Edible Fungi and Nutrition

Mushrooms or more generally fungi are neither plant nor animal; they do not synthesize their own food from the energy of the sun and they are not mobile. They are somewhat in between, though closer to animals according to their DNA. Some fungi are edible and some fungi are toxic, like wild plants and to lesser extent animals. However, the toxicity of some wild plants does not militate against the consumption of those that are recognized as edible. Wild mushrooms, on the other hand, are considered by most Americans to be poisonous toadstools. And as if this were not enough, it is generally believed that fungi have no nutritional value. So why would anyone want to eat them? The first reason is a gustatory matter; those who have tried wild fungi find them not only edible, but in some cases quite palatable. The second reason is a nutritional matter, also a reflection of what fungi are made of; they are relatively high in proteins and minerals. The fact is that there are many identifiable wild fungi that merit consideration as viable food alternatives to the plebeian meat and potatoes.

The consumption of edible fungi, though certainly of ancient origin, is not well documented in the historical record. Fungi were first used for medicinal and supernatural uses. The earliest known archaeological depictions of mushroom-like images are rock markings in the Tassilli Caves of the Sahara Desert that are about 7,000 years old. The dancing figures carrying mushroom-shaped objects are postulated to be members of a cult engaging in ritualistic activity. The Neolithic Oetzi was found after some 5,000 years of being frozen in ice in the Italian Alps with several pieces of Birch Polypore (Polyporus betulinus) on a thong around his neck, likely for treatment of intestinal worms and not for nutrition. Ancient Egyptian hieroglyphics suggest that mushrooms were thought to convey immortality, their use therefore restricted to the apotheosized pharaoh and his entourage. In ancient Greece in the city of Eleusis, the Temple of Demeter (the Goddess of Fertility) was the destination for pilgrims including Aristotle, Plato and Sophocles who participated in a yearly ceremony that involved the consumption of ambrosia that is thought to have been made from mushrooms. The resultant “Eleusian Mysteries” forever changed the participants in a manner that was never formally recorded, presumably hallucinogenic in nature. In Russia, eating mushrooms was believed to yield superhuman strength.

It is not known when the consumption of mushrooms (mycophagy) for nutrition began, though speculation is that trial and error during the “hunter-gatherer” epoch of human prehistory eventually led to the identification of those that were edible. However, there was cultural isolation and different regions became either mycophilic or mycophobic according to the ethnomycology theories of Gordon Wasson. The mycophobia of Anglo-Saxons is legendary, the noted herbalist John Gerard writing in his seminal Herball or Generall Historie of Plantes in 1597 that “Most of them do suffocate and strangle the eater.” Venner, a British writer of the 17th Century, was a bit more subtle: “Many phantasticall (sic) people doe greatly delight to eat the earthy excrescences called Mushrums (sic). They are convenient for no season, age, or temperament.” On the contrary, continental Europeans were and are mostly mycophilic, as were the Native Americans. Vincent Marteka in Mushrooms Wild and Edible contends that mushrooms were a staple of Indian cuisine and that the Iroquois “ranked the pleasure of eating wild mushrooms as virtually equal to that of eating meat.” This practice was not transferred to the colonists; the predominant British view that mushrooms were anathema had an overriding effect.

Most fungi have a cell structure that is comprised primarily of chitin just as plants cells are made primarily of cellulose. Chitin is the material that makes up the exoskeletons of insects and crustaceans; the chitinous structure of fungi imparts a texture and firmness that is reminiscent of meat. Chitin is a non-soluble protein that forms an amino polysaccharide molecule that is highly polarized; the distribution of atoms results in high concentrations of positive and negative charge at separated points on the molecule. The positively charged region forms ionic bonds with lipids (fats and similar substances) and bile, the resultant large polymer compound cannot be digested and is excreted from the body. Bile is produced by the liver to aid in the digestive process; its loss must be made up for with new bile, a process that uses cholesterol. Recent clinical studies have found that chitin consumption reduced body fat by 8 percent over a four week period and reduced cholesterol by 32 percent over a five week period. The reduction in fats and cholesterol contributes to cardiac health and thus to longevity. This has long been recognized by the Chinese, who consume mushrooms as a matter of health rather than nutrition.

In addition to chitin, fungi are also an excellent source of protein which is both necessary and sufficient for the growth of human body cells. The protein content of commercially grown edible mushrooms ranges from a high of 35 percent of dry weight (White or Button Mushroom Agaricus bisporus) to a low of 4 percent (Tree-Ear Auricularia auricula). This compares to 25 percent for milk, 39 percent for soybeans, and 13 percent for wheat. Thus mushrooms have more protein than most other foods. Of equal importance to the amount of protein is the quality of the protein, as determined by the relative concentration of the amino acids from which they are constituted. Eight amino acids are considered essential, as they cannot be synthesized by humans from other sources; they must be consumed directly. For a food to be a good source of protein it must have all of the essential amino acids; any deficiency in one results in a reduction in the synthesis of the other seven. This is the fundamental argument of the balanced diet prescription. Consuming foods that are low in the essential amino acid lysine, such as grains like wheat and rice, must be balanced with foods that are high in lysine, like mushrooms. In fact, all eight of the essential amino acids are contained in the most popular commercial mushrooms, including button mushrooms, oyster mushrooms (Pleurotus spp) and Shitakes (Lentinula edodes). In Mushrooms, Cultivation, Nutritional Value, Medicinal Effect, and Environmental Impact, Chang and Miles rank foods according to their essential amino acids according to adult dietary requirements in a quantitative index on a scale of 0 to 100. Mushrooms (98) rank just below meat (100) and milk (99), but well above spinach (76), and tomatoes (44).

Fungi have several other noteworthy nutritional attributes: they are rich in a number of important vitamins and minerals, they have low saturated fat, and they are low in calories. They are the best non-animal source of vitamin D and have relatively high levels of the vitamins niacin, thiamin (B1) and riboflavin (B2). Since one of the functions of fungi in mycorrhizal relationships with plants is the uptake of minerals, their high mineral content is not unexpected. Up to 70 per cent of the ash content of mushrooms consists of minerals, notably potassium. One medium sized Portabella mushroom (also Agaricus bisporus, the button mushroom) has more potassium than a banana, about twice as much as an 8 ounce serving of whole milk. The fat content of commercial mushrooms averages about 4 percent; of this, 72 percent are unsaturated or “good” fat that promotes HDL cholesterol. Animal fat is saturated or “bad” fat that abets LDL cholesterol. The most significant contribution to mushroom unsaturated fat is linolenic acid, one of the Omega 6 essential fatty acids. The caloric impact of mushroom consumption is nominal; 100 grams of mushrooms have about 25 calories.

While nutritional values have only been determined for fungi that are sold commercially, the similarity in the protein and vitamin content of the different cultivated types suggests that wild fungi would have similar levels. There are several readily identifiable wild mushrooms that offer unique flavor in addition to the nutritional attributes delineated above. For example, Chicken-of-the-Woods (Laetiporus sulphureus) is aptly named, as it looks like, cooks like and tastes like chicken; its distinctive sulfur orange coloring is mnemonically represented in the species name sulphureus. Chanterelles are readily identified by their yellow horn-shaped fruiting bodies; the genus name Cantharellus is from the Greek kantharos which means drinking vessel, the flagons of history being made in the shape of a horn. Puffballs range in size from a few centimeters to half a meter in diameter; their smooth, white, rounded exterior facilitates identification. The genus name for large puffballs is Calvatia, from the Latin calva, meaning bald, also an appropriate mnemonic. Small puffballs are in the genus Lycoperdon, which translates somewhat loosely as “wolf passing wind,” a reminder that a puffball must be harvested when young. Otherwise, the soft, creamy interior turns into spores that puff out a hole in the top, the result calling to mind the namesake canine bodily function.

It is a matter of record that the fast-food oriented American cultural diet has resulted in a host of weight and nutrition related maladies, among them diabetes and obesity. This is particularly troubling as it has now become apparent that children are increasingly at risk. The purveyors of children’s programming once addressed the need to promote healthy eating with Popeye, a can of spinach providing him the strength to overcome everything from ogres to crocodiles. It may be time for a fungal variant to stimulate better nutrition; an Italian sailor named Luigi Crimini and his ladylove Portia Bella?