Food Matrix as a Modulator of Spice Phytochemical Bioactivity: Evidence from In Vitro, Animal, and Human Studies

Spices contain numerous bioactive compounds with antioxidant, anti-inflammatory, antimicrobial, and metabolic effects. However, their biological activity depends strongly on the food matrix, which influences phytochemical stability, bioaccessibility, and physiological responses. This review evaluates the complex interactions between phytochemicals from selected spices-turmeric, ginger, cinnamon, and cloves-and various food components, including proteins, lipids, dietary fiber, and sweeteners. Drawing on evidence from in vitro models, animal studies, and human trials, the scope encompasses the effects of processing, encapsulation, and fermentation on bioactivity. The findings demonstrate that food matrices substantially modify the functionality of spice phytochemicals, rather than being merely passive carriers. Lipids, proteins, and dietary fiber improve compound stability and bioavailability, while fermentation and encapsulation further modulate their release and activity. Notably, dairy-rich systems significantly enhance the bioavailability of lipophilic compounds, such as curcuminoids. Human studies indicate that spice-containing foods may improve postprandial metabolic responses, endothelial function, oxidative status, and gut microbiota profiles. However, clinical evidence remains limited, with most human studies focusing on acute interventions rather than long-term effects. Future research must shift toward long-term clinical trials to establish chronic health benefits and explore a broader range of spices and food matrices. Key perspectives include clarifying the role of gut microbiota in metabolizing matrix-bound polyphenols and developing optimized delivery systems. Integrating molecular approaches with functional food design will be crucial for translating these interactions into effective dietary strategies.