A randomised controlled trial of vitamin D and omega-3 long chain polyunsaturated fatty acids in the treatment of irritability and hyperactivity among children with autism spectrum disorder

Abstract

Irritability and hyperactivity are common in children with Autism Spectrum Disorder (ASD). Because pharmacological treatments may have adverse effects, and despite limited evidence, caregivers/parents often use dietary supplements such as vitamin D and omega-3 fatty acids to address these behavioural symptoms. As a secondary objective of the VIDOMA (Vitamin D and Omega-3 in ASD) trial, we evaluated the efficacy of vitamin D, omega-3 long chain polyunsaturated fatty acid [omega-3 LCPUFA; docosahexaenoic acid (DHA)], or both on irritability and hyperactivity. New Zealand children with ASD (aged 2.5–8 years) participated in a 12-month randomized, double-blind, placebo-controlled trial of vitamin D (2000 IU/day, VID), omega-3 LCPUFA (722 mg/day DHA, OM), or both (2000 IU/day vitamin D + 722 mg/day DHA, VIDOM). The primary outcomes were the Aberrant Behaviour Checklist (ABC) domains of irritability and hyperactivity. Biomarkers (serum 25-hydroxyvitamin D [25(OH)D] and omega-3 index) and primary outcomes were measured at baseline and 12-months. Out of 111 children who completed baseline data collection, 66% completed the study (VID = 19, OM = 23, VIDOM = 15, placebo = 16). After 12 months, children receiving OM (-5.0 ± 5.0, P = 0.001) and VID (-4.0±4.9, P = 0.01) had greater reduction in irritability than placebo (0.8±6.1). Compared to placebo, children on VID also had greater reduction in hyperactivity (-5.2±6.3 vs. -0.8±5.6, P = 0.047). Serum 25(OH)D concentration (nmol/L, mean±SD) increased by 27±14 in VID and by 36±17 in VIDOM groups (P < 0.0001), and omega-3 index (%, median (25th, 75th percentiles)) by 4.4 (3.3, 5.9) in OM and by 4.0 (2.0, 6.0) in VIDOM groups (P < 0.0001), indicating a good compliance rate. The results indicate that vitamin D and omega-3 LCPUFA reduced irritability symptoms in children with ASD. Vitamin D also reduced hyperactivity symptoms in these children.