To the Editor: We have found that the free choline concentration of human milk varies during postnatal development and is sometimes markedly depressed in samples from women thought to be ingesting a choline-deficient diet. Choline is a precursor in the biosyntheses of phospholipids1 and of the neurotransmitter acetylcholine.2,3 In animals, ingestion of a diet deficient in choline results in hepatic, renal, growth, and memory disorders.4 Neonates must ingest choline-containing foods like milk in order to maintain blood choline concentrations at high levels5; these levels may be needed to supply adequate choline to rapidly growing tissues
