Ashwagandha
Ashwagandha root is an herbal remedy from the ayurvedic tradition of India that has been used for centuries to promote strength and stamina. It is considered an "adaptogen", a term used to describe herbs that improve physical energy, increase immunity to colds and infections, and increase sexual capacity.
Ashwagandha has mainly been used to restore male libido, cure impotence and increase male fertility. Recently, studies suggest that Ashwagandha is also effective in enhancing female libido.
The mechanism of action of ashwagandha is not fully understood, although research from India demonstrates that it has stress-protective properties similar to those of Asian ginseng.
A study published in 2000 by the "Journal of Ethnopharmacolgy" found that ashwaganda can increase swimming endurance and act as a cardioprotector and anticoagulant in rats and frogs. One group of German scientists reviewed the evidence on ashwaganda in small-animal tests and concluded that the herb contains steroid-like compounds that may produce resistance to physical, and biological stress. In a study published in "Neurochemistry International", researchers found that withania somnifera enhanced activity in nerve signals in the cortical and basal forebrain of male rats. The report speculated that this might partially explain the cognitive and memory enhancing reputation of the extract.