Chemical and Biological Liberation of Trimethylamine from Foods

Knowledge of the chemical composition of foods is essential before attempting dietary manipulation to manage an inborn error of metabolism. These data are usually obtained by chemical means within a laboratory. Avoidance of the ingested precursors of trimethylamine would greatly aid the control of a condition known as the “ fish-odour syndrome” (trimethylaminuria), but the appropriate dietary data are limited. In this context, 30 common foods were investigated to assess their “ trimethylamine-producing capacity” following both chemical (alkaline hydrolysis) and biological (ingestion and subsequent urine analysis) liberation techniques. All resultant samples were examined for trimethylamine by head-space gas chroma- tography. With the exception of fish and seafood (cod, mackerel, prawn), no association was observed between chemical and biological liberation values. Some foods (beef, biscuit, chicken, lamb, peanut, pork, soya) gave greater values following chemical hydrolysis that were not reflected in their biological results. Thus, data concerning trimethylamine levels in foods obtained from chemical hydrolysis studies cannot be used to predict successfully which particular foods will actually provide trimethylamine in the biological situation following ingestion.