What you may have heard
Herbal products containing Aristolochia (or related plants) can cause cancer. People worry because these products have been linked to kidney damage and cancers of the urinary tract.
What science tells us
Aristolochic acids are naturally occurring compounds in some Aristolochia species. Major agencies classify Aristolochic acids as human carcinogens, and they’re also potent kidney toxins; exposure occurs mainly through certain herbal products and, in some regions, contaminated foodstuffs (NIH).
Epidemiological Evidence
- Based on nationwide studies in Taiwan, Aristolochic acid exposure from specific Chinese herbal products is strongly associated with upper tract urothelial carcinoma (PubMed).
- During the Belgium outbreak in the 1990s, women given slimming pills later identified to contain Aristolochic acids developed severe nephropathy and had high subsequent risk of urothelial cancer (PubMed).
Laboratory Evidence / Supporting Evidence
Aristolochic acids forms specific DNA adducts and produces a distinctive mutational signature in human tumors.
IARC Carcinogen Classification
Group 1 – Carcinogenic to humans
How to reduce your risk
- Do not use herbal products that list Aristolochia or related species; avoid products of uncertain origin.
- Check FDA alerts and avoid any supplements flagged for Aristolochic acid contamination.
Bottom line
Human studies, molecular evidence, and global experience all point to aristolochic acids as causes of urothelial cancers, with clear risk reduction after exposure bans.