Safety of Ganoderma lucidum supplements

The use of natural products is a growing phenomenon both in Italy and in the rest of the world. Some mushrooms have been used by the Eastern traditional medicine for centuries to improve the general health, increase the immune defenses and as adjuvant for the treatment of chronic diseases. The Ganoderma lucidum, also known as reishi in Japan and língzhī in China, is a mushroom (see Figure) that can be consumed as tea, different types of beverages or nutraceutical preparation. Approved in Italy by the Ministry of Health as nutritional supplement, the G. lucidum is present on the market in different preparation (powder, extract) in addition to tea, coffee or chocolate blends.


Besides its general beneficial effects on health, G. lucidum is advertised as anticancer agent. Experimental studies in vitro have shown that the polysaccharides present in the G. lucidum modulate the immune system. In particular, they enhance the expression of the histocompatibility major complex in the melanoma cells, therefore improving the antigen presentation and promoting the immune response to viruses and tumors. However, preclinical studies are still ongoing and evaluating its real effectiveness as anticancer.¹
The hypoglycemic properties of the mushroom have also been studied in experimental models and it has been demonstrated that the triterpenes and polysaccharides isolated from G. lucidum inhibit the differentiation of adipocytes and produce beneficial effects, hypoglycemic, on diabetes mellitus type 2 in murine models.^2,3 The results of a recent study on mice⁴ reveal that G. lucidum decreases glycaemia and that its polysaccharides with high molecular weight can be used as prebiotic agents to prevent intestinal dismicrobism and metabolic disorders linked to obesity in overweight mice.
In order to understand and evaluate the potential risks associated to the use of natural products, the National Health Institute in Italy has established since 2002 a surveillance system of adverse reactions to these products.⁵ The database contains to date 1,284 spontaneous reports of adverse reactions to natural products. A database query resulted in 5 cases of adverse events to products containing G. lucidum, involving 4 women and one man. In two reports the patients described an increase of hepatic enzymes and in both cases the reaction resolved once the supplement was discontinued. The correlation between the use of the product and the consequent adverse reaction was evaluated as probable. In literature two cases of hepatoxicity in humans after the intake of G. lucidum have been described.⁶
One report describes one case of hypoglycemia in a woman who had been drinking for one week green tea blended with G. lucidum for detoxing and to improve her headache. The correlation was evaluated as possible both for the timings and for the in vitro studies present in literature that highlighted the hypoglycemic effects of this mushroom.^1,2
The last two reports concern a man with acute esophagitis after only 4 days of taking a product containing G. lucidum, that resolved after discontinuing the supplement, and a woman whom presented cardiorespiratory and pancreatic insufficiency after taking green tea with G. lucidum, but the event was not considered correlated because the patient already presented a critical clinic picture.
The products containing G. lucidum are, like many other natural products, available online, a channel hard to monitor. The consumer purchases without real guarantee on the quality of the product and without consulting a health professional. This might entail the risk of using the product for periods of time not in compliance with its characteristics or the risk of interactions with other drugs already administered. Besides, the Internet plays an important role in the dissemination of pseudo-scientific information from the website that sell these products. It is therefore necessary a correct information for the consumers whom, considering “natural” products safe, tend to take them naively and without awareness. These last considerations, together with the wide use of G. lucidum, might bring to an increase of the cases already discussed.