Prebiotic evaluation of cocoa-derived flavanols in healthy humans by using a randomized, controlled, double-blind, crossover intervention study

• Published in: The American journal of clinical nutrition Vol. 93; no. 1; pp. 62 - 72
• Main Authors: Tzounis, Xenofon, Rodriguez-Mateos, Ana, Vulevic, Jelena, Gibson, Glenn R, Kwik-Uribe, Catherine, Spencer, Jeremy PE
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 2011; American Society for Nutrition; American Society for Clinical Nutrition, Inc
• Subjects: Adult; adults; Antioxidants - metabolism; Bacteria; Bifidobacterium; Bifidobacterium - drug effects; Bifidobacterium - growth & development; Biochemistry; Biological and medical sciences; Biomarkers; blood chemistry; blood lipids; Blood Pressure; C-reactive protein; C-Reactive Protein - analysis; Cacao - chemistry; Clinical trials; Clostridium; Cocoa; cocoa products; Cross-Over Studies; Diet; Dietary supplements; Double-Blind Method; feces; Feces - microbiology; Feeding. Feeding behavior; Female; flavanols; Flavonoids - metabolism; Flavonoids - pharmacology; Fluorescence in situ hybridization; food intake; Fundamental and applied biological sciences. Psychology; Human subjects; Humans; intestinal absorption; intestinal microorganisms; Lactobacillus; Lactobacillus - drug effects; Lactobacillus - growth & development; large intestine; Male; men; Physiology; Prebiotics; small intestine; species diversity; Studies; triacylglycerols; Vertebrates: anatomy and physiology, studies on body, several organs or systems; women; Flavanol; Human; Double blind study; Evaluation; Cocoa; Prebiotics
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.3945/ajcn.110.000075

BACKGROUND: The absorption of cocoa flavanols in the small intestine is limited, and the majority of the flavanols reach the large intestine where they may be metabolized by resident microbiota. OBJECTIVE: We assessed the prebiotic potential of cocoa flavanols in a randomized, double-blind, crossover, controlled intervention study. DESIGN: Twenty-two healthy human volunteers were randomly assigned to either a high-cocoa flavanol (HCF) group (494 mg cocoa flavanols/d) or a low-cocoa flavanol (LCF) group (23 mg cocoa flavanols/d) for 4 wk. This was followed by a 4-wk washout period before volunteers crossed to the alternant arm. Fecal samples were recovered before and after each intervention, and bacterial numbers were measured by fluorescence in situ hybridization. A number of other biochemical and physiologic markers were measured. RESULTS: Compared with the consumption of the LCF drink, the daily consumption of the HCF drink for 4 wk significantly increased the bifidobacterial (P < 0.01) and lactobacilli (P < 0.001) populations but significantly decreased clostridia counts (P < 0.001). These microbial changes were paralleled by significant reductions in plasma triacylglycerol (P < 0.05) and C-reactive protein (P < 0.05) concentrations. Furthermore, changes in C-reactive protein concentrations were linked to changes in lactobacilli counts (P < 0.05, R² = -0.33 for the model). These in vivo changes were closely paralleled by cocoa flavanol-induced bacterial changes in mixed-batch culture experiments. CONCLUSION: This study shows, for the first time to our knowledge, that consumption of cocoa flavanols can significantly affect the growth of select gut microflora in humans, which suggests the potential prebiotic benefits associated with the dietary inclusion of flavanol-rich foods. This trial was registered at clinicaltrials.gov as NCT01091922.