Association between different dietary polyphenol subclasses and the improvement in cardiometabolic risk factors: evidence from a randomized controlled clinical trial
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Due to their different chemical structures and metabolism, polyphenol subclasses may have specific impact on cardiometabolic risk factors. Our aim was to evaluate whether the intake of different polyphenol subclasses is associated with clinical outcomes beneficially improved by polyphenols in a nutritional trial performed by our group (postprandial lipid response, glucose homeostasis, early insulin secretion and oxidative stress).
The present study is a secondary analysis of a nutritional intervention study with a diet naturally rich in polyphenols. The data are derived from 78 participants at high cardiovascular risk who completed the ETHERPATH trial. The associations between variations in polyphenol subclasses (phenolic acids, anthocyanidins, flavones, flavan-3-ols, flavonols and flavanones) and clinical outcomes beneficially influenced by polyphenols were firstly explored by Spearman’s correlation. Thereafter, adjustment for gender, age and body mass index (BMI) was run. Linear regression analysis was used to assess the class of polyphenols that best predicted the outcome.
Flavanone intake was inversely correlated with postprandial lipid response, whereas flavone intake was related to postchallenge glucose response. Anthocyanidins and flavan-3-ols associated positively with early insulin secretion. The decrease in urinary isoprostanes correlated with anthocyanidins, flavan-3-ols and flavonols. Correlations did not change after adjustment for gender, age, and BMI. Linear regression analysis showed an independent association between flavonols and urinary isoprostanes, whereas early insulin secretion was mainly associated with flavan-3-ols intake.
The results of this study show that a polyphenol-rich diet may have a pleiotropic effect on cardiometabolic risk factors thanks to the specific action of different polyphenol subclasses.
KeywordsFlavonoids Phenolic acids Lipid response Glucose homeostasis Urinary isoprostanes
The trial was supported by European Community’s Seventh Framework Programme FP7/2009-2012 under grant agreement FP7-KBBE-222639, Etherpaths Project and by “Ministero dell’Istruzione, dell’Università e della Ricerca,” Rome, Italy, PRIN 2010-2011—2010JCWWKM. We gratefully acknowledge Angela Giacco for skillful dietary assistance.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This study was approved by the Ethics Committee for the Biomedical Activity of the Federico II University of Naples.
Human and Animal Rights disclosure
All human rights were observed in keeping with the Declaration of Helsinki 2008 (ICH GCP), and with the ethical standards of the responsible committee on human experimentation (Ethics Committee for the Biomedical Activity of the Federico II University of Naples). There are no animal rights issues as this is a clinical study.
Written informed consent was obtained from all participants being included in the study.
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