Being exposed to high altitude means living under conditions of hypoxia, cold, aridity and high ultraviolet radiation. Exposure to high altitude (4340 m) results in testicular disturbances in men and rats. This was also observed during exposure to a simulated altitude of 4411 m, and also by the effects of cold. The changes included degeneration of the germinal epithelium and spermatogenic arrest.
Exposure of male rats to high altitude (4340 m) reduces body weight 3 days after their arrival. This reduction seems also to be due to increased serotonergic activity.
Maca (Lepidium meyenii) is a Peruvian hypocotyl belonging to the Brassicaceae family and grows exclusively between 4000 and 4500 m altitude in the central Peruvian Andes. The root, known as Maca, has been used traditionally by Peruvians living at high altitudes as a nutrient, an energizer and for aphrodisiac and/or fertilityenhancing properties. According to folk belief, Maca is a plant that enhances fertility in human and domestic animals, which tends to be reduced at higher altitudes. The biological activity of the plant is located in the root. The first evidence that Maca improved spermatogenesis was reported in male rats by Gonzales et al. (2001a) who found that oral administration to normal adult male rats of an aqueous extract from the roots of L. meyenii (Maca) for 14 days had a beneficial effect on spermatogenesis, acting on first mitosis (stages IX–XI). Thereafter, Gonzales et al. (2001b) demonstrated that Maca also improved sperm count and sperm motility in normal men without affecting serum testosterone, luteinizing hormone and follicle-stimulating hormone levels. Its nutritional capability has also been described in mice.