Early-onset bipolar disorder has significant morbidity and mortality. Development of safe, effective treatments to which patients will adhere is critical. Pharmacologic interventions for childhood bipolar spectrum disorders are limited and are associated with significant risk for adverse events. Diet and nutrition research suggests vitamins, minerals, and other nutrients are important underpinnings of general physical and mental health; furthermore, they may even be useful in treating mood dysregulation by providing a more favorable risk-benefit ratio than contemporary psychotropic agents. This article reviews the literature on multinutrient supplementation and mental health, and examines a case study of a 12-year-old boy with bipolar disorder and co-morbid diagnoses treated for 6 years with conventional medication and finally a multinutrient supplement. The multinutrient supplement in this case study is EMPowerplus (EMP+), a 36-ingredient supplement containing 16 minerals, 14 vitamins, 3 amino acids, and 3 antioxidants. It was used to treat a 12-year-old boy initially diagnosed with bipolar disorder not otherwise specified (BP-NOS) at age 6, and whose diagnosis evolved by age 10 to bipolar I (BP-I), mixed, with psychotic features. He also met criteria for generalized anxiety disorder by age 8 and obsessive-compulsive disorder by age 10. After 6 years of conventional treatment (ages 6-12), he received 14 months of EMP+. Symptom manifestation over 7 years is described in conjunction with treatment history. EMP+ resulted in outcome superior to conventional treatment. This report adds to accumulating preliminary evidence that further basic science and clinical studies of multinutrient supplements are warranted.