CHOLINE SUPPLEMENTATION ALTERS CARNITINE HOMEOSTASIS IN HUMANS AND GUINEA-PIGS

We have previously shown that supplementary choline causes significant decreases in urinary excretion of carnitine in humans. The objectives of the present work were to study this interaction in a different hum an population and on other body pools of carnitine in an animal model. In young adult women, daily choline supplementation (20 mg/kg body wt ) resulted in a 75% lower urinary carnitine excretion than in controls , without significantly altering plasma carnitine concentrations. Supp lementary choline was added to the ground diet of Sprague-Dawley rats (2.5 g/kg diet) and guinea pigs (3 g/kg diet). Choline supplementation had no effect on plasma concentrations or urinary excretion of carnit ine in the rats. In guinea pigs, however, choline supplementation resu lted in a significantly lower urinary excretion and higher plasma tota l carnitine concentrations. The skeletal muscle carnitine concentratio n was higher in the choline-supplemented guinea pigs, but not signific antly higher in other tissues. These studies demonstrated that choline supplementation results in decreased urinary excretion of carnitine i n young adult women, that guinea pigs are a suitable animal model for studying the effect of choline supplementation on carnitine status in humans, and that choline results in a conservation of carnitine in gui nea pigs and perhaps in humans.