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Potential health impacts of excessive flavonoid intake
1Division of Environmental Health Sciences, School of Public Health, University of California at Berkeley, 94720-7360, USA.
Abstract:
Plant flavonoids are common dietary components that have many potent biological properties. Early studies of these compounds investigated their mutagenic and genotoxic activity in a number of in vitro assays. Recently, a renewed interest in flavonoids has been fueled by the antioxidant and estrogenic effects ascribed to them. This has led to their proposed use as anticarcinogens and cardioprotective agents, prompting a dramatic increase in their consumption as dietary supplements. Unfortunately, the potentially toxic effects of excessive flavonoid intake are largely ignored. At higher doses, flavonoids may act as mutagens, pro-oxidants that generate free radicals, and as inhibitors of key enzymes involved in hormone metabolism. Thus, in high doses, the adverse effects of flavonoids may outweigh their beneficial ones, and caution should be exercised in ingesting them at levels above that which would be obtained from a typical vegetarian diet. The unborn fetus may be especially at risk, since flavonoids readily cross the placenta. More research on the toxicological properties of flavonoids is warranted given their increasing levels of consumption.
Insights
Plant flavonoids offer health benefits but excessive intake can be toxic. High doses may cause mutagenic and pro-oxidant effects, outweighing benefits, especially for pregnant women.
Area of Science:
- Biochemistry
- Toxicology
- Nutritional Science
Background:
- Plant flavonoids are widely consumed dietary compounds with diverse biological activities.
- Recent focus on antioxidant and estrogenic effects has increased flavonoid supplement use.
- Potential toxicological risks of high-dose flavonoid consumption are often overlooked.
Purpose of the Study:
- To review the dual nature of plant flavonoids, considering both beneficial and potentially toxic effects.
- To highlight the risks associated with excessive flavonoid intake, particularly in supplement form.
- To emphasize the need for further research into flavonoid toxicology.
Main Methods:
- Review of existing literature on flavonoid biological activities.
- Analysis of in vitro studies investigating mutagenic and genotoxic potential.
- Examination of research on antioxidant, estrogenic, and hormonal effects.
Main Results:
- Flavonoids exhibit potent biological properties, including antioxidant and estrogenic effects.
- At high doses, flavonoids can act as mutagens and pro-oxidants, generating free radicals.
- Flavonoids can inhibit enzymes involved in hormone metabolism, posing risks.
Conclusions:
- The adverse effects of excessive flavonoid intake may exceed their benefits.
- Caution is advised regarding flavonoid consumption levels beyond a typical diet.
- Further toxicological research is crucial due to increasing flavonoid supplement consumption, with special concern for fetal exposure.