Does the biomarker 15N-lactose ureide allow to estimate the site of fermentation of resistant starch?
We evaluated the effect of resistant starch (RS) and resistant starch with wheat bran (RS+WB) on the colonic ammonia metabolism in healthy volunteers using the biomarker (15)N-lactose ureide ((15)N-LU). Particularly, it was investigated whether this biomarker allowed to estimate differences in the site of fermentation. Ten volunteers were included in a placebo-controlled crossover study. They consumed in random order 2 x 15 g RS/day for 2 weeks and placebo for 2 weeks separated by 2 weeks wash-out. At baseline, on the first day of each intake period and after each intake period, they consumed a (15)N-labelled test meal and collected all urine in different fractions for 48 h. In ten other volunteers, the effect of 2 x 15 g RS/day and of 2 x 15 g RS + 2 x 6 g WB was compared. These volunteers collected urine and feces for 72 h. (15)N-content of urine and feces was measured using combustion-isotope ratio mass spectrometry. RS exerted a significant decrease in cumulative urinary (15)N-excretion which was different from placebo. The effect was most pronounced in the 6-24 h urine fraction which suggest fermentation in the proximal colon. The effect of RS+WB on cumulative urinary (15)N-excretion was not significantly different from the effect of RS. A less pronounced decrease in the 6-24 h fraction was observed suggesting less fermentation in the proximal colon whereas no indications for more distal fermentation were observed. Since about 80% of the cumulative urinary (15)N was recovered within 24 h, it was concluded that the biomarker (15)N-LU was useful to monitor processes in the proximal colon rather than in the distal colon.
Department of Gastrointestinal Research, Katholieke Universiteit Leuven, Leuven, Belgium.
Lieselotte
L
Cloetens
Vicky
V
De Preter
Henriette
H
De Loor
Paul
P
Rutgeerts
Kristin
K
Verbeke
D000328:Adult; D015415:Biomarkers / Q000378:metabolism / Q000652:urine; D003106:Colon / Q000378:metabolism*; D018592:Cross-Over Studies; D003903:Deuterium; D005243:Feces / Q000737:chemistry; D005260:Female; D005285:Fermentation; D006801:Humans; D007700:Kinetics; D007785:Lactose / Q000378:metabolism* / Q000652:urine; D008297:Male; D013058:Mass Spectrometry; D009587:Nitrogen Isotopes / Q000378:metabolism / Q000652:urine; D019936:Probiotics; D013213:Starch / Q000378:metabolism*; D014908:Triticum; D014508:Urea / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine; D016482:Urinalysis
D015415:Biomarkers; D009587:Nitrogen Isotopes; C121442:lactose ureide; D014508:Urea; D013213:Starch; D003903:Deuterium; D007785:Lactose