The Mushroom Chronicles
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 poisonous as is the case with wild plants; 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 generally and incongruously considered 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 gustatory; those who have tried wild fungi find them not only edible, but quite palatable. The second reason is nutritional; they are relatively high in proteins and minerals. The fact is that there are many identifiable wild fungi that merit consideration as a viable food alternative.
The consumption of edible fungi, though certainly of ancient origin, is not well documented in the historical record, 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. In that there was cultural isolation during this era, different regions became either mycophilic or mycophobic, as postulated by ethnomycology theory. The mycophobia of Anglo-Saxons is reflected in the writings of the noted herbalist John Gerard in the 1597 Herball or Generall Historie of Plantes that "most of them do suffocate and strangle the eater." On the contrary, continental Europeans were and are mostly mycophilic. Vincent Marteka in Mushrooms Wild and Edible contends that mushrooms were a staple of the Native American diet, noting that the Iroquois "ranked the pleasure of eating wild mushrooms as virtually equal to that of eating meat."
Fungi are an excellent source the protein; commercially grown edible mushrooms have protein compositions that range from a high of 35 percent of dry weight (White or Button Mushroom Agaricus bisporus) to a low of 4 percent (Wood Ear Auricularia auricula). This compares to 25 percent for milk and 13 percent for wheat. Of equal importance to the amount of protein is the quality of the protein, as determined by the relative concentration of its twenty constituent amino acids. Eight of the twenty are considered essential for adults since they cannot be synthesized from other sources and must therefore be consumed directly from food. A good source of protein must have all of the eight essential amino acids or it must be part of a balanced diet that does; any deficiency in one results in a reduction in the synthesis of the other seven. The most popular commercial mushrooms contain all of these essential amino acids. In "Mushrooms," Chang and Miles rank foods according to their essential amino acids in relation to adult dietary requirements in a quantitative index on a scale of 0 to 100. Mushrooms (98) rank just below meat (100) and well above spinach (76).
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. Fungi are the best non-animal source of vitamin D and have high levels of the vitamins niacin, thiamin (B1) and riboflavin (B2). Up to 70 per cent of the ash content of mushrooms consists of minerals, notably Potassium. One medium sized Portabella mushroom (a type of Agaricus bisporus) has more potassium than a banana and about twice as much as an 8 ounce serving of whole milk. Since one of the functions of fungi in mycorrhizal relationships with plants is the uptake of minerals, their high mineral content is not unexpected. The fat content of commercial mushrooms averages about 4 percent; of this, 72 percent is unsaturated fat that promotes HDL cholesterol as contrasted to animal fat that is saturated and 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.
Fungi have a cell structure that is comprised primarily of chitin just as plant cells are made primarily of cellulose. Chitin is better known as the material that makes up the exoskeletons of insects and crustaceans; the chitinous structure gives fungi the definitive texture and firmness distinct from vegetables and reminiscent of meat. Recent clinical studies have found that chitin consumption reduced body fat by 8 percent and cholesterol by 32 percent over a month long trial. It is hypothesized that this is because chitin 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 charged regions bond with fats and bile to create a large indigestible polymer compound that is excreted from the body. The liver makes up for the loss of bile with new bile, reducing cholesterol in the process. The reduction in fats and cholesterol contributes to cardiac health and thus to longevity, a fact long recognized by the Chinese, who have consumed mushrooms as a matter of health rather than nutrition for millennia.
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 or Sulfur Shelf (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 apparently calling to mind wolf wind.
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. Protein rich, low calorie, low fat and high fiber (chitin) fungi offer an attractive alternative. Popeye popularized spinach; perhaps "Morel Mary" could do the same for mushrooms.