Plant-based dietary biomarkers: from discovery to validation using mass spectrometry-based metabolomics

As diets shift globally toward plant-based foods, objective tools are needed to monitor intake and evaluate the resulting health outcomes. Biomarkers of dietary exposure offer complementary objective measurements for self-reported dietary assessment methods. Recent developments of mass spectrometry-based metabolomics have enabled the discovery of many emerging biomarkers for plant-based foods; yet a substantial gap remains between discovery and clinical application. This narrative review addresses the question: which plant-based food biomarkers are sufficiently validated for use in dietary exposure assessments, and which analytical and biological obstacles currently limit their application in population studies? Biomarkers reported in the literature were categorized as validated, emerging, or discovery-stage candidates. Analytical methodologies for biomarker quantification are also discussed, including high-resolution mass spectrometry platforms, and emerging techniques. Challenges identified in biomarker validation involve inter-individual metabolic variability, inadequate food specificity, and matrix effects in biological samples. Integration of foodomics databases with targeted validation studies potentially offers an efficient approach to speed up biomarker discovery. Multi-marker panels combining structurally different metabolites are promising for assessing complex plant-based dietary patterns.