Dose‐Dependent Increases in Ellagitannin Metabolites as Biomarkers of Intake in Humans Consuming Standardized Black Raspberry Food Products Designed for Clinical Trials

Abstract

Scope: Black raspberry (BRB) phytochemicals demonstrate anti-carcinogenic properties in experimental models, including prostate cancer. Two BRB foods, a confection and nectar, providing a consistent and reproducible product for human clinical studies are designed and characterized. Methods and results: Men with clinically localized prostate cancer are sequentially enrolled to a control group or one of four intervention groups (confection or nectar, 10 or 20 g dose; n = 8 per group) for 4 weeks prior to prostatectomy. Primary outcomes include: safety, adherence, and ellagitannin metabolism. Adherence to the intervention is >96%. No significant (≥grade II) toxicities are detected. Urinary urolithins (A, B, C, and D) and dimethyl ellagic acid (DMEA) quantified by Ultra high performance liquid chromatography tandem mass spectroscopy (UPLC/MS/MS) indicate a dose-dependent excretion yet heterogeneous patterns among men. Men in the BRB confection groups have greater urinary excretion of the microbial urinary metabolites urolithin A and DMEA, suggesting that this food matrix provides greater colonic microflora exposure. Conclusion: Fully characterized BRB confections and nectar are ideal for food-based large phase III human clinical studies. BRB products provide a bioavailable source of BRB phytochemicals, however large inter individual variation in polyphenol metabolism suggests that host genetics, microflora, and other factors are critical to understanding bioactivity and metabolism.

Urolithins: a Comprehensive Update on their Metabolism, Bioactivity, and Associated Gut Microbiota

“…[27] Several studies have reported the presence of Uro conjugates in plasma and urine of men with localized prostate cancer after consuming a pomegranate fruit extract, [28] a usual American diet, [29] or standardized black raspberry products. [30] Zhang et al [31] evaluated the functional capacity to metabolize (poly)phenols from a red raspberry drink in individuals with prediabetes and insulin resistance (PreDM-IR, n = 26) compared to a metabolically healthy reference group (n = 10). [31] * Primarily focused on the last five years.…”

Direct supplementation with Urolithin A overcomes limitations of dietary exposure and gut microbiome variability in healthy adults to achieve consistent levels across the population

“…A few interventional studies have investigated the presence of urolithin metabolites after intake of dietary fruits (strawberry and raspberry) and nuts (walnuts) in different study populations [11,12]. Investigators have also examined the association between different urolithin plasma profiles and health benefits, such as lowering cardiovascular risk in overweight populations [2,13,14].…”

A Review on Chromatography–Mass Spectrometry Applications on Anthocyanin and Ellagitannin Metabolites of Blackberries and Raspberries

“…A large inter individual variability in (poly)phenol metabolism was also found in the in vivo assessment of intake biomarkers after the consumption of black raspberry products intended for clinical trials [ 129 ]. These results, which corroborated with those on the previously mentioned study of García-Muñoz et al [ 39 ], highlighted that the factors such as the genetic background of the host, as well as its gut microbiome, are significant in elucidating the bioavailability of certain components and their metabolic pathways [ 129 ]. This clinical study assessed the effect of two different types of blackberry-rich products (confection or nectar, with doses of 10 or 20 g, respectively, and for a period of 4 weeks) on metabolite production in men with prostate cancer.…”

“…Hence, the NMR can result in failure to identify potentially significant components that are present at lower concentrations, which can be masked by larger chromatographic peaks [ 107 ]. Confection consumption led to the excretion of higher concentrations of urinary metabolites, namely, urolithin A and dimethylethylamine, indicating that food matrix is crucial with respect to colonic microbiome exposure [ 129 ].…”

“…The performance of UPLC-MS/MS (Table 2) indicated that the excretion of metabolites was analogous to the dose received by the subject, even though it was not homogenous among them. Prior to analysis, the chemical identity of all the evaluated compounds was confirmed after the assessment of hyphenated high-resolution mass spectrometry (HRMS) and NMR data [129]. While HRMS is tending towards being one of the most frequently utilized ultra-sensitive analytical methods, the combination of NMR and MS enables the acquisition of complementary information and the expansion of metabolomics coverage [130], whereas NMR also constitutes a high reproducible method [107].…”