The present study aimed at the identification of novel imidazole alkaloids derived from histamine or histidinol and generally investigating the occurrence of suchlike alkaloids in a variety of foodstuffs. Herein, N-caprylhistamine was synthesized and the glucosidic derivative N-caprylhistamine-β-glucoside was isolated from ripe tomato fruits and structurally characterized. The obtained reference standards were used for the extension of an established LC-MS/MS-based method for the quantitation of several imidazole alkaloids in tomato products. After validation for the two additional analytes and demonstrating the applicability of the method to nine other food matrices, 104 food items were screened for the occurrence of the described imidazole alkaloids. Remarkably, all of the investigated alkaloids were only quantifiable in tomato-based products and the occurrence of N-caprylhistamine and N-caprylhistamine-β-glucoside was reported for the first time. These imidazole alkaloids could thus be applicable as specific intake biomarkers for tomatoes and their biological activities as well as metabolic fate should be investigated in future research. © 2019 Elsevier Ltd