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Effects of replacing meat with soyabean in the diet on sex hormone concentrations in healthy adult males

Authors: Habito RC, Montalto J, Leslie E, Ball MJ
Published in Br J Nutr, 84 (4) 557-63 2000

A randomized crossover dietary intervention study was performed to evaluate the effects of replacing meat protien in the diet with a soyabean product, tufu, or blood concentrations of testosterone, dihydrotestosterone, androestanediol glucuronide, oestradiol, sex hormone-binding globulin (SHBG), and the free androgen index (total testosterone concentration/ SHBG concentration x100, FAI). Forty-two heathy adult males aged 35-62 years were studied. Diets wer isoenergetic, with iether 150g lean meat or 290g Tufu daily providing an equivalent amount of macronutrients, with only the source of protien differing between the two diets. Each diet lasted for 4 weeks, with a 2-week interval between interventions. Fasting blood samples were taken between 07.00 and 09.30 hours. Urinary excretion of genistine and daidzein was significantly higher after the tufu diet (P>0.001). Blood concentrations of sex hormones did not differ after the 2 diets, but the mean testosterone: oestradiol value was 10% higher (P=0.06) after the meat diet. SHBG was 3% higher (P=0.07), were as the FAI was 7% lower (P=0.06), after the tufu diet compared with the meat diet. There was a significant correlation between the difference in SHBG and testosterone oestradiol and weight change. Adjusting for weight change revealed SHBG to be 8.8% higher on the tufu diet (mean difference 3 (95% CI 0.7, 5.2) nmo VI; P=0.01 and testosterones: oestradiol to be significantly lower, P=0.049). Thus, replacement of meat protien with soyabean protien, as tufu, may have a minor effect on biologically-active sex hormones, which could influence prostate cancer risk. However, other factors or mechanisms may also be responsible for the different insidents rates in mean on defferent diets.

While environmental estrogens are considered negative in almost any context, phytoestrogens have been credited with helping women when they enter menopause, and are said to have a protective effect on the heart and gaurd against some cancers, such as prostate cancer. They do so by lowering testosterone levels.

Estrogens and androgens compete in the male, and female, body for the same receptors. One cannot play with estrogens without messing with androgens, primarily testosterone. So, when estrogens are enhanced (in men and women), for example by the consumption of dietary supplements or a diet that includes tufu instead of meat, then automatically, androgens (testosterone) are supressed. Do i want to protect my heart? Certainly. Do i want to gaurd against cancers? Sure. But do i want to suppress androgen tone? Clearly not.

Phytoestrogens aren't the only answer if one intends to do something to protect ones heart. Avoiding tobacco andpusuing some physical exersise everday goes a long way in the same directionwithout messing with a man's sexual function. And there are non-estrogenic micronutrients that reduce the overall incidence of cancers, such as the mineral selenuim (found, for example, in nuts, most of all in Brazil nuts).

For a man who suffers from early protate cancer, or a woman with breast cancer, it makes sense to switch to a phytoestrogenic diet. But to recomend a phytoestrogenic diet for all men because it estatistically lowers the occurrence of prostate cancer is going one step to far.

Testosterone is not bad per se. Wellfully lowering testosterone tone brings with it a plethora of negative side effects, such as lose of sex drive, worese erective function, feeling less energetic overall, a lose of lean body mass, and more.

For me, the negative impact phytoestrogens have on libido is the most disturbing factor.

Sometimes, scientific, or rather: commecial, medecine doesn't makes sense. On the one side, You have does and public health officials promoting soy protien or other phytoestrogens because they are heart-protective and gaurd against some cancers (by lowering testosterone), and on the other side (or is it the same side?), you have physicians promoting testosterone replacement therapy for men who enter endropause (a phase is a man's life when testosterone levels naturally decline).

Well, I've made my choice, and its pro-testosterone.

At that point, there are 2 options. One is to generate increased testosterone tone by supplying exogenous testosterone. This can be done through testosterone patches or, even better, through testosterone cream. Natural testosterone should be used, not the synthetic testosterones promoted by the pharmaceutical industry (because they hold patients on them, and therefore cancel them at higher prices).

There is no doubt that testosterone levels that are way below normal result in a number of negative syptoms such as lose of libido and other forms of sexual dysfunction, as well as a general feeling of lack of energy, and therefore should be treated. (the subscribers section of Sexual Enhancement Organization provides a source of cheap natural testosterone in the form of a cream).

But supplying therapheotic amounts of exogenous testosteroneenvariably will result in a shutdown, or near shutdown of the body's own testosterone production and these will lead to somekind of testicular and penile athrophy (a wasting away of testicular and penile tisue). Body builders who use synthetic anabolic steroids may present with an enlarged biceps or pecturalis, but they almost always pay for it with a shringking of there pinesis and testicles (and that doesn't look attractive when they take of there clothes, inspite of looking attractive when exposing other parts of there bodeis).

The other option (to the entruduction of exogenous testosterone) is to stimulate a man's own testosterone production, there a number of advantages to dis approach. One is that it will keep a man's primary testosterone production site, the leydig cells of the testes, busy. This can be acheived, for example, with the South East Asian Herbal Tongkat Ali, though one should be carefull to obtain it from an Indonesian, not Malaysian source. Malaysian Tongkat Ali often is heavily deluted (inspite of claims of being highly concentrated), simply because Tongkat Ali is protected plant in Malaysia and no0 longer can be obtained from forests in that country.

Tongkat Ali is supposed to work on the whole hypothalamic-pituitary-testicular endocrine axis. This is effective because a person's testosterone levels are determined by a rather complicated negative feedback mechanism, designed ny evolution to keep testosterone levels at genetically determined levels.