maca

Common names
Maca, black maca, red maca
Botanical names
Lepidium meyenii, Lepidium peruvianum
Parts used and where grown
Maca is a cruciferous
vegetable in the mustard family, related to radishes and turnips. Used as food and medicine in the Andes Mountains of Peru, it is not known to occur naturally anywhere else in the world. The four major cultivars of maca are red, black, cream, and purple; none has been definitely proven to be medicinally superior to any other.
Maca has been used in connection with the following conditions (refer to the individual health concern for complete information):
Science Ratings - Health Concerns
** - Low libido
** - Male infertility
* - Stress
*** - Reliable and relatively consistent scientific data showing a substantial health benefit.
** - Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
* -For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.
Historical or traditional use (may or may not be supported by scientific studies)
Maca root has been an important food for the native people in the Andes of Peru, including the Incas, for at least 2,000 years.1 It is eaten baked, dried, mixed with
milk, or in a variety of other forms and dishes. It is also traditionally believed to enhance strength, endurance, libido, and fertility.2
Active constituents
Maca contains substantial quantities of protein,
fat, fiber, and minerals including iron, which also contribute to its nutritional value. It also contains glucosinolates,3 the strong-smelling compounds that are responsible for the pungent smell and taste of mustard family plants. Neither these nor any other constituents in maca have definitively been shown to contribute to its actions.
Preliminary studies have shown that maca can increase libido in healthy men.4 It does this without influencing levels of testosterone or any other sex hormones.5 Healthy men who take maca have also been shown to have increased semen volume, increased sperm counts, and enhanced sperm motility.6
Numerous animal studies show that maca extracts can increase sex drive and improve fertility.7 8 9 Other studies support that it can relieve the negative effects of stress reactions.10 The red cultivar, though not the black or cream, also reduced enlarged prostates in rats.11

How much is usually taken?
The amount used successfully in studies so far has been 500 to 1,000 mg three times per day of dried root powder in capsules.12

Are there any side effects or interactions?
Glucosinolates can cause goiter (swollen thyroid gland with decreased activity) if taken in excess combined with a low-iodine diet. Though this is documented to occur with other glucosinolate-rich foods, it is not known if maca causes goiter.
At the time of writing, there were no well-known drug interactions with maca.