Mushrooms are considered as a delicacy with high nutritional and functional values, and sometimes accepted as nutraceutical foods; they are of considerable interest because of their organoleptic merit, medicinal properties, and economic significance. Ancient Greeks believed that mushrooms provided strength for warriors in battles, the Romans perceived them as the “Food of the Gods” and the Chinese culture treasured mushrooms as a health food, an “elixir of life.
The most cultivated mushroom worldwide is Agaricusbisporus, followed by Lentinusedodes, Pleurotus spp., and Flammulinavelutipes. Lentinusedodes is the most studied species and seems to have an antimicrobial action against both gram-positive and gram-negative bacteria. All varieties of mushrooms are low in calories, carbohydrate and fat, and contain modest amounts of proteins and fibre, plus various micronutrients.
Mushrooms are also recognized by chefs for their ability to create a savoury rich flavour called umami (this increases the deliciousness of foods), thanks to the presence of an amino acid called glutamate, which is also used in meats, fish & cheeses dishes, and when simmering soups.
Nutritional profile of mushrooms
One serving of wild edible mushrooms (150 g fresh weight) contains an average of 33 calories, 4.5 g of protein, 167 mg of calcium, 6.3 mg of iron and 2.72 mg of zinc. More importantly it has low levels of fat (0.412 g), carbohydrate and sodium. Because they are about 80-90% water, mushrooms do not freeze well, becoming mushy when defrosted.
Mushrooms are also a source of other micronutrients: some B vitamins (B2, B3, B5 & folate) & Vitamin D and minerals including phosphorus, selenium, copper and potassium.
Are mushrooms a good source of vitamin D?
Mushrooms sold in supermarkets are usually grown in dark, controlled environments indoors for mass production; so they will contain little if any vitamin D. But some manufacturers expose mushrooms to ultraviolet (UV) light; Such practice increases their vitamin D content, either by natural sunlight or a UV lamp. The ergosterol present in mushrooms uses UV light to produce ergocalciferol, a form of vitamin D2 only found in plants.
It is important to note humidity and cooking mushrooms in water do not appear to affect vitamin D content in mushrooms, but cooking them in fat (such as oils) can cause the vitamin to leach out because vitamin D is a fat-soluble vitamin.
Health benefits
Medicinal mushrooms have important health benefits and exhibit a broad spectrum of pharmacological activities, including antiallergic, antibacterial, antifungal, anti-inflammatory, antioxidative, antiviral, cytotoxic, immunomodulating, antidepressive, antihyperlipidemic, antidiabetic, digestive, hepatoprotective, neuroprotective, nephroprotective, osteoprotective, and hypotensive activities. Such activities are attributable to many bioactive metabolites present in the mycelium and in the fruiting body of the mushrooms, whose biological effect varies according to the chemical nature and the fungal specie.
The use of medicinal mushrooms for promoting and maintaining a good health and the treatment of diseases has been around especially in ancient times in Asian regions.
Some studies advocated that greater mushroom intake was associated with certain cognitive performance that suggests regular mushroom consumption may reduce the risk of cognitive decline and aids in the prevention or reversal of Parkinson and Alzheimer.
Also, animal and cell studies showed that mushrooms can stimulate the activity of immune cells, macrophages, and free radicals that can stop the growth and spread of tumor cells and therefore reduce the likelihood of cancer invasion and metastasis due to antitumoral attributes. Various polysaccharides in mushrooms including beta-glucans are believed to exert these cancer-fighting properties.
Mushrooms contain cholesterol lowering agents that may aid in the prevention or treatment of hypertension and high risk of stroke.
Mushrooms also contain polysaccharides that act as prebiotics (food for beneficial gut bacteria). Studies showed that these polysaccharides stimulate the growth and survival of beneficial bacteria strains like Lactobacillus and Bifidobacterium.
Mushrooms have a great nutritional importance because they are quite rich in micronutrients, and proteins with an important amount of essential amino acids, poor in fats and they are cholesterol free. They are very useful for vegetarian and vegan diets because they provide all the essential amino acids for adult requirements; also, mushrooms have a higher protein content than most vegetables. Although considered a vegetable, mushrooms are neither a plant nor animal food. They are a type of fungus that contains a substance called ergosterol, similar in structure to cholesterol in animals. Ergosterol can be transformed into vitamin D with exposure to ultraviolet light. Mushrooms vary in appearance with more than 10,000 known types, but generally they are distinguished by a stem, fleshy rounded cap, and gills underneath the cap.
Mushrooms are an excellent source of a variety of essential dietary micronutrients and contain high amounts of potent antioxidants that can mitigate oxidative stress and improve cognitive health. Also, mushrooms are uniquely high in the potent antioxidant ergothioneine; this sulphur amino acid is obtained exclusively through dietary sources, with mushrooms having the highest concentrations of any other dietary component. Ergothioneine has been reported to have neuroprotective properties.
Some Type of Mushrooms:
Button mushroom (Agaricus bisporus): it is the mildest-tasting mushroom and can be eaten raw or cooked
Chanterelle: the cap is a wavy golden trumpet-like shape
Cremini (baby bella): a young Portobello mushroom that is dark and firm
Enoki: long, thin white stems with small white caps that are eaten raw or cooked
Maitake: a head that resembles flowering leaves
Morel: the cap is a spongy dimpled oblong shape
Oyster: a fan-shaped delicate cap
Porcini: a reddish-brown rounded cap with a thick cylindrical stem
Portobello: a large brown thick cap with rich juicy flavor that work well as a meat substitute
Shiitake: a dark brown umbrella cap with a thin cream-colored stem
Truffle Mushroom: generally reserved for restaurant dishes, this pricy fungus is often classified as a mushroom, though there are slight differences. Truffles grow underground attached to the roots of trees, whereas mushrooms grow above ground. They don’t have a stem, which is distinctive of other mushrooms, and look like a small brown lumpy potato with a strong flavour and aroma.
Cooking mushrooms
Mushrooms are delicate and should be cleaned gently; the best ways to cook mushrooms is sautéing quickly over high heat, or simmering over low heat, such as in soups to preserve its nutrients. Although most edible mushrooms can be eaten raw, they can also be consumed pickled, sauté, purée as a spread on toast or mushroom ketchup. You can also add chopped cooked mushrooms into salads, omelettes, scrambled eggs, stir-fries, sauces or soups.
Mushrooms make a great replacement for meat because of their umami flavour. Replace about a quarter to a half of the meat in a recipe with chopped mushrooms.
Caution:
There are thousands of varieties of mushrooms, with different colours, shapes, and sizes. Because some wild mushrooms can cause stomach upset or allergic reactions, or may even be poisonous, your safest bet is to stick to supermarket varieties and avoid picking and eating raw wild mushrooms on your own.
References
https://www.hsph.harvard.edu/nutritionsource/food-features/mushrooms/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4320875/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7826851/
https://www.sciencedirect.com/science/article/abs/pii/S016503272100759X
https://www.hsph.harvard.edu/nutritionsource/elevate-your-plate/hearty-and-savory-plant-based/