Attention-deficit/hyperactivity disorder (ADHD) is a chronic psychiatric illness, which often co-occurs with other common psychiatric problems. Although empirical evidence supports the short-term efficacy of pharmacological and behavioural treatments, families often search for alternative treatment methods because of concerns about side effects and safety, cost and access, as well as fears about long-term exposure to psychotropic medications. This review presents the published evidence on use of broad-spectrum micronutrients to treat ADHD symptoms. This approach makes physiological sense in that nutrients are required for many critical biochemical reactions to occur, ranging from manufacturing neurotransmitters, to providing the mitochondria with essential nutrients for energy production, to assisting the gut to heal from inflammation. Multi-nutrient treatment approaches are an intriguing yet under-researched area; all but one of the trials conducted in the last decade have shown benefit for the treatment of ADHD symptoms, and the one negative trial likely used doses too low to effect change. However, the methodologies have varied widely from case-controlled studies to open-label trials to one randomized controlled trial. Sample sizes have typically been modest, although the effect sizes have tended to be medium to large. What is required now is replication, as well as investigation into the optimal ingredient range and optimal doses of nutrients. We discuss the proven and potential benefits of the broad-spectrum nutrient approach, considering the heterogeneous nature of ADHD.