Effect of the Mediterranean diet on the faecal long-chain fatty acid composition and intestinal barrier integrity: an exploratory analysis of the randomised controlled LIBRE trial

We recently showed that adherence to the Mediterranean diet increased the proportion of plasma n-3 PUFA, which was associated with an improved intestinal barrier integrity. In the present exploratory analysis, we assessed faecal fatty acids in the same cohort, aiming to investigate possible associations with intestinal barrier integrity. Women from the Lifestyle Intervention Study in Women with Hereditary Breast and Ovarian Cancer (LIBRE) randomised controlled trial, characterised by an impaired intestinal barrier integrity, followed either a Mediterranean diet (intervention group, n 33) or a standard diet (control group, n 35).At baseline (BL), month 3 (V1) and month 12 (V2), plasma lipopolysaccharide-binding protein, faecal zonulin and faecal fatty acids were measured.In the intervention group, faecal proportions of palmitoleic acid (16:1, n-7) and arachidonic acid (20:4, n-6) decreased, while the proportion of linoleic acid (18:2, n-6) and α linoleic acid (18:3, n-3) increased (BL-V1 and BL-V2, all P < 0·08).In the control group, faecal proportions of palmitic acid and arachidic acid increased, while the proportion of linoleic acid decreased (BL-V1, all P < 0·05).The decrease in the proportion of palmitoleic acid correlated with the decrease in plasma lipopolysaccharide-binding protein (ΔV1-BL r = 0·72, P < 0·001; ΔV2-BL r = 0·39, P < 0·05) and correlated inversely with adherence to the Mediterranean diet (Mediterranean diet score; ΔV1-BL r = -0·42, P = 0·03; ΔV2-BL r = -0·53, P = 0·005) in the intervention group. Our data show that adherence to the Mediterranean diet induces distinct changes in the faecal fatty acid composition. Furthermore, our data indicate that the faecal proportion of palmitoleic acid, but not faecal n-3 PUFA, is associated with intestinal barrier integrity in the intervention group.