Nutrients and bioactive compounds as modifiers of neurodegenerative trajectories: molecular mechanisms, translational barriers, and precision nutrition.

The Neurodegenerative diseases (NDs) such as Alzheimer's disease (AD), Parkinson's disease (PD), Multiple sclerosis (MS), and Amyotrophic lateral sclerosis (ALS) are a growing health burden across the world with minimal disease-modifying treatment and therapy. It is emerging that neurodegeneration is not only a progressive loss of neurons, but also a nutrient-sensitive systems-level dysfunction that takes the form of redox imbalance, chronic neuroinflammation, mitochondrial dysfunction, impaired proteostasis, and synaptic loss. The aging brain are more prone to metabolic vulnerability, and subclinical deficiencies in essential nutrients and bioactive dietary compounds may exacerbate cellular stress responses that contribute to disease progression. It summarizes the existing data on the effects of nutrients like vitamins, minerals, polyunsaturated fatty acids, and various phytochemicals in modulating neuronal homeostasis by regulating oxidative signaling, inflammatory cascades, mitochondrial resilience, autophagy, and synaptic plasticity. These nutrient-mediated effects collectively influence neuronal survival, synaptic integrity, and cognitive function by affecting disease susceptibility and progression. Additionally newer metabolites of the marine and microbiome act as new neuroactive agents. The evidence from in-vitro and preclinical models, translation to clinical benefit remains inconsistent due to heterogeneity in study design, bioavailability, blood- brain barrier penetration, dosing strategies and disease stage. This review highlights emerging potential of precision nutrition frameworks that integrate nutrigenomics, metabolomics, and microbiome interactions, and individualized metabolic profiling to enable context-dependent and stage-specific interventions. Moreover, conceptualizing neurodegeneration as a nutrient-sensitive, systems level disorder, propose a mechanistically informed and integrative approach that combine targeted nutritional strategies with pharmacological and lifestyle therapies to more effectively modify neurodegenerative trajectories.