Identifying the “Mushroom of Immortality”: Assessing the Ganoderma Species Composition in Commercial Reishi Products

Abstract

Species of Ganoderma, commonly called reishi (in Japan) or lingzhi (in China), have been used in traditional medicine for thousands of years, and their use has gained interest from pharmaceutical industries in recent years. Globally, the taxonomy of Ganoderma species is chaotic, and the taxon name Ganoderma lucidum has been used for most laccate (shiny) Ganoderma species. However, it is now known that G. lucidum sensu stricto has a limited native distribution in Europe and some parts of China. It is likely that differences in the quality and quantity of medicinally relevant chemicals occur among Ganoderma species. To determine what species are being sold in commercially available products, twenty manufactured products (e.g., pills, tablets, teas, etc.) and seventeen grow your own (GYO) kits labeled as containing G. lucidum were analyzed. DNA was extracted, and the internal transcribed spacer (ITS) region and translation elongation factor 1-alpha (tef1α) were sequenced with specific fungal primers. The majority (93%) of the manufactured reishi products and almost half of the GYO kits were identified as Ganoderma lingzhi. G. lingzhi is native to Asia and is the most widely cultivated and studied taxon for medicinal use. Illumina MiSeq sequencing of the ITS1 region was performed to determine if multiple Ganoderma species were present. None of the manufactured products tested contained G. lucidum sensu stricto, and it was detected in only one GYO kit. G. lingzhi was detected in most products, but other Ganoderma species were also present, including G. applanatum, G. australe, G. gibbosum, G. sessile, and G. sinense. Our results indicate that the content of these products vary and that better labeling is needed to inform consumers before these products are ingested or marketed as medicine. Of the 17 GYO kits tested, 11 kits contained Ganoderma taxa that are not native to the United States. If fruiting bodies of exotic Ganoderma taxa are cultivated, these GYO kits will likely end up in the environment. The effects of these exotic species to natural ecosystems needs investigation.

Autophagic flux disruption contributes to Ganoderma lucidum polysaccharide-induced apoptosis in human colorectal cancer cells via MAPK/ERK activation

“…Natural products with highly diverse bioactivities and functions play a vital role in drug discovery for treating diseases. Ganoderma lucidum (G. lucidum) is a medicinal mushroom that has been used in East Asian countries for over 2000 years [3][4][5] . A substantial number of preclinical and clinical studies have reported that G. lucidum has numerous pharmacological effects, including antioxidant, hypoglycemic, immune-regulatory, anti-diabetic, and anti-cancerous [5][6][7][8][9][10] .…”

Beta-glucan content and antioxidant activities of mushroom-derived food supplements

“…This in particular could be contributed to economically motivated adulteration and intentional substitution of mushroom-derived materials by some less expensive or lower quality ones. 16,17 Therefore, the requirement for chemical insights into the quality of mushroom supplements, based on the content of bioactive compounds, such as polysaccharides, has been recognized. 18 However, the quality of such products has not been the subject of extensive studies.…”

The ITS region provides a reliable DNA barcode for identifying reishi/lingzhi (Ganoderma) from herbal supplements

“…Reishi is one of the oldest herbal medicines in recorded history [reviewed in 15,16] and estimated to represent 2% of the herbal supplement industry [14]. It is recommended as an antiinflammatory and to enhance immunity [17,18].…”

“…The genus consists of approximately 80 species that fall into five or six clades -one of which is centered around G. lucidum sensu lato [21][22][23][24][25][26]. Because of their wood-decaying capabilities, several Ganoderma species have been investigated for biopulping [14] and bioremediation [27], however, it is most prized as a "model medicinal mushroom" [28] because of the putative health benefits of the triterpenoids and polysaccharides [29,30]. The G. lucidum clade consists of several species that are in taxonomic flux [22,24,25].…”

“…Ganoderma-specific primers developed by Cao et al [23] have been shown to improve PCR specificity. These primers have been used for barcoding reishi herbal supplements in previous studies (see [38] with limited sampling of reishi samples (n=4) and [14] with a broader retail sampling (n=14), but unclear how many unique suppliers were represented in the latter).…”