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

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.

Thirty Days of Montmorency Tart Cherry Supplementation Has No Effect on Gut Microbiome Composition, Inflammation, or Glycemic Control in Healthy Adults

“…Independent lab analysis of anthocyanins via high-performance liquid chromatography and total polyphenols via Ultraviolet-Visible Spectroscopy (Certified Laboratories, Mellville, NY) showed MTC juice provided 227 mg anthocyanins and 793 mg total polyphenols per 240 ml bottle while MTC capsules provided 330 mg anthocyanins and 760 mg total polyphenols per capsule. These values are within the ranges reported by previous studies using MTC products ( 29 ). Doses were in accordance with previous literature and to ensure similar levels of polyphenols and anthocyanins between formulations.…”

Polyphenol-rich tart cherries (Prunus Cerasus, cv Montmorency) improve sustained attention, feelings of alertness and mental fatigue and influence the plasma metabolome in middle-aged adults: a randomised, placebo-controlled trial

“…Other limitations within the current study include that baseline polyphenol intake was different between groups. Secondly, as discussed elsewhere (34) , the sugar content of MC and potential variability between batches need to be carefully considered in future research designs (71) . Thirdly, based on emerging evidence it is speculated that (poly)phenols might be beneficial compounds, however it should be acknowledged that MC contains other phytochemicals that might synergistically have an effect (30; 72; 73) .…”

The Influence of Tart Cherry (Prunus cerasus, cv Montmorency) Concentrate Supplementation for 3 Months on Cardiometabolic Risk Factors in Middle-Aged Adults: A Randomised, Placebo-Controlled Trial

“…Secondly, anthocyanin content is reported based on previous analysis, which was conducted in our laboratory; however, batch-to-batch variation can naturally occur due to growing conditions (e.g., soil, use of fertiliser, time of year, weather), storage, and processing. Additionally, the lack of specific analytics [ 72 ] in the current study needs to be considered while interpreting the findings. Lastly, BP was measured in the laboratory, which was shown to be reliable; however, a 24 h ambulatory BP could be more advantageous in establishing small changes in BP following MC supplementation [ 46 ], due to the large number of readings and avoidance of ‘white-coat hypertension’.…”