Mushrooms

An often under-appreciated food, mushrooms have been eaten and used as medicine for thousands of years. Traditional and folk medicine practitioners laud the bell-shaped fungi for their healing and cleansing properties. All varieties of mushrooms are low in calories and fat, and contain modest amounts of fiber and various nutrients. Perhaps the more interesting properties of mushrooms are their non-nutritive plant substances—polysaccharides, indoles, polyphenols, and carotenoids in which cell and animal studies have shown antioxidant, anti-inflammatory, and anticancer effects. [1] Mushrooms are also recognized by chefs for their ability to create savory rich flavors called umami, thanks to the presence of an amino acid called glutamate, which is also found in meats, fish, cheeses, and simmering soups.

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. China and the U.S. are among the top five producers of mushrooms worldwide.

Source Of

B vitamins (B2, B3, folate, B5)
Phosphorus
Vitamin D
Selenium
Copper
Potassium

Button mushrooms growing agains a black background

Are mushrooms a good source of vitamin D?

The quick answer is maybe. Because mushrooms sold in supermarkets are usually grown in dark, controlled environments indoors, they will contain little if any vitamin D. But some manufacturers expose mushrooms to ultraviolet (UV) light to increase their content of vitamin D, either by natural sunlight or a UV lamp. A substance in mushrooms called ergosterol then produces vitamin D2 (ergocalciferol), a form found only found in plants. Vitamin D2 is also added to fortified foods and supplements. The other main form of vitamin D is D3 (cholecalciferol) found in animal foods (egg yolks, oily fish) and supplements. Both will effectively raise blood levels of vitamin D, though D3 may be absorbed slightly better and break down more slowly than D2. [2]

The amount of vitamin D mushrooms contain varies widely and depends on how long the mushrooms are exposed to UV light. Estimates show that fresh wild mushrooms like chanterelles and morels can contain up to 1200 IU of vitamin D per 3.5-ounce serving, whereas mushrooms grown in darkened conditions like white button, shiitake, and oyster contain less than 40 IU. [3] However, button mushrooms that are exposed to sunlight can produce up to 400 IU vitamin D per 3.5-ounce serving though the exact amount depends on factors related to their UV exposure such as the time of day, season, latitude, and duration. Mushrooms treated with UV lamps can produce even higher amounts of vitamin D. Even after harvesting, mushrooms can continue to produce vitamin D, whether exposed to UV light from the sun or a lamp.

Dried mushrooms also contain the vitamin. Some estimates show dried mushrooms to contain about 600 IU of vitamin D2 per 3.5 ounces if stored in dark, cool, dry conditions for up to 6 months (the vitamin may start to break down after that time). [3]

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 it is fat-soluble.

Mushrooms and Health

Edible mushrooms like maitake and shiitake have also been used as medicine throughout history. Other mushrooms that are too tough to eat have been used solely for medicinal purposes such as reishi. Plant chemicals and components in mushrooms may exert antioxidant, anti-inflammatory, and anticancer effects, but the exact mechanism is still unclear and an area of active research. [4] Animal and cell studies show that mushrooms can stimulate the activity of immune cells, macrophages, and free radicals that can stop the growth and spread of tumor cells and cause existing tumor cells to die. [5] Various polysaccharides in mushrooms including beta-glucans are believed to exert these cancer-fighting properties. [4,6]

Cognition

Two epidemiological studies found that higher mushroom intake had protective effects on the brain in older adults. [7, 8] Components in mushrooms may prevent the growth of amyloid proteins related to dementia, and act as antioxidants, specifically an amino acid called ergothioneine. A 2019 cross-sectional study of 663 Chinese men and women 60 years of age and older found that those who ate more than 2 servings of mushrooms per week (1 serving = 3/4 cup cooked) compared with those who ate less than 1 serving per week had a reduced risk of mild cognitive impairment (MCI). [9] After adjusting for potential confounders (factors linked with cognitive decline) such as body mass index, cancer, diabetes, heart disease, and dietary intake of meat, vegetables, fruits, and nuts, the group with the higher intake of mushrooms had a 52% lower risk of developing MCI than the low intake group. This cross-sectional study only provided a snapshot of the prevalence of MCI in the participants at one point in time; the authors noted that a direct effect of mushrooms on cognition could not be made by this study. For example, it is possible that people who developed MCI had changed their diet that included less mushrooms. Epidemiological studies following people over time, measuring biomarkers for ergothioneine and other mushrooms substances, and randomized clinical trials that administer ergothioneine or other mushroom phytonutrients will help to shed light on its potential effect on cognition.

Gut health

Mushrooms contain polysaccharides that act as a prebiotic, or food for beneficial gut bacteria. Studies show that these polysaccharides stimulate the growth and survival of beneficial strains like Lactobacillus and Bifidobacterium. They remain undigested and therefore can reach the colon where these bacteria live. [10, 11]

Cardiometabolic diseases and cancer

In two large prospective cohort studies, mushroom consumption was not significantly associated with risk of type 2 diabetes, cardiovascular disease, [12] or cancer. [13] However, low levels of mushroom consumption in the populations may have limited the ability of these studies to detect significant associations. In addition, mushroom consumption was measured once at baseline and consumption patterns may have changed over time. Moreover, different types of mushrooms were not assessed in the Food Frequency Questionnaires.

Purchase

There are thousands of varieties of mushrooms, with different colors, 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.

The common button mushroom (Agaricus bisporus) is the most common in the U.S. It is the mildest-tasting mushroom and can be eaten raw or cooked.

Other types of mushrooms available for sale include:

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

Mushrooms that have been specially treated with UV light may carry a label on the front of the package that says “UV-treated” or “rich in vitamin D,” or display the exact amount of vitamin D they contain.

Black truffle on a cutting board with shavings

Is a truffle a mushroom?

This pricey delicacy typically reserved for restaurant dishes is a type of fungus that is generally 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. Truffles can have a strong flavor and aroma in contrast to the mild earthy or even neutral flavor of mushrooms. Common mushrooms grow year round, while truffles have a short growing season. Some truffles are famously expensive, at thousands of dollars per pound, such as the white truffle that grows about 3 months of the year and is difficult to find underground. Because of their rarity and top price, they may be served sparingly as fresh shavings or infused into sauces, and are often paired with rich cheese and meat dishes.

Storage

Select mushrooms with firm whole caps with an even texture. They should be refrigerated until use, but ideally within one week. Do not wash or clean them until just before using. Storing in a brown paper bag with the top open will help to absorb moisture and keep them from spoiling, as opposed to tight plastic wrapping that traps moisture. Because they are about 80-90% water, mushrooms do not freeze well, becoming mushy when defrosted.

Make

Mushrooms are delicate and should be cleaned gently. Either place them under gentle running water to release any dirt or brush dirt off with a dampened paper towel.

Cooking mushrooms in high-temperature water such as boiling and microwaving may cause its water-soluble nutrients (B vitamins, potassium) to escape in the cooking water. Sautéing quickly over high heat, or simmering over low heat, such as in soups, are ideal cooking methods for preserving nutrients.

Add chopped mushrooms into salads, omelets, scrambled eggs, stir-fries, pasta sauces, chilis, or soups.
Sauté mushrooms in olive oil and add to cooked pasta or whole grains.
Grill large portobello mushroom caps. Remove the stems and gills if desired. Marinate the mushrooms for 10 minutes in a favorite sauce. Grill for about 3 minutes each side until they caramelize.
Mushrooms make a great replacement for meat because of their umami flavor. Replace about a quarter to a half of the meat in a recipe with chopped mushrooms.

a cutting board of chopped ingredients including mushrooms carrots ginger garlic tofu and greens

What is umami?

Umami is considered the fifth basic taste, alongside sweet, sour, salty, and bitter. It is a savory flavor created by glutamates in food, most commonly found in meat, fish, sauces, soups, cooked, tomatoes, cheeses, soy sauce, and fermented foods. Mushrooms are one of the few plants foods that have strong umami flavor. Umami flavors can enhance low-sodium foods, reducing the need for added salt. Monosodium glutamate (MSG) is a processed form of glutamate and flavor enhancer in soups, Chinese foods, and processed meats. Some people describe temporary symptoms after eating foods high in MSG including headaches, flushing, and even chest pain. However, there is no definitive research to show that MSG causes these symptoms. The best treatment if one consistently experiences these symptoms is to avoid foods with MSG.

More recipe ideas and serving suggestions featuring mushrooms:

Did You Know?

Not all mushrooms are edible. Wild mushrooms with white gills or a ring around the stem are considered poisonous. Some other inedible mushrooms look like edible mushrooms, so unless one is trained in recognizing wild mushrooms, it’s best to find your mushrooms at the market!

References

Zhang JJ, Li Y, Zhou T, Xu DP, Zhang P, Li S, Li HB. Bioactivities and health benefits of mushrooms mainly from China. Molecules. 2016 Jul;21(7):938.
Wilson LR, Tripkovic L, Hart KH, Lanham-New SA. Vitamin D deficiency as a public health issue: using vitamin D 2 or vitamin D 3 in future fortification strategies. Proceedings of the Nutrition Society. 2017 Aug;76(3):392-9.
Cardwell G, Bornman JF, James AP, Black LJ. A review of mushrooms as a potential source of dietary vitamin D. Nutrients. 2018 Oct;10(10):1498. *Disclosure: G.C. worked as a consultant to the Australian mushroom industry prior to Sept 2017.
Wasser S. Medicinal mushroom science: Current perspectives, advances, evidences, and challenges. Biomedical journal. 2014 Nov 1;37(6).
Blagodatski A, Yatsunskaya M, Mikhailova V, Tiasto V, Kagansky A, Katanaev VL. Medicinal mushrooms as an attractive new source of natural compounds for future cancer therapy. Oncotarget. 2018 Jun 26;9(49):29259.
Huang X, Nie S. The structure of mushroom polysaccharides and their beneficial role in health. Food & function. 2015;6(10):3205-17.
Nurk E, Refsum H, Drevon CA, Tell GS, Nygaard HA, Engedal K, Smith AD. Cognitive performance among the elderly in relation to the intake of plant foods. The Hordaland Health Study. British journal of nutrition. 2010 Oct;104(8):1190-201.
Zhang S, Tomata Y, Sugiyama K, Sugawara Y, Tsuji I. Mushroom consumption and incident dementia in elderly Japanese: The Ohsaki Cohort 2006 Study. Journal of the American Geriatrics Society. 2017 Jul;65(7):1462-9.
Feng L, Cheah IK, Ng MM, Li J, Chan SM, Lim SL, Mahendran R, Kua EH, Halliwell B. The association between mushroom consumption and mild cognitive impairment: a community-based cross-sectional study in Singapore. Journal of Alzheimer’s Disease. 2019 Jan 1;68(1):197-203.
Nowak R, Nowacka-Jechalke N, Juda M, Malm A. The preliminary study of prebiotic potential of Polish wild mushroom polysaccharides: the stimulation effect on Lactobacillus strains growth. European journal of nutrition. 2018 Jun 1;57(4):1511-21.
Chou WT, Sheih IC, Fang TJ. The applications of polysaccharides from various mushroom wastes as prebiotics in different systems. Journal of food science. 2013 Jul;78(7):M1041-8.
Lee DH, Yang M, Giovannucci EL, Sun Q, Chavarro JE. Mushroom consumption, biomarkers, and risk of cardiovascular disease and type 2 diabetes: a prospective cohort study of US women and men. The American journal of clinical nutrition. 2019 Sep 1;110(3):666-74.
Lee DH, Yang M, Keum N, Giovannucci EL, Sun Q, Chavarro JE. Mushroom consumption and risk of total and site-specific cancer in two large US prospective cohorts. Cancer Prevention Research. 2019 Aug 1;12(8):517-26.

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