Maca has been cultivated and grown high in the Andean Mountains of Peru for thousands of years.
Like Rhodiola, it flourishes in extreme environments of freezing cold winds, strong sunlight, and high elevation (over 10,000 feet). There does appear to be a correlation between plants that survive in stressful circumstances and the adaptogenic effects that such plants have on the human body and mind.
The root of the maca plant has been used for centuries as a nutritive substance that raises the body’s state of resistance to disease by increasing immunity to stress while remaining nontoxic to the recipient.
The shelf life is an amazing seven years. Maca is powerfully abundant in amino acids, phytonutrients, healthy fatty acids, vitamins, and minerals. This superfood allegedly has the ability to increase energy and stamina, working directly on the hypothalamus and pituitary glands.
Once again, there are some indications of positive effect on mood.
About two tablespoons of maca powered root was used in the above studies. A good source of maca is the “premium” combination of Peruvian sources from “The Maca Team” available on the internet.
 Rubio, J., Caldas, M., Dávila, S., Gasco, M., & Gonzales, G. F. (2006). Effect of three different cultivars of Lepidium meyenii (Maca) on learning and depression in ovariectomized mice. BMC Complementary and Alternative Medicine BMC Complement Altern Med, 6(1). doi:10.1186/1472-6882-6-23.