Long term soy diet can make a monkey agro'

While soy may be beneficial to women in a variety of ways, research in monkeys suggests that it could have an adverse effect on the behavior of men, according to researchers from Wake Forest University Baptist Medical Center.

Reporting in the current issue of the scientific journal Hormones and Behavior, the researchers found that in male monkeys, "long-term consumption of a diet rich in soy isoflavones can have marked influences on patterns of aggression and social behavior." Isoflavones are a naturally occurring plant estrogen in soy protein.

"Although considerable attention has been directed at the potentially beneficial effects of isoflavones in reducing the risk of various cancers, osteoporosis, cardiovascular disease and postmenopausal symptoms, less effort has been invested in characterizing neurobehavioral effects," according to the study.

People have the concept that soy is only beneficial, said Jay R. Kaplan, Ph.D., professor of comparative medicine and anthropology, one of the investigators. "There is the thought that what is good for some is good for all and more is better."

But this research points out that not only does the dose make a difference, but so does the sex of the consumer, Kaplan said, adding that the study is consistent with emerging literature showing that soy can have a negative impact on the behavior of male rodents. Previous studies have shown no difference in aggression in females given large doses of soy, Kaplan said.

The study was done over 15 months with adult male monkeys who were divided into three groups and fed different amounts and types of protein. One group had about 125 mg of isoflavones a day. The second group had half that amount, and the third group's protein came from milk and animal sources.

"In the monkeys fed the higher amounts of isoflavones, frequencies of intense aggressive and submissive behavior were elevated," according to the study. "In addition, the proportion of time spent by these monkeys in physical contact with other monkeys was reduced by 68 percent, time spent in proximity to other monkeys was reduced 50 percent and time spent alone was increased 30 percent."

Isoflavone levels of 125 mg per day are higher than amounts consumed by many Asians, who typically eat more soy than other populations. But, the isoflavone levels are comparable to levels found in many dietary supplements sold in the United States.

The FDA approved a statement in 1999 that said, "25 grams of soy protein a day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease." Soy sales have grown from $940 million in 1990 to a projected $4 billion this year. Kaplan said that soy is the most widely used botanical by pre- and postmenopausal women.

"To the best of our knowledge, the present study may be the first to demonstrate that long-term consumption of isoflavones can alter patterns of agonistic and social behavior in primates," the researchers reported. "The present findings suggest that careful attention will be required to balance beneficial and potentially adverse effects."

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Greater bean and pulse intake linked to improved nutrient intake and diet quality in American adults