Bamboo salt is made by putting sea salt into a piece of bamboo packed with special clay at both ends then burned and dried up to 8 times. The selenium in the bamboo which is packed with the stuff, only coal in China has more, is transferred to the salt. Both as a "Medicinal Salt" and as "Bamboo Salt Soy Sauce" it is a source of Selenium in many diets with very positive therapeutic action, especially in the prevention of viral disease and cancer.