Lepidium meyenii

Lepidium meyenii
Root
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Brassicales
Family:	Brassicaceae
Genus:	Lepidium
Species:	L. meyenii
Binomial name
Lepidium meyenii Walp.
Synonyms
Lepidium peruvianum

Maca plants

Lepidium meyenii (maca) is an herbaceous biennial plant of the crucifer family native to the high Andes of Peru. It was found at the Meseta de Bombón close to Junin Lake in the Andes.^[1] It is grown for its fleshy hypocotyl (a fused hypocotyl and taproot), which is used as a root vegetable and a medicinal herb. Its Spanish and Quechua names include maca-maca, maino, ayak chichira, and ayak willku.

Botanical characteristics

The first westerner to describe this species was Gerhard Walpers who named it Lepidium meyenii in 1843. In the 1990s, Gloria Chacon made a further distinction of different species. She considered the widely cultivated natural maca of today to be a newer domesticated species, L. peruvianum.^[2] Most botanists today doubt this distinction, however, and continue to call the cultivated maca L. meyenii. The Latin name recognized by the USDA also continues to be Lepidium meyenii.^[3] Debate is still ongoing about the correct nomenclature and whether the distinction between meyenii and peruvianum is botanically correct.^[1]

The growth habit, size, and proportions of maca are roughly similar to those of radishes and turnips, to which it is related. The green, fragrant tops are short and lie along the ground.^[4] 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.^[4]

Root

Maca root powder

Maca is the only member of its 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. 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.^[5] 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.

Agronomy

Growth conditions

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.^[5] 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. 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.^[4]

Alpaca manure is used to fertilize maca croplands

Cultivation

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. The cultivation cycle is strictly linked to seasonality.^[1][4]

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.

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 plant naturally repels most root crop pests.

The harvest is done manually, with the leaves left on 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.^[4] 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.

Constituents

The average composition is 60-75% carbohydrates, 10-14% protein, 8.5% dietary fiber, and 2.2% fats. Maca is rich in the dietary minerals calcium and potassium (with low content of sodium), and contains the essential trace elements iron, iodine, copper, manganese, and zinc, as well as fatty acids including linolenic acid, palmitic acid, and oleic acids, and 19 amino acids.^[6] Maca contains polysaccharides.^[7]

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

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.^[5][8][9] Alkamides are present in maca.^[10]

Uses and preparation

Maca is mainly grown for the nutritional and health value of its root. The majority of harvested maca is dried. In this form, the hypocotyls can be stored for several years.^[1][11] 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 also can be mashed and boiled to produce a sweet, thick liquid, then dried and mixed with milk to form a porridge. 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.^[12] 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.^[13]

The growing demand of the supplement industry has been one of the primary reasons for maca's expanding cultivation in Peru and Bolivia.^[14] 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. Gelatinization was developed for maca specifically to mimic the activity of cooking, and to allow gentler digestion. Gelatinized maca is employed mainly for therapeutic and supplement purposes, but also can be used like maca flour, as a flavor in cooking. Available also is a freeze-dried maca juice, which is squeezed from the macerated fresh root, and subsequently freeze-dried high in the Andes.

Maca has been harvested and used by humans in the Andean Mountains for centuries. Contrary to frequent claims that maca's cultivation was common in what is today Peru, until the late 1980s, maca has been cultivated only in a limited area around Lake Junin, in central Peru. Historically, maca often was traded for lowland tropical food staples, such as corn, rice, manioc (tapioca roots), quinoa, and papaya. It also was used as a form of payment of Spanish imperial taxes.^[4][15][16] Maca was eaten by Inca imperial warriors before battles. Their legendary strength was allegedly imparted by the preparatory consumption of copious amounts of maca, fueling formidable warriors. After a city was conquered, the women had to be protected from the Inca warriors, as reportedly they became ambitiously virile from eating such quantities of maca. This is an endorsement for the masculine angle of maca's recent marketing campaign.^[17] Whether or not this often-repeated legendary use is true has yet to be determined. Those who have studied maca's history have not been able to locate formal mention of this particular use historically.^[13][18]

Maca root powder

Health effects

Maca has been marketed for its supposed benefits for sexual performance, although there is insufficient evidence that it helps with sexual or erectile dysfunction in older people.^[19][20][21] A 2016 systematic review found evidence from a limited number of studies supporting the use of maca for improvement in semen quality in healthy and infertile men.^[22] A 2011 review found limited evidence for the effectiveness of maca as a treatment for menopausal symptoms, with no evidence of its safety.^[23]

Safety

There are no pharmacokinetic data for maca.^[8] 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 an inhibitor of monoamine oxidase and possibility as a mutagen.^[8] 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.^[8] MTCA-like compounds are associated with craving behaviour.^[8]

Marketing potential

Due to its purported effects on fertility, maca grew in agricultural, commercial and research interest over the decades of the 1990s to 2014.^[1][24] 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 perceived, but unproven, health effects of the root's constituents supplied as an extract in a dietary supplement.^[1][24]

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.^[25]

References

External links

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