Soy Causes Intense Aggression & Submission in Males

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The study below seems to correlate with classic andropause symptoms.

It's likely any defenciencies or increases occured in hormone levels

not analyzed.

None of the behavioral changes are positive.

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Increased aggressive behavior and decreased affiliative behavior in

adult male monkeys after long-term consumption of diets rich in soy

protein and isoflavones.

Simon NG, Kaplan JR, Hu S, Register TC, MR.

Department of Biological Sciences, Lehigh University, Bethlehem, PA

18015, USA.

Horm Behav. 2004 Apr;45(4):278-84.

Estrogen produced by aromatization of gonadal androgen has an

important facilitative role in male-typical aggressive behavior that

is mediated through its interaction with estrogen receptors (ER) in

the brain. Isoflavones found in soybeans and soy-based dietary

supplements bind ER and have dose- and tissue-dependent effects on

estrogen-mediated responses. Yet, effects of isoflavone-rich diets on

social and aggressive behavior have not been studied. We studied the

effects of long-term (15 months) consumption of diets rich in soy

isoflavones on spontaneous social behavior among adult male

cynomolgus macaques (Macaca fascicularis) (n = 44) living in nine

stable social groups. There were three experimental conditions which

differed only by the source of dietary protein: casein and

lactalbumin (no isoflavones), soy protein isolate containing 0.94 mg

isoflavones/g protein, and soy protein isolate containing 1.88 mg

isoflavones/g protein. In the monkeys fed the higher amount of

isoflavones, frequencies of intense aggressive (67% higher) and

submissive (203% higher) behavior were elevated relative to monkeys

fed the control diet (P's < 0.05). In addition, the proportion of

time spent by these monkeys in physical contact with other monkeys

was reduced by 68%, time spent in proximity to other monkeys was

reduced 50%, and time spent alone was increased 30% (P's < 0.02).

There were no effects of treatment on serum testosterone or estradiol

concentrations or the response of plasma testosterone to exogenous

gonadotropin-releasing hormone (GnRH). The results indicate that long-

term consumption of a diet rich in soy isoflavones can have marked

influences on patterns of aggressive and social behavior.