The urinary excretion of amino acid conjugates in free living adult males

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Virginia Polytechnic Institute and State University


The objective of this research was to quantitatively assess the urinary excretion of glutamine and glycine conjugates in a free living population of young male adults, in order to establish a profile of detoxification via amino acid conjugation. Also, the effect of certain factors (vegetable, fruit, meat, and charbroiled food intake; tobacco, alcohol, caffeine, and marijuana use; exposure to chemicals and familial cancer incidence) on the urinary excretion of the amino acid conjugates were investigated. Three consecutive 24 hour urines were collected from 40 subjects who complied with a specific collection protocol. The urine samples were analyzed using a HPLC amino acid analyzer. The mean conjugated glutamine excreted was 1.30 mmole/24 hr or 8.74 x 10⁻² mmole/mmole creatinine/24 hr. The mean value for urinary conjugated glycine was 3.91 mmole/24 hr or 26.38 x 10⁻² mmole/mmole creatinine/24 hr. For glutamine conjugate excretion, vegetable, fruit, alcohol, chemical exposure and marijuana use showed marginally significant differences among their subgroups. For glycine conjugate excretion, meat, caffeine, chemical exposure, cancer and marijuana use showed marginally significant differences among their subgroups. An analysis of variance revealed a large degree of between-subject(inter) and within-subject(intra) variability. The coefficients of variation for glutamine and glycine for intervariabili ty were 51.1 and 53.4%, respectively, whereas the coefficients of variation for intra variability were 37.3 and 31.4%, respectively. Probably, the large variability masked any effects of diet, environment or genetics on the observed urinary conjugated amino acid excretion.