The metabolic fate of doubly stable isotope labelled heat-killed Lactobacillus johnsonii in humans.
OBJECTIVE
In this study, heat-killed Lactobacillus johnsonii (La1), doubly labelled with (13)C and (15)N (hk-dlLa1), was used to follow the metabolic fate after oral administration in humans.


METHODS
Experimental study.


METHODS
University of Rostock, Children's Hospital, Research Laboratory.


METHODS
Ten healthy adults aged 23-26 years.


METHODS
The subjects received 74.6 mg/kg body weight hk-dlLa1 and 10 g alpha-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. (13)C- and (15)N-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, (13)C- and (15)N-enrichment of fibrinogen amounted to 2 and 25 p.p.m. excess, respectively. The (13)CO(2)-exhalation amounted to 9.2% of the ingested dose. The urinary excretion of (13)C and (15)N 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 (13)C-and (15)N-enrichments of blood plasma fractions. The ingestion of hk-dlLa1 led to a (13)C- and (15)N-excretion of 59.2 and 54.1% of the ingested dose, respectively, of both stable isotopes.
Wutzke
K D
KD
Research Laboratory 'Gastroenterology and Nutrition', Children's Hospital, University of Rostock, Rostock, Germany. klaus-dieter.wutzke@med.uni-rostock.de
Berg
D
D
Haffner
D
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D000284:Administration, Oral; D000328:Adult; D001944:Breath Tests; D002247:Carbon Isotopes; D004063:Digestion; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D005772:Gastrointestinal Transit; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D007778:Lactobacillus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D008297:Male; D013058:Mass Spectrometry; D009587:Nitrogen Isotopes; D019936:Probiotics; D011887:Raffinose; D014556:Urine / Q000737:chemistry
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D011887:Raffinose