Dose‐Dependent Increases in Ellagitannin Metabolites as Biomarkers of Intake in Humans Consuming Standardized Black Raspberry Food Products Designed for Clinical Trials
K. Roberts, Elizabeth M. Grainger, Jennifer M. Thomas‐Ahner, Alice Hinton, Junnan Gu, Kenneth M. Riedl, Yael Vodovotz, Ronney Abaza, Steven J. Schwartz, Steven K. Clinton
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.