Mentha Essential Oils: Unraveling Chemotype-Dependent Biosynthesis and Assessing Evidence for Health-Promoting Activities

<i>Mentha</i> essential oils (EOs), renowned for their distinctive aromas and diverse biological activities, represent a key focus in phytochemical and pharmacological research. While numerous reviews have documented the general properties of mint EOs, a systematic and critical synthesis of recent advances linking chemotypic diversity to biosynthetic mechanisms and evidence-based health benefits remains lacking. This review aims to address this gap by comprehensively analyzing the structural variability of EOs across major <i>Mentha</i> species, elucidating the chemotype-dependent enzymatic and genetic regulation within the plastidial methylerythritol phosphate (MEP) pathway, and evaluating preclinical and clinical evidence supporting their health-promoting activities, including antimicrobial, antioxidant, anti-inflammatory, digestive, respiratory, cognitive-enhancing, and anticancer effects. By integrating findings from cutting-edge transcriptomic and genomic studies, we highlight how genetic variations and epigenetic factors influence monoterpene biosynthesis and ultimately shape bioactivity profiles. Furthermore, we critically assess challenges related to EO standardization, bioavailability, and clinical translation, and propose interdisciplinary strategies, such as metabolic engineering, nano-delivery systems, and structured clinical trial designs to overcome these barriers. This review not only consolidates the current understanding of <i>Mentha</i> Eos, but also provides a forward-looking perspective on their potential applications in functional foods, pharmaceuticals, and personalized health products.