Original Article
European Journal of Clinical Nutrition (2008) 62, 197–202; doi:10.1038/sj.ejcn.1602716; published online 14 March 2007
The metabolic fate of doubly stable isotope labelled heat-killed Lactobacillus johnsonii in humans
Guarantors: KD Wutzke and D Haffner.
Contributors: DB was principal investigator and doctoral candidate of KDW.
K D Wutzke1, D Berg1 and D Haffner1
1Research Laboratory 'Gastroenterology and Nutrition', Children's Hospital, University of Rostock, Rostock, Germany
Correspondence: Professor KD Wutzke, Research Laboratory 'Gastroenterology and Nutrition', Children's Hospital, University of Rostock, Rembrandtstra
e 16/17, D-18055 Rostock, Germany. E-mail: klaus-dieter.wutzke@med.uni-rostock.de
Received 17 May 2006; Revised 19 January 2007; Accepted 5 February 2007; Published online 14 March 2007.
Abstract
Objective:
In this study, heat-killed Lactobacillus johnsonii (La1), doubly labelled with 13C and 15N (hk-dlLa1), was used to follow the metabolic fate after oral administration in humans.
Design:
Experimental study.
Setting:
University of Rostock, Children's Hospital, Research Laboratory.
Subjects:
Ten healthy adults aged 23–26 years.
Intervention:
The subjects received 74.6 mg/kg body weight hk-dlLa1 and 10 g 
-D-raffinose together with breakfast. A sample of venous blood was taken after 2 h. Expired air samples were taken over 14 h, whereas urine and faeces were collected over a period of 48 h. 13C- and 15N-enrichments were measured by isotope ratio mass spectrometry. Hydrogen concentrations were measured by electrochemical detection.
Results:
The orocaecal transit time (OCTT) was reached after 3.4 h. After 2 h, 13C- and 15N-enrichment of fibrinogen amounted to 2 and 25 p.p.m. excess, respectively. The 13CO2-exhalation amounted to 9.2% of the ingested dose. The urinary excretion of 13C and 15N was 2.1 and 10.4% of the ingested dose, respectively, whereas the faecal excretion was 47.9 and 43.7% of the ingested dose, respectively.
Conclusions:
In comparison to OCTT of 3.4 h, both stable isotopes appear after 30 min in breath and urine, indicating that hk-dlLa1 is rapidly digested in the small bowel before reaching the caecum. This is confirmed by 13C-and 15N-enrichments of blood plasma fractions. The ingestion of hk-dlLa1 led to a 13C- and 15N-excretion of 59.2 and 54.1% of the ingested dose, respectively, of both stable isotopes.
Keywords:
13C, 15N-labelled Lactobacillus johnsonii, H2-breath test, heat-killed, orocaecal transit time, raffinose
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