Entomophagy, the practice of eating insects, has been a part of human diets from prehistoric times to the present day ^[1][2][3][1,2,3]. The eggs, larvae, pupae, and adults of certain insects are not only rich in fats, essential fatty acids; protein; essential amino acids; carbohydrates, including chitin and vitamins; and minerals [4], but also potentially present a sustainable alternative to traditional livestock production [5]. Insect farming requires less land, water, and feed, and produces fewer greenhouse gases, thus offering a potential solution to the environmental challenges posed by conventional animal agriculture [6]. Despite these benefits, entomophagy has only recently gained interest in Western countries [5]. In many cultures, insects are often perceived as dirty, disgusting, or as disease vectors, contributing to a neophobic cycle regarding entomophagy ^[6][7][6,7]. However, with the world population predicted to reach nine billion by 2050 and the demand for safe and sustainable food expected to increase by approximately 60% ^[8][9][10][8,9,10], alternative sustainable protein sources like insects are becoming increasingly important.

Insects offer a multitude of benefits that make them an attractive option for food consumption ^[11][17]. From a health perspective, insects are a rich source of protein, essential amino acids, fats, vitamins, and minerals, making them a highly nutritious food source ^[12][18]. Their nutritional profile can contribute to a balanced diet and help combat malnutrition and overnutrition, addressing key health concerns in many parts of the world ^[13][19]. Moreover, a recent review by Zhou et al. ^[14][20] found there was an annual increase in type 2 diabetes cases worldwide, while Lee et al. ^[15][21] agreed that obesity contributed to the increased development of diabetes. Furthermore, obesity increases the risk of developing a variety of diseases, including type 2 diabetes mellitus (T2D), cardiovascular disease, and cancers, all of which can negatively impact quality of life ^[16][22]. However, recent research regarding diet-induced obese mice found that Yellow mealworm (Tenebrio molitor) and Lesser mealworm (Alphitobius diapernius) proteins hindered weight gain and improved the metabolism of the obese mice ^[17][23]. Moreover, mealworms and their extracts are considered beneficial for metabolic health and improved metabolism, which may be due to a combination of components therein, including but not limited to protein ^[17][23], chitin ^[18][24], and fatty acids ^[19][25]. In addition, Seo et al. ^[20][26] found that Yellow mealworm (Tenebrio molitor) larvae extracts also improved metabolism by reducing hepatic steatosis and lowering plasma AST and ALT concentrations. In terms of environmental impact, insect farming presents a more sustainable alternative to traditional livestock farming. It requires less land, water, and feed, and produces fewer greenhouse gases, aligning with global efforts to mitigate climate change and promote sustainable food production. Moreover, certain insect species have shown resistance to various conditions, which could be beneficial in the context of insect farming ^[21][27].

Beyond health and environmental considerations, the cultivation of insects also holds socioeconomic benefits. Insect farming can provide income opportunities, particularly in rural areas where economic resources may be limited. This can contribute to poverty reduction and economic development, fostering resilience in vulnerable communities. In fact, a study focusing on the consumption of edible insects in Kinshasa, Congo, in a context of food crisis and shortage, found that individual and collective factors, as well as the context of consumption and emotional factors, influence insect consumption ^[22][28]. Thus, the practice of entomophagy, or insect consumption, holds promise not only as a solution to nutritional needs but also as a strategy for sustainable development and economic growth.

2. Nutritional Composition of Edible Insects

Edible insects are a potential source of dietary protein, including but not limited to, essential amino acids, monounsaturated, and polyunsaturated fatty acids. They are also a rich source of micronutrients including calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), phosphorous (P), selenium (Se), zinc (Zn), and riboflavin, pantothenic acid, biotin, and folic acid ^[23][24][25][14,143,144]. However, the overall nutritional composition of edible insects is dependent on the metamorphic stage of the insect, their diet, responses to their immediate environment, and the final processing methods, including but not limited to, drying, boiling, frying, and roasting ^[26][145]. The bioavailability of macronutrients and micronutrients, as defined by Melse-Boonstra ^[27][146], refers to the ‘fraction of an ingested nutrient that becomes available for use and storage in the body’. However, the rearing and processing methods of edible insects can influence their potential macronutrient and micronutrient composition. Further research undertaken by Ojha ^[28][147] found that the bioaccessability of such nutrients released from a food matrix during digestion and absorption can vary. Therefore, from a nutritional and health perspective, the digestibility and metabolized components of edible insects are the key aspects to be considered ^[29][30][31][148,149,150]. Further research on the bioavailability of macronutrients and micronutrients would be beneficial as there is a paucity of knowledge within this area. Furthermore, insect farming and production has the potential to positively contribute to “Transforming our world: the 2030 agenda for sustainable development”, as defined by the UN ^[23][32][14,29]. Insects are regarded as poikilotherm animals which are cold-blooded and therefore have a high feed conversion rate which enhances their efficiency in biotransformation processing of organic matter into insect biomass ^[33][34][133,134]. Almost 80% of the mass of most insects can be consumed and digested, whereas only 55% of chicken and pork, and 40% of cattle is consumed ^[35][36][31,135].

2.1. Macronutrients

A recent study conducted by Pal ^[37][151] found that the macronutrient composition of beef and crickets were comparable as crickets contained 205 g of protein and 68 g of fat per kg, while ground beef contained approximately 256 g of protein and 187 g of fat per kg. A similar study previously undertaken by Rumpold and Schluter ^[38][152] identified the macronutrient composition of potential edible insects.

2.1.1. Protein

Protein is globally recognized as a component of a healthy diet for humans ^[39][30]. The current increased demand for protein is in part due to socioeconomic changes, including but not limited to rising incomes, increased urbanization, and aging populations ^[37][151]. The protein content of invertebrates is derived from a range of amino acids found within insects, while the quality of the protein is determined by the presence of essential or non-essential amino acids, although the digestibility of the proteins must also be considered ^[26][145]. The Kjeldahl method is widely used to quantify the crude protein present in the insect, where content can range from 8% to 70% of dry mass ^[40][41][153,154]. The Dumas technique is also used to determine protein content ^[42][155]. Both techniques, which focus on nitrogen content, are recognized as standard methods of analysis. However, not all nitrogen contained in insects originates from proteins ^[43][35]. Therefore, it is possible that digestible protein content calculated in insects using the aforementioned methods may be overestimated. Previous research by Bosch ^[44][156] highlighted that some differences in protein digestibility from different insects resulted from different cuticular protein sclerotization. Thus, protein content calculated using the Kjeldahl analysis and conversion factors developed for other foods would be expected to overestimate the protein content of the whole insect, as it does not distinguish between easily digested proteins, inaccessible proteins, chitin, and other Nitrogen-rich molecules ^[40][153].

2.1.2. Fat

The fat content of invertebrates is high in monounsaturated and/or polyunsaturated fatty acids. Essential fatty acids, including the omega-3 fatty acids of α-linolenic acid and the omega-6 fatty acids of linoleic acid, are also present in insects. However, fat content can differ between species and even within a single species due to environmental factors, contaminants and, in particular, the individuals’ uptake of heavy metals ^[1][26][1,145]. Similarly, Bawa ^[29][148], for example, found that the fat content of A. domesticus was subsequently altered depending on the diet they consumed.

2.1.3. Fibre

Over consumption of locusts and grasshoppers without removing the legs can cause severe constipation in humans due to the large spines present on the tibia of the insects which can become embedded in the human the gut ^[1][45][1,141]. Furthermore, surgery is often required to remove the undigested spines ^[46][157]. Similarly, when patients in eastern Java, Indonesia, overconsumed roasted scarab beetles (Lepidiota spp.) surgery was also necessary to relieve total constipation caused by indigestible chitinous accumulation within the human gut. ^[1][47][1,158]. Therefore, when insects are consumed within the recommended limit of less than 30% of plate portion content they can potentially contribute positively to human consumption of fibre without any resulting constipation.

2.2. Antinutrients

Fibrous chitin is a structural nitrogen-based carbohydrate which is present in the exoskeleton of insects. Chitin may contain anti-nutrient properties related to negative effects associated with protein digestibility ^[48][15]. However, further research by Rumpold and Schluter ^[35][31] found that although chitin is considered indigestible by humans ^[49][159], chitinolytic enzymes produced by bacteria located in the human gastrointestinal tracts indicated that chitin and chitosan can be digested by humans. Furthermore, nutrient intake can also be reduced by the consumption of antinutrients such as tannin, oxalate, hydrocyanide, and phytate, all of which can be found in varying degrees in edible insects ^[50][71].

2.3. Micronutrients

Micronutrient levels vary greatly within insect species depending on their age and the development stage of their life cycle, all of which can also be influenced by their immediate environment ^[35][51][52][31,61,160].

Vitamins and Minerals

Environmental factors, contaminants, and metals acquired during a life cycle and processing exposure can influence the final mineral and vitamin content of the insect. Moreover, research conducted by Mattia ^[53][37] found that crickets and grasshoppers displayed antioxidant values superior, by up to three-fold, to those of orange juice and olive oil. Furthermore, Vitamin B12 occurs only in food of animal origin and can be found in T. molitor at 0.47 μg per 100 g and in A. domesticus at 5.4 μg per 100 g in adults and 8.7 μg per 100 g in nymphs ^[2][49][54][2,159,161]. A potential combination of micronutrients found in edible insects can be viewed in Figure 12.