Good nutritional status in early life is vital for neurodevelopment, but eating disorders like picky eating heighten risks of nutritional imbalance and dysbiosis. Dysregulated gut microbiomes are increasingly linked to gastrointestinal issues and neurodevelopmental disorders. Vitamin deficiency may aggravate these conditions, emphasizing the need for focused nutritional care. The gut microbiota plays a key role in brain function and development, offering potential as a therapeutic target. At present, supplementation of probiotics, prebiotics, vitamins and other nutrients is presumed to produce some benefits to neurodevelopmental disorders though robust data on their effectiveness remain scarce. We propose that vitamin deficiency and dysbiosis interact, influencing neurodevelopment and brain function. Our review identifies key substrates such as vitamins, short-chain fatty acids, cytokines, neurotransmitters, and tryptophan metabolites in this network and provides mechanistic insights into their roles in the pathogenesis of neurodevelopmental disorders, paving the way for personalized strategies to address these conditions. © 2026