Herbs & Supplements:
Reishi
Ganoderma lucidum

Principal Proposed Uses
  • Adaptogen (Improve Resistance to Stress)
Other Proposed Uses
  • Cancer Prevention, Autoimmune Diseases, Viral Infections, High Blood Pressure, Diabetes, Impaired Mental Function, Altitude Sickness, Ulcers, Insomnia

The tree fungus known as reishi has a long history of use in China and Japan as a semi-magical healing herb. More revered than ginseng and, up until recently, more rare, many stories tell of people with severe illnesses journeying immense distances to find it. Presently, reishi is artificially cultivated and widely available in stores that sell herb products.

What Is Reishi Used for Today?

Reishi is marketed as a kind of cure-all, said to strengthen immunity and help prevent and treat cancer. It is also said to be useful for autoimmune diseases (such as myasthenia gravis and multiple sclerosis), viral infections, high blood pressure, diabetes, impaired mental function, altitude sickness, ulcers and insomnia. However, while there has been a great deal of basic scientific research into the chemical constituents of reishi, reliable, double-blind studies are lacking.

Test tube studies indicate that reishi has “immunomodulatory” effects.^1-5 This means that reishi may affect the immune system, but not necessarily that it strengthens it. Similarly, preliminary evidence hints that reishi may have chemopreventive properties, suggesting that it may help prevent cancer.^4,6-12

Other highly preliminary forms of evidence suggest that reishi may have antiviral effects^13-19 and possibly anti-bacterial effects as well.²⁰ However, it is a long way from studies of this type to meaningful clinical uses.

Contemporary herbalists regard reishi as an adaptogen, a substance believed to be capable of helping the body resist stress of all kinds. (For more information on adaptogens, see the article on ginseng.) However, there is no meaningful evidence to support this belief.

Dosage

The usual dosage of reishi is 2 to 6 g per day of raw fungus, or an equivalent dosage of concentrated extract, taken with meals. In traditional Chinese medicine, reishi is often combined with related fungi, such as shiitake, hoelen, or polyporus. It is often taken continually for its presumed overall health benefits.

Safety Issues

Because it is used as food in Asia, reishi is generally regarded as safe. However, one study suggests that reishi impairs blood clotting.²¹ For this reason, prudence suggests that individuals with bleeding problems should avoid reishi; the herb should also be avoided in the period just before and after surgery or labor and delivery. Furthermore, individuals taking medications that impair blood clotting, such as aspirin, warfarin (Coumadin) heparin, clopidogrel (Plavix ), pentoxifylline (Trental ), or ticlopidine (Ticlid), should only use reishi under a doctor’s supervision.

Safety in young children, pregnant or nursing women, or those with severe liver or kidney disease has not been established.

Interactions You Should Know About

If you are taking blood-thinning medications, such as aspirin, warfarin (Coumadin), heparin, clopidogrel (Plavix ), pentoxifylline (Trental ), or ticlopidine (Ticlid), use reishi only under a doctor's supervision.

Last reviewed July 2002 by Medical Review Board

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