Because of the potential estrogenic properties of maca, there are safety concerns regarding its use by individuals with a history of estrogen-dependent cancers, such as some types of breast cancer.[1] While direct research on maca's effects in individuals with a history of breast cancer is limited, in vitro studies conducted on breast cancer cell lines have had mixed findings.
For instance, one in vitro study found that maca extract had no effect on MCF-7 (breast cancer) cell lines. However, it was also observed that macamides (a class of amide alkaloids found in maca) showed inhibitory effects similar to those of cisplatin (a chemotherapy drug) on five cancer cell lines, including MCF-7. Additionally, other studies have reported strong anticancer effects of benzyl isothiocyanate (BITC; a breakdown product of maca glucosinolates) in human breast cancer cells and in mice.[2][3][4]
Conversely, a 2022 study found that although maca root extract exhibited toxicity towards triple-negative breast cancer (TNBC) cell lines (which is potentially beneficial in reducing tumor cell viability), it also increased the migratory capacity of cancer cells and caused gene expression changes that might promote cancer progression.[5]
Given these mixed findings, until more conclusive evidence is available, it may be prudent for individuals with a history of estrogen-dependent cancers or people concerned about breast cancer to approach maca supplementation with caution.