(Portland, OR) -- Children with ADHD can have their symptoms improved by taking vitamins and minerals. A study by the Oregon Health & Science University confirmed results in a previous study in New Zealand. 54-percent of children who were given supplemental vitamins and minerals showed improvement in their symptoms compared to 18-percent in a placebo group. The study involved 135 children in Portland, Columbus, Ohio; and Alberta, Canada. The results were published in the Journal of the American Academy of Child and Adolescent Psychiatry.