Reishi, is a reddish-brown, glossy mushroom with a long tradition in Chinese and Indian medicine. The shroom is known as an adaptogen that supports the body's resistance to stress and has been linked to heart health, immune system and calming effects. Reishi is rich in polysaccharides, beta-glucans and triterpenes, making it popular as a dietary supplement. It is available in powder or capsules and is often used in teas or smoothies.