ACCELERATED UPTAKE OF AN INTRAVENOUSLY ADMINISTERED DOSE OF CHOLINE CHLORIDE IN CHOLINE-DEFICIENT HUMANS

The role of choline in the human diet continues to be debated, in part due to the lack of an appropriate assessment technique. Information r egarding the turnover of this nutrient in various body polls in humans is lacking. An intravenous infusion of (d(m)ethyl)-chloine chloride w as administered over 1 hour to human subjects fed either a choline-con taining (5 mmoles/day choline chloride) or a choline-deficient diet fo r 3 weeks. Blood samples were collected during the infusion and for 1 hour postinfusion. Plasma levels of choline, (d(9)methyl)choline, and phosphatidylcholine were measured. The uptake of (d(9)methyl)-choline from plasma was calculated by nonlinear regression analysis. In contro l subjects (n = 4), the half-life of (d(9)methyl)-choline in plasma wa s 7.0 +/- 0.85 minutes, while in deficient subjects (n = 6) it was 3.5 +/- 0.42 minutes (P < 0.004). Extracellular choline pools were also d ecreased in deficient subjects (mean +/- SEM; control: 2.6 +/- 0.2 mmo les; deficient: 2.0 +/- 0.2 mmoles; P < 0.05). The rate of appearance of unlabeled choline into the plasma was unaffected by the level of di etary choline. We conclude that intravenously administered choline chl oride is cleared more rapidly in humans fed a choline-deficient diet t han in control subjects, and that choline deficiency decreases choline pools in the body. Our results also indicate that an intravenous load test, similar to the one used in these studies, may be useful as a me thod of measuring choline nutriture.