Reishi mushrooms are best-known for their purported effects in boosting the immune system and helping fight off cancer. However, studies do not support the alleged benefits of reishi mushrooms.

The Susan G. Komen foundation, a cancer charity, has found insufficient or no evidence that reishi mushrooms are effective in:

• reducing symptoms of an enlarged prostate
• treating memory loss due to Alzheimer’s disease
• reducing noncancerous tumors in the rectum or colon
• treating clogged arteries
• alleviating stress
• reducing fatigue from cancer
• treating poisoning
• improving blood sugar levels in those with diabetes
• getting rid of stomach ulcers
• healing cold sores and genital herpes
• reducing human papillomavirus in the mouth
• treating lung cancer
• reducing fatigue
• treating altitude sickness
• treating hepatitis B
• alleviating asthma and bronchitis symptoms
• curing liver disease
• alleviating pain from shingles
• treating kidney disorders
• boosting the immune system
• treating viral infections
• curing HIV
• treating chronic fatigue syndrome
• treating prostate cancer
• helping people sleep

The Memorial Sloan Kettering Cancer Center also state that there is little or no evidence to suggest that reishi mushrooms treat:

• fatigue
• HIV
• high cholesterol
• high blood pressure
• inflammation
• a weak immune system
• urinary tract infections

However, research is ongoing on the potential benefits of reishi mushrooms. Laboratory test-tube studiesTrusted Source have found that they could be effective in fighting cancer and shrinking tumors.

There is also evidenceTrusted Source from in vitro and animal studies that reishi mushrooms may support the immune system, but high quality studies in humans are necessary before researchers draw any conclusions.