Reishi (Ganoderma)

Introduction

Reishi (Ganoderma lucidum), called lingzhi in China, is a woody bracket fungus that grows on trees. You can recognise it by its red-brown cap, glossy as if varnished, with pores underneath. Rare in the wild, it has been cultivated since the 1970s. Too tough to cook, it is used dried, powdered, as an extract or as a tea.

History

According to historical sources, reishi already appears in the Shennong Bencao Jing, one of the oldest Chinese herbal texts (around 200–250 CE). It is described again in Li Shizhen's Bencao Gangmu, published in 1596. In Chinese art it is a symbol of long life.

Traditional uses

It is traditionally prepared as a decoction: dried slices are simmered for a long time in water, giving a brown, bitter drink. Today it is mostly found in capsules, as a powder, or blended into coffee and tea.

Scientific studies

A 2004 controlled trial in 18 healthy adults (aged 22 to 52) compared 1.44 g of reishi a day with a placebo for 4 weeks: none of the measured markers changed significantly, with a slight trend towards lower blood lipids and higher antioxidant capacity measured in urine. The authors found no sign of liver, renal or DNA toxicity. Human studies are still few. Reishi is a food supplement, not a medicine.

Precautions

• Possible side effects: nausea, digestive upset, insomnia. A few cases of liver injury have been reported.
• Spore powder can raise a blood marker (CA72-4): tell your doctor before a blood test.
• Possible interactions with blood thinners, immunosuppressants and chemotherapy.
• Talk to your doctor before taking it, especially during pregnancy or breastfeeding.

Further reading: Memorial Sloan Kettering