TRIBULUS 40 is made for mature men, who can suffer a loss of vitality through stress, age, and the pressures of modern life. It is prepared from an extract of Tribulus Terrestris, which is rich in saponins whose action is invigorating, restorative, regenerative and stress-reducing (adaptogenes), producing an effect of rejuvenation or "new youthfulness". Studies have shown that protodioscine, Tribulus' principal active ingredient, enhances oxygenation of the tissues, which increases stamina, promotes a return to vitality and helps men remain active longer.