FORMATION OF METHYLAMINES FROM INGESTED CHOLINE AND LECITHIN

  • 1 January 1983
    • journal article
    • research article
    • Vol. 225  (2) , 320-324
Abstract
Humans ingest substantial amounts of choline and lecithin as part of common foods. Physicians have recently begun administering large doses of these compounds to individuals with neurological diseases. A significant fraction of ingested choline is destroyed by enzymes within gut bacteria, forming trimethylamine (TMA), dimethylamine (DMA) and monomethylamine (MMA). Some of these methylamines are eventually excreted into the urine, presumably after being absorbed and carried to the kidneys via the bloodstream. The methylamines formed after choline is eaten could be substrates for the formation of nitrosamines, which have marked carcinogenic activity. Choline chloride, choline stearate or lecithin (27 mmol) were administered to healthy human subjects. These treatments markedly increased the urinary excretion of TMA, DMA and MMA, with choline chloride having the greatest effect. Rats were treated with 2 mmol/kg b.wt. [body weight] of choline chloride or lecithin, and it was found that these treatments significantly increased urinary TMA excretion and did not alter DMA or MMA excretion. The choline chloride preparation contained no MMA, DMA or TMA; however, the choline stearate and all the commercially available lecithins tested were contaminated with methylamines. Prior removal of methylamines from the lecithin preparation minimized the effect of oral administration of this compound on methylamine excretion in urine of rats and humans.