Not All Maca Is Created Equal: A Review of Colors, Nutrition, Phytochemicals, and Clinical Uses

Abstract

Maca (Lepidium meyenii, Lepidium peruvianum) is part of the Brassicaceae family and grows at high altitudes in the Peruvian Andes mountain range (3500-5000 m). Historically, it has been used as a nutrient-dense food and for its medicinal properties, primarily in enhancing energy and fertility. Scientific research has validated these traditional uses and other clinical applications by elucidating maca's mechanisms of action, nutrition, and phytochemical content. However, research over the last twenty years has identified up to seventeen different colors (phenotypes) of maca. The color, hypocotyl size, growing location, cultivation, and post-harvest processing methods can have a significant effect on the nutrition content, phytochemical profile, and clinical application. Yet, research differentiating the colors of maca and clinical applications remains limited. In this review, research on the nutrition, phytochemicals, and various colors of maca, including black, red, yellow (predominant colors), purple, gray (lesser-known colors), and any combination of colors, including proprietary formulations, will be discussed based on available preclinical and clinical trials. The gaps, deficiencies, and conflicts in the studies will be detailed, along with quality, safety, and efficacy criteria, highlighting the need for future research to specify all these factors of the maca used in publications.

Keywords: Lepidium meyenii; Lepidium peruvianum; adaptogen; glucosinolates; hormones; maca; menopause; phenotype; prostate; reproductive health.

Scheme 1

Peruvian (left) and Chinese (right) maca. The Peruvian maca as shown on the left was cultivated in Junín (Ancash), Peru (4200 m above sea level), and the Chinese maca on the right is from Shangri-La, China (3180 m above sea level). The shapes presented below the photos indicate the variety in shapes of hypocotyls. As described by Meissner et al. [16], the Peruvian hypocotyl shape resembled the “Kimsa kucho” and “Ruyru” forms, while the Chinese maca hypocotyls were primarily classified as “Achka chupa” and “Aqochinchay,” resembling the appearance of ginseng, with a relatively small amount categorized as “Raku chupa”. Various explanations for the Chinese maca shapes have been provided, including injury from transplantation from greenhouses to outdoor, commercial plantation sites, invasion by nematodes or microbial and/or fungal soil infections from the relatively lower altitude, and less UV radiation to disinfect soil. The photo was provided with permission by Henry O. Meissner, Ph.D., as published in [16]. Reprinted from Meissner, H.O.; Xu, L.; Wan, W.; Yi, F. Glucosinolates profiles in Maca phenotypes cultivated in Peru and China (Lepidium peruvianum syn. L. meyenii). Phytochem. Lett. 2019, 31, 208–216., with permission from Elsevier (1874-3900/ @ 2019 Phytochemical Society of Europe. Published by Elsevier Ltd. All rights reserved.),The lower half of the photo (the figure) is reprinted originally from Meissner HO, Mscisz A, Kedzia B, Pisulewski P, Piatkowska E. Peruvian Maca: Two Scientific Names Lepidium Meyenii Walpers and Lepidium Peruvianum Chacon – Are They Phytochemical-ly-Synonymous? Int J Biomed Sci. 2015 Mar;11(1):1–15. PMCID: PMC4392557. This is an open-access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.5/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Figure 1

The parts of the maca plant. The maca plant has four distinct parts: the aerial parts, stem, hypocotyl, and root.

Figure 2

The predominant colors of maca and select phytochemicals. Representative images of glucosinolates (glucotropaeolin) sourced from [105], phytosterols (beta-sitosterol) sourced from [106], alkaloids (lepidiline A) from [107], thiohydantoin (2-thiohydantoin) from [108], macamide (macamide 1) from [109], and macaene from [110].

Figure 3

Endocrine system modulation by maca phenotypes.

Figure 4

The colors of maca. The seventeen colors of maca (L. peruvianum) as compiled by Meissner in [171]. While there may be several phenotypes, the predominant colors are black, gray, red, purple, white, and yellow. Of these main phenotypes, black, red, and yellow have been most well studied for their clinical effects.

Scheme 2

Examples of colored maca hypocotyls (black, red, yellow, purple). Photo courtesy of Symphony Natural Health, taken by Patrice Christensen.