EFFECT OF DIET ON URINARY-EXCRETION OF DESMOSINE AND HYDROXYLYSYL PYRIDINOLINE

To help validate the use of urinary desmosine (DES), isodesmosine (IDES), and hydroxylysyl pyridinoline (HP) as specific markers of host elastin and collagen degradation, respectively, a study was carried out on the effect of dietary elastin and collagen on urinary DES, IDES, and HP. Ingestion of a meal of calf ligamentum nuchae containing 33 g elastin, 500 mg DES, and 400 mg IDES produced a 10-fold increase in urinary DES and an 8-fold increase in IDES. The urinary DES values remained elevated for more than 10 days following the ingestion. We estimate that about 0.3 mg, or < 0.1%, of the ingested DES was excreted in the urine. Since ligamentum nuchae is not a usual ingredient of human diets, we also determined whether a more typical source and amount of DES, IDES, and HP might affect urinary DES, IDES, or HP values. Lean ground beef (454 g) was ingested. Our analysis showed that this meal contained 4 mg DES, 2 mg IDES, and 0.9 mg HP. The meat-rich diet caused a significant increase of 16 and 34% in the creatinine and DES content of the urine, respectively. When DES, IDES, and HP values were normalized for the urine creatinine content, diet had no effect on the measured amounts. The baseline values (mean +/- SE) for the volunteers before ingestion of the beef were 8.3 +/- 0.7 mu g DES/24 h, 8.3 +/- 0.6 mu g IDES/24 h, and 340 +/- 48 nmol HP/24 h; 5.7 +/- 0.5 mu g DES/g creatinine, 5.6 +/- 0.4 mu g IDES/g creatinine, and 26.9 +/- 2.2 nmol HP/mmol creatinine. We conclude that a meal high in elastin can dramatically affect urinary DES values, but a meal containing a large serving of lean beef does not alter the urine concentration of DES, IDES, and HP when normalized for urinary creatinine.