New book in Dutch

Eet vet word slank

Eet vet word slank gepubliceerd januari 2013

In dit boek lees je o.a.: * heel veel informatie ter bevordering van je gezondheid; * hoe je door de juiste vetten te eten en te drinken kan afvallen; * hoe de overheid en de voedingsindustrie ons, uit financieel belang, verkeerd voorlichten; * dat je van bewerkte vetten ziek kan worden.

Trick and Treat:
How 'healthy eating' is making us ill
Trick and Treat cover

"A great book that shatters so many of the nutritional fantasies and fads of the last twenty years. Read it and prolong your life."
Clarissa Dickson Wright

Natural Health & Weight Loss cover

"NH&WL may be the best non-technical book on diet ever written"
Joel Kauffman, PhD, Professor Emeritus, University of the Sciences, Philadelphia, PA

Soy Online Service
Phytoestrogens & Infertility

Phytoestrogens & Infertility

Nature's contraceptives

Phytoestrogens can make animals infertile, what about people?

(Read the British Food Standards Agencies Committee on Toxicity Report 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?

The ability of phytoestrogens to prevent reproduction in animals has been known about since the 1940's when 'clover disease' resulted in a high percentage of infertility among the flocks of Australian sheep farmers.  Since the early reports that first defined the phytoestrogen induced disorder, there have been numerous studies on sheep grazed on clovers.  The clovers typically contain high levels of isoflavones, which result in a range of estrogenic effects in grazing sheep.

The soy industry will tell that the the infertility effects of isoflavones are unique to sheep.  Well, Soy Online Service have learnt that the soy industry are particularly good at something: telling fibs, whoppers, porkies, call them what you like; bare-faced lies is what they are best at.  Don't just take our word for it, read it for yourself:

  • 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.  Read more on Cheetahs and Soybeans.
  • Reproductive health in Humans and Wildlife: are adverse trends associated with environmental chemical exposure?  Do phytoestrogens stop the stork?

So, if animals want to produce according to their kind they should avoid soy.  It's hardly what they'd be eating in the wild anyway is it?

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?  There is a wealth of evidence that shows that mammals exposed to estrogens during critical periods of sexual development can suffer a drastic reduction in fertility.  There is also strong evidence that soy phytoestrogens such as genistein can inhibit 17-b-hydroxysteroid oxidoreductase, an enzyme which is required for the synthesis of testosterone and the development of the CNS-gonadal axis.   There is also evidence that the soy isoflavones genstein and daidzein are genotoxic to human sperm.  It is quite possible, therefore, that phytoestrogens, along with other endocrine disrupting compounds such as DDT, may contribute to the worldwide decrease in male fertility.

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.

If there is still some question that phytoestrogens may affect male fertility, the case with women is much more clear cut.  In a UK feeding study involving premenopausal women, 60g of soy protein per day (containing 45 mg total isoflavones) for 30 days resulted in significant biological effects. These effects were a reduction in mean mid-cycle levels of LH and FSH to 33% and 53% respectively of the levels observed when the women were fed control diets that did not contain soy. Some individuals responded to the isoflavones less than others, however, in one individual LH and FSH levels were reduced to 17% and 32% of normal levels respectively.

In this study all of the women still ovulated but the effects of the isoflavones continued for three months after the diet ceased. Clearly there is potential for women who are exposed to dietary isoflavones to suffer sufficient reduction in LH and FSH levels that they might become anovulatory.  Additionally, in vitro genistein has been shown to block oocyte growth and disrupt follicle morphology, which raises a host of questions exposures at various life-stages, including the pre-natal period.

Premature puberty is also associated with reduced fertility. Read what the American Endocrine Society says here, Pseudo Puberty by the American Endocrine Society .

Further information on Reproductive Health can be found at


Further Reading

Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic.
Chavarro JE, Toth TL, Sadio SM, Hauser R. Hum Reprod. 2008 Nov;23(11):2584-90.
Department of Nutrition, Harvard School of Public Health, Boston, MA, USA.
These data suggest that higher intake of soy foods and soy isoflavones is associated with lower sperm concentration. Read the article here.


News from - A substance found in soy-based infant formula and over-the-counter dietary supplements affects the development of ovaries and eggs in female infant mice, according to a study conducted by researchers at the National Institutes of Health (NIH) and Syracuse University. Read the article here.


Component in Soy Products Causes Reproductive Problems in Laboratory Mice - From NIH News (National Institutes of Health) January 10, 2006 - Genistein, a major component of soy, was found to disrupt the development of the ovaries in newborn female mice that were given the product. This study adds to a growing body of literature demonstrating the potentially adverse consequences of genistein on the reproductive system. Read more about this here.

Endocrine disrupters and female reproductive health. McLachlan JA, Simpson E, Martin M.
Department of Pharmacology, Tulane University School of Medicine, and Environmental Endocrinology Laboratory, Center for Bioenvironmental Research, Tulane and Xavier Universities, New Orleans, LA 70118, USA. There is growing evidence of the impact of estrogenic contaminants in the environment. Studies have shown that male fish in detergent-contaminated water express female characteristics, turtles are sex-reversed by polychlorinated biphenyls (PCBs), male frogs exposed to a common herbicide form multiple ovaries, pseudohermaphroditic offspring are produced by polar bears, and seals in contaminated water have an excess of uterine fibroids. Endocrine-disrupting chemicals (those found in the external environment that can mimic or inhibit endogenous hormones) mostly exhibit estrogenic effects, but a few are anti-estrogenic or anti-androgenic. Many of these compounds are industrial contaminants, such as pesticides and plasticizers, and others are natural phytoestrogens found in plants such as soy and in herbal supplements. Recent work shows that human development can also be feminized by exposure to estrogenic chemicals. Estrogen is the key hormone in the initiation (puberty) and the end (menopause) of reproductive life in women and thus of considerable importance in women's health. The same chemicals that affect wildlife may affect breast growth and lactation, and could have a role in uterine diseases such as fibroids and endometriosis. New studies provide a mechanism of action for estrogenic chemicals and other endocrine disrupters at the molecular level (called epigenetics) that may help explain the long-term effects of endocrine disruption.


Eating Soy Can Decrease Your Fertility

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


Endometrial effects of long-term treatment with phytoestrogens: a randomized, double-blind, placebo-controlled study.
Unfer V, Casini ML, Costabile L, Mignosa M, Gerli S, Di Renzo GC.;

Fertil Steril. 2004 Jul;82(1):145-8.

Long-term treatment (up to 5 years) with soy phytoestrogens was associated with an increased occurrence of endometrial hyperplasia. These findings call into question the long-term safety of phytoestrogens with regard to the endometrium.

Full Abstract Here, More Here


Neonatal exposure to genistein induces estrogen receptor (ER)alpha expression and multioocyte follicles in the maturing mouse ovary: evidence for ERbeta-mediated and nonestrogenic actions.
Jefferson WN, Couse JF, Padilla-Banks E, Korach KS, Newbold RR. Biol Reprod. 2002 Oct;67(4):1285-96.

As a functional analysis, genistein-treated mice were superovulated and the number of oocytes was counted. A statistically significant increase in the number of ovulated oocytes was observed with the lowest dose, whereas a decrease was observed with the two higher doses.

Histological evaluations on Day 19 revealed a dose-related increase in multioocyte follicles (MOFs) in genistein-treated mice.

These data taken together demonstrate alterations in the ovary following neonatal exposure to genistein. Given that human infants are exposed to high levels of genistein in soy-based foods, this study indicates that the effects of such exposure on the developing reproductive tract warrant further investigation.

Full Abstract Here


Soy supplements can decrease normal sexual behaviour by as much as 70 per cent, a study of female rats has shown. New Scientist 17:45 14 November 03

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


Reproductive effects in male and female rats of neonatal exposure to genistein.
Nagao T, Yoshimura S, Saito Y, Nakagomi M, Usumi K, Ono H. Reprod Toxicol 2001 Jul-Aug;15(4):399-411

Body weights of male and female rats exposed to genistein at any dose level examined were lower than those of controls.

The number of females showing estrous cycle irregularities was increased by genistein treatment. The fertility of female rats exposed neonatally to genistein at 100 mg/kg was disrupted...

Female rats exposed neonatally to genistein at 100 mg/kg showed histopathologic changes in the ovaries and uterus...

The results of this study indicate that early neonatal exposure to genistein caused dysfunction of postpubertal reproductive performance as well as abnormal development of gonads in female but not in male rats.

Full Abstract Here


Acute and chronic effects of genistein, tyrphostin and lavendustin A on steroid synthesis in luteinized human granulosa cells.
Whitehead SA, Cross JE, Burden C, Lacey M. Hum Reprod 2002 Mar;17(3):589-94

Phytoestrogens, including genistein and other inhibitors of tyrosine kinases (TKs), inhibit specific steroidogenic enzymes. This study was designed to compare the effects of genistein, with two other TK inhibitors, on steroid synthesis in human granulosa luteal (GL) cells and to identify which steroidogenic enzymes they may affect.

Genistein directly inhibits 3 and 17beta-hydroxysteroid dehydrogenase activity, whilst tyrphostin has an acute stimulatory effect on aromatase activity. Over a longer time (24 and/or 48 h period), both TK inhibitors suppress steroid synthesis.

Full Abstract Here


The effect of phytoestrogens on the female genital tract.
Burton JL, Wells M. J Clin Pathol 2002 Jun;55(6):401-7

This review will discuss the evidence from both animal studies and humans for an effect of these ubiquitous compounds on the development of the human female genital tract, in addition to prolonging the menstrual cycle, alleviating symptoms of the menopause, and protecting against the development of endometrial carcinoma.

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


Effects of the dietary phytoestrogens daidzein and genistein on the incidence of vulvar carcinomas in 129/J mice.
Thigpen JE, Locklear J, Haseman JK, Saunders H, Grant MF, Forsythe DB.

Cancer Detect Prev 2001;25(6):527-32

Within one month, the incidence of vulvar carcinomas in mice fed the AIN-76A modified soy protein diet was significantly (P < .05) increased over those of mice fed the AIN-76A modified casein diet, the #5K96, or the # 5058 diet. At three months, the incidence of vulvar carcinomas in mice fed the soy protein diet was significantly (P < .05) increased over those of mice fed the NIH-31 diet or the PMI #5K96 diet.

We concluded that dietary levels of daidzein and genistein were associated with an increase in the incidence of vulvar carcinomas in mice

Soy isoflavone supplements antagonize reproductive behavior and estrogen receptor alpha- and beta-dependent gene expression in the brain.
Patisaul HB, Dindo M, Whitten PL, Young LJ. Endocrinology 2001 Jul;142(7):2946-52

Supplement treatment also resulted in a significant decrease in receptive behavior in estrogen- and progesterone-primed females. The observed disruption of sexual receptivity by the isoflavone supplement is probably due to antiestrogenic effects observed in the brain.

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


Combined effects of dietary phytoestrogen and synthetic endocrine-active compound on reproductive development in Sprague-Dawley rats: genistein and methoxychlor.
You L, Casanova M, Bartolucci EJ, Fryczynski MW, Dorman DC, Everitt JI, Gaido KW, Ross SM, Heck Hd H. Toxicol Sci 2002 Mar;66(1):91-104

An acceleration of vaginal opening (VO) in the exposed female offspring was the only observed effect of genistein at 300 ppm. Exposure to 800 ppm genistein or 800 ppm methoxychlor caused accelerated VO and also altered estrous cyclicity toward persistent estrus in the female offspring. The estrogenic responses to genistein and methoxychlor administered together were apparently accumulative of the effects associated with each compound alone.

Data from this study indicate that phytoestrogens are capable of altering the toxicological behaviors of other EACs, and the interactions of these compounds may involve complexities that are difficult to predict based on their in vitro steroid receptor reactivities.

Full Abstract Here




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