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

Polyphenols: Chemistry, bioavailability, bioactivity, nutritional aspects and human health benefits: A review

Polyphenols, including phenolics, alkaloids, and terpenes, are secondary metabolites that are commonly found in fruits, vegetables, and beverages, such as tea, coffee, wine, chocolate, and beer. These compounds have gained considerable attention and market demand because of their potential health benefits. However, their application is limited due to their low absorption rates and reduced tissue distribution efficiency. Engineering polyphenol-protein complexes or conjugates can enhance the antioxidant properties, bioavailability, and stability of polyphenols and improve digestive enzyme hydrolysis, target-specific delivery, and overall biological functions. Complex polyphenols, such as melanin, tannins, and ellagitannins, can promote gut microbiota balance, bolster antioxidant defense, and improve overall human health. Despite these benefits, the safety of polyphenol complexes must be thoroughly evaluated before their use as functional food additives or supplements. This review provides a detailed overview of the types of macromolecular polyphenols, their chemical composition, and their role in food enrichment. The mechanisms by which complex polyphenols act as antioxidative, anti-inflammatory, and anticancer agents have also been discussed.

Montmorency cherry supplementation enhances 15 km cycling time trial performance: Optimal timing 90-min pre-exercise

Montmorency cherry (MC) can improve endurance performance, but optimal pre-exercise timing of supplementation and influence of training status on efficacy are unknown. We investigated the effect of MC concentrate ingestion between 30- and 150-min pre-exercise in trained and recreational cyclists on 15-km time trial (TT) performance and exercise economy. Twenty participants (10 recreationally active, RA; 10 trained, T) completed 10 min of steady-state exercise (SSE) at 40%Δ (SSE) and a TT on four separate occasions following an unsupplemented (US), 30-, 90- or 150-min pre-exercise Montmorency cherry concentrate (MCC) supplementation conditions (MCC30/90/150min). Venous and capillary blood samples were taken at regular intervals pre- and post-SSE and TT. MCC significantly improved TT performance, but not exercise economy. The greatest improvement in performance occurred following MCC90min compared to US (US 1603.1 ± 248 s vs. MCC90min 1554.8 ± 226.7 s, 2.83% performance improvement). Performance was significantly enhanced for trained (US 1496.6 ± 173.1 s vs. MCC90min 1466.8 ± 157.6 s) but not recreationally active participants. Capillary [lactate] and heart rate were significantly greater during the TT for the 90-min dose timing (p < 0.05). In the MCC30min and MCC90min conditions, plasma ferulic (US 8.71 ± 3.22 nmol. L-1 vs. MCC30min 15.80 ± 8.69 nmol. L-1, MCC90min 12.65 ± 4.84 nmol. L-1) and vanillic acid (US 25.14 ± 10.91 nmol.L-1 vs. MCC30min 153.07 ± 85.91 nmol. L-1, MCC90min 164.58 ± 59.06 nmol. L-1) were significantly higher pre-exercise than in US and MCC150min conditions (p < 0.05). There was no significant change in muscle oxygenation status or plasma nitrite/nitrate concentration. MCC supplementation enhanced endurance exercise performance optimally when consumed ∼90 min pre-exercise producing maximal plasma phenolic metabolites during exercise. The ergogenic effect was greater for trained participants.

Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes

This review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, defined as "SPARKS", will have a beneficial effect on the function and regeneration processes of the gut-brain-muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, defined as "SMOULDER", will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the significance of these factors for overall well-being, suggesting that adopting the "SPARKS" approach may benefit not only athletes but also older adults and individuals with health conditions.

Dose-dependent effect of tart cherry on selected cardiometabolic risk factors: A GRADE-assessed systematic review and dose-response meta-analysis of randomized controlled trials

AIMS

This study aimed to clarify the effectiveness of tart cherries on anthropometric, lipid, and glycemic indices. We also aimed to clarify the appropriate dosage for this effect and suggest directions for future studies.

METHODS

PubMed, Scopus, and Web of Science were searched until May 2022. Twelve eligible trials were included. The pooled results were reported as weighted mean differences (WMD) and 95 % confidence intervals (CIs). The Cochrane risk of bias and GRADE tools were used to assess the risk of bias and certainty of the evidence, respectively.

RESULTS

Tart cherry generally showed no significant effects on cardiometabolic risk factors. But subgroup analysis revealed that tart cherry significantly lowered total cholesterol (WMD: -0.33 mmol/l; 95 % CI: -0.55, -0.10), triglyceride (WMD: -0.19 mmol/l; 95 % CI: -0.26, -0.12), and low-density lipoprotein cholesterol (WMD: -0.36 mmol/l; 95 % CI: -0.58, -0.14), in unhealthy populations. Additionally, subgroup analysis indicated that the favorable effects of tart cherry were more pronounced in a single dose, longer duration, elderly, and obese individuals. Dose-response analysis revealed that 20 ml concentrate has the greatest effect in reducing total cholesterol (WMD: -0.40 mmol/l; 95 % CI: -0.61, -0.19), triglyceride (WMD: -0.23 mmol/l; 95 % CI: -0.33, -0.13), and elevating high-density lipoprotein cholesterol (WMD: 0.20 mmol/l; 95 % CI: 0.17, 0.22).

CONCLUSIONS

Tart cherry supplementation did not have significant effects on anthropometric and glycemic indices, but can improve lipid profile, especially in a single dose, longer duration, and in elderly, obese, and unhealthy individuals.

Nutrient synergy: definition, evidence, and future directions

Nutrient synergy refers to the concept that the combined effects of two or more nutrients working together have a greater physiological impact on the body than when each nutrient is consumed individually. While nutrition science traditionally focuses on isolating single nutrients to study their effects, it is recognized that nutrients interact in complex ways, and their combined consumption can lead to additive effects. Additionally, the Dietary Reference Intakes (DRIs) provide guidelines to prevent nutrient deficiencies and excessive intake but are not designed to assess the potential synergistic effects of consuming nutrients together. Even the term synergy is often applied in different manners depending on the scientific discipline. Considering these issues, the aim of this narrative review is to investigate the potential health benefits of consuming different nutrients and nutrient supplements in combination, a concept we define as nutrient synergy, which has gained considerable attention for its impact on overall well-being. We will examine how nutrient synergy affects major bodily systems, influencing systemic health. Additionally, we will address the challenges associated with promoting and conducting research on this topic, while proposing potential solutions to enhance the quality and quantity of scientific literature on nutrient synergy.

Dose-dependent effect of tart cherry on blood pressure and selected inflammation biomarkers: A GRADE-assessed systematic review and meta-analysis of randomized controlled trials

Objectives

As a nutritious food, Tart cherries (Prunus cerasus L) benefit cardiovascular health. This study aims to clarify the effectiveness of Tart cherry in controlling blood pressure, heart rate, and inflammatory biomarkers, the appropriate dosage for this effect, and suggest directions for future studies.

Methods

PubMed, Scopus, and Web of Science were searched (up to May 2022), to identify eligible randomized controlled trials. It measured publication bias and was assessed for all outcomes. Evidence quality was evaluated using the Cochrane risk of bias tool and GRADE (Grades of Recommendations, Assessment, Development, and Evaluations).

Results

Regarding the 21 included trials, Tart cherry didn't affect blood pressure, heart rate, high-sensitive C-reactive protein, and interleukin-6 (P > 0.05). In contrast, with moderate certainty, it can reduce serum C-reactive protein (WMD: - 0.39 mg/l; 95% CI: - 0.74, - 0.05; P = 0.024) and with very low certainty can decrease tumor necrosis factor-alpha (WMD: - 0.14 pg/ml; 95% CI: - 0.27, - 0.02; P = 0.026). In addition, dose-response analysis implies that with each 30 ml elevation in dose, CRP reduces by 0.19 mg/l (95% CI: - 0.37, - 0.01).

Conclusions

Tart cherry can control inflammation by administering the proper dose. Even though tart cherry generally doesn't affect blood pressure and heart rate, further high-quality studies are needed to determine its effect.

The effect of dietary anthocyanins on biochemical, physiological, and subjective exercise recovery: a systematic review and meta-analysis

Anthocyanins (ACN), the sub-class of (poly)phenols responsible for the red-blue-purple pigmentation of fruit and vegetables, have gained considerable interest in sport and exercise research due to their potential to facilitate exercise recovery. A systematic literature search was performed using PubMed, The Cochrane Library, MEDLINE, SPORTDiscus and CINAHL. Thirty nine studies were included and the standardized mean difference (Hedges g) for creatine kinase (CK), anti-oxidative and inflammatory markers, strength, power and delayed onset muscle soreness (DOMS) indices were pooled in separate meta-analyses; meta-regression was also performed on reported ACN dose. Immediately post-exercise there was an increase in antioxidant capacity (g: 0.56) and reduced C reactive protein (g: -0.24) and tumor necrosis factor α (g: -40); p ≤ 0.02. Strength was improved with ACN at all time points (g: 0.45-0.67). DOMS (g: -0.23) was lower 24 hours post-exercise and power was improved 24 hours (g: 0.62) and 48 hours (g: 0.57) post exercise. The CK was lower 48 hours post-exercise (g: -0.31) and there was a trend for a positive association with ACN dose (p = 0.057). This systematic review provides new data showing ACN-rich foods promote functional and subjective recovery likely due to the antioxidant and anti-inflammatory properties of ACN.

Antioxidative properties of phenolic compounds and their effect on oxidative stress induced by severe physical exercise

Extensive research has found strongly increased generation of reactive oxygen species, free radicals, and reactive nitrogen species during acute physical exercise that can lead to oxidative stress (OS) and impair muscle function. Polyphenols (PCs), the most abundant antioxidants in the human diet, are of increasing interest to athletes as antioxidants. Current literature suggests that antioxidants supplementation can effectively modulate these processes. This overview summarizes the actual knowledge of chemical and biomechanical properties of PCs and their impact as supplements on acute exercise-induced OS, inflammation control, and exercise performance. Evidence maintains that PC supplements have high potency to positively impact redox homeostasis and improve skeletal muscle's physiological and physical functions. However, many studies have failed to present improvement in physical performance. Eleven of 15 representative experimental studies reported a reduction of severe exercise-induced OS and inflammation markers or enhancement of total antioxidant capacity; four of eight studies found improvement in exercise performance outcomes. Further studies should be continued to address a safe, optimal PC dosage, supplementation timing during a severe training program in different sports disciplines, and effects on performance response and adaptations of skeletal muscle to exercise.

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

Tart Montmorency cherries (MC) are a particularly rich source of anthocyanins and other polyphenols that have been shown to elicit antioxidant, anti-inflammatory and vasomodulatory actions. The current study aimed to determine the influence of chronic MC supplementation on cognitive function and mood. In a 3-month double-blinded, placebo-controlled parallel study, middle-aged adults (mean ± sd: 48 ± 6 years) were randomly assigned to either 30 ml twice daily of MC (n 25) or the same amount of an isoenergetic placebo (n 25). Cognitive function and mood were assessed before and after supplementation using a computerised cognitive task battery and visual analogue scales. Cerebral blood flow was also monitored by near-infrared spectroscopy during the task battery, and questionnaires were administered to determine subjective sleep and health status and plasma metabolomics were analysed before and after supplementation. After 3 months, the MC resulted in higher accuracy in digit vigilance (mean difference: 3·3, 95 % CI: 0·2, 6·4 %) with lower number of false alarms (mean difference: -1·2, 95 % CI: -2·0, -0·4) compared with the placebo. There was also a treatment effect for higher alertness (mean difference: 5·9, 95 % CI: 1·3, 10·5 %) and lower mental fatigue ratings (mean difference -9·5, 95 % CI: -16·5, -2·5 %) with MC. Plasma metabolomics revealed an increase in a number of amino acids in response to MC intake, but not placebo. These data suggest an anti-fatiguing effect of MC supplementation as well as the ability to improve sustained attention during times of high cognitive demand, this could be related to changes in amino acid metabolism.

Quality Characteristics and Inhibitory Xanthine Oxidase Potential of 21 Sour Cherry (Prunus Cerasus L.) Varieties Cultivated in China

This study aims to analyze the physicochemical characteristics and activities of 21 sour cherry cultivars in China. The evaluated accessions differ in several quality traits including weight, moisture, color, total soluble solids, and total acids. Glucose and malic acid were the predominant individual sugar and organic acid in all accessions. The potassium (K) and iron (Fe) were of the highest contents in Érid jubileum (453.887 mg/100 g FW) and Meili (2.988 mg/100 g FW), respectively. The contents of total phenolics (TP) were from 9.309 to 24.118 mg GAE/g DW, and total flavonoids (TF) were 8.935–27.198 mg RE/g DW, which were highly positively correlated (r = 0.892, p < 0.001). M-15, Érdi fubileum, and Érid jubileum showed the highest inhibitory effects on xanthine oxidase, and the IC₅₀ inhibitory were 2.619, 3.117, and 3.940 mg/ml, respectively. This work evaluated the quality and nutritional characteristics of 21 sour cherry cultivars grown in China and explored their potential as an innovative food ingredient for hyperuricemia by evaluating the inhibitory effects of xanthine oxidase. And these results provide valuable data and new ideas for the future sour cherry breeding program as well as a processing guide.

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

Tart cherries possess properties that may reduce inflammation and improve glycemic control, however human data on supplementation and the gut microbiota is equivocal. Processing (i.e., juice concentrate, dried, frozen) may affect the properties of tart cherries, and therefore alter their efficacious health benefits. Therefore, the purpose of this study was to investigate the effect of 30 days of supplementation with Montmorency tart cherry (MTC) in concentrate or freeze-dried form on the gut microbiome and markers of inflammation and glycemic control. Healthy participants with no known disease (n = 58, age: 28 ± 10 y, height: 169.76 ± 8.55 cm, body mass: 72.2 ± 12.9 kg) were randomly allocated to four groups and consumed either concentrate or freeze-dried capsules or their corresponding placebos for 30 days. Venous blood samples were drawn at baseline, day 7, 14, and 30 and analyzed for inflammatory markers TNF-alpha, uric acid, C-reactive protein, and erythrocyte sedimentation rate and glycemic control markers glycated albumin, glucose and insulin. A fecal sample was provided at baseline, day 14 and 30 for microbiome analysis. TNF-alpha was significantly lower at 30 vs. 14 days (p = 0.01), however there was no other significant change in the inflammatory markers. Insulin was not changed over time (p = 0.16) or between groups (p = 0.24), nor was glycated albumin different over time (p = 0.08) or between groups (p = 0.56), however glucose levels increased (p < 0.001) from baseline (4.79 ± 1.00 mmol·L^-1) to 14 days (5.21 ± 1.02 mmol·L^-1) and 30 days (5.61 ± 1.22 mmol·L^-1) but this was no different between groups (p = 0.33). There was no significant change in composition of bacterial phyla, families, or subfamilies for the duration of this study nor was there a change in species richness. These data suggest that 30 days of MTC supplementation does not modulate the gut microbiome, inflammation, or improve glycemic control in a healthy, diverse group of adults. Clinical Trail Registration:https://clinicaltrials.gov/ct2/show/NCT04467372, identifier: NCT04467372.

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

BACKGROUND

Tart Montmorency cherries (MC) have been shown to be rich in anthocyanins and other phytochemicals known to have anti-inflammatory properties and influence pathways that might improve cardiometabolic health. However, there is limited evidence for the longer-term use of tart cherries on these indices. The aim of the current study was to investigate the influence of MC concentrate on cardiometabolic health indices following a 3-month supplementation period.

METHODS

Fifty middle-aged adults (34 males and 16 females; mean ± SD age: 48 ± 6 years and BMI: 27.6 ± 3.7 kg/m2) completed a randomised, placebo-controlled parallel study in which they either received MC or an isocaloric placebo. Participants drank 30 mL of their allocated treatment twice per day for 3 months. Vascular function (blood pressure [BP], heart rate [HR], pulse wave velocity and analysis [PWV/A], and flow mediated dilation [FMD]) as well as indices of metabolic health (insulin, glucose, lipid profiles, and high sensitivity C reactive protein) were measured following an overnight fast before and after the 3 months.

RESULTS

No effect of the intervention between the groups was observed for vascular function or metabolic health variables following the intervention (p > 0.05). However, MC concentrate was shown to be safe and well-tolerated and, importantly, did not have any deleterious effects on these outcomes. In conclusion, MC has no influence on cardiometabolic indices in middle-aged adults.