We all likely knew a classmate in school who couldn’t sit still—a child who was often in trouble for fidgeting or doing silly, impulsive things that annoyed the teacher. Perhaps you were that kid or are now raising that type of child.

The National Survey of Children’s Health from the Centers for Disease Control and Prevention reported in late 2010 that an estimated 10% of American children aged 4–17 had attention deficit hyperactivity disorder (ADHD). Children with ADHD can be restless and challenging to handle. While many of them are prescribed drugs to control their impulses, a new study in The Lancet (February 5, 2011) suggests that a very restrictive diet could significantly reduce symptoms in kids with ADHD.

Study authors noted that the disorder can be brought on by external factors that in many cases can be controlled environmentally. The Impact of Nutrition on Children with ADHD (INCA) study was a randomized controlled trial that consisted of an open-label phase with masked measurements, followed by a double-blind crossover phase, according to the study abstract. Patients in the Netherlands and Belgium were enrolled via announcements in medical health centers and through media announcements. Randomization in both phases was individually done by random sampling.

  • In the first phase, children aged 4–8 who were diagnosed with ADHD were randomly assigned to one of two groups: the diet group was put on a restricted elimination diet for 5 weeks; the control group received instructions for a healthy diet.
  • The clinical responders (those with an improvement of at least 40% on the ADHD rating scale) from the diet group proceeded with a 4-week double-blind crossover food challenge phase (the second phase), in which high-IgG (immunoglobulins or antibodies in the blood) or low-IgG foods (classified on the basis of every child’s individual IgG blood test results) were added to the diet.

Researchers concluded that a “strictly supervised restricted elimination diet is a valuable instrument to assess whether ADHD is induced by food. The prescription of diets on the basis of IgG blood tests should be discouraged” without the supervision of a qualified professional, however.