However, humans have an active choline metabolic pathway, and other components of the choline metabolic pathway (e.g. phosphatidylcholine and betaine) may be interchangeable with choline post absorption but are resistant to gut bacteria metabolism (i.e. serum TMA does not increase). Thus, these other compounds would be expected to increase serum but with no impact on TMA or trimethylurea levels. An initial study of phosphatidylcholine supplementation in pregnant women was consistent with this hypothesis; infant offspring demonstrated improved cerebral inhibition; while no adverse events were identified for either mother or infant.