Effects of Dietary Polyphenols on Beneficial Microorganisms
Lactobacilli play a crucial role in the production of fermented foods, and they are thought
to perform a beneficial role as part of the colonic microbiota. They are found where
carbohydrate-rich substances are available and stand out for their beneficial effects in
human health.(43) Dietary polyphenols scarcely inhibit the growth of Lactobacillus group.
Evidence suggests that dietary polyphenols may even help stimulate growth of certain lactobacillus
strains.(44) Puupponen-Pimiä et al.(45) reported that berry phenolics selectively
inhibited pathogenic bacterial strains, both Gram-positive and Gram-negative, but interestingly
the lactic acid bacteria group was hardly affected. A similar trend was reported for
a polyphenolic extract from Mangifera indica L. seed, rich in tannins and flavones, which
inhibited Gram-positive rather than Gram-negative bacteria, but was not active against
lactic acid bacteria.(46) In addition, Lactobacillus acidophilus CECT 362 was resistant
to tea phenolic extracts, containing caffeine; (–)-epicatechin, (–)-epicatechin gallate, (–)-
epigallocatechin, (–)-epigallocatechin gallate, and gallic acid, whereas food-borne bacteria
were inhibited.(42)