Review of Analytical Methods and Reporting of the Polyphenol Content of Tart Cherry Supplements in Human Supplementation Studies Investigating Health and Exercise Performance Effects: Recommendations for Good Practice.

Vlad R Sabou,Joanna L Bowtell,Ying Liu,Mary F O'Leary,Paula N Brown,Susan Murch

doi:10.3389/fnut.2021.652094

Abstract

Tart cherries (TC) are a rich source of polyphenols that elicit antioxidant and anti-inflammatory effects. As a consequence, the effects of TC derived supplements on markers of human health, exercise performance and sleep have been investigated. Supplementation protocols have been highly variable across studies and the dose of bioactive compounds used has often been poorly characterized. Specific and non-specific analytical methods were employed for measuring the total polyphenol and anthocyanin content in TC supplements. This review critically analyses the supplementation protocols and the analytical methods used for the characterization of TC supplements, culminating in recommendations for good practice in the analysis and reporting of the polyphenol content and profile of TC products. A literature search was conducted using PubMed/Medline and Web of Science up to May 4th, 2020, including studies published in all years prior. Only articles written in English that provided a TC dietary supplement as opposed to fresh whole TC were included in this review. Forty-three studies were identified as eligible and included for analysis in this review. The studies investigated the effects of TC supplementation on various aspects of human health, exercise recovery and performance and sleep. Twenty studies conducted an analysis of TC supplement and reported total polyphenol/anthocyanin content. Six studies did not report the polyphenol content of the TC supplement used. Seventeen studies reported the TC supplement polyphenol content but this was derived from previously published studies and presumably different supplement batches. The duration of the supplementation protocol ranged from acute supplementation to 84 days, meanwhile the total polyphenol and anthocyanin dose ranged from 143 to 2,140 mg/day and 15 to 547 mg/day, respectively. Due to the variety of specific and non-specific analytical methods used, the relative efficacy of different doses and polyphenol blends cannot reliably be extrapolated from critical analysis of the literature. Future studies should conduct an analysis of the study supplement batch. In addition to analysis and reporting of total polyphenol content, specific analytical methods such as HPLC UV/MS should be used to quantify total and individual anthocyanin contents.

Highlights

Tart cherries (TC) are part of the Prunus species and are predominantly cultivated from the Montmorency cultivar [1]
In the studies that conducted direct analysis of the supplement used in the study, the total polyphenol dose supplemented by participants ranged from 143 to 2,140 mg/day, the anthocyanin dose ranged from 15 to 547 mg/day
The analytical methods used for determining the total polyphenol content of dietary supplements include several modified colorimetric methods based on the Folin-Ciocalteu or the Folin-Denis reagent and a liquid chromatography-mass spectrometry method, several studies did not indicate the analytical method used, despite reporting that an analysis was conducted

Summary

Introduction

Tart cherries (TC) are part of the Prunus species and are predominantly cultivated from the Montmorency cultivar [1]. The chemical composition of TC can be affected by many parameters such as cultivar, maturation stage, agricultural practices, and environmental conditions. The level of soluble solids increases as the fruit matures, whereas titratable acidity declines [2]. Water and carbohydrates are the major constituents of the fruit. All essential amino acids can be found in TC with an additional high level of melatonin in the Montmorency cultivar [3, 4]. Tart cherries are considered a good source of potassium; other minerals exist in low concentrations in the fruit. There are a wide range of vitamins in TC and a noticeably high level of vitamin A. The plant is rich in phenolic compounds which have become the focus of interest for consumers and researchers since these compounds are considered to confer their antioxidant and anti-inflammatory properties [6,7,8,9,10]

Objectives

Methods

Results

Discussion

Conclusion