THE EFFECT OF A SEMISYNTHETIC DIET ON THE PROFILE OF URINARY CONJUGATES IN MALE-ADULTS

The effect of a semisynthetic diet on urinary conjugate levels was det ermined in 18 male adults (22 to 40 years). Subjects consumed a self-s elected diet for 3 days and a semisynthetic diet for 7 days. Glucuroni des and mercapturates were quantified spectrophotometrically using nap hthoresorcinol and Ellman's reagents, respectively. Atomic absorption was used to measure barium chloride-precipitated sulfate for sulfoconj ugates. Conjugated amino acids were determined by high performance liq uid chromatography of phenylisothiocyanate derivatives. A multivariate analysis of variance was used to compare the means of the dietary per iods, and a repeated measures analysis with Helmert transformation,vas used to determine response to dietary change. Mercapturates and amino acid conjugates were most sensitive to dietary change, with quantitie s excreted decreasing by about 50% during the semisynthetic diet perio d (0.29 versus 0.16 mmol/24 hr; 5.99 versus 3.06 mmol/24 hr, respectiv ely). Glucuronides were the least responsive to dietary change, with n o significant difference between the means of the two diet periods (se lf-selected diet, 2.98; semisynthetic, 3.05 mmol/24 hr), Sulfoconjugat e levels exceeded those of the other conjugates measured. Sulfoconjuga tes were initially decreased an the semisynthetic diet (5.28 versus 3. 98 mmol/24 hr), but by day 4, sulfo-conjugate excretion began to incre ase. In summary the quantity of conjugates excreted were found to be s ensitive to dietary changes, with some pathways more responsive than o thers.