Protective role of L-methylfolate, vitamin B₂, and vitamin D₃ in modulating neurobehavioural and epigenetic outcomes of chronic stress

Chronic stress is a key risk factor for depression, while conventional antidepressants, though effective, often are associated with adverse effects. Nutritional approaches such as L-methylfolate, vitamin B₂, and vitamin D₃ offer safer alternatives by supporting neurotransmitter synthesis, one-carbon metabolism, and stress regulation. This study examined the preventive effects of a multivitamin combination in a chronic unpredictable mild stress (CUMS) rat model. Male and female Sprague Dawley rats were divided into control, CUMS + saline, or CUMS + multivitamin groups and treated for 21 days. Behavioural tests, cortical morphometry, neurotransmitter receptor expression, hepatic folate levels, DNA methylation, and METTL3 expression were assessed, alongside serum cortisol and biochemical markers of liver and kidney function. CUMS induced depressive-like behaviours, elevated cortisol, impaired organ function, reduced cortical thickness, and downregulated serotonergic, dopaminergic, and adrenergic receptors. Multivitamin supplementation restored behaviour, normalized cortisol and organ function, preserved cortical integrity and hepatic methylation, and upregulated METTL3. These findings highlight multivitamins as functional food-based strategies for the prevention of depression-like behaviour.