Betaine metabolism in human neonates and developing rats.

Proton nuclear magnetic resonance spectroscopy has been used to demonstrate the presence of high concentrations of betaine (up to 0.75 mol/mol creatinine) in the urine of normal healthy human neonates. Betaine is not normally excreted in adults. Excretion of betaine from birth to 7 days old was monitored. The excretion of betaine in rats from 21 days after birth to 40-45 days old was also monitored. A peak in excretion in the rats of 1.5-3 mol/mol creatinine occurred between days 30-35. The presence of a high concentration of betaine in the urine is unlikely to be caused by a relative lack of betaine homocysteine methyl transferase activity compared with adults but may relate to the disposal of dietary choline during development.