Oyster Mushroom (Pleurotus ostreatus)
Other Names
Hiratake (Japanese), ping gu (Chinese), tomogitake.
Natural Habitat
Temperate and tropical forests. Widely distributed in North America, Asia, Europe, and other continents.
Key Components
Polysaccharides, beta-glucans, lovastatin.
Overview
A choice culinary mushroom, oyster mushroom has a fleshy white or gray semicircular cap that resembles an oyster shell. Growing in layered clusters on deciduous trees, it is found throughout North America, Europe, and Asia1.
Oyster mushroom has an excellent nutritional profile. It is high in protein, with a near complete amino acid profile comparable to protein from animal sources. It also contains high levels of essential fatty acids, minerals, B vitamins, fiber, iron, and folic acid, and may be helpful in combating anemia2,3. Known for its cholesterol-lowering effects, oyster mushroom contains up to 2.8% lovastatin, the natural compound on which the cholesterol-lowering medication by the same name is based4. Oyster mushroom has been shown to reduce blood pressure, modulate immune response, inhibit tumor growth, help prevent blood clots, and have antibacterial properties5. The mushroom exhibits significant anti-aging effects, with a demonstrated ability to raise antioxidants to youth levels in murine models of aging.
In clinical studies with diabetic patients, oyster mushroom significantly lowered total cholesterol, triglycerides, blood glucose and blood pressure. When the mushroom was withdrawn the levels rose again, and resuming intake brought them back down6.
Numerous animal studies have also demonstrated oyster mushroom’s cholesterol-lowering ability7. The addition of oyster mushroom to the diet of Syrian hamsters completely eliminated the increase in liver cholesterol and triglycerides caused by a chronic alcohol intake, bringing levels below those of the control group given a normal diet8.
Oyster mushroom has demonstrated anti-cancer impact, inducing rapid apoptosis (cancer cell death) in studies9. Oyster mushroom prevented the development of bladder cancer and maintained nearly normal levels of immune activity in mice exposed to a carcinogen, compared to a control group not given the mushroom10. In vitro it showed a 76% inhibition rate against tumors11.
The marked antioxidant activity of oyster mushroom has been shown to alleviate liver toxicity, returning levels of key antioxidant enzymes such as glutathione back to near normal after carcinogen exposure12.
The antioxidant effects of oyster mushroom would seem to make it an excellent supplement for general health and anti-aging13. Studies have found that oyster mushroom improved antioxidant status during aging. Whereas the brains, hearts, and organs of old rats had diminished levels of glutathione, vitamins C and E compared to young ones, administration of oyster mushroom raised levels to where they did not differ significantly from their younger counterparts14.
Oyster mushroom may protect against age-related disorders involving free radicals, and was found to enhance gene expression of the important anti-oxidant enzyme catalase, which decreases free-radical induced protein oxidation15.
Oyster mushroom has significant antibacterial properties. One study testing its in vitro antimicrobial activity found various forms of the extract had 50%, 87%, and 57.5% inhibition against candida, E. coli, and B. subtilis, respectively16.
1 Hobbs, Christopher. Medicinal mushrooms: an exploration of tradition, healing & culture. No. Ed. 2. Botanica Press, 1995. 147.
2 Hobbs, Christopher. Medicinal mushrooms: an exploration of tradition, healing & culture. No. Ed. 2. Botanica Press, 1995. 147.
3 Bano, Zakia, S. Rajarathnam, and Keith H. Steinkraus. Pleurotus mushrooms. Part II. Chemical composition, nutritional value, post-harvest physiology, preservation, and role as human food. Critical Reviews in Food Science & Nutrition 27.2 (1988): 87-158.
4 Alarcon, Julio, et al. Production and purification of statins from Pleurotus ostreatus (Basidiomycetes) strains. Zeitschrift fur Naturforschung C 58.1/2 (2003): 62-64.
5 Gunde-Cimerman, Nina, and Ana Plemenitas. Hypocholesterolemic activity of the genus pleurotus (Jacq.: Fr.) P. Kumm.(Agaricales s. I., Basidiomycetes). International Journal of Medicinal Mushrooms 3.4 (2001).
6 Oyster mushroom reduced blood glucose and cholesterol in diabetic subjects.
7 Bobek, P., et al. Cholesterol-lowering effect of the mushroom Pleurotus ostreatus in hereditary hypercholesterolemic rats. Annals of Nutrition and Metabolism 35.4 (2008): 191-195.
8 Bobek, P., et al. Effect of oyster fungus (Pleurotus ostreatus) on serum and liver lipids of Syrian hamsters with a chronic alcohol intake. Physiological Research/Academia Scientiarum Bohemoslovaca 40.3 (1991): 327.
9 Gu, Yu-Huan, and Gowsala Sivam. Cytotoxic effect of oyster mushroom Pleurotus ostreatus on human androgen-independent prostate cancer PC-3 cells. Journal of Medicinal Food 9.2 (2006): 196-204.
10 Kurashige, S., Y. Akuzawa, and F. Endo. Effects of Lentinus edodes, Grifola frondosa and Pleurotus ostreatus administration on cancer outbreak, and activities of macrophages and lymphocytes in mice treated with a carcinogen, N-butyl-N-butanolnitrosoamine. Immunopharmacology and Immunotoxicology 19.2 (1997): 175-183.
11 Wolff, E. R. S., et al. Antimicrobial and antineoplasic activity of Pleurotus ostreatus. Applied Biochemistry and Biotechnology 151.2-3 (2008): 402-412.
12 Jayakumar, T., E. Ramesh, and P. Geraldine. Antioxidant activity of the oyster mushroom, Pleurotus ostreatus, on CCl4-induced liver injury in rats. Food and Chemical Toxicology 44.12 (2006): 1989-1996.
13 Powell, M., 2010. Medicinal Mushrooms: A Clinical Guide, Mycology Press, East Sussex U.K. 71.
14 Jayakumar, Thanasekaran, Philip Aloysius Thomas, and Pitchairaj Geraldine. “Protective effect of an extract of the oyster mushroom,< i> Pleurotus ostreatus</i>, on antioxidants of major organs of aged rats.” Experimental gerontology 42.3 (2007): 183-191.
15 Jayakumar, Thanasekaran, et al. An extract of the oyster mushroom, Pleurotus ostreatus, increases catalase gene expression and reduces protein oxidation during aging in rats. 中西醫結合學報 8.8 (2010): 774-780.
16 Wolff, E. R. S., et al. Antimicrobial and antineoplasic activity of Pleurotus ostreatus. Applied Biochemistry and Biotechnology 151.2-3 (2008): 402-412.
Research
1. Cholesterol-lowering effect of the mushroom Pleurotus ostreatus in hereditary hypercholesterolemic rats
Bobek, P., et al. Annals of Nutrition and Metabolism. 1991. 35 (4), 191-5.
In this in vivo rat study, researchers examined the effects of oyster mushrooms on cholesterol metabolism. The rats had a genetic sensitivity to dietary cholesterol. They were given a diet containing 4% oyster mushroom for several weeks. The rats showed no increases in blood levels of cholesterol at the four-week mark. At the seven-week mark, cholesterol had decreased in the rats eating the mushroom diet by 40% compared with the control group of rats who received no mushroom. Researchers determined that the lowered cholesterol was associated with lower levels of LDL and VLDL cholesterol.
2. Effect of oyster fungus (Pleurotus ostreatus) on serum and liver lipids of Syrian hamsters with a chronic alcohol intake
Bobek, P., et al. Physiological Research. 1991. 40 (3), 327-332.
Researchers examined the effects of oyster mushroom on cholesterol in rats. One group of rats consumed chronic amounts of alcohol for two months. The group of control rats consumed no alcohol. By the end of the test period, the former group had increases in blood cholesterol, triglycerides, and phospholipid concentration. In addition, VLDL cholesterol increased while HDL cholesterol decreased. When oyster mushroom was given along with the alcohol, however, cholesterol levels fell below those of control rats. Triglycerides and VLDL cholesterol decreased by 30%; HDL cholesterol remained the same. Researchers attribute the higher cholesterol and triglyceride levels to the alcohol and the subsequent decreases to the mushroom intervention.
3. Dose- and time-dependent hypocholesterolemic effect of oyster mushroom (Pleurotus ostreatus) in rats
Bobek, P., et al. Nutrition. 1998. 14 (3), 282-286.
The effects of varying doses and treatment duration of oyster mushroom on cholesterol were studied in rats. Rats were divided into groups and given a cholesterol-containing diet and one of three dosage levels of oyster mushroom for a period of 8 to 28 weeks. The lowest dose of mushroom had no effect on cholesterol levels; the medium and high doses reduced cholesterol levels in a dose-dependent manner. The highest dose of mushroom reduced blood cholesterol by up to 46% and liver cholesterol by up to 30%. Higher doses of mushroom induced other beneficial changes in the liver as well.
4. Hypocholesterolemic activity of the genus Pleurotus (Jacq.: Fr.) P. Kumm. (Agaricales s. I., Basidiomycetes)
Gunde-Cimerman, N., and Plemenitas, A. International Journal of Medicinal Mushrooms. 2001. 3 (4).
In this review article, the authors discuss the many benefits of Pleurotus (oyster mushroom). This mushroom helps boost immune activity, lowers blood sugar levels, has an anti-clotting effect, suppresses tumor growth, inhibits inflammation, decreases blood pressure, and has anti-microbial effects. It also helps to reduce blood and liver cholesterol levels, especially LDL cholesterol.
5. Dietary mushroom (Pleurotus ostreatus) ameliorates atherogenic lipid in hypercholesterolaemic rats
Hossain, S., et al. Clinical and Experimental Pharmacology and Physiology. 2003. 30 (7), 470-475.
Researchers studied the effects of oyster mushroom on cholesterol and on plasma levels of antioxidants. This series of in vivo experiments involved two types of rats: those with high cholesterol, and those with normal cholesterol levels. The high cholesterol rats given powdered oyster mushroom experienced significantly decreased triglyceride, LDL, and total cholesterol levels while HDL (“good”) cholesterol levels increased. Plasma antioxidant levels were also reduced. Rats with normal cholesterol who were given the oyster mushroom experienced no significant changes.
6. Evidence for the anti-hyperlipidaemic activity of the edible fungus Pleurotus ostreatus
Opletal, L., et al. British Journal of Biomedical Science. 1997. 54 (4), 240-243.
Researchers looked at the effects of oyster mushroom on cholesterol in this in vivo experiment. Two types of rats were used: one group had normal cholesterol, while the other had hereditary high cholesterol. Researchers gave the rats either dried oyster mushroom or an ethanol extract of oyster mushroom. The ethanol extract had a limited effect. The dried mushroom had a significant effect, more than doubling plasma triglyceride levels in both types of rats. The dried oyster mushroom also decreased cholesterol in the liver of both types of rats. Both the extract and the dried mushroom improved phospholipid to cholesterol ratios in both types of rats. Researchers conclude that oyster mushroom may help prevent or treat atherosclerosis.
7. Oyster mushroom reduced blood glucose and cholesterol in diabetic subjects
Khatun, K., et al. Mymensingh Medical Journal. 2007. 16 (1), 94-99.
In this clinical trial, researchers looked at the effects of oyster mushroom on 89 diabetic patients. Regular testing and evaluation throughout the 24-day test period revealed beneficial results. The mushroom significantly lowered blood pressure, blood sugar, total cholesterol, and triglycerides. Starting and stopping the mushroom treatment during this period confirmed the results. No toxic effects were observed.
8. Cytotoxic effect of oyster mushroom Pleurotus ostreatus on human androgen-independent prostate cancer PC-3 cells
Gu, Y.H., and Sivam, G. Journal of Medicinal Food. 2006. 9 (2), 196-204.
Researchers studied the effects of 23 different mushrooms and mushroom polysaccharides on cancer cells in vitro. They identified an extract of oyster mushroom as the most effective. When PC-3 cancer cells were treated with the water-soluble oyster mushroom extract, cell death occurred within two hours. The extract also greatly inhibited the cells’ tumor colony forming ability. The mushroom extract worked in a dose-dependent manner. Further investigation suggested that the active compounds in the extract are proteins or polypeptides.
9. Effects of Lentinus edodes, Grifola frondosa and Pleurotus ostreatus administration on cancer outbreak, and activities of macrophages and lymphocytes in mice treated with a carcinogen, N-butyl-N-butanolnitrosoamine
Kurashige, S., et al. Immunopharmacology and Immunotoxicology. 1997. 19 (2), 175-183.
In this in vivo study, researchers looked at the effects of three mushrooms on cancer in mice. The mice were divided into four groups, and a carcinogenic chemical was given to all of them to induce cancer. Three different types of mushrooms, including oyster mushroom, were each given to one group of mice. The fourth group of mice, the control group, received no mushroom. 35% of the mice given oyster mushroom remained cancer free, as did 53 to 65% of the other mushroom mice. 100% of the control mice developed cancer. Mice given the carcinogen alone had suppressed macrophage and NK cell activity. Mice given the mushrooms, including oyster mushroom, had greater macrophage and NK cell activity. Lymphocytes from the mushroom-eating mice were more cytotoxic against cancer cells as well.
10. Antioxidant activity of the oyster mushroom, Pleurotus ostreatus, on CCl(4)-induced liver injury in rats
Jayakumar, T., et al. Food and Chemical Toxicology. 2006. 44 (12), 1989-1996.
In this in vivo experiment, researchers studied the effects of oyster mushroom on liver damage in rats. Liver damage was induced and the damage was confirmed by measuring typical blood markers such as SGOT, SGPT, SALP, and others. The induced liver damage also decreased the activity of antioxidant enzymes. The rats were then given oyster mushroom; antioxidant levels increased significantly and blood markers of liver health returned to healthier levels. Researchers conclude that oyster mushroom helps protect the liver in rats.
11. Protective effect of an extract of the oyster mushroom, Pleurotus ostreatus, on antioxidants of major organs of aged rats
Jayakumar, T., et al. Experimental Gerontology. 2007. 42 (3), 183-191.
In this in vivo study, researchers looked at the effects of oyster mushroom on the antioxidant levels of older rats. Researchers compared levels of antioxidants in the organs of older and younger rats; the younger rat organs contained significantly greater amounts of glutathione, vitamins C and E, superoxide dismutase, and other antioxidant enzymes. The older rats were given oyster mushroom extract for a period of time and their antioxidant status was again measured. Results indicated that treatment with oyster mushroom increased antioxidant levels in older rats to levels similar to those of younger rats. Researchers believe that mushroom extract may be beneficial in boosting antioxidant activity in older individuals, conferring numerous health benefits.
12. An extract of the oyster mushroom, Pleurotus ostreatus, increases catalase gene expression and reduces protein oxidation during aging in rats
Jayakumar, T., et al. Zhong Xi Yi Jie He Xue Bao. 2010. 8 (8), 774-780.
In this study, researchers compared catalase gene expression in three groups of rats: young rats, older rats, and older rats given oyster mushroom extract for 30 days. The rats were euthanized, and their livers and kidneys were examined. The organs of those given oyster mushroom showed greater CAT (catalase, an antioxidant enzyme) gene transcription compared to the older rats not given the mushroom. The treated rats also had lower protein carbonyl levels in their organs. Researchers conclude that oyster mushroom boosts CAT activity and may help protect against free radical damage associated with aging.
13. Effect of the oyster fungus on glycaemia and cholesterolaemia in rats with insulin-dependent diabetes
Chorvathova, V., et al. Physiological Research. 1993. 42 (3), 175-179.
In this in vivo study involving rats with insulin-dependent diabetes, researchers looked at the effects of oyster mushroom on blood sugar and cholesterol levels. The rats were fed a diet containing 4% oyster mushroom and 0.1% cholesterol. Results were measured at the two-month mark. The diabetic rats given mushroom had lower fasting and post-meal blood sugar levels; insulin levels did not change. Blood cholesterol levels improved, with LDL and VLDL levels falling significantly. Cholesterol levels in the liver also declined. Triglycerides were unaffected.
14. Antimicrobial and antineoplasic activity of Pleurotus ostreatus
Wolff, E.R., et al. Applied Biochemistry and Biotechnology. 2008. 151 (2-3).
In this series of in vitro experiments, researchers looked at the antimicrobial and anti-cancer effects of oyster mushroom (Pleurotus ostreatus). Researchers produced five different preparations from fresh and dehydrated parts of the oyster mushroom. They tested each preparation against various microbes. Three of them were over 50% effective against Candida albicans; one was effective against E. coli and another effective against B. subtilis. When tested for anti-tumor activity, all the preparations were approximately 70% effective against tumor cell development. Researchers also prepared a cultured broth of oyster mushroom and tested it for anti-tumoric properties; it was 76% effective.
15. The inhibition of human tumor cell proliferation by RNase Po1, a member of the RNase T1 family, from Pleurotus ostreatus
Kobayash, H., et al. Bioscience, Biotechnology, and Biochemistry. 2013. 77 (7), 1486-1491.
Researchers examined the effects of a compound, RNase Po1 from oyster mushroom, on malignant tumor cells. Testing revealed that the compound suppressed multiplication of human neuroblastoma and leukemia cells. Researchers identified distinct structural changes in the leukemia cells due to treatment with the mushroom compound, which acted in a dose dependent manner. Researchers conclude that the compound stimulates cell death in cancer tumor cells.
16. Preliminary results on antigenotoxic effects of dried mycelia of two medicinal mushrooms in Drosophila melanogaster somatic mutation and recombination test
Kylyc, A., and Yesilada, E. International Journal of Medicinal Mushrooms. 2013. 15 (4), 415-421.
Dried mycelia of two mushrooms, Trametes versicolor and Pleurotus ostreatus, were studied for their ability to protect against genetic damage. Mitomycin C was used to induce cell mutation. Both species of mushrooms demonstrated antigenotoxic properties by protecting the cells from the mutations.
17. Anti-allergic effect of pleuran (beta glucan from Pleurotus ostreatus) in children with recurrent respiratory tract infections
Jesenak, M., et al. Phytotherapy Research. 2013.
doi: 10.1002/ptr.5020.
In this double-blind, placebo-controlled study, researchers looked at the effects of pleuran on allergic response. Pleuran, a beta glucan isolated from oyster mushroom, is a recognized immune modulator. Study participants were children with recurrent respiratory tract infections. When given pleuran, the children displayed more stable blood levels of IgE (a marker for allergic activity) and a reduction in peripheral blood eosinophilia (increased levels are an indicator of allergic response). Researchers believe pleuran has potential benefits in the treatment of allergies.
18. Enhanced antiproliferative effects of aqueous extracts of some medicinal mushrooms on colon cancer cells
Arora, S., et al. International Journal of Medicinal Mushrooms. 2103. 15 (3), 301-314.
The effects of various mushroom extracts from three mushrooms were evaluated on cancer cells. An aqueous extract of Pleurotus ostreatus (oyster mushroom) and an ethanol extract of Macrolepiota procera were the most effective against breast, kidney, and especially colon cancer cells. The extracts inhibited cancer cell proliferation and viability.
19. Antihypercholesterolemic and antioxidative effects of an extract of the oyster mushroom, Pleurotus ostreatus, and its major constituent, chrysin, in Triton WR-1339-induced hypercholesterolemic rats
Anandhi, R., et al. Journal of Physiology and Biochemistry. 2013. 69 (2), 313-323.
In this in vivo study involving rats, researchers looked at the effects of oyster mushroom extract on cholesterol reduction and antioxidant activity. One particular compound in the mushroom, chrysin, was also studied. Rats with high cholesterol were given bodyweight-adjusted doses of mushroom extract and chrysin for seven days. Blood sugar levels, cholesterol, and liver enzymes decreased significantly while antioxidant markers increased. The rats receiving the chrysin, as opposed to the extract, realized greater benefits, almost as much benefit as is conferred by the cholesterol drug lovastatin.
20. Pleuran (beta glucan from Pleurotus ostreatus): an effective nutritional supplement against upper respiratory tract infections?
Majtan, J. Medicine and Sport Science. 2012. 59, 57-61.
In this review, researchers looked at the effects of beta glucan from oyster mushroom on the frequency and symptom duration of upper respiratory infections in athletes. A variety of different beta glucans were tested for this purpose. The most effective one was identified as pleuran, an insoluble beta glucan from oyster mushroom. Athletes given this beta glucan demonstrated reduced symptoms of upper respiratory tract infections. Research indicates that it supports natural killer cell activity.
