Used by the Incas to increase fertility and as an aphrodisiac. Also known as Peruvian Viagra, Maca is used to treat impotence, erectile dysfunction, increase fertility and increases sexual desire or libido.

The active components are macamides.  The macamides or maca alkaloids are components that act in the hypothalamus and adrenal glands regulating hormone levels and increasing energy and virility.  Maca increases blood flow to the pelvic area stimulating potency. Improves sperm production and motility and increases female fertility.  Maca root contains copper, a mineral important for fertility and zinc a mineral constituent of sex hormones. 

(Accessed on 11 August 2015 http://www.botanical-online.com/english/aphrodisiacs.htm )