Safety of Maca

Maca became popular in the 1990s as a supplement, however, maca has been used for thousands of years by Peruvians as a food source and for its medicinal properties (1). Andean people consume maca in various ways (1–3):

• Macachincha: A fermented, sweet drink

• Pachamanca: Roots baked in an underground pit

• Mazamorra: Boiled and eaten as a porridge

• Made into jams, pudding, alcoholic cocktails and empanadas

• Consumed as a juice

It has been noted that Peruvians consume up to 100 grams of maca per day, on average (1).

Therefore, it is not surprising to see that studies have shown maca to be very safe, overall (3). Using an LD50 toxicity test, more than 15g/kg body weight in mice and more than 7.5 g/kg body weight in rats found no adverse or toxicity concerns (4,5). This dose is much higher than a human would consume. Further, no liver or neurological toxicity occurred in animal models at 1 g/kg/body weight and 10g/kg body weight, respectively (3).

Limited adverse effects have been noted in human clinical trials. This includes:

• Minor gastrointestinal symptoms (N=2), using a gelatinized black maca from an undisclosed location. This did not inhibit the participants from continuing with the trial (6)

• Possible starch intolerance (N=1), using a gelatinized yellow maca from Peru (7)

• These events were reported as transient and did not lead to discontinuation of the supplement. The form, color, location grown, and agricultural methods of the maca used in this study were not reported (8).GI upset (N= 5), headache (N=2), irritability (N= 2), panic attack (N=1), urinary frequency (N=1), blurry vision (N=1), sleep disruption (N=1), increased sweating (N=1), increased dreaming (N=1), thicker menstrual discharge (N=1), and fibromyalgia exacerbation (N=1).

One case report described a manic episode that occurred after taking a supplement for 2 weeks that contained maca, though the details are unclear as to the dose and other ingredients in the supplement (9). Another single report (male, 64 years old) described the side effect of restless leg syndrome when maca was taken with Mianserin (an antidepressant) (10). Fresh pulverized maca taken for 60 days in a dose of 115 grams per day, resulted in no adverse liver or renal toxicity (3).

One study reported that 4% of participants did not like the taste, however, this was not a safety concern (11).

In 2009, the United States Pharmacopeia conducted an evaluation to investigate safety concerns. It was concluded that maca root, maca root powder, and maca root dry extract, posed no safety concerns, as there were no serious adverse events. This data was reevaluated in 2017, and it remains that maca did not pose safety concerns (3).

With this in mind, safety concerns have recently arisen in the literature. Dokkedal-Silva, et al. expressed concerns about the safety of the plant, in part due to the concerns about it being a stimulant and the effect it, therefore, may have on sleep (12). However, this is debatable since maca is accepted to be an adaptogen within botanical medicine (13), in which simulant-like activities would occur only if this was needed to restore homeostasis. Another group noted concerns about the toxicity of the alkaloids present in maca and has suggested establishing minimum acceptable levels in food and supplement sources (14).

One publication pointed out concerns from a study published in 2007 about one of maca’s chemical compounds, MTCA (methyltetrahydro-B-carbolines) (11). While the effects of MTCA may pose health risks (inhibiting monoamine oxidase enzyme and playing a role in addiction), the findings of MTCA in maca have been disputed since the compound is deactivated during the preparation (boiling) process (15,16) and the polyphenols in maca inhibit the detrimental effects, concluding this compound is non-toxic (16).

In summary, maca is considered safe, with toxicity levels tested well above what is normally consumed by humans as a food or supplement source. Minor adverse effects may be experienced by a small number of people, though they seem transient and do not appear to contribute to the cessation of use.