Dietary plant bioactive compounds: context-dependent roles as antinutrients or beneficial phytochemicals-a...

Dietary plant bioactive compounds have traditionally been classified as either beneficial phytochemicals or harmful antinutrients; however, emerging evidence suggests that most of these compounds exhibit dual functionality depending on the context. This review integrates current knowledge of the phytochemical-antinutrient continuum, highlighting that the biological effects of these compounds vary and are influenced by factors such as concentration, chemical structure, food matrix, processing conditions, and host-related variables, including the gut microbiota and nutritional status. Major compound classes, including phytic acid, tannins, glucosinolates, lectins, saponins, and enzyme inhibitors, are discussed to illustrate how structural features underlie both health-promoting effects, such as antioxidant, anti-inflammatory, anticancer, and metabolic regulatory activities, as well as adverse antinutritional effects, including mineral chelation, enzyme inhibition, impaired digestibility, and reduced nutrient bioavailability. A context-dependent functional classification framework is proposed that groups dietary plant bioactive compounds as primarily beneficial phytochemicals with conditional antinutrient effects, balanced dual-function compounds, or primarily antinutrients with emerging beneficial roles. The review also evaluates how conventional and emerging processing technologies, including soaking, germination, fermentation, thermal processing, extrusion, high-pressure processing, pulsed electric fields, ultrasound, cold plasma, and irradiation, can shift compounds along the phytochemical-antinutrient continuum. Translationally, understanding this continuum is important for functional food design, sustainable plant-based diets, dietary guidance, and precision nutrition, particularly for populations with mineral deficiencies, thyroid vulnerability, gastrointestinal disorders, or distinct gut microbiota profiles. Key research gaps include limited human clinical evidence, incomplete mechanistic understanding, and the need for standardized analytical methods, dose-response thresholds, and validated biomarkers of exposure and response.