The effects of green tea and curcumin on COMT and MAO pathways in nutrigenetics-based epigenetic approaches: Clinical benefits and the balanced management of psycho-oncological risks

The worldwide prevalence of all cancer types continues to rise. In this context, the psychological burden of cancer—particularly anxiety and depression—has emerged as a critical yet frequently overlooked component of comprehensive oncological care. In addition to clinical and psychosocial factors, growing evidence suggests that epigenetic mechanisms significantly influence both cancer biology and mental health, indicating that gene-environment interactions may affect psychological vulnerability in oncology contexts. Nutrigenetics-based epigenetic approaches enable personalized dietary and nutraceutical interventions based on individual genetic variability. Green tea catechins and curcumin are widely used bioactive compounds due to their epigenetic and anticancer potential. However, by altering the activity of catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO), important enzymes that degrade dopamine, norepinephrine, and serotonin, these substances have an impact on monoaminergic neurotransmission. Functional polymorphisms in the COMT and MAO genes may lead to substantial interindividual differences in mood regulation, stress responsiveness, and anxiety susceptibility. This review addresses molecular, clinical, and psycho-oncological aspects of the effects of green tea and curcumin on COMT and MAO pathways within a nutrigenetics-based epigenetic nutrition framework. The findings emphasize that the potential clinical benefits of epigenetically active nutraceuticals should be evaluated through a genotype-guided, individualized, and balanced approach.