The nature-versus-nurture debate has long raged over the origin of violentbehavior: is it in the genes, or in the upbringing? William Walsh, Ph.D., and his colleagues at the Health Research Institute in Illinois think they have a third possibility: it's in the body, in the form of nutritional imbalances.
In a study published in Physiology and Behavior, Walsh compared the results of blood tests given to 135 assaultive men to those of 18 controls with no history of violence. It turned out that the violent males had lower zinc and higher copper levels than the controls, and that the more imbalanced the ratio, the more severe and more frequent were their aggressive outbursts.
Walsh's colleague, Ronald Isaacson, Ph.D., says that while its relationship to violent behavior is unclear, "zinc plays an important role in brain function, and thus in mental well-being." (High levels of copper have also been linked to hyperactivity and schizophrenia.) Of course, says Isaacson, "the causes of assaultive behavior are much more complicated than blood copper and zinc"; not only may societal and familial influences be involved, but perhaps other chemical imbalances as well. Still, when the young men were treated for their zinc deficiency and copper overload, their assaultive episodes declined substantially.
