Reishi Mushrooms as Remedy?

Without question, the reishi mushroom is a real head-turner. With its glossy, gradient crimson surface, the mushroom has been used medicinally by the Chinese for thousands of years. Studies now suggest that the Chinese are on to something.

Reishi mushrooms (Ganoderma lucidum or G. lucidum) may have potential cancer-fighting properties. “Reishi mushrooms contain complex sugars known as beta-glucans that have been shown to stop the growth and prevent the spreading of cancer cells in laboratory and animal studies,” says K. Simon Yeung, manager of Memorial Sloan-Kettering Cancer Center’s “About Herbs” website.

The mushrooms also could play a role in cancer prevention, says Daniel Sliva, senior investigator of Indiana University Health Methodist Hospital’s Cancer Research Laboratory in Indianapolis. Sliva’s study, published in the journal PLOS One, found that triterpenes-ganoderic acids (steroid-like molecules found in Reishi mushrooms) prevented colitis-associated colon cancer in mice and rats. New data from Sliva’s research suggests that an extract containing a standardized mixture of triterpenes-ganoderic acids and polysaccharides (a carbohydrate found in Reishi mushrooms) could inhibit breast cancer metastasis. “Triterpenes-ganoderic acids appear to suppress inflammation and kill cancer cells with limited toxicity to bystander cells, while polysaccharides stimulate the immune system,” Sliva says. This immunity boost is particularly important to those whose systems have been weakened by cancer treatments.

A variety of mushrooms are widely used in Asian countries for therapeutic purposes. “More than 90 percent of cancer patients in countries like China and Japan use supplements, including medicinal mushrooms,” says Yeung. Their use in the Western Hemisphere has grown over the past decade. Still, Yeung cautions that the benefits and risks of reishi mushroom dietary supplements need to be better assessed in well-designed clinical trials. “Most of the current findings are not based on human studies,” he says. One exception is a review of five clinical trials conducted in China. The review, published in the May 2012 issue of The Cochrane Library, found that people with various cancers who took reishi mushroom supplements responded more positively to chemotherapy and radiation treatments than those who didn’t. Four of the reviewed studies also showed that taking the supplements while undergoing cancer treatments improved quality of life.

More than 90 percent of cancer patients in countries like China and Japan use supplements, including medicinal mushrooms.

Reishi mushroom supplements can be found at health stores and online, sold as powders, liquid extracts, capsules and even as teas. (A 2007 International Journal of Oncology study suggests that a green tea extract combination may increase the mushroom’s breast cancer-fighting properties.) Although the mushrooms grow wild in certain areas of the U.S., foraging for them isn’t advised: consuming the wrong mushroom could prove fatal. Besides, reishi mushrooms take on the strong, woody flavor of the trees from which they sprout. Yeung likens eating one to “chewing on tree bark.”

Certainly popping a supplement sounds more appealing, but patients should always check with their doctor before adding a supplement to their daily diets. “The mushroom’s antioxidant effects could interfere with chemotherapeutic agents that rely on free radicals,” Yeung comments. Reishi mushrooms also have an anti-clotting property, which means they shouldn’t be taken with blood thinners, including aspirin. And, while there are case reports suggesting that reishi mushrooms may have some positive effects on liver cancer, one of the supplement’s known side effects is liver toxicity.