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Search online for “mushrooms” and you’ll find thousands of recipes for yummy ways to use this versatile fungus. Now, search for “functional mushrooms,” and the results are a bewildering mix of promotions for companies selling powders, pills, and an array of health claims.

Reishi: Mushroom of Immortality

Although large-scale trials in humans are lacking right now, the research is growing, and much of it is focusing on reishi, or ganoderma lucidum. Long known as the “mushroom of immortality,” reishi is one of the most widely used medicinal mushrooms in the world. According to the National Cancer Institute, reishi “has been used as medicine for a very long time in East Asia. It was thought to prolong life, prevent aging, and increase energy. In China, it is being used to strengthen the immune system of cancer patients who receive chemotherapy or radiation therapy.”

Reishi and Insomnia

Reishi’s ability to strengthen the immune system is closely related to some of its most popular uses—easing anxiety, fatigue, and insomnia.  A 2011 pilot clinical trial suggested that “spore powder of reishi may have beneficial effects on fatigue and quality of life… without any significant adverse effect.”

According to the National Institute of Health, Reishi “has shown good clinical outcomes in the treatment of insomnia, restlessness, and palpitation.” And, a 2024 overview of studies using animal subjects concluded that there is enough evidence to lead to the development of Reishi recipes that are specifically designed to help with anti-fatigue and sleep.

Smart Buying Guide

With literally hundreds of functional mushroom products on the market today, and dozens of Texas-based mushroom farms, individual growers and markets, it’s smart to know a few basic buying guidelines. Because the Food and Drug Administration does not regulate supplements like it does with food, registered dietitians at the University of Utah urge caution and judgment when purchasing mushroom supplements, as contamination and toxicity may be a concern. 

For all functional mushroom products, Consumer Reports says it’s important to go directly to the manufacturer’s website and buy from there. Other advice includes buying organic products and checking the country of origin. They recommend that consumers make sure the mushrooms are not grown in China: “The air pollution in China is notorious.”

Also, look for a third-party seal: "The supplements that are doing clinical research, or third-party testing for quality assurance, are going to be more expensive. You’re paying for quality. Look for a seal from a legitimate third party, like US Pharmacopeia (USP).”