Maca – (Lepidium meyenii, Lepidium peruvianum)
Peruvian maca (Lepidium meyenii) is a root native to the Andean region, cultivated for at least 2000 years. It belongs to the Brassicaceae family and grows in high-altitude regions characterized by rocky formations, intense sunlight, strong winds, and extreme weather conditions, unsuitable for the growth of many other species. The indigenous population traditionally consumes maca which has a unique flavor and an aroma like caramel. The roots or hypocotyls are consumed cooked or stored dried and can be used for juices, soups, and extracts, and for enriching other foods with their powder.
Maca root has different colors that are responsible for positively influencing its pharmacological and biological action. Yellow maca corresponds to about 60% of all maca hypocotyls harvested in Peru. It is the most widely used and researched form among all maca products. Its properties increase energy, improve concentration, and balance hormones. Red maca accounts for about 25% of the annual harvest and is the sweetest and highest in phytochemical levels among maca powders with all litter colors. It is known as the most effective type for women because of its hormonal balance effects and its action on bone health. The black maca is the rarest of all colors, accounting for about 15% of the annual harvest. Studies have shown that it is the most effective form for men, especially for muscle gain, endurance, mental focus, and libido.
Various bioactivities of maca include enhanced reproductive health, antifatigue, antioxidation, neuroprotection, antimicrobial activity, anticancer, hepatoprotection, immunomodulation, and improving skin health and the digestive system’s function. Animal studies suggest maca may increase endurance, enhance sexual function, and improve memory deficits. It also demonstrated antidepressant and postmenopausal hormone-modulating effects.
The Peruvian maca has a high nutritional value like cereal grains and a better composition compared to other hypocotyls, such as potatoes, carrots, and turnips. It is rich in fiber, many essential amino acids, fatty acids, and other nutrients, including vitamin C, copper, iron, and calcium. Besides these essential nutrients, this root contains bioactive compounds responsible for benefits to the human body, which has caused a considerable increase in its consumption in the last 20 years worldwide.
When fresh, this root has 80% water content, leaving a small portion for the other nutrients. Hence, a study of the dry matter reveals that this root is rich in protein (8.87–11.6%), with a small lipid portion (1.09–2.22%), in addition to 8.23–9.08% fiber, 4.9–5.0% ash, and 54.61 to 60.00% carbohydrates, where 23.41% is sucrose, 1.55% glucose, 4.56% oligosaccharides, and 30.42% polysaccharides.
Maca also contains glucosinolates, mostly benzylglucosinolate, along with hydroxy or methoxylated benzyl derivatives and tryptophan-derived compounds, and depending on the phenotype (red, yellow, purple, or black) may be associated with different biological effects.
In vitro, maca or its constituents have demonstrated antiviral, antioxidant, anti-inflammatory, analgesic, or neuroprotective activities. Animal studies suggest maca may increase endurance, enhance sexual function, and improve memory deficits. It also demonstrated antidepressant and postmenopausal hormone-modulating effects.
Only a few small trials have been conducted in humans. Maca consumption was associated with lower serum IL-6 levels and higher health status. In men, preliminary findings suggest supplementation may enhance subjective sexual well-being. In women, several studies suggest maca improves both antidepressant- and menopause-induced sexual dysfunction. Gonzales et al. suggested that black maca may cause an increase in sperm count compared to the use of yellow maca. In turn, the red maca is effective against benign prostatic hyperplasia. Black, yellow, and red macas showed effects on depression.
Nguyen et al demonstrated the neuroprotective activity of maca extracts in vitro in neurons subjected to oxidative stress with H2O2. The neuroprotective effect of these substances is historically attributed to their antioxidant action. However, nowadays, scientists have known that antioxidant action is not solely responsible for the ability to prevent or reverse neuronal dysfunction and cognitive deficits. Recent studies point to several other potential mechanisms, such as anti-inflammatory action, regulation of transcription factors, and protein inhibition. Macamides present in maca extracts are believed to be the active compounds responsible for the neuroprotective effect through the inhibition of Fatty acid amide hydrolase (FAAH). FAAH inhibits anandamide endocannabinoid degradation that is involved in cell proliferation of neural progenitor cells, involving CB1 and CB2 receptors in this process. Reactive oxygen (ROS) and nitrogen (RNS) species (in the forms of superoxide, hydroxyl radical, peroxyl, H2O2, and peroxynitrite) are implicated in the etiology of degenerative disorders due to excessive production and release of excitatory neurotransmitters. Maca could indirectly prevent the formation of ROS/RNS by a modulatory mechanism of neurotransmitter release, and thus help protect cells from pathological changes. Also, an inflammatory marker, cytokine IL-6, at a severe level was reduced in maca users, and this was associated with a better quality of life, which may indicate an anti-inflammatory maca property.
In vitro, both methanolic and aqueous extracts of maca exhibit estrogenic activity. A methanol maca extract demonstrated antiviral activity against Flu-A and Flu-B viruses. An isolated N-alkylamide from maca root exerted cannabimimetic actions. Maca polysaccharides demonstrated radical scavenging activity. Macamides, normally not present in fresh plants but introduced during traditional drying practices, are fatty acid amide hydrolase inhibitors that modulate the release of neurotransmitters. Antidepressant-like effects were associated with the activation of both noradrenergic and dopaminergic systems and the attenuation of oxidative stress.
In animal models, maca powder enhanced serum luteinizing hormone (LH) levels in female rats during the proestrus LH surge in a dose-dependent manner, suggesting it may enhance fertility. In postmenopausal models, maca modulates hormone levels particularly by decreasing follicle-stimulating hormone (FSH) levels.
In humans, although maca does not affect serum levels of LH, FSH, prolactin, testosterone, or estradiol in men, it appears to modulate some hormone levels in women in some studies but not others. Increased LH and decreased FSH that corresponded with improved sexual functioning in postmenopausal women are potentially attributed to a negative feedback loop, resulting in increased androgen production. It may also exert androgenic effects at the testosterone receptor on target organs without affecting testosterone or gonadotrophin levels. At the same time, the benefits of maca for antidepressant-induced sexual dysfunction in women may be more a function of advancing age rather than menopausal status, as there was no correlation with estrogen levels.
Ai Z, Cheng AF, Yu YT, et al. Antidepressant-like behavioral, anatomical, and biochemical effects of petroleum ether extract from maca (Lepidium meyenii) in mice exposed to chronic unpredictable mild stress. J Med Food. May 2014;17(5):535-542.
Almukadi H, Wu H, Bohlke M, et al. The macamide N-3-methoxybenzyl-linoleamide is a time-dependent fatty acid amide hydrolase (FAAH) inhibitor. Mol Neurobiol. Oct 2013;48(2):333-339.
Balick MJ,.Lee R. Maca: from traditional food crop to energy and libido stimulant. Altern Ther Health Med 2002;8:96-8.
Brooks NA, Wilcox G, Walker KZ, et al. Beneficial effects of Lepidium meyenii (Maca) on psychological symptoms and measures of sexual dysfunction in postmenopausal women are not related to estrogen or androgen content. Menopause. Nov-Dec 2008;15(6):1157-1162.