Omega-3 polyunsaturated fatty acids improve intestinal barrier integrity—albeit to a lesser degree than short-chain fatty acids: an exploratory analysis of the randomized controlled LIBRE trial

ABSTRACT: PURPOSE: Adherence to the Mediterranean diet is associated with beneficial health effects, including gastrointestinal disorders. Preclinical studies suggest that omega-3 polyunsaturated fatty acids (n-3 PUFAs), found in Mediterranean foods like nuts and fish, improve intestinal barrier integrity. Here, we assessed possible effects of n-3 PUFAs on barrier integrity in a randomized controlled trial. METHODS: We studied 68 women from the open-label LIBRE trial (clinicaltrials.gov: NCT02087592) who followed either a Mediterranean diet (intervention group, IG) or a standard diet (control group, CG). Study visits comprised baseline, month 3, and month 12. Barrier integrity was assessed by plasma lipopolysaccharide binding protein (LBP) and fecal zonulin; fatty acids by gas chromatography with mass spectrometry. Median and interquartile ranges are shown. RESULTS: Adherence to the Mediterranean diet increased the proportion of the n-3 docosahexaenoic acid (DHA) (IG + 1.5% [0.9;2.5, p < 0.001]/ + 0.3% [− 0.1;0.9, p < 0.050] after 3/12 months; CG + 0.9% [0.5;1.6, p < 0.001]/ ± 0%) and decreased plasma LBP (IG − 0.3 µg/ml [− 0.6;0.1, p < 0.010]/ − 0.3 µg/ml [− 1.1; − 0.1, p < 0.001]; CG − 0.2 µg/ml [− 0.8; − 0.1, p < 0.001]/ ± 0 µg/ml) and fecal zonulin levels (IG − 76 ng/mg [− 164; − 12, p < 0.010]/ − 74 ng/mg [− 197;15, p < 0.001]; CG − 59 ng/mg [− 186;15, p < 0.050]/ + 10 ng/mg [− 117;24, p > 0.050]). Plasma DHA and LBP (R(2): 0.14–0.42; all p < 0.070), as well as plasma DHA and fecal zonulin (R(2): 0.18–0.48; all p < 0.050) were found to be inversely associated in bi- and multivariate analyses. Further multivariate analyses showed that the effect of DHA on barrier integrity was less pronounced than the effect of fecal short-chain fatty acids on barrier integrity. CONCLUSIONS: Our data show that n-3 PUFAs can improve intestinal barrier integrity. Trial registration number: The trial was registered prospectively at ClinicalTrials.gov (reference: NCT02087592). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00394-023-03172-2.