The Benefit of Omega-3 Fatty Acid-Based Diets on Attention-Deficit Hyperactivity Disorder through the Brain-Gut Axis: A Systematic Review of Randomized Controlled Trials

Abstract

Attention-Deficit Hyperactivity Disorder (ADHD) is one of the most prevalent mental conditions in children and young adolescents. While stimulants are the first-line treatment, diet-based supplements, particularly omega-3 fatty acids, are being investigated for their additional benefits. Omega-3 fatty acids influence the microbiota-gut-brain axis through anti-inflammatory and antioxidant properties, modulation of gut microbes, and stimulation of the immune system, highlighting their potential as crucial dietary supplements for individuals with ADHD. This review aims to comprehensively summarize current evidence on the benefits of omega-3 fatty acids in patients with ADHD, both clinically and in terms of biological markers, to elucidate their advantages and underlying mechanisms for future research applications. A comprehensive literature search of relevant studies available in English was conducted on PubMed/MEDLINE, Web of Science, and Wiley Online Library databases from 1987 until December 2023. Articles were selected based on inclusion and exclusion criteria, resulting in thirty-six studies being included in this review. Twenty-one of the thirty-six studies reported benefits of omega-3, showing improvements in rating scales, behavioral functions, or both. However, two studies indicated that omega-3 supplementation could worsen adverse effects on behavior or aggression rating scales, particularly in pregnant women and newborns with long-term follow-up. Most of the studies focused on children diagnosed with ADHD documenting a reduction in ADHD symptoms among individuals supplementing with omega-3 fatty acids. Our systematic review provides evidence that omega-3 polyunsaturated fatty acids are beneficial in improving clinical symptoms of ADHD in adolescents and adults, potentially by increasing beneficial gut microorganisms, and removing endotoxins that cause pro-inflammatory responses. Future research should involve larger sample sizes, longer durations, and determination of optimal omega-3 sources for ADHD treatment.