In a study of healthy humans, a drink high in cocoa flavanols showed a prebiotic effect, increasing both lactobacilli and bifidobacteria, while reducing bad bacteria in the gut.
The University of Reading, England, researchers noted that cocoa flavanols undergo limited absorption in the small intestines, so they amply reach to the large intestines, where they deliver their digestive benefits. They results were published in the American Journal of Clinical Nutrition.
In the study, 22 healthy volunteers were randomly assigned to take either a High-Cocoa Flavanol (HCF) drink (494 mg cocoa flavanols/d) or a control low-cocoa flavanol (LCF) drink (23 mg cocoa flavanols/d) for 4 weeks. A 4 week washout was then followed by a crossover to the other arm.
Researchers collected fecal samples before and after each intervention and measured bacterial counts using fluorescent in situ hybridization. Other biochemical and physiologic markers were also measured. Daily consumption of the HCF drink significantly increased the bifidobacterial (P < 0.01) and lactobacilli (P < 0.001) populations but significantly decreased clostridia counts (P < 0.001), compared to consumption of the control (LCF) drink.
In addition, HCF also reduced plasma triacylglycerol (P < 0.05) levels and C-reactive protein (CRP, P < 0.05) concentration, which was linked to changes in lactobacilli counts (P < 0.05, R(2) = -0.33 for the model). These results were accompanied by cocoa flavanol-induced bacterial changes in mixed-batch culture experiments.
The researchers concluded, “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.”
23 March 2011