Mycelium: A Nutrient-Dense Food To Help Address World Hunger, Promote Health, and Support a Regenerative Food System (2024)

Abstract

Keywords: mycelium, mycofoods, hunger, sustainability, protein, micronutrients

Introduction

The United Nations Sustainable DevelopmentGoal 2 (UNSDG2) requiresa multidisciplinary approach to achieve its aim of ending hunger whileproviding food and nutrition security within a sustainable agriculturalsystem by 2030.¹ Achieving this goal requirestransformational innovations that can be rapidly scaled given thatas of 2020 approximately 720–811 million people suffer fromhunger, with another 2.4 billion being moderately or severely foodinsecure.² Malnutrition increasingly coexistsas both undernutrition driven by food insecurity and obesity drivenby nutrition insecurity in many regions of the world.^3,4 This conundrum emphasizes the urgent need for the development ofaffordable foods desirable for global consumers and dense in bioavailablenutrients that are required for improving public health. In additionto the development of affordable foods providing better nutrition,an associated challenge will be manufacturing these foods within afood system that is environmentally beneficial and enables resilientagriculture practices.⁵

New developmentswith plant-based proteins have created opportunitiesto improve public health and environmental sustainability while reducingdependence on animal-based food products. Increasingly, dietary recommendationsinclude a greater intake of plant-based foods to reduce noncommunicablechronic disease burden in both the developing and developed world.^6,7 In addition to opportunities for improving public health, plant-baseddiets can lower the impact of food systems on the environment by reducingwater use and the production of greenhouse gases.⁸ However, potential concerns of plant-based diets includethe bioaccessibility of essential nutrients not produced endogenouslyor in sufficient quantity to support health that then must be obtainedfrom the diet and “limiting” amino acids that are notpresent in sufficient quantity to stimulate protein synthesis. Representativeof these concerns are populations with limited dietary protein diversityand a high incidence of anemia, stunting, and other health conditionsassociated with micronutrient deficiencies. Finally, any changes toan existing food system should be adaptable to the local environmentand economic conditions and be sensitive to cultural practices.⁹

In addition to diets containing more plant-basedfoods, myceliumproduced from filamentous fungi offers opportunities to develop foodproducts that have desirable flavor and texture characteristics thatare high in protein quality while providing fiber and essential micronutrients.Historically, not new to the food supply, fungal mycelium has gainedinterest, as technological advances have aided its formation intoa protein biomass for food production. Some of these products arereferred to as mycoprotein.^10,11 Here, we review thepotential of mycelium as a sustainable category of food well positionedto reduce malnutrition and enable the goal of zero hunger. We willfirst provide a basic understanding of mycelium while outlining thehistorical perspective of mycelium as a food. This historical perspectiveis followed by a discussion regarding the nutritional compositionof mycelium, its potential benefits for public health, and futureresearch needs in this context. Finally, we discuss the potentialof mycelium-based foods, or mycofoods, as an affordable, scalable,and environmentally sustainable new source of high-quality proteinfor global consumers.

Mycelium Basics

Fungi are one of the largest groupsof eukaryotic organisms onthe planet. They play many ecological roles in the environment includingnutrient and carbon cycling and have been documented to be intimatelyinterconnected with other organisms existing in mutualistic, pathogenic,and saprotrophic lifestyles.¹² The fungalkingdom has enormous diversity, and recent estimates have indicatedthat the species count may range from two to 11 million species, withabout 155,598 fungal species formally described to date.¹³⁻¹⁵ Analysis of metabarcoding data has suggested an even larger speciesnumber as high as 1.7–13.2 million species.¹⁶ Thus, fungi are considered one of the largest and leastexplored biodiverse resources on the planet.

Accordingly, therehas been historical debate, more so than anyother group of eukaryotic organisms, as to which groups to includeor exclude within a taxonomical group. With advances in technologyand expansion in knowledge over the years, most notably in genomics,there has been a shift in the phylogenic classification methodologiesemployed, moving from taxonomy based on mostly shared key morphological,ecological, and physiological characteristics, to more reliance onthe similarity of relevant DNA sequences.¹⁷ In addition to a large diversity of species identified via DNA sequencing,fungi also have a diversity of morphological growth forms that arestill in use for taxonomical classification. Prior to DNA sequencing,the historical reliance mostly on morphological characteristics addedto the complexity of classification.¹² Forexample, one characteristic that has aided in species identificationis the size of reproductive structures. If the reproductive structureis visible to the naked eye (i.e., mushroom-forming fungi), the fungusis referred to as a macrofungus. If the reproductive structure isnot visible to the naked eye (i.e., yeast), the fungus is referredto as a microfungus. Although considered as artifical taxonomic characters,the terminology is still useful for identification purposes and communicationto the public. Additionally, teleomorph refers to fungi in the sexualstate and anamorph refers to those in an asexual state. However, somefungi species have only been identified as anamorphs, with these specieshistorically referred to as fungi imperfecti, demonstrating the complexityof a classification system based predominantly on morphological characteristics.With the implementation of modern molecular systematic methodologies,the taxonomy of fungi lacking distinct reproductive morphologicalstructures has been better resolved.

Most commonly, fungi growvegetatively in the form of elongatedcells or hyphae that are often branching and tubelike in appearance.A network of hyphal cells growing together are referred to as mycelium.Within the different taxonomical groups of fungi, hyphae tend to begenerally uniform, with some exceptions, for example, the presenceor absence of cross-walls within hyphal cells, referred to as septa.In addition, not all fungi grow as hyphae but some grow as discretesingle yeast cells. Some species are dimorphic and can switch betweenhyphal and yeastlike growth stages, with intermediate stages referredto as pseudohyphae. However, the term mycelium is not limited to fungi,but also occurs in other non-fungi organisms including those in Chromista.¹² For the purpose of this review, we focus onfungal mycelium.

The kingdom fungi have undergone many phylogeneticrevisions inthe past century,¹² with advances in high-throughputsequencing generating large amounts of meaningful DNA sequencing.Recent phylogenetic analysis has proposed 18 phyla, nested in 9 subkingdomsof fungi (Table 1).¹⁷ Within the fungi kingdom, the two main phylamost commonly used in food production are Basidiomycota and Ascomycota;however, some members of the lesser-known Mucoromycota such as Mucor species and Rhizopus species arealso used in the production of fermented food products.

Historical Perspective of Mycelium

Fungi have beenidentified in the fossil record that spans manydifferent time periods in earth’s geological history. Thereare many reports of fungi in fossil records. Recently, fossilizedfungal mycelium was discovered in sedimentary rocks in the DoushantuoFormation in Guizhou Province of China, from the Ediacaran periodwhich is estimated to be from approximately 635 to 541 million yearsago.¹⁸ In another study, fossilized structureswere described that were morphologically consistent with that of fungi,preserved in the shale of the Grassy Bay Formation in Arctic Canada.These specimens were estimated to be possibly over 1 billion yearsold.¹⁹ In addition to the various ecologicalroles that fungi play, such as nutrient and carbon cycling, fungiprovide a source of food for a diversity of organisms. There are manyexamples of fungi as a food source for organisms including plants,microbes such as bacteria, fungi, and ciliates, and animals includingmollusks, insects, birds, and mammals. Fungi, such as truffles andmushrooms, may have once played a greater role as food for vertebrates;however, it has been hypothesized that as the chemical diversity oftoxins in some fungal species increased, some mammals may have diversifiedtheir food sources to reduce fungal intake.²⁰

Fungi play a major role in traditional food culture and society,with a long-documented history of intake of a variety of fungi byhumans. As microfungi produce a suite of functional metabolites, fermentedfoods are a primary source of intake. Fermenting microfungi such as Aspergillus oryzae and yeasts such as Zygosaccharomycessp., Brettanomyces sp., and Saccharomyces sp. often producemetabolites that preserve food that can increase food safety, suchas ethanol, 2,3 -butanediol, and 2-phenylethanol. They can also producevarious organic acids, such acetic acid, propanoic acid, and butanoicacid. These metabolites not only inhibit spoilage and pathogenic microorganismsbut also often impart desirable sensory characteristics to the food.Yeasts have a long history of use in the production of different typesof breads and fermented beverages including wine and beer. Some otherexamples of microfungi used in traditional foods include Rhizopus species to produce tempe and koji, Aspergillus speciesto produce miso and soy sauce, and Penicillium speciesto produce cheeses, such as Roquefort and Camembert (Table 2).

The consumption of macrofungi, which include mushroom-formingfungi,also has a long history of human consumption and is still a majorfood source throughout the world. Mushrooms, including wild and cultivatedmushrooms, are the fleshy reproductive structure of some macrofungi,most commonly from Basidiomycota including the common button and sh*takemushrooms but also from Ascomycota, which includes morel mushroomsand truffles. In 2019–2020, alone, the U.S. mushroom crop totaled816 million pounds, with a total sales value of $1.15 billion USD.²¹ Mushrooms are an abundant source of vitaminsand other nutrients and are an important contributor to a healthydiet. Mushrooms are low in calories, fat, and sodium and are richsources of beneficial food constituents such as fiber, selenium, potassium,riboflavin, niacin, and ergosterol that with ultraviolet (UV) lightexposure produces vitamin D2.²²

Inaddition to the well-known traditional fungi-based foods (i.e.,mushrooms, some cheeses, and soy sauce), the use of fungal myceliumas a food source has been of increasing scientific and commercialinterest, especially for certain species that have a good safety profileand can be utilized as a source of high-quality protein and desirablenutrient profile (Table 3). Moreover, mycelial species promoted for commercialization havefast growth rates, good texture, and flavor profile and can be producedin a sustainable and environmentally friendly manner. Thus far, commerciallyproduced mycelium is most commonly derived from the cultivation ofmicrofungi from Ascomycota; however, there are some examples of theutilization of mycelium from mushroom-forming macrofungi from Basidiomycota,such as Lentinula edodes, which producesh*take mushrooms. In this example, since the mycelium or vegetativegrowth form of the fungus is used in the food product, the productis not referred to as a mushroom, but rather a mycelium. The sameis true for mold-forming microfungi used in food products. A moldis a reproductive structure of some microfungi, analogous to a mushroombeing the reproductive structure of some macrofungi. If the myceliumof a microfungus is used in the food product, the product itself isnot a mold, but rather mycelium from a mold-forming fungus. In contrast,a mold may form on some cheeses, so the term mold is accurate in thosecases. Further complicating the nomenclature, the term mold oftenhas negative connotations since most consumers associate the termmold with mycotoxins and mold allergies, even though edible mold-formingfungi are used to produce many commonly consumed foods, such as tempeh,miso, soy sauce, and some cheeses. Thus, there will be a need forconsumer education on the differences between toxic molds, ediblemolds, and mycelium from mold-forming fungi. Moreover, as new mycofoodsemerge, the documentation of their safety^23,24 will further aid in consumer acceptance of these foods into themainstream global food market.

Mycelium Flavor

Innovative approaches in food chemistry,including textural modificationsand in-process flavor development, present an opportunity to designnovel mycelium-based food products with enhanced flavor and texture.These technologies can help meet the consumer’s “flavor”and “texture” expectations of mycelium-based food productsin a sustainable and environmentally friendly manner. Mycelium-basedfood products typically have a bland or slightly mushroom-like flavorprofile, and as a result, most commercial products have added ingredientssuch as spices, yeast extract, or natural flavors added (i.e., chicken,beef, etc.). Accordingly, there is an opportunity for more consumerresearch to determine optimized flavor profiles that are the mostappealing to consumers and develop technologies to enhance the flavorwithout the addition of natural flavors. One current area of researchis the development of desirable in-process flavor, utilizing the knowledgeof the fundamental biochemistry and flavor chemistry naturally presentin different fungi. For example, different species of mushrooms canproduce a wide variety of flavors such as Boletus pallidoroseus, with the aroma of beef bouillon, Laetiporus sulphureus, with the flavor and texture of chicken, Boletussensibilis that smells like curry, andLactarius camphoratus with a maple syrup aroma. Rawmushrooms contain a pool of aroma precursors (i.e., amino acids, peptides,and sugars) that when cooked react to generate odorants that elicitthe unique flavor of the cooked mushroom. For example, the lobstermushroom, which is a Russula or Lactarius species of mushroom that has been parasitized byHypomyceslactifluorum, has a prominent seafood-like flavorthat develops after only after thermal treatment. The seafood-likeflavor is hypothesized to be derived from odorless precursors presentin the raw mushroom that upon heating generate seafood-like flavors.Slight differences in the amino acid composition can drastically affectthe final flavor chemistry of the cooked product. Many fungi containthe flavor chemistry potential to generate a wide variety of flavorsboth endogenously and through thermal treatment. This knowledge mayalso be applied to mycelium-based food products; however, furtherresearch is needed in this area.

Mycelium Composition

The Dietary Guidelines for Americans2020–2025 recommendsthat an individual’s diet contain a variety of protein foodsfrom both animal and nonanimal sources.⁶ Foods within the latter are complex whole foods, considerably lowerin saturated fat and sodium, while providing dietary fiber, vitaminsand minerals, and additional nonessential bioactives. While increasedintakes of plant-based foods lower the risk for the development ofchronic disease,²⁵ protein quality canbe a concern as the cell wall structure and the presence of antinutritionalfactors can limit both micronutrient and amino acid availability.^26,27 The intake of a variety of nonanimal source proteins that ensurecompleteness of overall essential amino acid intake may overcome theseissues. In addition, the provision of protein isolates can improveamino acid availability, but may lower the content of fiber and otherbeneficial nutrients and bioactives in comparison to the whole foodsource.^26,28

Within the nonanimal protein realm,mycelium research to date showspromise for this food’s incorporation into a healthy diet.Similar to plant proteins, mycelium is low in total fat, which isprimarily unsaturated, and a source of fiber (Table 4). On a dry matter basis, the protein contentof fungi such as mycelium is on the order of 20–30%.²⁹ Moreover, commercialized species such as Fusarium venenatum and Neurosporacrassa are considered high quality in protein witha company-reported protein digestibility-corrected amino acid score(PDCAAS) at or near 1.0.^23,30 This indicates that100 g of protein from these products provide at or near 100% of theessential amino acids³¹ (Table 5). Moreover, the filamentousnature of mycelium allows for food production via fermentation intoproducts that mimic the texture of meat.³² Mycelial protein is incorporated into a multilayered cellular wallstructure of polysaccharides, predominately consisting of β-glucanand a smaller proportion of chitin in the innermost layer near theplasma membrane.³³ Chitin, a hom*opolymerof β-1,4-linked N-acetyl glucosamine units, is the main fibrouspolysaccharide found in insect cytoskeletons, fish scales, and fungi.³⁴ The soluble fiber β-glucan from cerealscomprise β-1,4 and β-1,3 linked glucose units, with thecholesterol-lowering effects of cereal β-glucan intake beingwell documented.³⁵ For mycelium, the innermostcell wall predominately consists of either lineal β-1,3 glucanunits or β-1,3 glucan units with β-1,6 linkages at branchingpoints.³³

Depending on the growth substrate, the micronutrientprofiles ofmycelium can vary (Table 4), yet may be a dietary vehicle for the delivery of a numberof essential micronutrients of concern, particularly for populationgroups that solely consume a plant-based diet, and includes iron,zinc, and vitamin B12.^36,37 Indeed, a serving of certaincommercially available mycelial products can be considered a highsource of zinc, folate, copper, riboflavin, niacin, and pantothenicacid, providing at least 20% of the daily value, while a good sourceof iron (Table 4).^30,38,39 Additionally, mycelium is lowin phytate, which can make it a more bioavailable nonanimal proteinsource of micronutrients such as zinc.⁴⁰ Although promising, data from dietary intervention trials are neededto confirm the bioaccessibility of essential micronutrients from mycelium.

Depending on the species and growing conditions, mycelium can bea source of a number of bioactive compounds. This includes ergothioneine,a derivative of histidine and betaine that exists as a tautomer ofthiol and thione. At physiological pH, thione is dominant, makingergothioneine less reactive and resistant to autoxidation.⁴¹ Ergothioneine can be found in a variety of foods,most likely derived from the presence of fungi either near or at theroot level.⁴² While the biological roleof ergothioneine is still being defined, low ergothioneine levelshave been associated with age-related chronic and neurodegenerativediseases.⁴¹ Both macro- and micro fungiproduce additional bioactives and pigments as a protective responseagainst UV-light-induced oxidative stress. This includes carotenoids,such as neurosporaxanthin and γ-carotene, produced from Neurospora^43,44 and ergosterol or vitamin D2.²⁹

On a global basis, reducing food waste and loss is of interestfor long-term environmental sustainability as well as food and healthsecurity. Upcycling of food waste streams provides for the reincorporationof nutrients into the food system, and for an industry sector, createsa resilient circular bioeconomy.⁴⁵ Examplesinclude the mycelial fermentation of soybean cake and tofu waste,into oncom and tempeh, resulting in increased protein content andnutrient bioaccessibilty.⁴⁶ For livestock,mycelial fermentation of agricultural waste streams reintroduces fiberand protein back into the food system.⁴⁷ Moreover, depending on the waste stream, mycelial fermentation allowsfor the incorporation of bioactive peptides and plant-derived secondarymetabolites, such as flavonoids, known for their health-promotingproperties into mycofoods.^48,49

Mycelium and Health

A number of studies have reportedpositive impacts of mycelialextracts on the immune system, cancer, and cirrhosis in invitro and animal models and human participants.^29,47,50,51 Focusing specifically on mycelial intake as a whole food, a limitednumber of dietary intervention trials suggest positive impacts onglycemic response.⁵² In an oral glucosetolerance test, healthy participants consumed either a beverage providing17 g of mycoprotein and 75 g of carbohydrate (50 g as glucose) oran energy, protein, and carbohydrate-matched control beverage. Frombaseline to 60 min post beverage intake, the participants had an 8.75and 20% reduction in their area under the curve (AUC) glucose andinsulin responses, respectively.⁵³ No significantintervention effects for postprandial glucose were observed when healthymen consumed beverages providing 20 g of milk or mycoprotein (0.7and 4.0 g total carbohydrate, respectively). However, plasma hyperinsulinemiawas slower and more sustained compared to a similar amount of milkprotein.⁵⁴ Similar to this, postprandialglucose response was not significantly impacted in individuals withan overweight or obese BMI who were provided several different levelsof mycoprotein (at 44, 88, and 132 g) or a protein-matched and isoenergeticamount of chicken in risotto (delivering 25–30 g of total carbohydrate).⁵⁵ In the same trial, insulin sensitivity as measuredby the Matsuda index was significantly greater at the highest levelof mycoprotein intake compared to the same amount of chicken, whilethe insulinogenic index, a measure of beta-cell output, was 18, 15,and 30% lower with low, medium, and high intakes of mycoprotein, respectively,compared to chicken.⁵⁵

Beyond metabolicresponses, mycelium intake suppresses appetiteand energy intake,⁵² with a noted needfor data over prolonged periods of intake.⁵² In this regard, early dietary intervention trials enrolling individualswith slightly elevated cholesterol levels demonstrate the potentialof mycelium intake to lower cholesterol levels. In a 3-week metabolicstudy, diets providing 190 g of mycelium (Fusariumvenenatum) per day significantly lowered LDL cholesterolby a mean difference of 21% for those consuming a diet matched forcalories with the provision of animal protein.⁵⁶ Similar results were observed in a follow-up trial of freeliving adults, who consumed cookies with or without approximately130 g of mycelium equivalents for 8 weeks.⁵⁷ Taken together, these data suggest the potential of mycelium tohave positive impacts on cardiometabolic health; however, these studiesare limited to one mycelial species and will need confirmation asproducts are developed from additional species.⁵⁸ Moreover, for the most part, studies to date have beenunder controlled dietary conditions, with more data needed on thepotential health impacts of currently available commercial productswhen they are incorporated into the daily diet.

The abovementionedlipid-lowering effects may be due to increasedintakes of the mycelium-derived fiber. Improvements in gut healthand lower LDL cholesterol levels have been reported with chitin supplementation.Toward this end, there is considerable interest in fungi-derived chitin-glucancomplexes.^34,59 Animal models to date suggestthat fungal-derived β-glucan may produce similar results astheir cereal-derived counterparts.⁶⁰ Fermentablefibers such as β-glucan can produce short-chain fatty acidsthat suppress 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), therate-limiting enzyme for cholesterol synthesis, along with activatingsterol regulatory element-binding proteins (SREBP)-2 to increase hepaticLDL-receptor gene expression that helps clear cholesterol.⁴⁵ Both mycelium and mycelium-derived fiber increasedpropionate and butyrate production in an in vitro fermentation model.⁶¹ It is important to note that the glycosidicbonds can differ between plant fungi kingdoms, and food processingmay influence any functional effect. Indeed, recent in vitro data suggest that although β-glucans are released to a greaterextent from plants, β-glucan release from mycelium can be enhancedwith cooking.⁶²

The anabolic response,or muscle protein synthesis, is stimulatedwith the rise of plasma essential amino acids, particularly leucine,while muscle protein breakdown (catabolism) is inhibited by hyperinsulinemiain the postprandial period.⁵⁴ Data collectedto date suggest that amino acid bioavailability, and ultimately thestimulation of muscle protein synthesis, is considerably differentwith mycelium intake compared to that of animal-based protein. First,animal proteins such as milk produce a rapid (within 30 min) risein essential amino acids coupled with hyperinsulinemia. In contrast,18 g of protein from Fusarium venenatum produces a similar but more sustained hyperinsulinemia and hyperaminoacidemiacompared to 16 g of milk protein intake.⁵⁴ These observations are potentially functionally significant, asresting and post exercise muscle protein synthesis rates were indeedgreater with mycelium protein intake compared to milk protein intake.⁶³

Mycelium and Environmental Impact

The UNSDG2 aims toend hunger, and achieve food and nutrition securitywithin a sustainable agricultural system by 2030.⁶⁴ Achievement of this goal was already off track prior tothe COVID-19 pandemic that escalated already deteriorating food security,with 12% of the global population estimated as severely food insecurein 2020.⁶⁴ The multidisciplinary approachof UNSDG2 to address worldwide hunger includes the development ofa*gricultural systems that are sustainable and regenerative, in thatthey maintain ecosystems and protects resources as opposed to industrialagricultural systems that lead to environmental degradation, includingair and water pollution, soil depletion, and diminishing of biodiversity.⁶⁵ For protein, forecasts are for a 50% increasein meat production on twice as less arable land by 2050 in order tosupply global nutritional demand.⁶⁶ Tomeet both growing demand and increasingly severe constraints, foodcompanies must drive sustainable innovation to produce large amountsof high-quality, safe protein that preserves limited resources, includingland and water. Moreover, the developed products will need to be accessibleand affordable to the global population, with the goal of decouplingthe cost and ability to eat a healthy diet with persistent high levelsof income inequality.⁶⁴

The termnovel and future foods (NFFs) describes a group of foodsthat utilize nontraditional agricultural practices to produce a sourceof protein that addresses the environmental impacts of food. Ingredientsgrouped under this category include but are not limited to mycelium,insect meal, microalgae, and cell-cultured meat.⁶⁷ In a recent environmental impact model that also optimizedfor nutritional adequacy and feasibility of intake, NNFs yielded substantialreductions in environmental pressures related to land use (LU), wateruse (WU), and global warming potential (GW) when compared to traditionalEuropean dietary patterns.⁶⁸ Environmentalpressures against the traditional European diets, when including insectmeal, cultured meat and milk, algae protein, mycelium, and bacteriaas NFFs, had a predicted mitigation of 87% LU, 84% WU, and 83% GW.Although an optimized vegan diet (VEG) had the largest impact on GW(85% mitigation), NFFs had a greater impact on WU and LU comparedto VEG (83% and 81%, respectively).⁶⁹ However,this study represents the eating habits of 8% of the worldwide population,demonstrating the need for research that includes the impact of NFFswithin other dietary patterns, societies, and ethnicities.⁶⁸

When one aims to reduce the environmentalimpact of a diet, nutritionquality can be a concern, particularly when one food group for another.Shifting diets away from animal-sourced foods (ASFs) to a more plant-baseddiet may provide less stress to environmental resources. However,plant foods can be less favorable in their essential nutrient compositionand bioaccessibility compared to ASFs.^70,71 One optionto overcome this limitation is the incorporation of NFFs into a plant-basedor a limited ASF dietary pattern that still promotes a reduction inenvironmental stress.⁶⁹ In the aforementionedstudy by Mazac et al., replacing ASFs with NFFs in a traditional Europeandietary pattern not only reduced environmental impacts but also metnutrient needs.⁶⁹ This study also indicatesthat the inclusion of smaller amounts of ASFs by optimizing the currentdiet to recommended levels of intake will also lower the environmentalimpact, and minimal inclusion of NFFs will help meet nutrition needs.For the NSFs utilized in this study, mainly insect meal, culturedmilk, microbial protein, and mycelium demonstrated the best nutritioncontent and environmental impact; however, lifecycle analysis assessmentson NFFs are limited at this time and further research is recommended.

As described above, mycelium is a good quality protein, providingessential micronutrients similar to those of meat. Current modelingalso suggests that replacing ASFs with mycelium can have a positiveimpact on the environment.^72,73 Accounting for alloutputs of food production—feed production, manure storage/spreading,enteric methane, and processing and packaging of the finished product—carbonfootprint estimates of mycofoods were 10 and 4 times less comparedto beef or chicken, respectively.⁷² ForWU per gram of protein produced, mycelium was 10 and 3 times lessthan beef and chicken, respectively, along with 10 and 2 times lessLU than beef and chicken, respectively.⁷² More recently, Humpenöder et al. estimated that the per capitasubstitution of 20% of ruminant-derived protein for mycoprotein offsetsfuture LU and CO2 emissions by half by 2050, while also lowering methaneemissions.⁷³ While promising, studies arelimited to one species of mycelium and will need to account for variationsin the technologies utilized to grow mycelial protein and the ingredientsused in their production.

Data to date suggest that the incorporationof mycelium into adietary pattern can lend toward reducing the negative impacts of thefood system on the environment. However, world hunger and food insecurityare inextricably linked between social inequality and access to healthyfood options; therefore, the key to replacing ASFs within the foodsystem will be the availability and affordability of any alternativeprotein source. While healthy and sustainable diets, such as the EAT-Lancethave been proposed, the cost of such a diet is predominately drivenby plant-based foods, with a large percentage of per capita householdincome (up to 89%) needed to afford this dietary pattern in lowerversus higher income countries.⁷⁴ Proteinaffordability is dependent on costs of production; ASF can take severalweeks to years, while the production of plant-sourced proteins throughtraditional agricultural practices can take several months with thepotential for weather-related loss in crop production (Table 6). Given the nutritional valuethat is comparable to that of ASF, but with reduced environmentalimpact, NFFs such as mycelium are an appealing option. As innovationsin this field work toward the production of these products at scaleand at a lower cost, mycelium is appealing as a nutrient dense sourceof protein providing fiber and essential micronutrients that can begrown in a relatively short period. Indeed mycelium research indicatesthat protein production can happen in days instead of months or years;however, the strain, media, and growing conditions all play a rolein predicting the growth rate.⁷⁵

For NFFS such as mycelium to be part of the solutionto solve hungerand food insecurity, there is a need for an investment in resourcesand infrastructure to scale production. These resources include findingways to reduce production costs to make these ingredients affordableto all, in addition to interventions that educate and promote theuse of these ingredients as a staple in the diet.⁶¹ A recent survey of European consumers reports that 56%of respondents had not heard of the term “fungal or mycoprotein”.⁷⁶

Mycelium and Food Technology To Grow Mycofoods

Cultivatingmycelium offers a variety of different technologiesand methods, some having been used for hundreds of years and othershaving been developed in the past century. The two most common myceliumproduction systems are solid-state and submerged fermentation.¹¹ In solid-state fermentation,mycelium is grown on a solid substrate that is usually a food sourcesuch as a grain or a legume, with the mycelium-permeated substrateharvested and used as is or processed further. This method has beencommonly employed to make products such as tempeh.⁷⁷ In submerged fermentation, mycelium is grown primarilyin liquid media with specific nutrients, and often separated by filtrationor by other means prior to use or can undergoes further processing.¹¹ Large-scale submerged fermentation has beenpracticed with mycelium starting with the manufacturing of penicillinand has progressed with developments in fermentation for more advancedproducts such as food additives and enzymes.⁷⁸ Some practices of mycelium submerged fermentation are being usedfor direct human food cultivation.⁷⁹

Solid-state, submerged, or other hybrid methods each have theirown advantages. For instance, while solid-state systems are generallythought to have lower upfront capital investments, the volumetricproductivities and speed of growth in submerged fermentation makesthis to be the mycelium cultivation technology of choice. In orderfor mycelium to become a sustainable human nutrition solution andalleviate global hunger, there is a need for substantial investmentin both solid-state and submerged fermentation to unlock significantlymore mycelium production capacity. With this said, a recent techno-economicanalysis suggests that mycoprotein production can be on par with globallyrelevant sources, such as beef, utilizing existing manufacturing technologies.⁸⁰ Therefore, further advances may enable mycoproteinproduction to surpass beef and approach even cheaper animal-basedcommodity proteins such as poultry. Thus, the opportunity to improveglobal health outcomes through nutrition that achieves key measuresof environmental sustainability via increased production of mycoproteinseems to be based on a firm foundation regarding economics and positivereturns on related investments.

Technology advances have enabledthe production of mycelium intoscalable biomass for use as an alternative sustainable food product.With its quality protein, essential micronutrient profile, and lowerimpacts on land and water, plus reduced greenhouse gas production,incorporation of mycofoods into food systems can aid in the achievementof UNSDG2 goals to end hunger and achieve food and nutrition securitywithin a sustainable and regenerative agricultural system. Althoughpromising, the limited data on the potential health impacts of myceliumintake need to include confirmatory data across mycelial species.This includes data from diverse population groups across the lifespan.In this regard, while initial studies on the anabolic effects of myceliumare promising, there is also a need for data on the ability of myceliumprotein intake in support of human growth. Future considerations alsoinclude adapting production of mycofoods to utilize local resourcesand create education programs that demonstrate how these ingredientscan fit with current cultural practices and meet consumer taste preferences.The ultraprocessed nature of many current plant-based meat mimeticsincluding the addition of sodium, sugar, saturated fat, and additivesto enhance flavor, texture, and color is a concern for both healthprofessionals and consumers.^81,82 The filamentous natureand nutrient density of certain types of mycelium, coupled with thepotential for innovations in fungi flavor, can enable mimetic productdevelopment that requires fewer additives for flavor and texture,with less sodium and low saturated fat. Moreover, mycelium’sunique properties enable its use as an ingredient in other productformulations and represent an opportunity to reduce the need for otheradditives within alternative plant protein-based recipes. Therefore,mycelium represents a significant opportunity to help usher in a newera of product development produced at scale that is considered healthyyet with fewer ingredients and has a sensory profile that is complexwith depth. Once achieved, mycelium will certainly be appealing asan environmentally friendly, nutrient dense protein source that canaid in the reduction of global hunger.

Special Issue

Published as part of Journalof Agricultural and Food Chemistryvirtual special issue “The Future of Agricultureand Food: Sustainable Approaches to Achieve Zero Hunger”.

Author Contributions

All authorsprovided their input on the structure along with editing of the manuscript.R.R.H., J.P.M., and J.S. wrote the initial draft of text. J.P.M. andJ.S. created the tables.

Notes

R.R.H., J.P.M.,C.L.K., and H.H.S. are members of the Scientific Board for Meati Foods,J.S. is a consultant for Meati Foods, and B.S.M. and J.M.W. are bothemployees of Meati Foods.

Notes

The authorsdeclare the following competing financial interest(s): R.R.H., J.P.M.Jr., C.L.K., and H.H.S. are members of the Scientific Board for Emergy,Inc., J.S. is a consultant for Emergy, Inc., B.S.M. and J.M.W. areboth employees of Emergy, Inc. This work was supported in part bythe USDA National Institute of Food and Agriculture Hatch Project#7004508.

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