Plasma metabolomic signatures in children with autism spectrum disorder and their modulation following a gluten-free modified ketogenic diet

Gluten-free modified ketogenic diets (GF-MKD) have gained interest as adjunct nutritional interventions in autism spectrum disorder (ASD). However, evidence regarding their systemic metabolic effects in children, particularly from non-Western populations, remains limited. An untargeted plasma metabolomics analysis was performed using liquid chromatography–tandem mass spectrometry (LC–MS/MS) in 10 Indian children with ASD and 10 age- and sex-matched neurotypical controls. Multivariate and machine learning–based approaches were applied to identify metabolites distinguishing ASD from controls. Children with ASD subsequently underwent a three-month GF-MKD intervention, after which plasma metabolomic profiles and autism severity, assessed using the Childhood Autism Rating Scale (CARS), were re-evaluated. At baseline, children with ASD exhibited a distinct plasma metabolomic signature characterized by elevated L-leucine, a marked increase in coumarin (~ 6-fold), and reduced betaine levels. This metabolic profile differentiated ASD from controls with high discriminative accuracy (AUC = 0.93). Pathway enrichment analyses indicated alterations in branched-chain amino acid metabolism and one-carbon metabolic pathways. Following GF-MKD intervention, plasma levels of L-leucine and coumarin decreased by approximately 46% and 60%, respectively, while betaine levels showed a modest increase. Clinically, participants demonstrated a significant reduction in CARS scores (median decrease: 4.5 points; p < 0.05), indicating improvement in autism-related behavioural symptoms. No diet-related adverse effects were observed. Indian children with ASD display a modifiable plasma metabolomic profile involving key amino acid and methyl-donor pathways. Modulation of these metabolic disturbances following GF-MKD intervention was accompanied by behavioural improvement. These findings support the potential role of targeted dietary strategies in ASD and highlight the need for larger, randomized controlled trials to clarify underlying mechanisms and long-term clinical outcomes. Not applicable