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Phytoestrogens & Male Health

Phytoestrogens can affect male animals health and fertility, what about people?

"For the males, decreased sperm count and enlarged prostates. The treatment altered virtually every aspect of the reproductive system. The place next to the testes, the duct system called the epididymis where the sperm are stored prior to being ejaculated -- it was abnormally small, which could account also for lowered sperm count in the ejaculate. But we know also the testis is making fewer sperm. We see changes in growth rate as well. One of the interesting things is that these very low doses of estrogen increase rates of growth. The animals were actually growing larger than they would have normally. It was really quite a dramatic effect. The females went into puberty early. And we saw changes in behavior, changes in reactivity to the presence of other animals in the environment. Essentially the animals looked to be somewhat hyper-reactive to stimuli. We have, in other words, effects on brain and behavior. We're also seeing changes in liver enzyme activity which determines the way we respond to external chemicals, how fast we clear drugs, how we metabolize drugs.

In other words, in every aspect of physiology that we look for, we see effects. And they're permanent. And the important thing about what I'm talking about is we are only exposing babies to these chemicals for very, very short periods of time in development and the consequences are for the rest of the life of that individual. Once you change the development of an organ there is no way to undo that effect. It's a life sentence -- that's a lifetime consequence. Medical science can't undo the development of organs."  Fredrick Vom Saal, Professor of Biological Sciences, University of Missouri in an interview on estrogenic chemicals in the environment conducted in February 1998 by Doug Hamilton, producer of FRONTLINE's "Fooling With Nature." Full interview can be found here

From simple laboratory mice to the unusual case of the phytoestrogen sensitive captive cheetahs, there is ample evidence that dietary phytoestrogens cause infertility in a variety of animals.  Why would this be?  Like the other toxins in soybeans, the phytoestrogens are present in the soybean to ensure its survival.   What better way to discourage predators than to make sure they aren't able to reproduce?

But what about humans?   Some, such as Richard Sharpe and Theo Colborn, have suggested that the trend toward lower male fertility is due to environmental estrogens, including the soy phytoestrogens.   But is there any evidence that phytoestrogens may place males at risk of reduced fertility? Also see quotes from Food Safety - a 21st Century Issue, by Professor Shaw in the New Zealand Science Review.  The human sperm count decrease over the past five decades might relate to the introduction of soya to the western diet and the increasing popularity of vegetarianism - a sting in the tail for apparently healthy eating.  More information is available from an article published in The Dominion, Wellington September 3 2001.

Nagata and colleagues have reported an inverse association between soy product intake and serum hormone concentrations in Japanese men.  Research has demonstrated that chemical compounds can have a number of other effects on male health including decreasing prostate gland weight, lower testosterone levels, along with inducing significant testicular cell death and necrosis.

It's important to recognize that testosterone and dihydrotestosterone, the two androgens, play fundamental roles in penis development in alligators, as they do in humans. So, if we in fact have abnormalities in an alligator due to environmental contaminants, and changes in phallus size, we should be looking at humans.

Lois J Guillette Ph.D.

 He is Professor of Zoology at the University of Florida. Guillette has studied alligators in Florida for over ten years. Based on Theo Colborn's work, and the findings at the 1991 Wingspread conference in Wisconsin, he shifted his research to hormones -- asking whether environmental contaminants could be affecting alligator health and development.

Interviewed by Doug Hamilton, producer of FRONTLINE's "Fooling With Nature." Interview conducted November 1997.

"Caponised males? A half helping of man".   W. David Kubiak reports that "...a steady diet of miso, tofu, soy sauce and so on might not be best for leadership trainees or aspiring Lotharios".

There is also a wealth of evidence that shows that mammals exposed to estrogens during critical periods of sexual development can suffer a drastic reduction in fertility.  For example

• Effects of exposure environmental estrogens on rats Male Reproductive Health
• Other estrogenic effects of isoflavones on dogs and fish
• And what about the ridiculous feeding of captive cheetahs soy protein?  It seems cheetahs are particularly sensitive to isoflavones as well.  So if you care at all about your pet feline, take a tip from Soy Online Service and don't expose them to cat food containing soy.
• Effects are not limited to vertebrates alone, read about the effects on the humble male Grasshopper.

See quotes from Food Safety - a 21st Century Issue, by Professor Shaw in the New Zealand Science Review.  The human sperm count decrease over the past five decades might relate to the introduction of soya to the western diet and the increasing popularity of vegetarianism - a sting in the tail for apparently healthy eating.  More information is available from an article published in The Dominion, Wellington September 3 2001.

Congenital abnormalities of the male genital tract are also increasing, and once again soy phytoestrogens may be implicated, according to a study that found a higher incidence of birth defects in male offspring of vegetarian, soy-consuming mothers.  There are also links between high soy diets during pregnancy and nursing and eventual developmental changes in children.

In another  research communication, Japanese scientists found that the presence of tyrosine protein kinase inhibitor genistein retarded the repair of gastric mucosal cells, suggesting that genistein may retard the healing of gastric ulcers.

Also read our pages on the effects of phytoestrogens on thyroid, immune and cognitive function.

Further information on Reproductive Health can be found at http://www.fertilityawareness.net/.

Further Reading

Exposure of juvenile rats to the phytoestrogen daidzein impairs erectile function in a dose-related manner in adulthood.
Pan L, Xia X, Feng Y, Jiang C, Cui Y, Huang Y., J Androl. 2008 Jan-Feb;29(1):55-62.

Pan et al results suggest that exposure of juvenile rats to daidzein in a relatively large amount could adversely affect penile erection in adulthood.

Full Abstract Here

The effect of isoflavone extract ingestion, as Trinovin, on plasma steroids in normal men.
Lewis JG, Morris JC, Clark BM, Elder PA., Steroids 2002 Jan;67(1):25-9

We therefore question the value of Trinovin, at the recommended dosage, as offering protective effects against prostate disease by mechanisms involving either significant modulation of plasma steroid or SHBG levels. In contrast the increase in dihydrotestosterone plasma levels could be seen as possibly detrimental.

Full Abstract Here

Hidden soy in fast foods have been linked to cutting men's fertility.  Read more Here

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

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).

Full Abstract Here

New research confirms the risk of soy foods to mens' fertility once again.

Soya may be making men infertile.  Read an article by James Chapman published in the Daily Mirror Here.

New Findings May Support Soy-Dementia in Men. Article by Ian Williams Goddard, August 9, 2003

Manipulation of prenatal hormones and dietary phytoestrogens during adulthood alter the sexually dimorphic expression of visual spatial memory.

Lund TD, Lephart ED. BMC Neurosci. 2001;2(1):21. Epub 2001 Dec 18.

Full Abstract Here

Dietary supplements of soya flour lower serum testosterone concentrations and improve markers of oxidative stress in men.
Gardner-Thorpe D, O'Hagen C, Young I, Lewis SJ. Eur J Clin Nutr 2003 Jan;57(1):100-6

Total serum testosterone fell in volunteers taking the soya scones (19.3-18.2 nmol/l; 95% CI 1.01, 1.12; P=0.03)

Full Abstract Here

Regulation of male sex hormone levels by soy isoflavones in rats.
Yi MA, Son HM, Lee JS, Kwon CS, Lim JK, Yeo YK, Park YS, Kim JS., Nutr Cancer 2002;42(2):206-10

The study showed a reduction of plasma DHT along with an increase in total plasma androgen in rats fed soy flour or semipurified isoflavones for 1 wk. These results suggest that soy isoflavone intake may reduce plasma DHT level.

Full Abstract Here

Exposure to Genistein During Gestation and Lactation Demasculinizes the Reproductive System in Rats.
Wisniewski AB, Klein SL, Lakshmanan Y, Gearhart JP. J Urol 2003 Apr;169(4):1582-1586

Exposure to the phytoestrogen genistein (Indofine Chemical Co., Somerville, New Jersey) can disrupt normal male sexual differentiation.

Males exposed to genistein had smaller anogenital distance and testis size, and delayed preputial separation. Perinatal exposure to genistein also caused long-term dysfunction in reproductive behavior, in which adult males exposed to genistein were less likely to mount, intromit and ejaculate during mating tests. Males exposed to genistein also had lower testosterone concentrations in adulthood.

Perinatal genistein exposure results in transient and lasting alterations in masculinization of the reproductive system. These results extend our knowledge of the effects of early genistein exposure on male development and may have implications for human health in terms of potential relationships of endocrine disrupters and urogenital abnormalities thought to be increasing in incidence in boys and men.

Full Abstract Here

Mums-to-be warned:  Do not eat soya, London Metro 13/02/03.  Read this article Here.

The phenotype of the aromatase knockout mouse reveals dietary phytoestrogens impact significantly on testis function.
Robertson KM, O'Donnell L, Simpson ER, Jones ME. Endocrinology 2002 Aug;143(8):2913-21

Our study highlights the importance of estrogen in spermatogenesis and shows that relatively low levels of dietary phytoestrogens have a biological effect in the testis.

Full Abstract Here

Estrogen and spermatogenesis.
O'Donnell L, Robertson KM, Jones ME, Simpson ER. Endocr Rev 2001 Jun;22(3):289-318

This review highlights the ability of exogenous estrogen exposure to perturb spermatogenesis and male fertility, as well as the emerging physiological role of estrogens in male fertility, suggesting that, in this local context, estrogenic substances should also be considered "male hormones."

Full Abstract Here

Infant feeding with soy formula milk: effects on the testis and on blood testosterone levels in marmoset monkeys during the period of neonatal testicular activity.
Sharpe RM, Martin B, Morris K, Greig I, McKinnell C, McNeilly AS, Walker M. Hum Reprod 2002 Jul;17(7):1692-703.

SMA-fed males had mean testosterone levels of 2.8-3.1 ng/ml, typical of the 'neonatal testosterone rise', whereas SFM-fed males exhibited consistently lower mean levels (1.2-2.6 ng/ml); paired comparison in SMA-and SFM-fed co-twins at day 35-45 revealed 53-70% lower levels in 11 of 13 co-twins fed with SFM (P = 0.004).

Further evidence for suppression of testosterone levels in SFM-fed males came from comparison of the frequency of low testosterone levels (<0.5 ng/ml). In historical controls aged 35-45 days, two out of 22 values were <0.5 ng/ml, a similar frequency as found in control SMA-fed males (one out of 15 values <0.5 ng/ml). In contrast, 12 out of 15 values for SFM-fed males were <0.5 ng/ml (P < 0.001).

Based on the average isoflavone content of the SFM brand used, intake of isoflavones was estimated at 1.6-3.5 mg/kg/day in the SFM-fed marmosets which is 40-87% of that reported in 4 month human infants fed on a 100% SFM diet. It is therefore considered likely that similar, or larger, effects to those shown here in marmosets may occur in human male infants fed with SFM. Whether the changes described result in longer-term effects is under investigation.

Full Abstract Here

Neonatal exposure to genistein reduces expression of estrogen receptor alpha and androgen receptor in testes of adult mice.
Shibayama T, Fukata H, Sakurai K, Adachi T, Komiyama M, Iguchi T, Mori C. Endocr J 2001 Dec;48(6):655-63

Our results exhibited that the disruption of gene expression continued for long term such as 3 months after administration of genistein, even if no effect was found at conventional reproductive-toxicological level. We have shown that neonatal administration of weak estrogenic compound (genistein) affects male reproductive organs at molecular levels in adulthood.

Full Abstract Here

Neurobehavioral actions of coumestrol and related isoflavonoids in rodents.
Whitten PL, Patisaul HB, Young LJ. Neurotoxicol Teratol 2002 Jan-Feb;24(1):47-54

Treatment of rat dams with a 100-ppm coumestrol diet from birth to postnatal day (PND) 21 induced premature anovulation in female offspring, and treatment from birth to PND 10 suppressed sexual behavior in male offspring.

Full Abstract Here

Cross-species and interassay comparisons of phytoestrogen action.
Whitten PL, Patisaul HB. Environ Health Perspect 2001 Mar;109 Suppl 1:5-20

In vivo data show that phytoestrogens have a wide range of biologic effects at doses and plasma concentrations seen with normal human diets. Significant in vivoresponses have been observed in animal and human tests for bone, breast, ovary, pituitary, vasculature, prostate, and serum lipids. The doses reported to be biologically active in humans (0.4--10 mg/kg body weight/day) are lower than the doses generally reported to be active in rodents (10--100 mg/kg body weight/day), although some studies have reported rodent responses at lower doses.

Full Abstract Here

Genistein exerts estrogen-like effects in male mouse reproductive tract.
Strauss L, Makela S, Joshi S, Huhtaniemi I, Santti R. Mol Cell Endocrinol 1998 Sep 25;144(1-2):83-93

...genistein (2.5 mg s.c./kg of body weight/day for 9 days) reduced testicular and serum testosterone concentrations, pituitary LH-content and prostate weight.

These results suggest that in adult males, genistein induces the typical estrogenic effects in doses comparable to those present in soy-based diets.

Developmental estrogenization and prostatic neoplasia.
Santti R, Newbold RR, Makela S, Pylkkanen L, McLachlan JA. Prostate 1994;24(2):67-78

Full Abstract Here