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Additional file 3: Table S3. The composition and nutrient levels of pigs’ diets (as-fed basis).

Additional file 2: Table S2. The composition and nutrient levels of piglets’ creep diets (as-fed basis).

Additional file1: Table S1. The composition and nutrient levels of sows' diets (as-fed basis).

Background and Purpose The analysis of human faecal metabolites can provide an insight into metabolic interactions between gut microbiota and the host organism. The creation of metabolic profiles in faeces has received little attention until now, and reference values, especially in the context of dietary and therapeutic interventions, are missing. Exposure to xenobiotics significantly affects the physiology of the microbiome, and microbiota manipulation and short‐chain fatty acid administration have been proposed as treatment targets for several diseases. The aim of the present study is to give concomitant concentration ranges of faecal sterol species, bile acids and short‐chain fatty acids, based on a large cohort. Experimental Approach Sterol species, bile acids and short‐chain fatty acids in human faeces from 165 study participants were quantified by LC–MS/MS. For standardization, we refer all values to dry weight of faeces. Based on the individual intestinal sterol conversion, we classified participants into low and high converters according to their coprostanol/cholesterol ratio. Key Results Low converters excrete more straight‐chain fatty acids and bile acids than high converters; 5th and 95th percentile and median of bile acids and short‐chain fatty acids were calculated for both groups. Conclusion and Implications We give concentration ranges for 16 faecal metabolites that can serve as reference values. Patient stratification into high or low sterol converter groups is associated with significant differences in faecal metabolites with biological activities. Such stratification should then allow better assessment of faecal metabolites before therapeutic interventions.

WOS:000397023600129; International audience; Inflammatory bowel diseases (IBD), after disease onset, typically progress in two cyclically repeated phases, namely inflammatory flare and remission, with possible nutritional status impairment. Some evidence, either from epidemiological, clinical, and experimental studies indicate that the quantity and the quality of dietary protein consumption and amino acid supplementation may differently influence the IBD course according to the disease phases. For instance, although the dietary protein needs for mucosal healing after an inflammatory episode remain undetermined, there is evidence that amino acids derived from dietary proteins display beneficial effects on this process, serving as building blocks for macromolecule synthesis in the wounded mucosal area, energy substrates, and/ or precursors of bioactive metabolites. However, an excessive amount of dietary proteins may result in an increased intestinal production of potentially deleterious bacterial metabolites. This could possibly affect epithelial repair as several of these bacterial metabolites are known to inhibit colonic epithelial cell respiration, cell proliferation, and/ or to affect barrier function. In this review, we present the available evidence about the impact of the amount of dietary proteins and supplementary amino acids on IBD onset and progression, with a focus on the effects reported in the colon.