The Kingdom of Plantae is considered the main source of human food, and includes several edible and medicinal plants, whereas mushrooms belong to the Kingdom of fungi. Higher plants and macro-fungi (mushrooms) are important species, which have many common attributes (e.g., the nutritional and medicinal ones), although they have many differences. Higher plants can form their own food (which contains chlorophyll as autotrophic) from sunlight, water, and CO2, whereas mushrooms as saprophytes can biodegrade dead organic matter by extracting enzymes. Fungi are considered, in general, decomposers, pathogens, parasites, or mutualists. There are a lot of similar characteristics between mushrooms and higher plants, but there are also many differences among them, especially from the human health point of view.
1. Introduction
A great challenge faces humanity in producing edible plants, which should contain enough amounts of mineral nutrients, and are required for human nutrition
[1]. Although both plants and humans require, in general, the same mineral elements for their healthy growth and development, the ideal future crops for human nutrition should not include toxic elements in the edible parts
[2][3]. Mineral elements in the soil are taken up by the plant roots and transported to the edible parts for human consumption through various different transporters. Therefore, several studies focus on the edible plants from different points of view for human health, including (
i) studies of plant functional traits for human health, especially unconventional edible plants
[4][5][6]; (
ii) producing biofortified plants with a focus on the malnutrition/medicinal attributes
[7][8][9][10][11][12], (
iii) nutritional aspects of plant-based diets for human diseases
[13][14][15], (
iv) studies of plant secondary metabolites and their extraction as bioactive compounds
[16][17], (
v) anti-nutrients of major plant-based foods
[18], (
vi) food security and plant nutrition under problems of climate change
[19], and (
vii) using mushrooms as bioindicators for pollution and its risks to health
[20].
The production of enough food for the global population needs more efforts to exploit every inch to cultivate and produce foods, as well as energy at the same time, because food and energy are essential components for human life and sustainable development
[21]. The production of food and energy gives rise to competition for cultivated soil. The arable land that is already used for the cultivation of foods should be increased for more food production, without any deducted lands for energy production. There is a difficult equation concerning the energy–food nexus, which should be solved as reported in many studies on the energy–food nexus from different points of view, such as the production of biofuel based on the water–food–energy nexus
[22], rice production and its nexus of food–energy–emissions
[23], the scarcity risk of the energy–food nexus
[21], and sustainable dairy farming under the security of energy, food, and water
[24]. New non-exploited areas such as polluted or marginal soils for energy production through soil restoration are considered sustainable solutions for producing energy
[25].
Higher plants and macro-fungi (mushrooms) are important species, which have many common attributes (e.g., the nutritional and medicinal ones), although they have many differences. Higher plants can form their own food (which contains chlorophyll as autotrophic) from sunlight, water, and CO
2, whereas mushrooms as saprophytes can biodegrade dead organic matter by extracting enzymes
[26]. Fungi are considered, in general, decomposers, pathogens, parasites, or mutualists
[27].
2. Plant and Human Nutrition for Sustainability
Nutrition in plants and human presents many similarities and differences. It is the process of obtaining or providing the organism with food necessary for its growth and health. This nutrition has a strong link to Sustainable Development Goals as a part of the global public agenda, which can contribute to the structuring of global sciences and research
[28]. Not surprisingly, considering the lessons learned from Covid-19, the required scientific studies should focus on the area of sustainability and human health
[28][29]. Richardson and Lovegrove
[29] reported on the nutritional status of some micronutrients (Cu, Fe, Se, and Zn, and vitamin D, A, B vitamins, and vitamin C) and their possible and modifiable risk factor for COVID-19, which support the normal functions of the human immune system. They confirmed that avoiding deficiencies in the intakes of these micronutrients in patients could strengthen their resilience to the COVID-19 pandemic. Finally, a number of important nutrients need to be considered that could be found in vegetables, fruits, or edible plants (
Figure 1).
Figure 1. The problem of producing enough foods needs fertile soil, which supplies the cultivated plants with proper nutrients. Shown are photos of some edible plants, which can supply human with needed nutrients for human health. The photos in details from the upper photos (tomato and pepper), in the middle (maize and strawberry), and in the lower photos of Jerusalem artichoke tubers and fruits of color pepper, which show a good nutritional status as an important source for human health. All photos by El-Ramady.
3. Phytomedicine and Human Health
The science of producing medicines from herbs or medicinal plants could be defined as phytomedicine. The historical background of this science may date back to early in human evolution or several thousand years ago, when humans isolated, extracted and purified many drugs from medicinal plants in ancient times for human health
[30]. Phytomedicine also involves all clinical, pharmacokinetic, pharmacological, and toxicity-based studies of medicinal plants besides the exploring of different mechanisms of herb extracts
[31]. Medicinal plants are in a continuous process of exploration, resulting in the unearthing of novel plant-based pharmaceuticals to understand the molecular mechanisms of conventional medication and its active ingredients, which may help the renovation of plant-derived medications and detection of novel phyto-agents
[31]. Phytomedicine may include several issues such as using medicinal plants as wound healing agents
[32][33], natural anti-microbials from plants
[34], herbal therapy or remedies
[35], herbal cosmeticology
[36], phytopharmaceuticals
[37][38], phyto-pharmacology
[39] using the herbal bioactivities in drug delivery systems like the ocular
[40], pulmonary
[41], transdermal
[42], and vaginal and rectal drug delivery systems
[43]. Therefore, it is very important to know exactly what people eat to stay healthy for a long time as conveyed by the term “nutraceuticals”
[44]. This term was coined by Stephen De-Felice, who referred to pharmaceuticals and nutrients. There are many different kinds of nutraceuticals, such as dietary supplements, functional foods, dietary fibers, medical foods, prebiotics, and probiotics. Nutraceuticals can improve human health through enhancing the absorption of nutrients, supporting the micro-flora of the gastrointestinal system, and increasing detoxification. Nutraceuticals may have some limitations, including their slow mode of action and lack of strict control over the quality and concentration of ingredients
[44].
4. Higher Plants and Mushrooms: A General Comparison
Higher plants have many similarities and differences to macro-fungi (mushrooms) as presented in Figure 2A,B. Both higher plants and mushrooms are living organisms belonging to one domain (Eukarya) and are considered, in general, vegetarian as well as both of them possessing distinguishing attributes for human health. High plants are located in the Kingdom of Plantae, but mushrooms are in the Kingdom of Fungi. They can also be used as edible sources for medicinal activities.
Figure 2. (A) This is the first part of a comparison between higher plants and mushrooms from different points of view, such as taxonomy (using Jerusalem artichoke as an example of a higher plant and champignon as a mushroom), structure, nutrition, reproduction and growth. (B) This is the second part of a comparison between higher plants and mushrooms including more different points of view such as the pigments, cultivation and their nutritional/medicinal attributes.
There are also many differences between them, especially the nutrition mode, which depends on their content of pigments or chlorophyll, as well as the reproduction method, and the main structure of each one. From this point, mushrooms are fungi organisms that have no chlorophyll; thus, they cannot form their own food, but they are saprophytes (can release some enzymes to biodegrade organic matters and convert them into simple compounds to obtain their necessary foods). The main method for reproduction of mushrooms is by spores, and not all mushrooms can be cultivated like plants
[26][45][46]. Some species of both higher plants and mushrooms have nutritional and medicinal attributes, and are called medicinal plants or mushrooms. There are several kinds of mushrooms, which can in general be categorized into edible, medicinal and poisonous mushrooms, as reported by El-Ramady et al.
[47]. More dimensions for the sustainable applications of mushrooms could be found in Elsakhawy et al.
[48] and El-Ramady et al.
[49] whereas the sustainable production of medicinal plants is a great challenge, especially under the adverse conditions reported in detail by Aftab
[50].
5. Unconventional Foods of Plants and Mushrooms
There are several classifications of plants, which depend on a specific categories such as higher and lower plants based on the existence of flowers or vascular system; common and unconventional edible plants; traditional and modern wild edible plants
[51]; cultivated and wild edible plants
[52], and conventional and unconventional food plants
[53]. The common attributes that can be existed in edible mushrooms and edible plants are being consumable foods and having a nutritional value, such as desirable content of proteins, carbohydrates, or vitamins. Many studies on unconventional foods derived from plants or mushrooms have been published in different locations all over the world for plants
[53][54][55] or mushrooms
[56][57]. Increasing attention has been noticed to this group of underutilized plants, which have many different terms such as unconventional vegetables or traditional vegetables, alternative food plants, famine foods, wild edible plants, and plants for the future
[54][58]. Therefore, there is an urgent need for unconventional medicinal/food plants with consideration of their potential under the initiative of “from flask to patient” and “from field to fork”
[59].
There are many innovative technologies in food production acting as food frontiers, which can achieve eco-sustainability and the security of global food, seeking for more sustainable future. These food frontiers may include controlled-environment agriculture
[60], climate-driven northern agricultural expansion
[61], cellular agriculture
[62], entomophagy
[63] and seaweed aquaculture
[3][64][65]. Based on the single-cell protein in macro-fungi/mushrooms, many possibilities exist to use agricultural residues and wastes because of their fast growth, high cell densities, long history of use, and simple reactor design. However, they have many challenges, including a need for non-food carbon substrates and a possibility for existing mycotoxins
[62]. The main target that attracts several scientists all over the world is how to find “plant protein-based meat and dairy analogues” especially under climate change
[66][67][68], and single-cell proteins derived from mushrooms as reported by Stephan et al.
[69] in
Table 1. Mushrooms contain many bioactive compounds (e.g., phenolics, polysaccharides, polyketides, steroids, triterpenoids, etc.), are considered nutraceuticals, a vegan protein source (up to 45%), and food flavor agents for the food industry
[70]. The protein content in mushrooms depends mainly on the mushroom species and the edible part of the mushroom (i.e., fruiting body and mycelium), where the most common mushrooms
Pleurotus ostreatus, Agaricus biosporus, and
Lentinus edodes (Berg) have protein (%) in fruiting body and mycelium as follows (36 and 25.70), (45.9 and 47.1), and (23.5 and 17%), respectively in fruiting body and mycelium
[70].
Table 1. Some examples of plant protein-based meat and dairy analogues and their sources.
On the other hand, many plants are considered plant-based foods that are rich in their content of proteins such as legumes, grains (mainly quinoa), nuts, and certain fruits like apricots, avocados, guavas, peaches, and raspberries
[67]. Quinoa, as a pseudo-cereal crop, is considered important protein crop because of its amino acidic profile, gluten-free, high antioxidant content, bioactive properties, high nutrient content (i.e., Ca, P, B, Fe, K, Mg) and vitamins like B1, B2, B3, B6, and E
[67]. Quinoa can also be used as an alternative for vegan diets, including in quinoa-based gels
[80][81], quinoa protein isolates
[82][83], to produce high-quality protein and low-cost enriched pasta
[84], and quinoa protein fortification
[85].