Reishi is used as an immune stimulant by cancer and HIV patients. Reishi also might help to prevent the growth and proliferation of tumors. In addition, MSKCC states that reishi has been found to increase the number of antioxidants in the blood plasma and enhance the immunity of advanced-stage cancer patients. Reishi might, however, interact negatively with certain cancer drugs, and if you have cancer you should take reishi only under the supervision of your doctor. Reishi is thought to support and promote cardiovascular health and Traditional Chinese Medicine practitioners use it for the treatment of coronary artery disease. Reishi is used to prevent high blood pressure and heart disease, lower high cholesterol levels and improve blood flow to the heart. Reishi also helps to prevent blood clots by keeping the blood thin and preventing it from clumping, a condition known as platelet aggregation. Traditional Chinese Medicine uses reishi to slow aging; build resistance to disease; reduce inflammation; cleanse the blood; support liver, kidney and nerve function; enhance strength and stamina; and improve lower urinary tract function in men. It also is used to treat hay fever, insomnia, fatigue, viral infections, stomach ulcers, depression and impotence. These uses are based on anecdotal evidence, however, and not on solid scientific research.