Vol. 10, No. 4, 2004 Page 3
Earlier this year, Neal Simon and colleagues reported that male macaques fed high-soy diets exhibited significantly more aggression than those ingesting low levels of soy (see related article, Crime Times, 2004, Vol. 10, No. 3, Page 4). The researchers speculated that a diet high in soy— which contains hormone-mimicking phytoestrogens— alters the effects of estrogen receptors in ways that promote aggressive behavior.
A new study by Tim Moore et al., this one involving male hamsters, reports similar findings. In this study, adult hamsters fed a diet high in phytoestrogens reacted more aggressively to a non-threatening intruder than control animals fed a phytoestrogen-free diet. In addition, testosterone levels were higher in the phytoestrogen-fed hamsters than in the controls. When the researchers repeated the results with juvenile hamsters, only nonsignificant increases in aggression were seen in the phytoestrogen-fed group, but this group again had higher testosterone levels. Post mortem studies of both adult and juvenile phytoestrogen-fed hamsters revealed alterations in binding for vasopressin 1A receptors.
The researchers conclude, "These data present the first evidence that phytoestrogens can affect aggressive behavior and, concurrently, alter hormonal status and stimulate changes in the brain of male hamsters."
"The neurobehavioral effects of phytoestrogens in male Syrian hamsters," T. O. Moore, M. Karom, and L. O'Farrell, Brain Research, Vol. 1016, No. 1, July 30, 2004, 102-10. Address: Tim Moore, Department of Psychology, Clark Atlanta University, 223 James P. Brawley Drive, Atlanta, GA 30314, tmoore1@bellsouth.net.