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De Preter et al (2004) The in vivo use of stable isotope-labelled biomarkers lactose-[15N]ureide and [2H4]tryosine to assess the effects of pro- and prebiotics on the intestinal flora of healthy human volunteers.

De Preter et al (2004) The in vivo use of stable isotope-labelled biomarkers lactose-[15N]ureide and [2H4]tryosine to assess the effects of pro- and prebiotics on the intestinal flora of healthy human volunteers.

Citation

De Preter V, Geboes K, Verbrugghe K, De Vuyst L, Vanhoutte T, Huys G, Swing J, Pot B, Verbeke K (2004). The in vivo use of the stable isotope-labelled biomarkers lactose-[15N]ureide and [2H4]tyrosine to assess the effects of pro- and  prebiotics on the intestinal flora of healthy human volunteers. British Journal of Nutrition 92:439-446

Objective

To investigate whether the consumption of a probiotic (Lactobacillus casei Shirota, LcS) or a prebiotic (lactulose) would reduce levels of one or more urinary biomarkers for toxic bacterial metabolites in the colon.

The end products of bacterial fermentation of proteins in the colon, such as amines, NH3, phenolic compound and thiols, have been implicated in the pathogenesis of certain diseases. 

Methods

In a randomised, single-blinded, placebo-controlled, crossover study healthy subjects (n=19) consumed either a probiotic (containing 6.5 x109 LcS), a prebiotic (10g lactulose) or the respective placebo twice a day for two weeks, with an intervening two week washout period. Subjects consumed a test meal containing two labelled biomarkers (lactose-[15N]ureide and [2H4]tyrosine) at weeks two, four and six. Urine samples were collected at baseline and over a 48 h period following consumption of the test meal, for analysis of urinary phenolic compounds, total nitrogen content and 15N.

Results

Urinary analysis showed a significant reduction in production of the toxic bacterial metabolites (p-[ring-2H4]cresol and [15N]urea ) after probiotic consumption (P = 0.032 and P = 0.047 respectively) which was significantly different to the placebo group (P = 0.042 and P = 0.016 respectively). Prebiotic supplementation also resulted in a reduction in the above metabolites (P = 0.035 and P = 0.046 respectively) which was significantly different from the placebo group (P = 0.005 and P = 0.029 respectively).

Conclusions

The data showed that reduction in concentrations of potentially toxic bacterial fermentation metabolites in the colon, associated with consumption of the probiotic LcS or the probiotic lactulose, can be reliably monitored in vivo by a tracer technique using stable isotope-labelled biomarkers.

 
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