Maca (Lepidium meyenii)

Lepidium meyenii, known as maca or Peruvian ginseng, is an edible herbaceous biennial plant of the Brassicaceae family (ie, broccoli and cabbages are also part of this family) that is native to South America in the high Andes mountains of Peru. It was found exclusively at the Meseta de Bombón plateau close to Lake Junin in the late 1980s.[1] It is grown for its fleshy hypocotyl that is fused with a taproot, which is typically dried, but may also be freshly cooked as a root vegetable. If it is dried, it may be further processed into a flour for baking or as a dietary supplement. It also has uses in traditional medicine. As a cash crop, it is primarily exported as a powder that may be raw, or processed further by the supplement industry: gelatinized or made into an extract.

The Biology of Maca plants

The growth habit, size, and proportions of maca are roughly similar to those of radishes and turnips, to which it is related, but it also resembles a parsnip. The green, fragrant tops are short and lie along the ground.[5] The thin, frilly leaves sprout in a rosette at the soil surface, not growing more than 12–20 cm (4.7–7.9 in) in height. The leaves show a dimorphism according to reproductive stage. They are more prominent in the vegetative phase, and are continuously renewed from the center as the outer leaves die. The off-white, self-fertile flowers are borne on a central raceme, and are followed by 4–5 mm (0.16–0.20 in) siliculate fruits, each containing two small 2.0–2.5 mm (0.079–0.098 in) reddish-gray ovoid seeds. Seeds are the maca’s only means of reproduction. Maca reproduces mainly through self-pollination and is an autogamous species. The genome consists of 64 chromosomes. From experiments with different day lengths, maca is a short-day plant.[1] Some sources consider the maca to be an annual plant, as in favorable years it can complete a lifecycle within a year.[5]

Maca is the only member of the Lepidium genus with a fleshy hypocotyl, which is fused with the taproot to form a rough inverted pear-shaped body. Maca does vary greatly in the size and shape of the root, which may be triangular, flattened circular, spherical, or rectangular, the latter of which forms the largest roots. Traditionally, native growers have acknowledged four varieties of maca, based on their root color: cream-yellow, half purple, purple, and black; varying levels of anthocyanin is primarily responsible for the color differences.[2]

Maca hypocotyls may be gold or cream, red, purple, blue, black, or green. Each is considered a “genetically unique variety”, as seeds of the parent plants grow to have roots of the same color. Specific phenotypes (in maca, ‘phenotype’ pertains mainly to root color) have been propagated exclusively to increase commercial interest.[6] Cream-colored roots are the most widely grown and are favored in Peru for their enhanced sweetness and size. Black maca is both sweet and slightly bitter in taste.

The natural environment of the maca is at 11-12ºS latitude and at an elevation of 3,800–4,400 m (12,500–14,400 ft) above sea level.[6] At this elevation, temperatures of the growing season vary from −2 to 13 °C (28 to 55 °F) in monthly mean minimum or maximum, respectively. Temperatures can decline, however, as low as −10 °C (14 °F) and frosts are common. Of the cultivated plants, maca is one of the most frost tolerant.[7] Strong winds and sunlight also are characteristics of the native habitat of the maca. Maca today is still mainly cultivated in Peru, in the high Andes of Bolivia, and to a small extent also in Brazil.[5] Maca can be cultivated beyond its natural elevation range, over 4,400 m (14,400 ft) above sea level.[8]

Alpaca manure is used to fertilize maca croplands

Maca (Peruvian ginseng) seedlings usually emerge about one month after sowing with the onset of the rainy season in October. In the vegetative phase, until May to June, the lower part of the hypocotyl, as well as the upper part of the tap root, grows in size. After 260 to 280 days, it is formed to the harvestable hypocotyl. If the root is left in the soil, it is dormant for two to three months in the time of the cold, dry season until August. Then it will form a generative shoot on which the seeds ripen five months later. One plant is capable of forming up to 1000 tiny seeds, 1600 of which weigh about one gram. Thus, only relatively few plants are needed for propagation. The plants for cultivation are selected for preferred size and color, then placed 50–100 mm deep in pits with alternate layers of grass and soil to protect them from drying out. They are fertilized heavily, as maca is a soil exhaustive crop.[2] The cultivation cycle is strictly linked to seasonality.[1][5]

Traditionally, land preparation was done by hand. Nowadays, tractor plowing also is used. As maca grows on sites where no other crops can be cultivated, it is often found after long fallows of sheep grazing pastures.[1] Maca croplands thus traditionally are only fertilized with sheep and alpaca manure; however, fertilizer application could prevent soils from depleting in nutrients.

Almost always organic

Weeding or pesticide application usually is not necessary as the climate is not suitable for most weeds or pests. Nearly all maca cultivation in Peru is carried out organically, as maca itself is seldom attacked.

Maca is sometimes interplanted with potatoes, as it is known to maca farmers that the Macao plant naturally repels most root crop pests. The harvest is done manually, with the leaves left in the field as livestock feed or organic fertilizer.

The yield for a cultivated hectare may reach an estimated 15 tons in fresh hypocotyls resulting in around 5 tons of dried material.[5] According to the Ministry of Agriculture of Peru, however, average maca yields for 2005 were only 7 t/ha, with a great variation between different sites.[1] Although maca has been cultivated outside the Andes, it is not yet clear whether it develops the same active constituents or potency outside of its natural habitat. Hypocotyls grown from Peruvian seeds form with difficulty at low elevations, in greenhouses, or in warm climates.

Recent Economic Boom

Due to its purported effects on fertility, maca grew in agricultural, commercial and research interest over the decades of the 1990s to 2014.[1][14] Market studies showed low acceptance of the particular maca taste by consumers when first exposed to it, creating a barrier for popularity of this food as a culinary vegetable. The economic interest existed more in the alleged health effects of the root’s constituents supplied as an extract in a dietary supplement.[1][14]

By 2014, agricultural and market interest for maca grew in China, but with challenges from Peruvian institutions who accused Chinese companies of illegally exporting maca and of biopiracy, as several Chinese patents had been filed to improve the propagation and genetic diversity of maca.[15]

Maca is mainly grown for consumption of its root. The majority of harvested maca is dried. In this form, the hypocotyls can be stored for several years.[1][16] In Peru, maca is prepared and consumed in various ways, although traditionally it is always cooked. The freshly harvested hypocotyl may be roasted in a pit (called huatia), and is considered a delicacy. Fresh roots usually are available only in the vicinity of the growers.

The root can also be mashed and boiled to produce a sweet, thick liquid, then dried and mixed with milk to form a porridge, mazamorra.[7] The cooked roots are also used with other vegetables in empanadas, jams, or soups. The root may be ground to produce a flour for bread, cakes, or pancakes. If fermented, a weak beer called chicha de maca may be produced. In 2010, a U.S.-based brewery called Andean Brewing Company, became the first company to produce and commercialize beer made from maca under the brand KUKA Beer.[17] From the black morphotype, a liquor is produced. Also, the leaves are edible or may serve as animal fodder. They can be prepared raw in salads or cooked much like Lepidium sativum and L. campestre, to which it is closely related genetically.

The prominent product for export is maca flour, which is a baking flour ground from the hard, dried roots. It is called harina de maca. Maca flour (powder) is a relatively inexpensive bulk commodity, much like wheat flour or potato flour. The supplement industry uses both the dry roots and maca flour for different types of processing and concentrated extracts. Another common form is maca processed by gelatinization. This extrusion process separates and removes the tough fiber from the roots using gentle heat and pressure, as raw maca is difficult to digest due to its thick fibers and goitrogen content.

Biochemisty and Nutrients

(1R,3S)-1-Methyltetrahydro-carboline-3-carboxylic acid found in maca

The average composition is 60-75% carbohydrates, 10-14% protein, 8.5% dietary fiber, and 2.2% fats.[9] Maca contains polysaccharides.[10] Maca contains glucotropaeolin, m-methoxyglucotropaeolin, benzyl glucosinolates, polyphenols, (1R,3S)-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid, and p-methoxybenzyl isothiocyanate.[6][11][12] Alkamides are present in maca.[13]

A 7 g (1 tablespoon) serving of maca root powder contains 20 calories, 4 g carbohydrates, 1 g protein, and 0 g fat. Maca is rich in calcium, potassium, iron, and iodine. It also contains copper, manganese, zinc, vitamin C, riboflavin (vitamin B2), and thiamine (vitamin B1) [R].

https://www.ncbi.nlm.nih.gov/pubmed/15037892

Red and black maca have high levels of choline [R]. Red maca is high in GABA [R]. The main active compound in maca is the alkaloid macaridine. It has not been found in any other plant [R]. Maca also contains macamides, which are are fatty acids unique to maca. Glucosinolates are active components of maca and contribute a bitter flavor. Fresh maca has 10 times the glucosinolates of other cruciferous vegetables. Red maca has the most glucosinolates, followed by black and yellow [R, R].

https://www.ncbi.nlm.nih.gov/pubmed/26508907

Maca also contains polyphenols [R].

Mechanisms of Action

Maca contains macamides, which are fatty acids that affect the endocannabinoid system [R]. Macamides increase anandamide levels by blocking fatty acid amide hydrolase (FAAH), an enzyme that breaks down anandamide [R]. Anandamide acts on the cannabinoid CB1 receptor to produce feelings of happiness. Black maca reduces hemoglobin levels in individuals living at high altitude [R]. Elevated hemoglobin levels at high altitude are associated with chronic mountain sickness [R]. Maca neutralizes free radicals and protects against oxidative stress [R, R]. Maca increases total white blood cell levels (in fish) [R]. Maca increased IGF-1 levels in human cartilage, which may be responsible for Maca’s benefit to bone health [R]. Maca decreases angiotensin-converting enzyme (ACE) activity, which lowers the availability of angiotensin, a hormone that raises blood pressure [R].

Benefits

Maca has been marketed for its claimed traditional medicinal effects.[20][21][22] A 2016 systematic review found limited evidence from a small number of studies to improve semen quality in healthy and infertile men.[23] A 2011 review found mild evidence for the effectiveness of maca as a treatment for menopausal symptoms[24]   Below, a few of the purported and reported benefits.

1. Increasing libido

The most well-known benefit of maca root is its potential to increase libido. There is some scientific evidence to support this claim. For example, an older study from 2002 found that men who took 1.5 or 3 grams (g) of maca per day experienced increased libido compared to those who received a placebo. A 2010 review of studies on maca and sexual functioning found some evidence to suggest maca could improve libido, but the authors cautioned that more research is required. A 2015 study found that maca root may help reduce sexual dysfunction in postmenopausal women who were taking an antidepressant.

Taking maca for 12 weeks increased sexual desire in a study (DB-RCT) of 57 healthy men [R]. In a study of 20 men and women, taking maca for 12 weeks improved antidepressant-induced sexual dysfunction and increased sex drive in a study of 20 men and women. These effects were strongest with 3 g of daily supplementation [R]. In a study of 8 men, maca extract taken for 2 weeks increased sex drive [R].

Maca extract taken for 12 weeks increased erectile function and sexual well-being in a study (DB-RCT) of 50 men with mild erectile dysfunction [R]. In a study (DB-RCT) of 14 healthy postmenopausal women, 6 weeks of maca supplementation reduced sexual dysfunction [R]. Black maca increased sperm count, volume, and quality in a study of 9 healthy men [R].

2. Reducing erectile dysfunction

Maca root could also have benefits for people with erectile dysfunction (ED). A small study in 2009looked at the effect of consuming 2.4g of maca root per day for 12 weeks on participants’ perception of their general and sexual well-being. The study participants were males with mild ED. Those taking maca root experienced a more significant increase in sexual well-being than those taking a placebo.

3. Boosting energy and endurance

Some athletes and bodybuilders use maca root as a supplement to increase energy and performance. Some evidence exists to support this. A pilot study in 2009 found that using maca extract for 14 days improved performance for male cyclists in a 40-kilometer time trial. However, the results were not significantly different from the improvement seen in those taking a placebo. However, the same study found that maca extract improved libido in the participants who used it. However, the sample size of this study was very small, so more research is needed to confirm the results.

4. Increasing fertility

Another widespread use of maca root is to increase fertility, particularly in men. A 2016 review found some evidence that maca root may increase semen quality in both fertile and infertile men. However, more research is needed.

Maca contains flavonoids, which are thought to improve mood and reduce anxiety. A study in 14 postmenopausal women found that maca may reduce feelings of anxiety and depression. Also, a 2015 study found that maca could reduce symptoms of depression in Chinese postmenopausal women.

6. Reducing blood pressure

It is possible that maca root can also help to improve blood pressure. The same 2015 study also found that 3.3g of maca per day for 12 weeks lowered blood pressure in Chinese postmenopausal women.

7. Reducing sun damage

An older study in an animal model found that maca might help protect the skin from UV rays. Another animal study in 2011 found that extracts from maca leaves might help prevent the formation of sunburn cells.

8. Fighting free radicals

Maca root also promotes natural antioxidants in the body, such as glutathione and superoxide dismutase.

Antioxidants help to fight off free radicals, which can damage cells in the body. Some people believe antioxidants can help prevent some health conditions, including heart disease and cancer.

9. Reducing menopause symptoms

Some proponents of maca root believe it may help balance levels of the hormone estrogen. During perimenopause, the stage before a woman reaches menopause, estrogen levels fluctuate and cause a variety of symptoms. One study found that postmenopausal women who took two daily tablets containing maca experienced reduced symptoms, such as hot flashes and night sweats.

10. Improving learning and memory

There is some evidence to suggest that maca can improve learning and memory. For example, a 2011 study found that maca could improve memory in mice.

A 2014 review of the literature suggested that maca may have benefits for learning and memory performance. Researchers suggested that it could be helpful in treating conditions that affect these processes, such as Alzheimer’s disease. However, only research on animal models is currently available, so it is unclear whether maca will have the same benefits in humans.

 

11. Maca Decreases Anxiety and Depression

In rats, maca reduced depression-like behaviors [R]. Maca taken for 6 weeks lowered anxiety and depression symptoms in studies (DB-RCTs) of 43 postmenopausal women [R, R]. In a study (DB-RCT) of 197 people, 12 weeks of maca supplementation improved mood [R].

12. Maca Improves Osteoarthritis Symptoms

Reparagen, a compound comprised of 83% maca, improved pain, stiffness, and physical function in a study (DB-RCT) of 95 osteoarthritis patients [R].

13.  Maca Reduces Inflammation and Oxidative Stress

Black maca decreased markers of oxidative stress in mice [R]. In a study of 50 people, those who regularly consumed maca had lower levels of inflammation (IL-6) than those who did not [R].

14. Maca Balances Female Sex Hormones

Maca powder taken for 2 months lowered follicle stimulating hormone and luteinizing hormone, and increased estrogen and progesterone in a study (DB-RCT) of 20 postmenopausal women [R].

15 Maca Reduces Blood Sugar Levels

Black maca lowered blood glucose in a study (DB-RCT) of 197 adults [R].

16. Maca Increases Exercise Performance

In a pilot study (DB-RCT) of 8 endurance cyclists, 2 g of maca taken for 2 weeks improved cycling performance [R].

17. Maca Reduces Chronic Mountain Sickness

Chronic mountain sickness is a lack of adaptation to high altitude [R]. Maca consumption was associated with reduced prevalence of chronic mountain sickness in a study of adults [R].

Red maca lowered chronic mountain sickness symptoms in a study (DB-RCT) of 197 adults [R].

18. Maca May Improve Cognitive Function

Maca improved learning in mice, with black maca showing the strongest effects [R]. Black maca protects against memory impairment in mice [R, R, R].

19. Maca May Shrink an Enlarged Prostate

In animals with enlarged prostates due to excess testosterone, red maca extract reduced prostate size [R, R].

20. Maca May Protect Skin from UV Exposure

Maca extract applied to the skin of rats protected from UV radiation [R]. Red, black, and yellow maca applied to the skin of rats prevented the development of sunburn cells and other signs of UV damage. Maca also showed substantial antioxidant effects [R].

Discussion

Monoamine Oxidase Inhbitors

The presence of 1R,3S-1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) in the extracts of maca indicate a potential safety issue as a monoamine oxidase inhibitor and possibility as a mutagen.[11] Due to these potential mutagenic properties of MTCA, the Agency for Sanitary Security in France warned consumers about the possible health risks of powdered maca root, a declaration disputed on the assumption that MTCA would be deactivated by boiling to process maca roots.[11] MTCA-like compounds are associated with craving behaviour.[11]

Besides the above-mentioned issue, whose alleged mutation effect continues to be unproven among humans, maca is not currently associated with any health risks in most people and is unlikely to cause any side effects in moderate doses.The majority of the research above has been performed by one lab in Peru, so use caution when interpreting the results. Residents of the Andes Mountains in Peru consume up to 100 g of maca per day without side effects [R]. However, natives advise consuming only dehydrated or boiled maca root because raw maca may cause health issues [R]. In clinical studies, maca is well-tolerated up to 3 g/day [R].

 

Conclusion

Maca has a range of potential health benefits, particularly for sexual health. However, the evidence behind these health benefits is weak, as many studies used small sample sizes or animal models. Researchers need to carry out more large-scale studies in humans to determine if maca is effective. Although there are few health risks associated with taking maca, most people can try maca without experiencing any adverse side effects.

References

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  17. ^ New For TAP NY (Part Two): The KUKA Andean Brewing Company Archived2016-03-04 at the Wayback Machine
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