Carotenoids modulate fermentation of inulin ex vivo in IBS and overweight adult gut microbiota

Carotenoids have direct antioxidant and anti-inflammatory health benefits. Owing to their low bioavailability, they also reach the colon, yet their microbiome interactions remain poorly characterized. We investigated how β-carotene (BC), lutein (LU), lycopene (LY) and zeaxanthin (ZE), at biological relevant doses (between 1 and 60 mg/d), impact composition and metabolite production of irritable bowel syndrome (IBS) and overweight (OW) adult gut microbiota using the ex vivo SIFR ® fermentation system (systemic intestinal fermentation research). Fresh fecal samples were collected from 12 donors ( n = 6 per cohort) and incubated for 24 h under anaerobic conditions, with carotenoids administered alone or in combination with prebiotic inulin (IN, tested at 2.5 g/day). We observed phenotype-specific microbiota characteristics for each cohort at baseline. Carotenoids alone had only minor effects but in combination with prebiotic inulin significantly altered community composition (Bray-Curtis dissimilarity, P < 0.05) and enhanced short-chain fatty acid (SCFA) production. Most carotenoids increased butyrate production vs. inulin alone with ZE (at 2 mg/d) in IBS (+ 7.6%) and LU (at 60 mg/d) in OW (+ 8.0%) showing the strongest effects (p adjusted