Essiac and Flor-Essence herbal tonics stimulate the in vitro growth of human breast cancer cells
clinical paper · 2006
SUMMARY
Laboratory study finding that Essiac and Flor-Essence stimulated proliferation of both estrogen-receptor-positive and estrogen-receptor-negative human breast cancer cell lines in vitro, and that both tonics interact directly with the estrogen receptor. The authors tested both products at 1%-8% and extended Flor-Essence testing to 16%-32% because the final concentration reaching human target cells was unknown. DOI confirmed via `npm run verify-identifiers` (Crossref) 2026-08-17.
NOTES
A peer-reviewed laboratory finding directly contrary to the products’ marketed anticancer purpose: Essiac and Flor-Essence stimulated the growth of human breast cancer cells in vitro at 1%, 2%, 4%, and 8%. In MCF-7 cells, 16% Flor-Essence produced growth not significantly different from controls and 32% was cytotoxic. The authors explicitly said the final concentration reaching human target cells was unknown. Central to this case’s evidentiary-failure section.