Metabolic fate of dietary carnitine in human adults: Identification and quantification of urinary and fecal metabolites

Journal Article · Mon Apr 01 04:00:00 EST 1991 · Journal of Nutrition; (USA)

OSTI ID:5526653

Rebouche, C J; Chenard, C A ^[1]

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1. Univ. of Iowa College of Medicine, Iowa City (USA)

Results of kinetic and pharmacokinetic studies have suggested that dietary carnitine is not totally absorbed and is in part degraded in the gastrointestinal tract of humans. To determine the metabolic fate of dietary carnitine in humans, we administered orally a tracer dose of methyl-{sup 3}H L-carnitine with a meal to subjects who had been adapted to a low-carnitine diet or a high-carnitine diet. Urinary and fecal excretion of radiolabeled carnitine and metabolites was monitored for 5 to 11 d following administration of the test dose. Total radioactive metabolites excreted ranged from 13 to 34% (low carnitine diet) and 27 to 46% (high carnitine diet) of the ingested tracer. Major metabolites found were ({sup 3}H)trimethylamine N-oxide (8 to 39% of the administered dose; excreted primarily in urine) and ({sup 3}H)gamma-butyrobetaine (0.09 to 8% of the administered dose; excreted primarily in feces). Urinary excretion of total carnitine was 42 to 95% (high carnitine diet) and 190 to 364% (low carnitine diet) of intake. These results indicate that oral carnitine is 54 to 87% bioavailable from normal Western diets; the percentage of intake absorbed is related to the quantity ingested.

• OSTI ID: 5526653
• Journal Information: Journal of Nutrition; (USA), Journal Name: Journal of Nutrition; (USA) Vol. 121:4; ISSN 0022-3166; ISSN JONUA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
ANIMALS
BETAINE
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
CARBOXYLIC ACIDS
CARNITINE
COUNTING TECHNIQUES
DIET
DRUGS
FECES
HYDROGEN COMPOUNDS
HYDROXY ACIDS
ISOTOPE APPLICATIONS
LIPOTROPIC FACTORS
MAMMALS
MAN
MATERIALS
METABOLISM
METABOLITES
ORAL ADMINISTRATION
ORGANIC ACIDS
ORGANIC COMPOUNDS
PRIMATES
QUATERNARY COMPOUNDS
SCINTILLATION COUNTING
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES
VITAMIN B GROUP
VITAMINS
WASTES