Substitution, Grain Filler and Mislabeling in Mushroom Supplements
What published analyses found about species substitution, starch from grain and mislabeling in mushroom products, why it matters, and what the studies do not show.
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.
"Adulteration" means a product is not what it claims to be, whether by substitution, dilution or an added substance. "Mislabeling" means the label says something the contents do not support. Published analyses have looked at both in mushroom products. This page reports what those analyses found. They are a handful of studies, not a survey of the whole market, and no brands are named here.
Information here is for general education. It is not medical advice.
What researchers found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Are cordyceps products what they say? | In Thailand, 65 oral cordyceps products sold online were examined. 54.3% were judged falsified, mainly through substitution of C. sinensis with C. militaris, missing labeled species or the wrong form. [1] | One country, convenience sample, 2026 |
| Hidden drugs | In the same Thai study, 6.2% of products were adulterated with corticosteroids. [1] | Same study; not found in other sources we read for mushrooms |
| Do labels make disease claims? | 73.8% of the Thai products made disease claims through social media. [1] | Same study |
| Is grain mistaken for mushroom? | A chaga study compared wild-harvested chaga canker, Inonotus obliquus mycelium and fermented grain products. Starch was found in the fermented grain products and not in authentic canker. [2] | One species; one study |
| Fraud in the high-value caterpillar fungus market | A 2025 review describes mislabeling, substitution, adulteration and artificial enhancement of Chinese cordyceps. [3] | Review of a specific high-value product |
| Functional mushrooms sold for immune health | A review says top-selling botanicals including functional mushrooms can be adulterated with lower grade ingredients, non-target plants or synthetic compounds, partly because of supply chain issues. [4] | Narrative review; no rate given in the abstract we read |
| How common is grain filler in lion's mane or reishi products sold in the US? | Proper evidence not found. We searched PubMed for starch, beta-glucan and mycelium-grain analyses of commercial products and found only the chaga study above. | Not assessed |
Substitution is not the same as grain-based mycelium
Mycelium grown on grain is a product type, described on its own page: Mycelium Grown on Grain. In the chaga study, the fermented grain products were compared with authentic chaga canker and were found to be starch-rich. [2] The study's authors frame the issue as a need to tell genuine canker from misrepresented products. [2] Whether a given label is misleading depends on what it says about the part used and the form. See Fruiting Body vs Mycelium.
Why it matters
- Evidence does not transfer. If the species or part in the bottle differs from the label, the studies you read may not apply. See Mushroom Names.
- Hidden ingredients carry risks. NCCIH notes the FDA has found prescription drugs, including anticoagulants such as warfarin and anticonvulsants such as phenytoin, in products sold as supplements. [5] NCCIH ties this mainly to products promoted for weight loss, sexual enhancement and bodybuilding. [5] We did not read an FDA finding of such drugs in a mushroom product. The Thai cordyceps study did find corticosteroids. [1]
- Why the Thai study was done. The study says an outbreak of acute kidney injury linked to cordyceps products in Thailand prompted it. [1] The abstract does not say what caused the outbreak.
How testing can detect problems
Researchers use DNA barcoding, chemical fingerprints and starch tests. [6] [2] See Quality Testing and Certificates of Analysis. One barcoding study found it could distinguish commercial Ganoderma lucidum and G. sinense products from other Ganoderma species. [7]
What a reader can do
You cannot check species by looking at a capsule. You can read the label closely, see How to Read a Mushroom Supplement Label, ask the company which species, part and form it uses, and talk to a pharmacist about interactions. If a product causes a reaction, see Side Effects, Allergic Reactions and Reporting. Related guidance is in Adulteration, Substitution and Mislabeling of Herbal Products.
Frequently asked questions
Are mushroom supplements often fake?
Proper evidence not found for an overall rate. In one Thai survey of 65 online cordyceps products, 54.3% were judged falsified. [1] That result cannot be applied to other mushrooms or countries.
What is grain filler?
The term is not defined in the sources we read. A chaga study found starch in fermented grain products and not in authentic chaga canker. [2]
Can a mushroom supplement contain a hidden drug?
NCCIH says the FDA has found prescription drugs in products sold as supplements, mainly those promoted for weight loss, sexual enhancement and bodybuilding. [5] A Thai cordyceps study found corticosteroid adulteration in 6.2% of 65 products. [1]
Does "mycelium on grain" mean the product is mislabeled?
Not by itself. It is a product type. Whether the label clearly says what the product is made from is the question. See Mycelium Grown on Grain.
How do I report a problem with a product?
See Side Effects, Allergic Reactions and Reporting. Tell a clinician or pharmacist about any reaction and show them the label.
References
- Post-marketing surveillance of cordyceps products online: identifying falsified products and regulatory challenges. BMC Complement Med Ther 2026 Read 2026-10-23.
- Comparative Study of Chaga (Inonotus obliquus) Dietary Supplements Using Complementary Analytical Techniques. Int J Mol Sci 2025 Read 2026-10-23.
- Chinese cordyceps products, geographic traceability and authenticity assessment: current status, challenges, and future directions. Crit Rev Biotechnol 2025 Read 2026-10-23.
- 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 Read 2026-10-23.
- National Center for Complementary and Integrative Health, Using Dietary Supplements Wisely Read 2026-10-23.
- DNA barcoding for identification of consumer-relevant mushrooms: A partial solution for product certification? Food Chem 2017 Read 2026-10-23.
- Identification of commercial Ganoderma (Lingzhi) species by ITS2 sequences. Chin Med 2015 Read 2026-10-23.