Exposure studies are the first step in predicting bioactivity of phytochemicals in humans. Due to the interaction between phytochemicals, their food matrix, the gut microbiome and the host, the resulting exogenous metabolites in systemic circulation vary largely between individuals. Nutrikinetics is an extension of the classical pharmacokinetic concept with explicit model adaptations. The concept relies on integrated deployment of metabolic profiling, multi-level data analysis and population-based single compartment modelling. Nutrikinetics is expected to make critical contributions in understanding how phenotypes and the food matrix modulate bioactivity of dietary phytochemicals, in particular when gut microbial bioconversions are involved.