Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2020 Nov 4;9(11):1606.
doi: 10.3390/foods9111606.

A Review of Registered Clinical Trials on Dietary (Poly)Phenols: Past Efforts and Possible Future Directions

Mirko Marino  1 , Cristian Del Bo'  1 , Daniela Martini  1 , Marisa Porrini  1 , Patrizia Riso  1   2
Affiliations

A Review of Registered Clinical Trials on Dietary (Poly)Phenols: Past Efforts and Possible Future Directions

Mirko Marino et al. Foods. .

Abstract

In recent years, the increasing number of studies on polyphenol demonstrates the efforts in elucidating the potential role of these bioactives on human health. This study reviews the main topics and characteristics of clinical trials on polyphenols registered over the last 20 years, in order to track past and current efforts as well as to highlight the main research gaps in this field. The review was conducted by collecting trials registered in ClinicalTrials.gov and International Standard Randomised Controlled Trial Number (ISRCTN) registry. Overall, 750 clinical trials were selected and included in the final evaluation. Most of the trials were performed on extracts or pure compounds followed by studies conducted on polyphenol-rich foods, in particular berries. A total of 520 clinical trials focused on health effects, 55 on bioavailability, and 175 on both. Regarding outcomes, 139 registered intervention studies had the lipid profile and blood pressure as primary outcomes. The overview provided by this analysis also emphasizes the emerging interest in new outcomes related to polyphenols intervention such as microbiota composition and the evaluation of inter-individual variability in response to the intake of polyphenols. Our review underlines the need of further trials covering unexplored or debated research aspects and provides insights for the design and development of future intervention studies and related research areas.

Keywords: bioactive compounds; clinical trials; food; food extracts; health outcomes; human nutrition.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram of the literature search process. Legend: ISRCTN: International Standard Randomised Controlled Trial Number.
Figure 2
Figure 2
Number (a) and trend of registered trials on polyphenol-rich foods (b) and extracts or pure compounds (c).
Figure 3
Figure 3
Main polyphenol-rich foods (a) used in clinical trials and their trend (b).
Figure 4
Figure 4
Main polyphenol-rich extracts (a) used in clinical trials and their trend (b).
Figure 5
Figure 5
Main classes of pure polyphenols used in clinical trials (a) and their trend (b).
Figure 6
Figure 6
Health status of subjects included in the registered clinical trials.
Figure 7
Figure 7
Number (a) and trend (b) of studies assessing the bioavailability or the health effects of polyphenols.
Figure 8
Figure 8
Primary outcomes (a) and their trend (b) assessed during clinical trials on polyphenols.
Figure 9
Figure 9
Countries with the highest number of registered studies on polyphenol-rich foods (a) and extracts (b). Legend: “low”: <10 registered trials; “medium”: 10–49 registered trials; “high”: >50 registered trials. Locations not reporting clinical trials on polyphenols are colored in grey.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. PubMed. [(accessed on 30 April 2020)]; Available online: https://pubmed.ncbi.nlm.nih.gov/
    1. Adebooye O.C., Alashi A.M., Aluko R.E. A brief review on emerging trends in global polyphenol research. J. Food Biochem. 2018;42:e12519. doi: 10.1111/jfbc.12519. - DOI
    1. Abbas M., Saeed F., Anjum F.M., Afzaal M., Tufail T., Bashir M.S., Ishtiaq A., Hussain S., Suleria H.A.R. Natural polyphenols: An overview. Int. J. Food Prop. 2017;20:1689–1699. doi: 10.1080/10942912.2016.1220393. - DOI
    1. Pérez-Jiménez J., Neveu V., Vos F., Scalbert A. Identification of the 100 richest dietary sources of polyphenols: An application of the Phenol-Explorer database. Eur. J. Clin. Nutr. 2010;64:S112–S120. doi: 10.1038/ejcn.2010.221. - DOI - PubMed
    1. D’Archivio M., Filesi C., Di Benedetto R., Gargiulo R., Giovannini C., Masella R. Polyphenols, dietary sources and bioavailability. Ann. Ist. Super. Sanita. 2007;43:348–361. - PubMed