Hoodia has been used for thousands of years by the San Bushmen of the Kalahari Desert to counter hunger and thirst on hunting trips. Hoodia has been studied by many scientists the past few years to determine what ingredients of hoodia are responsible for this effect on the appetite. Most of the study has focused on an active ingredient called P57 which is now believed to be the main active ingredient of hoodia. In laboratory animal test scientist discovered that animals with P57 injections resulted in dramatic reductions of food intake.