Phytochemicals From Herbs and Spices: Their Absorption, Metabolism, and Relationship to Clinical Outcomes.

This article appears as part of the supplement "The Role of Spices and Herbs on Supporting Healthy Diets and Improving Nutritional Status," sponsored by the McCormick Science Institute. Results of clinical trials suggest that herbs and spices (H/S) may provide health benefits by influencing risk factors associated with chronic diseases. Phytochemicals found in H/S, such as terpenoids, flavonoids, and phenolic acids, are biologically active compounds that are potentially responsible for these beneficial effects. In this review, we have summarized our past and current research on the phytochemical composition of H/S and the metabolic fate of these compounds following both acute and regular intake of selected H/S. We also briefly discuss associations with clinical outcomes. Our data indicate that certain phytochemicals unique to specific H/S, such as piperine in black pepper and carnosic acid in rosemary, are metabolized after intake and can remain in the circulation for extended periods. In contrast, others are cleared more rapidly, often within a few hours. Some phytochemical metabolites that are cleared more slowly in the bloodstream may serve as biomarkers of H/S intake. Postprandial evaluation and kinetic profiling offer valuable insights into the absorption and clearance patterns of these compounds, shedding light on the time frames during which they may exert biological effects. Tracking metabolite kinetics alongside changes in clinical markers helps to clarify the potential contribution of specific phytochemicals to health outcomes. Further research is needed to explore dose-dependent effects of H/S on circulating metabolites and clinical outcomes, which will enhance our understanding of the mechanisms that account for their biological activity.

© The Author(s) 2026. Published by Oxford University Press on behalf of the International Life Sciences Institute.