What the study found
Polyphenols can have two different kinds of biological effects depending on dose and context: they may support redox homeostasis, signaling pathways, and protective enzyme systems at dietary levels, but high-dose supplementation or pharmacological use may also cause pro-oxidant activity, enzyme inhibition, endocrine disruption, and organ toxicity.
Why the authors say this matters
The authors conclude that polyphenol biology needs to be understood beyond a simple antioxidant view. They suggest that dosing strategies should reflect polyphenols' hormetic nature, variable bioavailability, and individual physiological context to preserve benefits while avoiding harm.
What the researchers tested
This is a review article that summarizes current knowledge on the dual effects of polyphenols. It draws on experimental and clinical studies reporting beneficial effects, adverse outcomes, and proposed mechanisms.
What worked and what didn't
At physiological dietary levels, polyphenols were described as beneficial through effects on redox balance and protective pathways. At higher doses, reported problems included carcinogenic effects, impaired iron absorption leading to anemia, thyroid hormone disturbances, hepatotoxicity, nephrotoxicity, and gastrointestinal intolerance.
What to keep in mind
The abstract describes limitations in general terms rather than as a formal list. It notes that future research should clarify dose-response relationships, pro-oxidant and endocrine-disrupting mechanisms, and long-term safety in clinical settings.
Key points
- Polyphenols may be beneficial at dietary levels but harmful at high doses.
- The abstract describes a hormetic dose-response pattern, meaning effects change with dose.
- Reported adverse outcomes include anemia, thyroid disturbances, liver toxicity, kidney toxicity, and gastrointestinal intolerance.
- Possible mechanisms include metal ion chelation, cytochrome P450 interference, and reactive quinone formation.
- The authors call for clearer dose-response studies and long-term clinical safety evaluation.
Disclosure
- Research title:
- Polyphenols show both beneficial and harmful dose-dependent effects
- Authors:
- Stanislava Vranková, Martina Cebová, Jana Klimentová, Olga Pechanova
- Institutions:
- Institute of Normal and Pathological Physiology of the Slovak Academy of Sciences, Comenius University Bratislava
- Publication date:
- 2026-02-16
- OpenAlex record:
- View
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