The Oyster mushroom is best known as a food, but its chemistry has attracted scientific interest too, including one discovery that surprised researchers in the 1990s. This article looks at what has been studied, what the animal and human research found, its limitations, and what can reasonably be concluded.
Why researchers are interested
The Oyster mushroom (Pleurotus ostreatus) is one of the most widely cultivated mushrooms in the world, grows naturally on dead hardwood including in Britain, and is easy and cheap to grow, which makes it convenient to study. See How Oyster Mushrooms Grow and Pleurotus Species Explained. Three features in particular have drawn research attention.
Lovastatin
In 1993, Slovenian researchers led by Nina Gunde-Cimerman reported that fungi of the Pleurotus genus produce lovastatin, also known as mevinolin, and in 1995 they confirmed it was present in the fruiting bodies. Lovastatin is better known as a prescription cholesterol-lowering medicine, originally developed from a different fungus.
This is a genuinely surprising finding, but it needs context. The amount of lovastatin in Oyster mushrooms varies with strain, growing conditions and which part of the mushroom is measured, and is generally far below a medicinal dose. Oyster mushrooms and their extracts are not a substitute for prescribed medicine. If you take a statin or any other cholesterol medicine, speak to your GP before adding any supplement.
Ergothioneine
Oyster mushrooms are a good dietary source of ergothioneine, an unusual compound the body absorbs through a dedicated transporter. See Ergothioneine Explained.
Beta-glucans
Like most mushrooms, Oyster mushrooms contain beta-glucans in their cell walls. A purified beta-glucan from Oyster mushrooms, known as pleuran, has been studied as an isolated ingredient, but a purified isolate is not the same as a whole-mushroom extract. See What Are Beta-Glucans? and Oyster Mushroom Compounds Explained.
The three tiers of evidence
Laboratory studies
Laboratory studies have examined Oyster mushroom extracts and isolated compounds in cells. As with all mushrooms, these don’t reliably predict effects in people. See In Vitro, Animal and Human Studies.
Animal studies
Much of the Oyster mushroom research comes from animal feeding studies, particularly a series by Slovak researchers in the 1990s. In one, rats were fed a high-cholesterol diet with 1%, 2.5% or 5% of dried Oyster mushroom added, and the researchers reported lower blood cholesterol as the mushroom content increased. These studies used whole mushroom as a substantial part of the animals’ diet, in rats deliberately fed a high-cholesterol diet, so they tell us little about people or about extracts.
Human studies
Human research on Oyster mushrooms is very limited.
Schneider et al., 2011 (Germany). Twenty young adults aged 20 to 34 were randomised to eat a daily soup containing 30 g of dried Oyster mushrooms, or a tomato soup as a comparison, for 21 days. The researchers reported lower levels of blood fats called triglycerides and of oxidised LDL in the mushroom group. The change in total cholesterol did not reach statistical significance, and there was no effect on LDL or HDL cholesterol. Thirty grams of dried mushroom is a large amount, equivalent to several hundred grams of fresh mushrooms, eaten as food. The study was small and short, and its participants weren’t blinded, since they could see and taste what they were eating.
Reading the evidence together
- Food is not an extract. Most research involves eating substantial amounts of whole mushroom. That tells us little about extracts or tinctures.
- Very few human studies. The main human trial involved 20 people for three weeks.
- Animal models are artificial. Rats fed high-cholesterol diets are a long way from typical human diets.
- Lovastatin content varies. The amount present in any given mushroom or product is not usually known.
Safety
Oyster mushrooms are a widely eaten food and are generally considered safe to eat when cooked. Anyone with a mushroom allergy should avoid them. Oyster mushrooms release large numbers of spores, and people who work in Oyster mushroom growing rooms have been reported to develop allergic lung reactions; this is an occupational issue rather than one of eating the mushrooms. Because Oyster mushrooms contain some lovastatin, anyone taking cholesterol-lowering medicine should speak to their GP before taking an Oyster mushroom supplement. If you are pregnant, breastfeeding, taking medication or managing a health condition, speak to your GP or pharmacist before taking any mushroom supplement. Tinctures also contain alcohol.
What we can reasonably conclude
Oyster mushrooms are a nutritious, widely eaten food with some genuinely interesting chemistry, including naturally occurring lovastatin and ergothioneine. But the research consists mostly of animal feeding studies and a very small number of short human studies using whole mushrooms as food. It doesn’t support specific claims about what Oyster mushroom products do in people, and no health claims are authorised for Oyster mushrooms in the UK.
What remains uncertain
- Whether findings from eating large amounts of whole mushroom apply to extracts.
- How much lovastatin, ergothioneine or beta-glucan different products contain.
- Whether small, short-term findings would hold up in larger, longer, blinded trials.
What better evidence would look like
Larger, longer, blinded trials of a clearly characterised material, with its content of key compounds measured and reported.
Our approach
We make our Oyster tincture from UK-grown Oyster mushrooms, extracted in hot water and alcohol, and describe it by what it is and how it’s made, not by what it might do. For the wider picture, see The Complete Guide to Oyster Mushrooms.
References
- Gunde-Cimerman N, Friedrich J, Cimerman A, Benički N. Screening fungi for the production of an inhibitor of HMG CoA reductase: production of mevinolin by the fungi of the genus Pleurotus. FEMS Microbiology Letters. 1993;111:203–206.
- Gunde-Cimerman N, Cimerman A. Pleurotus fruiting bodies contain the inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase: lovastatin. Experimental Mycology. 1995;19(1):1–6.
- Bobek P, Ozdín L, Kajaba I. Dose-dependent hypocholesterolaemic effect of oyster mushroom (Pleurotus ostreatus) in rats. Physiological Research. 1997;46:327–329.
- Schneider I, Kressel G, Meyer A, Krings U, Berger RG, Hahn A. Lipid lowering effects of oyster mushroom (Pleurotus ostreatus) in humans. Journal of Functional Foods. 2011;3(1):17–24.
Study titles are reproduced as published and are not claims made by Spore & Bloom.
