Polyporus umbellatus, also known as Zhu Ling or Umbrella Polypore, stands out for its widespread use in both traditional and modern medicine. This mushroom is native to China and other Asian countries, but it is now cultivated and studied worldwide due to its health-promoting properties.

Polyporus umbellatus belongs to the Polyporaceae family, which includes over 2,000 species of mushrooms worldwide. This species is a saprotrophic fungus that grows on dead or dying hardwood trees, such as oak, maple and birch, in temperate and subtropical forests. Its fruiting body, which emerges from the tree bark in late summer or early autumn, is a large, umbrella-shaped mushroom with a brownish-yellow or reddish-brown cap that can reach up to 30cm in diameter. The cap is smooth and slightly sticky when moist and it has several radiating, concentric zones with a white margin. The under-surface of the cap is covered with tiny, white-to-yellowish pores that release the spores for reproduction.

For centuries, Polyporus umbellatus has been used in Chinese medicine for its diuretic, anti-inflammatory, anti-tumour and anti-viral properties. Recent scientific studies have confirmed some of these health benefits and shed light on the active compounds responsible for them.

Polysaccharides, particularly beta-glucans, are the main bioactive components in Polyporus umbellatus. These complex carbohydrates have immune-modulating effects by stimulating the activity of white blood cells and enhancing the production of cytokines, which are signalling molecules that regulate inflammation and immunity. Some studies have also suggested that beta-glucans from Polyporus umbellatus can inhibit the growth and metastasis of cancer cells by inducing apoptosis (programmed cell death) and reducing angiogenesis (the formation of new blood vessels).

Other phytochemicals found in Polyporus umbellatus include triterpenoids, steroids, flavonoids, phenolic acids and volatile oils. These compounds have antioxidant, anti-inflammatory and anti-microbial properties that may contribute to the mushroom's health benefits. For instance, triterpenoids such as pachymic acid and dehydropachymic acid have been shown to inhibit the proliferation and migration of cancer cells by targeting various signalling pathways.

Several clinical trials have investigated the therapeutic potential of Polyporus umbellatus in humans and some examples are shown below:

-                      A randomised, double-blind, placebo-controlled trial in 2008 investigated the effects of a Polyporus umbellatus extract (called PSK) in patients with advanced gastric cancer who underwent chemotherapy. The study enrolled 340 patients and found that the PSK group had significantly longer overall survival and disease-free survival than the placebo group. The researchers concluded that PSK could enhance the efficacy of chemotherapy and improve the prognosis of gastric cancer patients.

-                      Another randomised, double-blind, placebo-controlled trial in 2014 evaluated the effects of a Polyporus umbellatus extract (called PUPP) on immune function and quality of life in patients with chronic hepatitis B virus infection. The study enrolled 120 patients and found that the PUPP group had significant improvements in immune parameters, liver function and quality of life compared to the placebo group. The researchers suggested that PUPP could be a promising adjuvant therapy for chronic hepatitis B.

-                      Similarly, another randomised, double-blind, placebo-controlled trial in 2019 examined the effects of a Polyporus umbellatus extract (called LVE) on renal function and inflammation in patients with chronic kidney disease. The study enrolled 80 patients and found that the LVE group had significant improvements in renal function, inflammatory markers and quality of life compared to the placebo group. The researchers suggested that LVE could be a potential therapeutic option for chronic kidney disease patients.

Overall, these clinical trials suggest that Polyporus umbellatus has promising therapeutic potential in various health conditions, although further research is needed to confirm and optimise its clinical use.

Although Polyporus umbellatus has a long history of safe use in traditional medicine, some studies have reported potential toxicity or adverse effects when consumed in large amounts or in combination with certain drugs. For instance, the mushroom may interact with blood-thinning medications or immunosuppressive drugs and cause bleeding or infections. Moreover, some cases of liver damage or allergic reactions have been reported in people who consumed high doses of Polyporus umbellatus supplements or extracts.

Therefore, it is recommended to consult a healthcare professional before using Polyporus umbellatus for medicinal purposes, especially if one has a pre-existing medical condition or is taking medications.

Apart from its medicinal properties, Polyporus umbellatus has potential industrial applications in various fields. For example, the mushroom's mycelium (the vegetative part of the fungus) can be used to produce enzymes, organic acids and bioactive molecules for food, feed and cosmetic industries. In addition, the mushroom's fruiting body contains a high percentage of chitin, a biopolymer that has applications in agriculture, waste treatment and biomedical engineering.

In conclusion, Polyporus umbellatus is a valuable natural source with significant potential for drug development and various other applications. However, while studies have shown its promising potential as a therapeutic agent further research is needed to enhance its clinical use and elucidate its mechanisms of action.

 

Renald Blundell is a biochemist and biotechnologist with a special interest in Natural and Alternative Medicine. He is a professor at the Faculty of Medicine and Surgery, University of Malta

 

Emma Camilleri is currently a medical student at the University of Malta