Immune Function
Mushroom beta-glucan trials measured immune cells and infections in athletes, children and older adults. Each result belongs to one product, so here is what was tested and found.
Content last updated . This page has not been medically reviewed.
Safety first. Supplements can cause side effects and interact with medicines. Read mushroom safety and interactions before you use any mushroom product.
"Immune support" is the most common mushroom claim on labels. The research behind it is real but narrow: specific beta-glucan products, tested in specific groups, with mixed measures. A change in a blood marker is not the same as fewer infections, and a result for one mushroom product does not transfer to another.
Terms in plain words
Beta-glucans are one group of biologically active polysaccharides (long sugar-based molecules) that are found in mushrooms and also in yeast. [1] "Pleuran" is an insoluble beta-glucan from the oyster mushroom Pleurotus ostreatus (Jacq.) P.Kumm. [2] Names below were checked on GBIF as accepted. [3] Most trials used a purified or concentrated product, not mushrooms eaten as food.What human trials found
| Mushroom and product type | Who, how long | What it found | Our label |
|---|---|---|---|
| Oyster mushroom beta-glucan (pleuran) | 50 athletes, 3 months | Fewer upper respiratory infection symptoms and more circulating natural killer (NK) cells than placebo [2] | promising but limited |
| Oyster mushroom beta-glucan, 100 mg a day | 20 elite athletes, 2 months, pilot | NK cell activity fell 28% in the placebo group after hard exercise but not significantly in the beta-glucan group [4] | limited (small pilot, immune marker only) |
| Oyster mushroom beta-glucan in a syrup with vitamin C | 175 children (average age about 5.7) with frequent respiratory infections, 12 months, vs vitamin C alone | 36% of the treated children had no respiratory infection versus 21% with placebo [5] | promising but limited |
| Oyster mushroom beta-glucan, no control group | 1,030 preschool children, 3 months plus 3 months follow-up | Fewer infections than the same months the year before; open-label, so it cannot rule out other explanations [6] | insufficient evidence (no control group) |
| Chewable pleuran product with vitamin D and zinc | 249 children, randomized, 3 months vs vitamin D and zinc | 2.35 versus 2.77 total respiratory infections (P = 0.042) [7] | promising but limited; the comparison product also contained vitamin D and zinc |
| Shiitake (Lentinula edodes) mycelium beta-glucan, 2.5 mg a day | 42 healthy older adults, 6 weeks, crossover | B-cell numbers differed between groups; NK cells rose in both groups, with no group difference; other immune measures unchanged [8] | limited (biomarkers only) |
| Reishi (Ganoderma lucidum) beta-glucan | Healthy adults aged 18-55, 84 days | More T-lymphocytes and NK cells and higher immunoglobulin A than placebo; no infection outcome in the abstract [9] | biomarker change; limited |
A review summarizing beta-glucan research for respiratory infections concluded that oyster mushroom beta-glucan has been studied in children and athletes, while adult studies mostly used yeast-derived beta-glucans. [1]
What these results do not show
- Biomarkers versus health outcomes: more NK cells or T-cells in a blood test do not by themselves show fewer infections.
- Product specific: the children's trials used branded, standardized products (we do not name them). A powder, tea or capsule from another maker is a different thing; see mushroom extracts and fruiting body, mycelium and beta-glucans.
- Labels may not match contents: a review of testing for popular botanical products marketed for "immune health", including functional mushrooms, described adulteration with inaccurate labeling. [10]
- Proper evidence not found, in our searches, for reishi or shiitake preventing infections in healthy adults.
Cancer and immune claims
Reishi has been studied alongside chemotherapy and radiotherapy. A Cochrane review of five trials reported higher counts of some immune cells but did not find enough evidence to justify reishi as a first-line cancer treatment, and rated trial quality as generally unsatisfying. [11] Anyone in cancer care should tell their team about every product; see mushrooms and cancer patients.Frequently asked questions
Do mushrooms boost the immune system?
Some beta-glucan products changed immune cell measures in small trials, but "boosting" is not a medical outcome and results are product specific. [9][8]
Do mushrooms prevent colds in children?
Trials of specific oyster mushroom beta-glucan products reported fewer respiratory infections, but they tested particular products and one had no control group. [5][6]
Are mushroom supplements safe with immune-suppressing medicines?
Ask the prescriber or pharmacist first. We did not find a source on this page that settles it.
Is reishi proven against cancer?
No. A Cochrane review did not find sufficient evidence to justify it as a first-line treatment. [11]
Can I trust "immune support" on a label?
Be cautious. A review reported adulteration and inaccurate labeling in popular products marketed for immune health. [10]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
- Autoimmune conditions, immune-suppressing medicines and transplants: ask the prescribing clinician before any immune-active product; see autoimmune conditions and immune-stimulating products and mushrooms, autoimmune conditions and transplants.
- Children: the trials used specific products in children with frequent infections. Ask a pediatrician before giving a child any supplement; see mushroom supplements for children and teenagers.
- Frequent infections can have causes a clinician should check; start with getting sick often and mushrooms for immunity compared with herbs.
- Product quality matters; see quality testing and certifications.
References
- Jesenak M, Urbancikova I, Banovcin P. Respiratory tract infections and the role of biologically active polysaccharides in their management and prevention. Nutrients. 2017. PubMed 28726737. Read 2026-10-22.
- Bergendiova K, Tibenska E, Majtan J. Pleuran (beta-glucan from Pleurotus ostreatus) supplementation, cellular immune response and respiratory tract infections in athletes. Eur J Appl Physiol. 2011. PubMed 21249381. Read 2026-10-22.
- GBIF Secretariat. GBIF Backbone Taxonomy species match for Hericium erinaceus, Ganoderma lucidum, Cordyceps militaris, Ophiocordyceps sinensis, Pleurotus ostreatus and Lentinula edodes. Read 2026-10-22.
- Bobovčák M, Kuniaková R, Gabriž J, Majtán J. Effect of pleuran (beta-glucan from Pleurotus ostreatus) supplementation on cellular immune response after intensive exercise in elite athletes. Appl Physiol Nutr Metab. 2010. PubMed 21164546. Read 2026-10-22.
- Jesenak M, Majtan J, Rennerova Z, et al. Immunomodulatory effect of pleuran (beta-glucan from Pleurotus ostreatus) in children with recurrent respiratory tract infections. Int Immunopharmacol. 2013. PubMed 23261366. Read 2026-10-22.
- Rennerova Z, Picó Sirvent L, Carvajal Roca E, et al. Beta-(1,3/1,6)-D-glucan from Pleurotus ostreatus in the prevention of recurrent respiratory tract infections: an international, multicentre, open-label, prospective study. Front Pediatr. 2022. PubMed 36324817. Read 2026-10-22.
- Jesenak M, Prokopova E, Bozensky J, et al. Novel chewable pleuran-based supplement decreases respiratory tract infections in children: a randomised controlled trial. Adv Ther. 2025. PubMed 41085920. Read 2026-10-22.
- Gaullier JM, Sleboda J, Øfjord ES, et al. Supplementation with a soluble beta-glucan exported from Shiitake medicinal mushroom, Lentinus edodes mycelium: a crossover, placebo-controlled study in healthy elderly. Int J Med Mushrooms. 2011. PubMed 22164761. Read 2026-10-22.
- Chen SN, Nan FH, Liu MW, et al. Evaluation of immune modulation by beta-1,3;1,6 D-glucan derived from Ganoderma lucidum in healthy adult volunteers, a randomized controlled trial. Foods. 2023. PubMed 36766186. Read 2026-10-22.
- You H, Abraham EJ, Mulligan J, et al. Label compliance for ingredient verification: regulations, approaches, and trends for testing botanical products marketed for "immune health" in the United States. Crit Rev Food Sci Nutr. 2024. PubMed 36123797. Read 2026-10-22.
- Jin X, Ruiz Beguerie J, Sze DM, Chan GC. Ganoderma lucidum (Reishi mushroom) for cancer treatment. Cochrane Database Syst Rev. 2016. PubMed 27045603. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.