Relatively rare and undiscovered in the West, Reishi and other mushrooms have been revered as herbal medicines for thousands of years in Japan and China.
Emperors of the great Chinese dynasties and Japanese royalty drank teas and concoctions of the mushroom for vitality and long life. The ancient Taoists were constantly searching for the elixir of eternal youth, and Reishi was believed to be among the ingredients.
In ancient time, reishi in medicine was considered so auspicious that its medical efficacy has been attested to in the oldest Chinese medical text (presumed to be over 2,000 years old).
The book, which is known in Japan as "Shinnoh Honsohkyo", is now accepted as being the original textbook of Oriental medical science. In it, 365 kinds of medicines are classified and explained. The medicines are basically classified into 3 categories: 120 of them are declared to be "superior" medicines, another 120 are classified as "average" medicines, and the remaining 125 are placed in the "fair" category. The "superior" medicines are called "God's Herbs" and they are for perpetual youth and longevity - the medicines of the legendary wizards.
The "average" category medicines are those which can be taken as a tonic, and those in the "fair" category are taken to remedy specific ailments. One must be careful about the volume taken of the "average" and "fair" category medicines, and should never take them continuously. However, the book states that for "superior" medicines, any amount can be taken as desired on a continuous basis with no unfavorable effects. Of the superior medicines listed in the text, reishi was rated number one.