A method useful for providing a phytonutrient to a subject via mediation of the subject's microbiome is disclosed. The method includes administering a phytofunctional composition to a subject change the phytonutrient producer status of the subject. The method may also include identifying a phytonutrient producer status of the subject by assessing a level of at least one of a preselected phytonutrient and a preselected phytonutrient precursor compound within the subject. A phytofunctional composition useful in the method is also disclosed, and comprises a phytonutrient precursor compound and an active agent. The active agent comprises a probiotic and/or a prebiotic, and is adapted to mediate production of the preselected phytonutrient in the gastrointestinal tract of the subject, thereby changing the phytonutrient producer status of the subject.