Urine lactulose and rhamnose
Urinary excretion of orally consumed lactulose and rhamnose is a well-established measure of intestinal permeability [Urine lactulose and rhamnose results obtained from LC–MS/MS analysis were adjusted for variations in renal function by dividing by urine creatinine. Urine creatinine was analysed using Roche 2nd generation kinetic colorimetric assay based on the Jaffé method performed on the COBAS® C501 analyser (Roche, Burgess Hill, UK). The inter-assay CV ranged from 1.3–2.1% and intra-assay ranged between 1.6–4% across the assay working range. External quality control (UK NEQAS) return showed an inter-laboratory CV of 2.2%. Values used for analysis were calculated by multiplying the amount of lactulose and rhamnose recovered in urine by the volume of urine produced, and then dividing this by the amount (g) consumed. Data are presented as mg/L.