Well-cooked mushrooms serve as a daily antibacterial fiber for the intestine and can replace the daily raw carrot.[1] Their compounds include aromatase inhibitors, the sugar trehalose, sterols such as ergosterol, and flavonoids. Most of the research below used the white button mushroom (Agaricus bisporus).

I think the immune function of the mushrooms that drew me back to them after all those years, that they were like an animal turned the inside out as far as immunity goes. We live with rotten stuff on the inside, and they live embedded in rotting stuff. And so they have to have mechanisms that allow them to not be destroyed by all of these toxins and pathogens in their environment. And what they live in is essentially what we have to deal with in our intestine. And for many years, as long as anything, I've been interested in endotoxin.

— Ray Peat[2]

Preparation

[edit]

Long boiling breaks down the heat-sensitive hydrazines, the suspected carcinogens in mushrooms, and about an hour drastically lowers them while the anti-cancer compounds such as the aromatase inhibitors remain.[3] Frying works when the mushrooms are heated until they turn slightly translucent.[4] Long-cooked mushrooms turn rubbery; grinding them in a food processor after cooking avoids this, and mushroom soup is one use.[5]

The hydrazine-containing toxins that Toth and others wrote about are destroyed by heat. Since extracts made by boiling the mushrooms for three hours were very active, I think it's good to boil them from one to three hours.

— Ray Peat[6]
  • Agaritine, a phenylhydrazine derivative, measured 165–457 mg/kg (mean 272) in 28 supermarket Agaricus samples, highest in the cap skin and gills and lowest in the stem. Boiling moved about 50% of it into the broth within 5 minutes and degraded 20–25%; after 2 hours of boiling about 10% remained in the solid mushroom. Frying in oil or butter cut it by 35–70%, microwaving to one third, dry baking by about 25%, and freeze-drying not at all (food chemistry study).[7]
  • Agaritine is a weak carcinogen in mice; extrapolated to humans, the estimated lifetime extra cancer risk is about 1 in 100,000. A 2020 toxicology review advises against eating raw or poorly cooked button mushrooms or true morels and recommends boiling them for at least 10 minutes and discarding the water (review).[8]

Gut and endotoxin

[edit]

A fairly quick transit time keeps the small intestine free of bacteria, and antiseptic foods such as cooked mushrooms, bamboo shoots and raw carrots help limit endotoxin.[9] Mushrooms grow in decaying matter loaded with bacteria and produce anti-inflammatory and antibacterial substances that suppress bacterial growth.[10] See Endotoxin load.

Raw carrots, cooked bamboo shoots, and cooked mushrooms contain antibiotics that are safe to use everyday. Like tetracycline and the macrolide antibiotics, they (especially mushrooms) are also antiinflammatory.

— Ray Peat[11]
  • 100 g of blanched white button mushroom eaten daily for one week raised the salivary IgA secretion rate by 53% and 56% at weeks 1 and 2 in 12 healthy adults, while 12 controls on their normal diet had no change; the rate returned to baseline by week 3 (small randomized trial).[12]

A good daily portion of cooked mushrooms can lower endotoxin and nitric oxide production enough to shift the progesterone/estrogen ratio and raise body temperature.[13] For detoxification, fibrous foods such as cooked mushrooms, raw carrots and citrus are preferable to sodium thiosulfate.[14]

Estrogen and aromatase

[edit]

Estrogen has excitatory, anti-GABA effects in the brain, and some of the mushrooms' protective effects result from inhibiting aromatase, the enzyme that synthesizes estrogen, and also from blocking estrogen receptors. Enzyme studies show that a variety of molecules in the common white button mushroom contribute to these anti-estrogen effects, and inhibit cancer cell growth.

— Ray Peat[15]
  • A heat-stable water extract of white button mushroom suppressed aromatase activity in human placental microsomes in a dose-dependent way, with mixed-type kinetics pointing to more than one inhibitor, and it lowered aromatase activity and proliferation in aromatase-transfected MCF-7 breast cancer cells (in vitro).[16]
  • The main active compounds were unsaturated fatty acids (linoleic, linolenic and conjugated linoleic acid); only conjugated linoleic acid blocked testosterone-driven growth of those cells. In nude mice carrying the same tumor cells, the mushroom extract reduced tumor cell proliferation and tumor weight (cell and mouse study).[17]

Cancer

[edit]

The effects of mushrooms on cancer are parallel to those of progesterone, inhibiting a wide variety of cancer promoting mechanisms. One of the major mushroom sterols, ergosterol, has been identified as an anticancer agent. Besides the cell-stabilizing trehalose and steroids, mushrooms contain a variety of flavonoids, including some that are found in citrus fruits, such as rutin, luteolin, and apigenin.

— Ray Peat[18]
  • In a Chinese case-control study of breast cancer, daily fresh mushroom intake went with much lower risk, and adding green tea lowered it further.[19]
  • Across 17 observational studies, the highest mushroom intake went with a pooled relative risk of 0.66 for total cancer and 0.65 for breast cancer; 11 of the 17 were case-control studies open to recall and selection bias (meta-analysis).[20]

Brain and mood

[edit]
  • Ergothioneine, an antioxidant that the body absorbs through a dedicated transporter and mushrooms supply, fell in whole blood beyond age 60 in elderly Singaporeans, and plasma levels were lower in those with mild cognitive impairment than in age-matched controls (cross-sectional study).[21]
  • In 496 people in Singapore, plasma ergothioneine was lowest in the 207 with dementia (160 of them with Alzheimer's disease), intermediate in the 201 with cognitive impairment but no dementia, and highest in the 88 without impairment. Lower levels also went with more white matter hyperintensities, thinner cortex and smaller hippocampal volumes (cross-sectional study).[22]
  • In a one-year pilot trial in 19 people aged 60 and over with mild cognitive impairment, 25 mg of ergothioneine three times a week improved scores on a verbal learning test and kept plasma neurofilament light chain stable, while it rose on placebo. Blood counts and kidney and liver markers did not change (double-blind RCT).[23]
  • In older Japanese adults, high serum ergothioneine went with a substantially lower risk of dementia (cohort study).[24] The lower risk held whether daily vegetable intake was above or below the median.[25]
  • Among 14,150 Chinese adults aged 65 and over, eating mushrooms and algae daily went with 29% lower odds of cognitive impairment, and occasional intake with 25% lower odds (cross-sectional study).[26]
  • In Korean adults, regular mushroom eating went with fewer new depressive symptoms, more so in women and people aged 40 and over (cohort study).[27]

Diabetes, pregnancy and heart

[edit]
  • In Korean adults aged 40 and over, the highest mushroom intake went with lower type 2 diabetes incidence in both sexes (cohort study).[28]
  • 100 g of white button mushroom daily from before pregnancy through week 20 lowered gestational hypertension (4.1% vs 8.2%), preeclampsia (0.7% vs 2.1%), gestational diabetes (3.9% vs 5.5%) and macrosomia (2.1% vs 7.1%) against placebo in 1,162 women in Shandong, China (randomized trial).[29]
  • In Swedish adults followed for about two decades, higher plasma ergothioneine went with less coronary disease, cardiovascular death and death from any cause (cohort study).[30]

Vitamin D

[edit]

Mushrooms contain ergosterol, which ultraviolet light converts to vitamin D2 (ergocalciferol). Mushrooms gathered outdoors need only a few hours of daylight, and less than an ounce of mushroom powder produced a distinct rise in serum vitamin D in supplement studies.[31]

  • UV-B at 1.5 J/cm² raised the vitamin D2 content of button mushrooms from under 1 to 491 μg per 100 g. In 26 young adults with serum 25(OH)D at or below 50 nmol/L, a mushroom soup giving 28,000 IU of D2 a week for 5 winter weeks raised 25(OH)D by 3.9 nmol/L a week, close to the 4.7 nmol/L from the same dose as a supplement (randomized trial).[32]
  • Across 6 trials, UV-exposed mushrooms did not significantly raise total serum 25(OH)D. In the 3 European trials, where baseline levels were low, total 25(OH)D rose by 15.2 nmol/L; across trials, 25(OH)D2 rose by 20.6 nmol/L while 25(OH)D3 fell by 13.3 nmol/L (meta-analysis).[33]

Safety

[edit]
  • Allergy: a 33-year-old man had facial and lip swelling, breathlessness, cough and trouble swallowing minutes after a white button mushroom pizza. Skin prick tests were positive to both raw and cooked mushroom, so cooking did not remove the allergen (case report).[34] See Allergy.
  • Wild mushrooms: cyclopeptide (amatoxin) species cause 90–95% of deaths from eating mushrooms. Of 204 amatoxin poisonings reported to two French poison centers from 2013 to 2019, 78% developed raised liver enzymes, a third had acute kidney injury, 2.5% needed a liver transplant and 4.4% died; digestive symptoms began about 11–14 hours after eating (case series).[35]
  • Morels: raw or undercooked fresh or dried true morels caused digestive illness with red blood cell breakdown, and very large servings a temporary neurological syndrome with cerebellar signs (review).[8]

Recipes

[edit]
Basic mushroom preparation
From ReciPeatsBasic mushroom preparation

A simple everyday method.

Gelatin mushroom sauce
From ReciPeatsGelatin mushroom sauce

Mushrooms paired with gelatin.

Cream of mushroom
From ReciPeatsCream of mushroom

A comforting everyday preparation.

All mushroom recipes

Varieties

[edit]
  • White button (Agaricus bisporus), the species in most of the studies on this page.

See also

[edit]


References

[edit]
  1. ↑ Ray Peat, "Generative Energy #31: Safe Supplements", Generative Energy, 54:33
  2. ↑ Ray Peat, "Generative Energy #19: Talking with Ray Peat", Generative Energy, 50:53
  3. ↑ Ray Peat, "Ask the Herb Doctor: Progesterone vs Estrogen, Listener Questions (Part 1)", KMUD, 40:23
  4. ↑ Ray Peat, "Mushrooms", Ray Peat Email Q&A
  5. ↑ Ray Peat, "Genetics & Cancer; Homeopathy; Stroke Prevention & More", One Radio Network, 1:10:08
  6. ↑ Mushrooms: observations and interpretations, Ray Peat Newsletter, 2015
  7. ↑ Schulzová V, Hajslová J, Peroutka R, Gry J, Andersson HC. "Influence of storage and household processing on the agaritine content of the cultivated Agaricus mushroom," Food Additives and Contaminants. 2002;19(9):853-862. doi:10.1080/02652030210156340. PMID Influence of storage and household processing on the agaritine content of the cultivated Agaricus mushroom.
  8. ↑ 8.0 8.1 Lagrange E, Vernoux JP. "Warning on False or True Morels and Button Mushrooms with Potential Toxicity Linked to Hydrazinic Toxins: An Update," Toxins. 2020;12(8):482. doi:10.3390/toxins12080482. PMID Warning on False or True Morels and Button Mushrooms with Potential Toxicity Linked to Hydrazinic Toxins: An Update.
  9. ↑ Ray Peat, email correspondence, "Starch," raypeatemails.com.
  10. ↑ Ray Peat, "Your Many Health Questions Answered", One Radio Network, 57:38
  11. ↑ Ray Peat, "Dietary Guidelines: Natural Food Antibiotics", Ray Peat Forum
  12. ↑ Jeong SC, Koyyalamudi SR, Pang G. "Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers," Nutrition. 2012;28(5):527-531. doi:10.1016/j.nut.2011.08.005. PMID Dietary intake of Agaricus bisporus white button mushroom accelerates salivary immunoglobulin A secretion in healthy volunteers.
  13. ↑ Ray Peat, "Ask the Herb Doctor: Endocrinology (Part 2)", Ask the Herb Doctor, 28:42
  14. ↑ Ray Peat, email, Diet (General), raypeatemails.com.
  15. ↑ Mushrooms: observations and interpretations, Ray Peat Newsletter, 2015
  16. ↑ Grube BJ, Eng ET, Kao YC, Kwon A, Chen S. "White button mushroom phytochemicals inhibit aromatase activity and breast cancer cell proliferation," Journal of Nutrition. 2001;131(12):3288-3293. doi:10.1093/jn/131.12.3288. PMID White button mushroom phytochemicals inhibit aromatase activity and breast cancer cell proliferation.
  17. ↑ Chen S, Oh SR, Phung S, et al. "Anti-aromatase activity of phytochemicals in white button mushrooms (Agaricus bisporus)," Cancer Research. 2006;66(24):12026-12034. doi:10.1158/0008-5472.CAN-06-2206. PMID Anti-aromatase activity of phytochemicals in white button mushrooms (Agaricus bisporus).
  18. ↑ Mushrooms: observations and interpretations, Ray Peat Newsletter, 2015
  19. ↑ Zhang M, Huang J, Xie X, Holman CD. "Dietary intakes of mushrooms and green tea combine to reduce the risk of breast cancer in Chinese women," International Journal of Cancer. 2009;124(6):1404-1408. doi:10.1002/ijc.24047. PMID Dietary intakes of mushrooms and green tea combine to reduce the risk of breast cancer in Chinese women. 1,009 cases and 1,009 controls; at least 10 g fresh mushrooms daily OR 0.36 vs none; plus at least 1.05 g dried green tea leaves daily OR 0.11.
  20. ↑ Ba DM, Ssentongo P, Beelman RB, et al. "Higher Mushroom Consumption Is Associated with Lower Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies," Advances in Nutrition. 2021;12(5):1691-1704. doi:10.1093/advances/nmab015. PMID Higher Mushroom Consumption Is Associated with Lower Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies.
  21. ↑ Cheah IK, Feng L, Tang RMY, Lim KHC, Halliwell B. "Ergothioneine levels in an elderly population decrease with age and incidence of cognitive decline; a risk factor for neurodegeneration?," Biochemical and Biophysical Research Communications. 2016;478(1):162-167. doi:10.1016/j.bbrc.2016.07.074. PMID Ergothioneine levels in an elderly population decrease with age and incidence of cognitive decline; a risk factor for neurodegeneration?.
  22. ↑ Wu LY, Cheah IK, Chong JR, Chai YL, Tan JY, Hilal S, Vrooman H, Chen CP, Halliwell B, Lai MKP. "Low plasma ergothioneine levels are associated with neurodegeneration and cerebrovascular disease in dementia," Free Radical Biology and Medicine. 2021;177:201-211. doi:10.1016/j.freeradbiomed.2021.10.019. PMID 34673145.
  23. ↑ Yau YF, Cheah IK, Mahendran R, Tang RM, Chua RY, Goh RE, Feng L, Li J, Kua EH, Chen C, Halliwell B. "Investigating the efficacy of ergothioneine to delay cognitive decline in mild cognitively impaired subjects: A pilot study," Journal of Alzheimer's Disease. 2024;102(3):841-854. doi:10.1177/13872877241291253. PMID 39544014.
  24. ↑ Meng X, Ohara T, Nishioka K, et al. "Serum ergothioneine and risk of dementia in a general older Japanese population: the Hisayama Study," Psychiatry and Clinical Neurosciences. 2025;79(12):808-816. doi:10.1111/pcn.13893. PMID Serum ergothioneine and risk of dementia in a general older Japanese population: the Hisayama Study. 1,344 adults aged 65+, median 11.2 years; top vs bottom quarter HR 0.54, 0.56 fully adjusted.
  25. ↑ Meng 2025 (Hisayama Study), subgroup analysis by serum ergothioneine and daily vegetable intake split at the medians (0.693 μmol/L, 165 g/day): high ergothioneine with low vegetables HR 0.58 (95% CI 0.39-0.87), high ergothioneine with high vegetables HR 0.59 (0.37-0.93), low ergothioneine with high vegetables HR 0.81 (0.52-1.25, not significant), against low ergothioneine with low vegetables. doi:10.1111/pcn.13893. PMID Serum ergothioneine and risk of dementia in a general older Japanese population: the Hisayama Study.
  26. ↑ Yang Y, Zhu D, Qi R, Chen Y, Sheng B, Zhang X. "Association between Intake of Edible Mushrooms and Algae and the Risk of Cognitive Impairment in Chinese Older Adults," Nutrients. 2024;16(5):637. doi:10.3390/nu16050637. PMID Association between Intake of Edible Mushrooms and Algae and the Risk of Cognitive Impairment in Chinese Older Adults.
  27. ↑ Park SK, Oh CM, Ryoo JH, Jung JY. "The protective effect of mushroom consumption on depressive symptoms in Korean population," Scientific Reports. 2022;12(1):21914. doi:10.1038/s41598-022-26549-5. PMID The protective effect of mushroom consumption on depressive symptoms in Korean population. 87,822 adults; 30 g serving three or more times a week vs rare or none, HR 0.86.
  28. ↑ Kim YM, Woo HW, Shin MH, Koh SB, Kim HC, Kim MK. "A prospective association between dietary mushroom intake and the risk of type 2 diabetes: the Korean Genome and Epidemiology Study-Cardiovascular Disease Association Study," Epidemiology and Health. 2024;46:e2024017. doi:10.4178/epih.e2024017. PMID A prospective association between dietary mushroom intake and the risk of type 2 diabetes: the Korean Genome and Epidemiology Study-Cardiovascular Disease Association Study. 16,666 adults; top vs bottom quarter IRR 0.65 men, 0.70 women.
  29. ↑ Sun L, Niu Z. "A mushroom diet reduced the risk of pregnancy-induced hypertension and macrosomia: a randomized clinical trial," Food & Nutrition Research. 2020;64. doi:10.29219/fnr.v64.4451. PMID A mushroom diet reduced the risk of pregnancy-induced hypertension and macrosomia: a randomized clinical trial.
  30. ↑ Smith E, Ottosson F, Hellstrand S, et al. "Ergothioneine is associated with reduced mortality and decreased risk of cardiovascular disease," Heart. 2020;106(9):691-697. doi:10.1136/heartjnl-2019-315485. PMID Ergothioneine is associated with reduced mortality and decreased risk of cardiovascular disease. 3,236 adults, median 21.4 years; per SD HR 0.85 coronary disease, 0.79 cardiovascular death, 0.86 all-cause death.
  31. ↑ Ray Peat, "Ask the Herb Doctor: Vitamin D", KMUD, 15:31
  32. ↑ Urbain P, Singler F, Ihorst G, Biesalski HK, Bertz H. "Bioavailability of vitamin D2 from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial," European Journal of Clinical Nutrition. 2011;65(8):965-971. doi:10.1038/ejcn.2011.53. PMID Bioavailability of vitamin D₂ from UV-B-irradiated button mushrooms in healthy adults deficient in serum 25-hydroxyvitamin D: a randomized controlled trial.
  33. ↑ Cashman KD, Kiely M, Seamans KM, Urbain P. "Effect of Ultraviolet Light-Exposed Mushrooms on Vitamin D Status: Liquid Chromatography-Tandem Mass Spectrometry Reanalysis of Biobanked Sera from a Randomized Controlled Trial and a Systematic Review plus Meta-Analysis," Journal of Nutrition. 2016;146(3):565-575. doi:10.3945/jn.115.223784. PMID Effect of Ultraviolet Light-Exposed Mushrooms on Vitamin D Status: Liquid Chromatography-Tandem Mass Spectrometry Reanalysis of Biobanked Sera from a Randomized Controlled Trial and a Systematic Review plus Meta-Analysis.
  34. ↑ Cunha IM, Marques ML, Abreu C, Bartolomé B, Moreira da Silva JP. "Anaphylaxis to Agaricus bisporus," Einstein (São Paulo). 2020;18:eRC5478. doi:10.31744/einstein_journal/2020RC5478. PMID Anaphylaxis to Agaricus bisporus ingestion.
  35. ↑ Lecot J, Cellier M, Courtois A, et al. "Cyclopeptide mushroom poisoning: A retrospective series of 204 patients," Basic & Clinical Pharmacology & Toxicology. 2023;132(6):533-542. doi:10.1111/bcpt.13858. PMID Cyclopeptide mushroom poisoning: A retrospective series of 204 patients.