to protect food security in the future. One such option might be increased production and consumption of edible insects. While not part of the typical 21st century diet in Europe or the United States, insects are common ingredients across the globe, particularly in the tropics. An estimated 2bn people live in contexts where the practice of eating insects – termed entomophagy – is embraced and there are more than 2,100 known edible species to choose from1. Insects have been a critical part of the diet throughout human history, likely helping our hominid ancestors meet nutrient needs and develop larger brains. Today, they appear in many traditional dishes and are being incorporated into new products. Farming insects for human food and animal feed is a burgeoning industry, motivated in part by consumer concerns regarding the environmental, health and sustainability aspects of food. Insects typically require less land, water and feed than conventional livestock, while emitting fewer GHGs2. Their relatively short lifespans, faster time to maturity and high fecundity rates make them ideal contenders for resource efficient farming in variable contexts. It is difficult to generalise across species and growth parameters, but characteristically insects are akin to meat – rich in protein and fat, low in carbohydrates; they also provide favourable fatty acids, essential minerals and even some vitamins. Beyond their rich nutrient content, insects offer other possible health benefits to humans that have yet to be fully explored, including those stemming from bioactive compounds with antioxidant or other properties and dietary fiber. Insect consumption is not without risks, however. Food safety considerations for insects are crucial, as they are potential sources of hazard and allergens in the diet. Here, we highlight current understanding of the benefits and risks associated with insect consumption. Benefits: nutrient composition and quality A primary motivation for eating insects is high-quality protein. Insects are touted for their beneficial amino acid profiles, digestibility and crude protein content, which is generally comparable and sometimes exceeds that of conventional meats. Grasshoppers, for example, can average about 70% protein by dry weight. Additionally, edible insects characteristically provide all essential amino acids for human nutrition. Although in vitro studies report variable digestibility across insects, processing methods and models, when fed to rats and compared to casein in a true protein digestibility study, insects performed very well with values between 67 and 95.8% digestibility3. In summation, insect protein is an adequate alternative to other animal-sourced proteins and ideally suited to supplement insufficient diets. Many species provide lysine and other amino acids deficient in common cereal, tuber and legume-based diets, which could help at-risk populations obtain all essential amino acids and avoid protein deficiency. The fat profiles of many edible insects mirror those found in fish. For example, breakdown of total fat in Acheta domesticus, a commonly consumed cricket species, is about 20% saturated fat and over 50% polyunsaturated fats (PUFAs), similar to what is found in salmon. The major PUFAs are omega-3 and omega-6 forms, which are important in brain and nervous system development and functioning. However, the ratio of PUFAs in the diet matters, as high omega-6:omega-3 ratios contribute to inflammation. Although an optimal ratio has not been established, calculating the USDA (United States Department of Agriculture) recommended intakes of each of these fats would suggest intakes of ~10:1 or lower4. The amount and types of fats present in edible insects vary by species, life stage and with insect diet. However, a recent review showed that Tenebrio molitor (mealworm) and some species within Orthoptera, including several grasshoppers and crickets, had beneficial PUFA ratios5 suggesting that numerous insects may be a good dietary source of omega-3 fats. In addition to protein and beneficial fats, insects provide numerous critical micronutrients, including relevant concentrations of zinc, iron and B vitamins, which could prove especially beneficial to public health in contexts where undernutrition is prevalent (Table 1). Questions remain about the bioavailability of insect iron, as it is packaged in both heme and nonheme forms, and human intervention trials are scant. Several in vitro and animal studies have demonstrated that bioavailability is quite good, comparing favourably to plant-based iron and in the case of some species, meat. In one study, infants who consumed caterpillar enriched cereal for 12 months showed higher iron concentrations and lower rates of anemia than children who did not consume the cereal6. Unprocessed insects are good sources of B vitamins including biotin, pyridoxine (B6), riboflavin (B2), pantothenic acid, folic acid, niacin and cyanocobalamin (B12). Table 1. Nutrient composition of edible insects – by dry weight Species Common Name Order Insect lifestage Protein (g/100g DM) Iron (mg/100g DM) Folate (mcg DFE/100g DM) Vitamin B12 (mcg/100g DM) Acheta domesticus House cricket Orthoptera Adult 63.28 7.06 474.55 48.98 Bombyx mori Domesticated silkworm Lepidoptera Larvae & pupa 58.60 6.84 299.16 0.26 Cirina forda Emperor shea moth Coleoptera Larvae 41.35 18.63 Gonimbrasia belina Mopane worm (caterpillar) Lepidoptera Larvae 56.87 23.94 Gryllus bimaculatus Two-spotted cricket/ African field cricket Orthoptera Adult 54.89 15.73 Locusta migratoria Migratory locust Orthoptera Adult 53.40 6.23 0.84 Oecophylla smaragdina Weaver ant Hymenoptera Adult 49.96 18.41 Rhynchophorus ferrugineus Asian palm weevil/sago larvae Coleoptera Larvae 31.54 4.70 Rhynchophorus phoenicis African palm weevil Coleoptera Larvae 30.14 33.02 200.00 11.39 Ruspolia differens Green cone-headed cricket Orthoptera Adult 43.94 18.64 530.00 1.04 Samia ricini Eri silkworm Lepidoptera Pupa 56.29 27.97 Schistocerca gregaria Desert locust Orthoptera Adult 53.82 5.38 Tenebrio molitor Yellow mealworm Coleoptera Larvae 51.59 5.53 403.36 0.77 Mealworms Jeff Miller, senior photographer at UW-MadisonInsects provide numerous critical micronutrients, including relevant concentrations of zinc, iron and B vitamins, which could prove especially beneficial to public health in contexts where undernutrition is prevalent. Vitamin B12 is of particular concern to populations that eat a majority plant-based diet, and while only a few insects have been assessed for B12 content, the domestic house cricket (A. domesticus) has been shown to contain an impressive 8 mcg per 100g fresh weight7. A recent modelling study estimated that population wide consumption of just five grams of edible insects per day could alleviate significant risk of nutritional deficiency, putting 67m fewer people at risk of protein deficiency, 166m fewer people at risk of zinc deficiency, 237m fewer people at risk of folate deficiency and 251m fewer people at risk for vitamin B12 deficiency across several regions of Africa and Asia8. Mealworm powder Jeff Miller, senior photographer at UW-Madison Health benefits beyond nutrition A unique nutritional aspect of insects, relative to other animal foods, is the presence of dietary fiber, predominantly in the form of chitin. Chitin is a biopolymer made up of repeating n-acetyl-glucosamine units and is the primary component of insect and shellfish exoskeletons and fungal cell walls. Fungal chitins are cross-linked with β-glucans and can modulate the gut microbiota to improve digestive health. In contrast, animal-based chitin is complexed with protein, predominantly melanin, and its effects on digestive health have not been studied. Regardless of origin, dietary chitin serves as insoluble fiber, regulating transit through the digestive system to improve regularity and reduce constipation. Chitosan is a deacetylated derivative of chitin, and its solubility and bioactivity is dependent on degree of deacetylation (DDA) and molecular weight (MW). Although properly processed edible insects are generally safe to eat, like any food there are potential hazards associated with consumption. A continuum of structures between chitin and chitosan can be found in insect exoskeletons. For example, house crickets have ratios of ~½-¾ chitosan:chitin9. Chitin can be deacetylated enzymatically or by treatment with either acidic or basic solutions. Thus, the acidity of the stomach may result in some deacetylation of chitin, as well as breaks in the β1-4 glycosidic linkages, resulting in formation of chitosan and/or lower MW chitooligosaccharides. Additionally, chitinolytic enzymes occur in several mammalian species, including humans, further supporting the hypothesis that some conversion and hydrolysis of chitin occurs in the mammalian gut. However, there are currently no studies of chitin digestibility to determine the extent to which this happens. Low MW chitosans with high DDA are soluble in acidic solutions, forming a gel in the digestive tract. This soluble fiber increases water absorption, contributes to satiety and reduces absorption of dietary cholesterol. A meta-analysis of 14 randomised, controlled clinical trials utilising chitosan for weight loss, lipid metabolism and blood pressure demonstrated significant improvements in these outcomes compared to placebo10. In vitro studies have demonstrated that chitin and chitosan have antimicrobial properties; additionally, it has been suggested that chitosan is fermentable and may act as a prebiotic. Insect-derived chitosan has been shown to stimulate the growth of probiotic organisms in mice, while consumption of whole insects has been shown to alter the gut microbiota in ex vivo human fecal incubations11 and in healthy adults12. The selectivity of microbial suppression and stimulation by chitin/chitosan in the gut warrants further study to establish human health impacts. Recent in vitro studies have identified and categorised several bioactive compounds in edible insects and theorised as to their potential to reduce health risks and promote immune function. Insects may specifically be good sources of biologically active peptides with antioxidant and anti-inflammatory activity that could play a role in the progression or emergence of hypertension, cardiovascular disease, metabolic syndrome and type 2 diabetes. Several studies indicate peptides from some insects inhibit the angiotensin-converting enzyme (ACE)13, which causes vasoconstriction and increases in blood pressure. Some evidence suggests that insect bioactive peptides may also inhibit cyclooxygenase-2 activity (COX) with implications for inflammation. Additionally, α-Glucosidase may be inhibited by insect peptides, which could be useful to help treat type 2 diabetes by suppressing hyperglycemia14. In the case of bioactive peptides, heat treatment may be beneficial, positively impacting antioxidant properties of peptides from insect protein. Overall, bioactive potential of peptides from insects is likely similar or higher than other foods, but rigorous human trials are needed to further identify, characterise and understand bioactive compounds present in insects and their direct or indirect impacts on humans who eat them. Risks and food safety concerns Although properly processed edible insects are generally safe to eat, like any food there are potential hazards associated with consumption. As animal products, food safety concerns from insects arise primarily from their rich moisture and nutrient content, which can provide an ideal habitat for microbes. Contamination may also arise during rearing, processing and storage. Research on the microbiological aspects of edible insects is relatively sparse, but as with all animal foods, there is a risk of parasitic and enteric bacterial contamination, particularly when eating insects raw15. To avoid these risks, edible insects should be handled in the same manner as conventional meat using clean and sanitised processing areas, avoiding cross-contamination and cooking to adequate temperatures. Since many commercial insect products are dried and packaged, an additional concern is spore-forming bacteria, which can enter a dormant state when stressed and survive periods of dryness, exposure to chemicals and extreme heat until optimal conditions return. Botulism, caused by Clostridium botulinum toxin, can be a risk with entomophagy if insects are improperly handled or stored. A survey of dried, shelf-stable insect protein products showed that all had a pH of 5.5 or higher16, which exceeds the target value of 4.6 to prevent spore-forming anaerobic bacteria like Clostridium botulinum from producing botulism toxin. However, this risk can be mitigated by reducing the overall water activity (Aw) to <0.97. Across the samples surveyed, the Aw was <0.7. While this limits growth of spore formers, there is potential for them to remain dormant in this range and become vegetative if Aw increases. Aerobic spore-formers, such as Bacillus cereus, have also been found at higher levels in processed insect powders, such as dried powders from crickets or mealworms, than in fresh insects. This is likely due to stressors incurred during processing, which can induce sporulation. B. cereus is transmitted when food is improperly handled or insufficiently cooked and can cause severe illness, characterised by vomiting and diarrhea within one-five hours of consumption. The maximum safe load of B. cereus is 104 Colony Forming Units (CFUs)/gram; however, concentrations of up to 6.610 CFUs/ gram have been observed in processed insect samples, representing a significant risk to consumers if the dried products are not handled correctly16. Mealworm tempeh John WilsonPhysical hazards unique to insect consumption have not been well researched, but are relevant given that some species have spines, horns and irritating hairs that may be caught in the throat or cause minor lacerations in the mucus membranes of the body. Some producers attempt to mitigate microbiological risks by withholding food from the insects for several days prior to processing. The efficacy of this practice needs further research. One study observed no reduction of microbial load in mealworms that were purged in this manner, suggesting that purging may not effectively clear the gut of potentially harmful microorganisms, or that microbial contamination may not originate in the insect gut16. To reduce these risks, it is recommended that vegetative microbial loads are minimised using heat treatments like blanching or sterilisation prior to further processing to reduce the overall concentration of spore-formers in the final product. Chemical contamination in insect foods is also a concern, such as bioaccumulation of heavy metals (e.g. arsenic, cadmium, cobalt, chromium, nickel, lead, tin and zinc), although there is little evidence of harm to-date. In addition, carcinogenic persistent organic pollutants, like dioxins, have been found to accumulate in insects in levels below that of conventional meat production. Concentrations tend to be higher in fresh insects than processed products, possibly due to the dilution of concentrations with the addition of secondary ingredients. Flame retardants have also been observed in processed insect protein products. A recent study detected six different phosphate flame retardants in mealworm and wax moth larvae samples. Finally, pesticides, such as vinyltoluene and pentaflouropropionic acid, have been detected in edible insect products, likely from their environment or feed. To date, reports of these chemicals in insects indicate concentrations below the safe maximum level allowed17. While these data suggest that consuming insects will not result in acutely toxic exposures, there may be potential for bioaccumulation in human tissue with regular consumption and more research is needed to determine the long-term risks. Physical hazards unique to insect consumption have not been well researched, but are relevant given that some species have spines, horns and irritating hairs that may be caught in the throat or cause minor lacerations in the mucus membranes of the body. The physical risks of consuming specific insect species need to be assessed individually. A range of allergic reactions have been documented from eating insects, from mild to severe; however, there is no evidence that insects pose a greater risk of allergy responses than other foods. Eating insects may elicit Immunoglobulin E (IgE) allergic reactions in some consumers and a potential cross reactivity response between individuals with shellfish allergies and people who have allergic responses to insects has been documented18. Similar reactions have also been observed in people who are allergic to dust mites. Cross reactivity occurs between plant and animal species that are taxonomically related, and in the case of shellfish and insects, IgE response has been attributed to tropomyosin and arginine kinase, common allergens associated with arthropods generally. As a result, individuals who experience allergic reactions to shellfish and house dust mites are advised to avoid eating insects. Chitin is also a known allergen, though it is generally considered more of an occupational hazard than a food safety risk. While there are legitimate food safety concerns in consuming insect protein, these are ubiquitous across every food product, particularly animal-sourced foods. As insect protein grows as a viable food source, best practices continue to be developed to ensure the safety of the consumer. Conclusions Edible insects offer a promising array of potential health benefits to consumers even beyond their nutrient composition. This, in tandem with their purported environmental advantages, justifies continued industry development and scholarship on this topic. Although research exploring the gamut of potential hazards across the thousands of edible insect species is meager at best, consumers without food allergies can proceed with confidence if they obtain insects known to be edible from food-grade producers and cook them thoroughly. Historical evidence demonstrates general safety given that insects have been consumed by humans across the globe for thousands of years and are allowable at small concentrations in every packaged food product. Insects are not the ‘future of food’, as they are sometimes hailed, nor are they a silver bullet to address our convoluted environmental and health challenges today. They do indeed reflect an important food of the past, and the present, that has the potential to be scaled to benefit humans and the environment in the future provided appropriate precautions are implemented. Valerie J. Stull1*, John Wilson2 and Tiffany Weir2, 1 University of Wisconsin-Madison, USA; 2 Colorado State University, USA *Corresponding author. Dr Stull is an interdisciplinary environmental scientist with expertise in edible insects, sustainable food systems, and global health at the University of Wisconsin-Madison. email vstull@wisc.edu References 1Jongema, Y. 2017. List of edible insects of the world. 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