Agarikon (Fomitopsis officinalis)

Agarikon (Fomitopsis officinalis, also known as Laricifomes officinalis) is the rarest and most historically significant fungus on this list. Ancient Greek physicians, including Dioscorides, described its use for pulmonary tuberculosis. Ötzi the Iceman — the 5,300-year-old natural mummy discovered in the Alps — was found carrying Agarikon among his belongings, suggesting its medicinal use predates written history. Today, Agarikon is one of the most ecologically endangered medicinal fungi in North America, largely confined to old-growth forests, and its cultivation is pioneered exclusively by Paul Stamets' Fungi Perfecti operation in Washington State. The antiviral research on Agarikon is the most compelling aspect of its scientific profile. Preclinical studies published in Mycology demonstrated inhibition of influenza A (H1N1), influenza A (H5N1), and herpes simplex viruses in laboratory settings. In vitro tests have shown Agarikon extracts reduce SARS-CoV-2 plaque formation in infected cell cultures. Most significantly, Agarikon (Fomitopsis officinalis) was included as an active component in the polypore mushroom mycelium combination tested in a 2025 randomized clinical trial examining whether mushroom supplementation could enhance COVID-19 vaccine immune response — published as a UCSD-affiliated trial. The trial found that participants in the mushroom supplement arm showed enhanced immune activation markers post-vaccination compared to placebo. The immunological mechanism involves agaricin and other sesquiterpenes alongside complex polysaccharides that modulate pattern recognition receptor signaling. Agarikon's polysaccharides activate macrophages and NK cells through Dectin-1 and TLR-2 pathways. Host Defense Agarikon is produced from mycelium cultivated on organic brown rice — priced at approximately $49.99 for 60 capsules — making it the most expensive single-species product on this list, reflecting both its rarity and the proprietary cultivation process. Typical dosing is 500–1,000 mg daily. Human-specific clinical data remains limited compared to lower-ranked entry points like Shiitake or Tremella, which places it at rank 9 despite remarkable preclinical and historical credentials.