Objectives: This study evaluated the prebiotic effect of a moderate intake of extra virgin olive oil (Evoo) and red wine (Rw) polyphenols on modulating the gut microbiota composition and the improvement of metabolic risk factors in obese subjects with high insulin resistance (HIR).
Methodology: 10 obese patients with HIR (HOMA-IR>5.5) and 10 lean subject with low insulin resistance (HOMA-IR< 3.3) were included in a randomized and controlled intervention study. After a washout period both study groups consumed a normo-caloric Mediterranean diet with added Evoo (50 g/dayl) and the same diet plus red wine (270 ml /day) over a 30-day period for each one.
Results: The Chao and Shannon indices of each study group suggested similar bacterial richness and diversity in the fecal samples between both study groups. 16S rRNA pyrosequencing showed that the dominant bacterial composition differ significantly between the study groups after the two diet intake periods respect to their basal level. In HIR patients, polyphenols from Eoov and Rw significantly increased the number of fecal bifidobacteria and Butyricimonas (intestinal barrier protectors) and significantly decreased the abundance of Rikenellaceae, Desulfovibrionaceae and Prevotella (opportunist pathogen and mucin-degrading bacterial). Moreover, in the HIR patients, triglycerides, glucose and CRP levels decreased and HDL cholesterol levels increased after the two intake periods and this was associated with a rise in Bifidobacterium and Butyricimonas and a decrease in Clostridium, respectively.
Conclusion: A Mediterranean diet supplemented with Evoo and Rw polyphenols increased HDL levels and decreased triglyceride and CRP levels in HIR patients, improving associated cardiovascular risk. Changes in gut microbiota in these HIR patients could be responsible for the improvement of these metabolic markers. Modulation of the gut microbiota by Evoo and Rw polyphenols could be an effective strategy to manage metabolic diseases