Shiitake (Lentinula edodes): The Medicinal Mushroom Behind Lentinan

The scientist who recovered a long-known truth

In Japan it is an official medicine; in much of the West, only a food supplement. We are talking about the same Lentinula edodes mushroom (shiitake), whose power has been quietly used in the East for some 3,000 years. For centuries, Eastern wisdom linked mushrooms with health and life, while Western medicine dismissed it as a fairy tale. In 1936, Dr. Kisaku Mori decided to test what really lay behind those "tales." Thousands of studies, collaboration with scientists worldwide, and the book Mushrooms as Health Foods followed. Diabetes, influenza, liver disease, cancer — in each area Lentinula edodes showed effects. Western medicine did not start treating with mushrooms; it only finally began to document it.

Why does one mushroom affect so many different functions?

Such a question can sound suspicious — if something affects everything, it usually means it affects nothing. In the case of Lentinula edodes, the answer lies in its structure: this mushroom contains several distinct, chemically unrelated active compounds, each working through its own biochemical mechanism:

• Lentinan — a mushroom polysaccharide (a beta-1,3/1,6-D-glucan) that acts as an immunomodulator, binding to immune-cell receptors and activating the defence chain. It was approved in Japan in 1985 as an adjunct to oncological treatment.
• Eritadenine — a compound found almost exclusively in Lentinula edodes, which acts on cholesterol metabolism in the liver via COMT inhibition.
• Lentinacin (KS-2) — activates interferon production and shows antiviral effects.
• AHCC (Active Hexose Correlated Compound) — a polysaccharide fraction studied as an immune-support agent alongside vaccination.

This is not one "miracle" compound. It is a mushroom with several independently acting components.

Effect on immunity and significance in oncology

The immunomodulating effect of Lentinula edodes is its most scientifically documented aspect, with hundreds of clinical studies. On the tumour: studied for suppressing cancer-cell proliferation, encouraging apoptosis (natural cell death) and blocking angiogenesis. On immunity: studied for increasing NK (natural killer) cell activity, activating macrophages and T-cells, and stimulating cytokine production (IL-2, IL-12, IFN-γ). Alongside chemotherapy: studied for strengthening chemotherapy's effect, reducing side effects, improving quality of life and lengthening survival. In Japan, mushroom-polysaccharide preparations have been standard adjunctive oncology care since 1985 — not alternative medicine, but standard practice. Always consult your treating doctor first, especially if you take immunosuppressants.

Eritadenine and cholesterol metabolism

This is an aspect rarely discussed but clinically documented. Eritadenine — found almost exclusively in Lentinula edodes — acts via COMT (catechol-O-methyltransferase) inhibition. Its mechanism differs from statins: instead of blocking cholesterol production, it works on cholesterol metabolism in the liver. For prevention, and together with dietary correction, it is studied as a scientifically grounded choice rather than merely "a little help" — though extracts do not replace statins at critical levels. (See more: cholesterol.)

Antiviral and antibacterial properties

Lentinacin (KS-2) activates interferon production — the body's main antiviral defence system — studied against influenza, HSV (herpes simplex) and HIV. Lentinan has shown activity against bacteria and fungal infections in vitro. This is not an antibiotic substitute, but an activated immune system naturally strengthens resistance to seasonal threats.

A mushroom or an extract — these are not the same

The crucial distinction: eating shiitake is not the same as a concentrated, standardised extract. The active polysaccharides dissolve only in water, so only water-based extraction yields the compounds that matter — alcohol extracts and simple mushroom powders are far too weak. For results, a standardised, water-based extract is essential.