What the study found
The review found that polyphenols can act in two different ways: they may support redox balance and protective enzyme systems at dietary levels, but high-dose supplementation or pharmacological use may produce pro-oxidant and toxic effects. The authors describe this as a hormetic, dose-dependent pattern, meaning the effect changes with the amount taken.
Why the authors say this matters
The authors conclude that polyphenol biology needs to be understood beyond a simple antioxidant model. They suggest that dosing strategies should account for hormesis, variable bioavailability, and individual physiological context so benefits can be optimized without harmful side effects.
What the researchers tested
This was a review article that summarized current knowledge on the dual effects of polyphenols. It drew on experimental and clinical studies examining their beneficial actions, adverse outcomes, and proposed mechanisms.
What worked and what didn't
At physiological dietary levels, polyphenols were reported to modulate redox homeostasis, signaling pathways, and protective enzyme systems. At higher doses, the review reports adverse outcomes including carcinogenic effects, impaired iron absorption with anemia, thyroid hormone disturbances, hepatotoxicity, nephrotoxicity, and gastrointestinal intolerance.
What to keep in mind
The abstract emphasizes that outcomes depend on dose, bioavailability, and context, so the same compounds may not have the same effects in every setting. The review also notes that future research should better define dose-response relationships, clarify mechanisms, and evaluate long-term safety; specific limitations of the review itself are not described in the available summary.
Key points
- Polyphenols may be beneficial at dietary levels but harmful at higher doses.
- The review describes a hormetic dose-response pattern for polyphenols.
- Reported harms include anemia, thyroid disturbances, liver toxicity, kidney toxicity, and gastrointestinal intolerance.
- Proposed mechanisms include metal ion chelation, cytochrome P450 interference, and reactive quinone formation.
- The authors call for better dose-response data and long-term safety studies.
Disclosure
- Research title:
- Polyphenols show both beneficial and harmful dose-dependent effects
- Authors:
- Stanislava Vranková, Martina Cebová, Jana Klimentová, Olga Pechanova
- Institutions:
- Comenius University Bratislava, Comenius University Bratislava, Comenius University Bratislava, Institute of Normal and Pathological Physiology of the Slovak Academy of Sciences, Institute of Normal and Pathological Physiology of the Slovak Academy of Sciences, Institute of Normal and Pathological Physiology of the Slovak Academy of Sciences, Institute of Normal and Pathological Physiology of the Slovak Academy of Sciences
- Publication date:
- 2026-02-16
- DOI:
- 10.1002/ptr.70268
- OpenAlex record:
- View
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