Significance of Medicinal Mushrooms in Integrative Oncology: A Narrative Review

Abstract

Medicinal mushrooms are widely used in East Asia for the treatment of various diseases, especially in complementary cancer care. While there is a growing interest in medicinal mushrooms in Western countries and an increasing number of pre-clinical studies indicate distinct anti-cancer and regenerative properties, little is known about their potential relevance for clinical practice. This review aims to provide an overview of the clinical evidence, significance and potential role of medicinal mushrooms in complementary cancer care. Scientific databases for (randomized) controlled clinical trials evaluating whole spectrum formulations of medicinal mushrooms (mushroom powder and mushroom extracts) in cancer patients during and/or after conventional oncological treatment were searched. Eight studies met our inclusion criteria (eight randomized controlled trials, one controlled clinical trial). The medicinal mushrooms investigated were Agaricus sylvaticus (two trials), Agaricus blazei murill (two trials), Antrodia cinnamomea (one trial), Coriolus versicolor (one trial) and Ganoderma lucidum (three trials); all were compared to placebo and administered orally. A variety of cancer entities, outcomes and treatment durations were observed. Study results suggested beneficial effects of medicinal mushrooms, particularly quality of life and reduction of adverse effects of conventional therapies. Also, positive effects on antitumor activity and immunomodulation were reported, e.g., an increased activity of natural killer cells. In addition, results might suggest a longer survival of cancer patients receiving mushroom preparations, although in most studies this was not significant when compared to placebo. Adverse events of treatment with medicinal mushrooms were poorly reported; gastrointestinal reactions and a decrease in platelet cell count occurred in some cases. The methodological quality of most studies was generally unsatisfying and most results were insufficiently reported in several respects. Medicinal mushrooms may have a therapeutic potential for cancer patients during and after conventional oncological care with regards to quality of life, reduction of adverse effects of conventional care and possibly other surrogate parameters like immune function. There is an urgent need to investigate the safety and possible interactions of medicinal mushrooms. High-quality clinical research is warranted in order to clarify the potential of medicinal mushrooms in cancer therapy.

Medicinal Mushrooms: Bioactive Compounds, Use, and Clinical Trials

“…Today, they are among the most commonly used of all integrative, complementary, and alternative therapies, especially in the field of oncology. This is especially the case in Asian countries, where mycotherapy has ancient and deep-rooted origins, while in Western areas, the application of mushrooms in medical therapies is still rather limited, especially in conventional medical institutions [ 5 , 20 ]. However, this is still a complex field in many respects.…”

“…However, this is still a complex field in many respects. First of all, although a great deal of research has been carried out to highlight their various beneficial properties and thus their potential use in therapeutics, many mushrooms have only been tested in vitro or in vivo in animal models, mainly mice and rats, with little or no scientific support in vivo in humans [ 5 , 6 ]. Thus, although supplement companies often specify research to support their product claims, these are preclinical or even in vitro studies.…”

“…In addition to all this, numerous other factors often limit the validity of the clinical studies conducted to date, even in the case of promising results. They often involve too small a sample (among other things, the enormous variability in sample size makes it difficult to compare the various studies), or lack a control or placebo group, or the two groups compared are numerically very different, there is a very frequent lack of replication, adverse events are poorly reported or investigated, the statistical methods are deficient, and the results are poorly described in various respects [ 5 , 6 , 9 , 66 ].…”

“…Their use for promoting and maintaining a good state of health and the treatment of diseases has been around since ancient times in Asian regions, while in the West, this approach is considerably more recent. Medicinal mushrooms (MMs) are reported to have numerous pharmacological actions such as antimicrobial, anti-inflammatory, immunomodulatory, antidiabetic, cytotoxic, antioxidant, hepatoprotective, anticancer, antioxidant, antiallergic, antihyperlipidemic, and prebiotic properties, among others [ 2 , 3 , 4 , 5 ]. These activities are attributable to many bioactive metabolites present in the mycelium but above all in the fruiting body, whose biological effect varies according to the chemical nature and whose distribution varies according to the fungal species.…”

“…On the other hand, a small number of clinical studies carried out on humans and published in the peer-reviewed literature are available. Clinical studies are necessary to assess the efficacy of medicinal mushrooms within the complex human body system but also to assess their safety [ 2 , 5 , 6 ].…”