PROTON NMR-STUDIES OF BETAINE EXCRETION IN THE HUMAN NEONATE - CONSEQUENCES FOR CHOLINE AND METHYL-GROUP SUPPLY

Proton NMR spectroscopy was used to determine the magnitude and temporal variation of betaine excretion in the human neonate and infant with respect to choline supply and demand. The results show that betaine excretion, which is present 1 day after birth, increases to reach a maximum of nearly 1.5 mol/mol creatinine at 2-3 months of age. Excretion then declines and is less than 0.2 mol/mol creatinine after 1 year. Comparison of estimated total excretion from these results with the calculated dietary choline (the precursor of betaine) intake from breast milk or proprietary feeds was made. The results indicated that during part, if not most, of the neonatal period betaine excretion might exceed the choline intake. The apparent insufficiency of dietary choline to satisfy both metabolic needs and the high betaine excretion suggests that of the two routes for remethylation of homocysteine to methionine, the folate-dependent pathway may be more important in the neonate. Consideration of the demand on methyl group supply for biosynthesis and for choline incorporation into phospholipids emphasizes the vital role played by remethylation in development and the possible need for alternative (endogenous) sources of choline.