Cordyceps sinensis is a fungus that has been used by traditional Chinese herbalists for its energizing and adaptogenic properties for centuries. Cordyceps has numerous bioactive compounds, including polysaccharides and nucleosides, which have been studies for their broad range of biological activities. Modern scientific studies have shown that Cordyceps constituents posses free radical scavenging properties and suggest that they may also support a healthy immune system and promote normal vascular function.