"Maté consumption plays a significant and independent role in the development of upper aeodigestive tract cancers," and "Maté drinking should be considered one of the risk factors for cancer of the neck and head."
"Berberine is a plant alkaloid isolated from the roots and bark of several herbs. Some of these herbs include:
Barberry (Berberis vulgaris), Berberis integerrima. Berbamine and berberine are found in the plant barberry.
Coptis chinensis or Berberis aristata
Goldenseal (Hydrastis canadensis)
Oregon Grape (Berberis aquifolium)
Phellodendron Amurense
Yerba mansa (Anemopsis californica).
The berberine alkaloid can be found in the roots, rhizomes, stem, and bark of the plants. Berberine-containing plants are used medicinally in many traditional medical systems, including Ayurvedic herbal and Chinese herbal medicine.
Coptis chinensis rhizome -- Golden Thread -- Huang Lian -- Intense yellow color most likely due to high content of berberine, which is very bitter in taste"
High levels of carcinogenic polycyclic aromatic hydrocarbons in mate drinks.
Kamangar F, Schantz MM, Abnet CC, Fagundes RB, Dawsey SM.
Cancer Epidemiol Biomarkers Prev. 2008 May;17(5):1262-8.
PMID: 18483349
doi: 10.1158/1055-9965.EPI-08-0025
The beverage maté: a risk factor for cancer of the head and neck.
Goldenberg D, Golz A, Joachims HZ.
Head Neck. 2003 Jul;25(7):595-601. Review.
PMID: 12808663
DOI: 10.1002/hed.10288