Strawberry, Garlic and Kale Consumption Increase Urinary Excretion of Dimethylamine and Trimethylamine in Humans

Dimethylamine (DMA) is the immediate precursor of carcinogenic N-nitrosodimethylamine (NDMA). In vitro and in vivo experiments using whole strawberries, and garlic and kale juices were conducted to determine concentrations of DMA and trimethylamine (TMA) in foods and urine. Experimental diets [an amino-rich diet as nitrosatable precursors in combination with added nitrate-containing drinking water without (TD1) or with whole strawberries or garlic or kale juices (TD2, TD3 and TD4, respectively), or a diet of low in nitrate and amino (TD5) were incubated in simulated saliva and gastric juices at 37$^{\circ}C$ for 1 hour. We also studied the urinary excretion of DMA and TMA after consumption of the experimental diets (TD1~TD5). Urine samples were obtained for 18 hrs after consumption of experimental diets and concentrations of DMA and TMA were measured in the digested diet and urine. The DMA concentration after incubation in experimental diets (TD1~TD5) was 4.7$\pm$0.3, 6.7 $\pm$0.2, 7.9$\pm$0.2, 7.1$\pm$0.2 and 0.3$\pm$0.1 mg/kg, respectively. Urinary excretion of DMA (TD1~TD5) was 22.0$\pm$5.0, 28.3$\pm$4.3, 29.2$\pm$4.1, 27.4$\pm$4.5 and 20.4$\pm$3.1 mg/18 hr, respectively. Consumption diets with added strawberries or juices of kale or garlic increased urinary TMA and DMA, suggesting that those precursors were excreted and not converted to the carcinogen, NMDA.