Prebiotic potential of olive leaf by-product throughout in vitro human colon fermentation

Olive leaf represents a promising source of novel ingredients with potential health benefits, being rich in dietary fiber and phenolic compounds. This study aimed to evaluate the prebiotic effects of olive leaf bioactive compounds through in vitro human colonic fermentation. The phenolic compounds identified prior to fermentation included hydroxytyrosol, vanillin, oleuropein, and tyrosol. Olive ground leaf significantly promoted the fermentation of colonic microbiota with respect to positive control (FOS) by enhancing the growth of probiotic strains, such as Bifidobacterium spp. or Clostridum leptum , and producing short-chain fatty acids, such as acetate, butyrate and propionate, related to health benefits. Furthermore, olive leaf showed a lower Firmicutes:Bacteroidetes ratio compared to FOS, resulting in a beneficial effect on gut microbiota composition. These findings support the potential of olive leaf as a functional ingredient with prebiotic properties, offering promising applications in the development of novel foods or ingredients aimed at improving human health. • Hydroxytyrosol and tyrosol were the most notable compounds found in OL after fermentation. • Olive leaf significantly enhanced colonic microbiota fermentation in comparison to fructooligosaccharides. • In vitro colon fermentation of olive leaf resulted in higher levels of short-chain fatty acids than fructooligosaccharides. • Olive leaf showed a lower Firmicutes: Bacteroidetes ratio compared to fructooligosaccharides.