Soy, phyto-oestrogens and male reproductive function: a review

REVIEW ARTICLE

Soy, phyto-oestrogens and male reproductive function:a reviewChristopher R. Cederroth,* Jacques Auger,� Celine Zimmermann,* Florence Eustache� and Serge Nef*

*Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland, �Service d’Histologie-

Embryologie, Biologie de la Reproduction ⁄ CECOS, Hopital Cochin, Paris, and �Service d’Histologie-Embryologie-Cytogenetique, Biologie de la

Reproduction ⁄ CECOS, Hopital Jean Verdier, Bondy, France

Introduction to endocrine-disrupting chemical(EDCs) and phyto-oestrogens

Epidemiological studies conducted over the last 50 years

report an increased incidence of human male reproduc-

tive disorders. These health problems include failure of

the testis to descend into the scrotum (cryptorchidism),

hypospadias, increased incidence of testicular cancer and

low semen quality. These disorders have been regrouped

under the term Testis Dysgenesis Syndrome (TDS)

(Skakkebaek et al., 2001). In northern America, the fre-

quency of cryptorchidism, hypospadias and testicular can-

cer has almost doubled between the 1970s and 1990s

(Toppari, 2002). This rapid increase of reproductive

disorders suggests that environmental and ⁄ or life-style

factors, such as exposure to endocrine disruptors, are the

most likely causes. Endocrine disrupting chemicals were

defined by the U.S. Environmental Protection Agency as

‘exogenous agents that interfere with synthesis, secretion,

transport, metabolism, binding action or elimination of

natural blood-borne hormones that are present in the

body and are responsible for homeostasis, reproduction

and developmental processes.’ EDCs are highly hetero-

geneous in structure and widespread in our environment.

They include synthetic organic compounds such as pesti-

cides (e.g. methoxychlor, dichloro-diphenyl-trichloroe-

thane, DDT), fungicides (vinclozolin), pharmaceutical

agents (e.g. diethylstilbestrol, DES), chemicals used as

industrial solvents or lubricants and their byproducts

(polychlorinated biphenyls, PCBs, dioxins), plastics

(bisphenol A, BPA), plasticizers (phthalates), butyltins

and flame-retardant polybrominated diphenyl ether

(PBDE), to name a few.

Less attention has been paid to the action of natural

plant-derived endocrine disruptors, termed phyto-oestro-

gens. Phyto-oestrogens are non-steroidal compounds that

can bind to both oestrogen receptor (ER)-a and ER-bbecause of their ability to mimic the conformational

structure of oestradiol (Kuiper et al., 1997, 1998). Phyto-

oestrogens are found in many vegetables and are particu-

larly abundant in soy products. Genistin and daidzin, two

major soy isoflavone glucosides, are present at high con-

centrations in soybeans and soybean-derived products

and are a major source of xeno-oestrogen exposure in

both humans (e.g. soy-based formula for infants; tofu)

and animals (most commercially available diets). The two

Keywords:

androgen, dietary soy, endocrine disruptors,

genistein, isoflavones, phyto-oestrogens,

reproduction, spermiogenesis,

spermatogenesis

Correspondence:

Serge Nef, Department of Genetic Medicine

and Development, University of Geneva

Medical School, 1211 Geneva 4, Switzerland.

E-mail: [email protected]

Received 20 July 2009; revised 11 September

2009; accepted 25 September 2009

doi:10.1111/j.1365-2605.2009.01011.x

Summary

There is growing interest in the possible health threat posed by the effects of

endocrine disruptors on reproduction. Soy and soy-derived products contain

isoflavones that mimic the actions of oestrogens and may exert adverse effects

on male fertility. The purpose of this review was to examine the evidence

regarding the potential detrimental effects of soy and phyto-oestrogens on male

reproductive function and fertility in humans and animals. Overall, there are

some indications that phyto-oestrogens, alone or in combination with other

endocrine disruptors, may alter reproductive hormones, spermatogenesis,

sperm capacitation and fertility. However, these results must be interpreted

with care, as a result of the paucity of human studies and as numerous reports

did not reveal any adverse effects on male reproductive physiology. Further

investigation is needed before a firm conclusion can be drawn. In the mean-

time, caution would suggest that perinatal phyto-oestrogen exposure, such as

that found in infants feeding on soy-based formula, should be avoided.

international journal of andrology ISSN 0105-6263

304ª 2009 The Authors

Journal compilation ª 2010 European Academy of Andrology • International Journal of Andrology 33 (2010), 304–316

major isoflavones, genistein and daidzein, are present in

soy as b-d-glycosides, namely genistin and daizin, which

are biologically inactive (Setchell, 1998). The conversion

to their corresponding bioactive aglycones (genistein and

daidzein) by bacterial b-glucosidases in the intestinal wall

permits their absorption by the intestinal tract. Daidzein

can be further metabolized to equol, and indeed this

compound along with genistein and daidzein are the

major isoflavones detected in the blood and urine of

humans and animals (Setchell, 1998). In rodents, equol is

the major circulating metabolite among isoflavones, rep-

resenting up to 70–90% of all circulating isoflavones.

While all rodents are equol producers, only 30% of

humans are able to metabolize daidzein into equol

(Atkinson et al., 2005). In addition to its oestrogenic

activity, genistein has also been reported to act through

other mechanisms, including acting as a tyrosine kinase

inhibitor or an antioxidant (Akiyama et al., 1987; Vedava-

nam et al., 1999).

Numerous studies have investigated the plasma concen-

trations of phyto-oestrogens and their metabolites in

humans and animals consuming a diet with or without

soy (Adlercreutz et al., 1993a,b; Coward et al., 1996; Mor-

ton et al., 1994). In humans consuming soy-free diets,

plasma concentration of isoflavones are usually in the

nanomolar range £40 nm see (Morton et al., 1994; van

Erp-Baart et al., 2003). By contrast, acute ingestion of

dietary soy leads to a rapid increase in the plasma con-

centration of isoflavones to the micromolar range

(Adlercreutz et al., 1993a,b; Xu et al., 1994; King &

Bursill, 1998; Watanabe et al., 1998). Certain Asian popu-

lations may consume up to 1 mg ⁄ kg of body weight per

day, and infants fed soy-based formula ingest even higher

amounts of isoflavones relative to their body mass: the

mean daily consumption of total isoflavones ranges from

6 to 9 mg ⁄ kg in 4-month-old infants fed exclusively with

soy-based infant formulas (SBIFs), resulting in plasma

isoflavone concentrations (980 lg ⁄ L) much higher than

that of infant fed cow’s milk formula or human breast

milk (9.4 and 4.7 lg ⁄ L respectively) (Setchell et al., 1997,

1998).

Soy isoflavones have received much attention as a

result of their potential health benefits. Soy consumption

in oriental countries correlates with low incidences of

breast and invasive prostate cancers, improvements in

metabolic parameters and amelioration of age-related dis-

eases e.g. cardiovascular diseases, osteroporosis (Ceder-

roth & Nef, 2009; Sacks et al., 2006; Setchell, 1998; Tham

et al., 1998). However, exposure to high levels of phyto-

oestrogens, either from a lifetime of exposure or during a

critical period of development, could also have potentially

detrimental effects on fertility and reproductive functions.

In particular, some concerns have been raised with regard

to the high isoflavone content of SBIFs and the possible

adverse effects on infants (Irvine et al., 1995, 1998a,b;

Setchell et al., 1997, 1998). Based on current estimates,

the prevalence of the feeding of infants with SBIFs is high

(25% in the USA), and these products represent the

breast milk substitute of choice (Barrett, 2006). It has

been reported that human infants fed exclusively on

SBIFs have blood levels of isoflavones that are at least

fivefold higher than adult humans who eat a soy-rich diet

(Setchell et al., 1997; Irvine et al., 1998a,b).

Experimental and clinical studies addressing the effects

of soy and phyto-oestrogens on the reproductive system

have produced conflicting and somewhat confusing

results. The purpose of this review is to examine the evi-

dence, or the lack of evidence, regarding the potential

detrimental effects of soy and phyto-oestrogens on male

reproductive function and fertility in animals and

humans.

Lack of standardization of animal and clinicalstudies

Numerous studies have investigated the potential detri-

mental effects of soy and ⁄ or isoflavones on reproductive

function (see Tables 1–5). Unfortunately, comparisons

between different animal or clinical studies are hampered

by the lack of standardization of soy nomenclature, the

various formulations (soy proteins, pure isoflavones, etc),

doses and routes of exposure (dietary, injection and

gavage) and the differences in time (gestation, perinatal

or adult) and duration of exposure. Comparisons are fur-

ther hampered by major disparities in the subsequent

analyses performed to evaluate the effects and elucidate

the mechanisms by which phyto-oestrogens and soy

potentially affect reproductive and endocrine functions.

All of these variables make it difficult to compare and

evaluate the absence or presence of putative benefi-

cial ⁄ detrimental effects of soy and phyto-oestrogens on

male fertility. In fact, numerous studies have described an

absence of effects on serum testosterone levels, testis

weight and sperm abundance. Most of them assessed

organ weights as an indicator of endocrine disruption,

without evaluating the reproductive efficiency per se

through fertility tests, which represent the true physiolog-

ical outcome of a disruptive effect of a given compound.

Reproductive and hormonal effects of soy andphyto-oestrogens in men and primates

There is a relative paucity of studies available designed to

evaluate the effects of soy and phyto-oestrogens on fertil-

ity or reproductive hormones in human males (Table 1).

Mitchell et al. evaluated the effects of phyto-oestrogen

C. R. Cederroth et al. Phyto-oestrogens and male fertility

ª 2009 The AuthorsJournal compilation ª 2010 European Academy of Andrology • International Journal of Andrology 33 (2010), 304–316 305

supplementation (500 mg of a daily supplement contain-

ing 40 mg of genistein, daidzein and glycitein) for

2 months among 14 young men. Semen quality was not

influenced by isoflavone extracts, nor did serum concen-

trations of oestradiol, testosterone, FSH and LH differ

from pre-supplementation values (Mitchell et al., 2001).

By contrast, a cross-sectional analysis comparing dietary

intake of soy food and isoflavones to semen quality

parameters among 99 men found an inverse correlation

between soy ⁄ isoflavone intake and sperm concentration

(Chavarro et al., 2008). Neither sperm motility, sperm

morphology nor ejaculate volume was affected. These last

results should be taken with caution, in particular as a

result of the fact that men enrolled for this study were

selected from subfertile couples at an infertility clinic.

Furthermore, the intakes of total and specific isoflavones

(daidzein, genistein and glycitein) were not measured in

blood serum, but instead estimated by summing the isof-

lavone contributions of dietary habits in a questionnaire.

Two additional studies investigated the effects of die-

tary soy intervention on male reproductive hormones.

Habito et al. (2000) performed a crossover study of 42

men who consumed either 150 g lean meat or 290 g tofu

daily (approximately 70 mg of isoflavones) for four con-

secutive weeks. Soy intake did not influence oestradiol,

testosterone and dihydrotestosterone levels, although

SHBG levels were 9% higher (p = 0.01). Similarly,

another study performed with 35 men consuming

400 mL of soymilk (approximately 48 mg isoflavones)

daily for 8 weeks, did not find an effect on blood concen-

tration of oestradiol, total or free testosterone, or SHBG

(Nagata et al., 2001). By contrast, Nagata et al. (2000)

have reported an inverse correlation between soy product

intake and serum androgen and oestrogen concentration

in men. This cross sectional analysis of soy product intake

and reproductive hormones was performed with 69 Japa-

nese men with an average isoflavone intake of 22 mg ⁄ day.

Of note, the significance of the inverse correlation with

the serum concentration of total and free testosterone was

borderline (r = )0.25, p = 0.05 and r = )0.25, p = 0.06

respectively).

Isoflavones may also alter the maturation or capacita-

tion of human spermatozoa. It has been recently shown

that low concentration of genistein (at a concentration of

1, 10 and 100 nm) caused an accelerated capacitation and

acrosome loss in human spermatozoa in vitro (Fraser

et al., 2006). If such response were to occur in vivo, this

could result in a larger percentage of the sperm popula-

tion lacking the ability to fertilize an ovum – previously

acrosome-reacted spermatozoa have lost the plasma mem-

brane over the anterior part of the sperm head and thus

are unable to bind to the zona pellucida, a prerequisite

for successful fertilization (de Lamirande et al., 1997).Tab

le1

Hum

anst

udie

sev

aluat

ing

the

effe

cts

of

ges

tational

and

post

-nat

alex

posu

reto

isoflav

ones

on

fert

ility

and

mal

ehorm

ones

Hum

anst

udie

sev

aluat

ing

the

effe

cts

of

isoflav

one

inta

keon

mal

ere

pro

duct

ion

Ethnic

gro

up

Die

t

Isoflav

one

inta

ke

(mg

⁄day

)

Dura

tion

of

exposu

re

No.

subje

cts

Plas

ma

isoflav

one

leve

ls(l

M)

Urine

isoflav

one

leve

ls(n

g⁄l

mol

crea

tinin

e)

Sper

m

pro

duct

ion

Sper

m

motilit

y

Sem

inal

volu

me

Blo

od

horm

one

leve

lsRef

eren

ce

Cau

casi

anTo

fu70

4w

eeks

21

(21)

ND

G:

201

D:

401

ND

ND

ND

T:N

oef

fect

Hab

ito

etal

.,(2

000)

Cau

casi

anSo

yex

trac

t40

2m

onth

s15

G:

1

D:

0.5

ND

No

effe

ctN

oef

fect

No

effe

ctT,

LH,

FSH

:

No

effe

ct

Mitch

ellet

al.,

(2001)

Cau

casi

anSo

yfo

od

<22.3

Less

and

more

than

2m

onth

s

100

ND

ND

Dec

reas

edN

oef

fect

No

effe

ctN

DC

hav

arro

etal

.,(2

008)

Japan

ese

Soym

ilk76.8

8w

eeks

17

(17)

ND

ND

ND

ND

ND

T:N

oef

fect

Nag

ata

etal

.,(2

001)

Japan

ese

Soy

pro

duct

30

Life

long

69

ND

ND

ND

ND

ND

T:D

ecre

ased

Nag

ata

etal

.,(2

000)

For

contr

olgro

ups,

the

num

ber

of

indiv

idual

s(n

)is

show

nin

par

enth

eses

.

ND

,not

det

erm

ined

;G

,gen

site

in;

D,

dai

dze

in;

T,te

stost

erone.

Phyto-oestrogens and male fertility C. R. Cederroth et al.



Fraser et al. also demonstrated that, when genistein was

tested in combination with other endocrine disruptors

such as non-ylphenyl and 8-pre-nylnaringenin, their

adverse effects on sperm were more pronounced. This

highlights the importance of testing different mixtures of

EDCs, as humans and animals are likely to be exposed to

more than one xenobiotic.

Although these studies have investigated the reproduc-

tive and endocrine effects of adult exposure to soy food

and isoflavones, one major issue remaining is whether

exposure during infancy causes detrimental male repro-

ductive effects in adulthood. So far, in the USA, millions

of infants have been fed with soy formulas over decades

without detrimental effects (Badger et al., 2009). One of

the rare studies that has assessed the adult reproductive

effects of soy formula consumption during infancy in

humans reports that no significant differences in onset of

puberty or in reproductive functions were found in com-

parison with those fed with milk formulas (Strom et al.,

2001). However, the true relevance of this study has been

the subject of controversy, as result of the lack of direct

measurements of hormone levels and reproductive func-

tions (Goldman et al., 2001; Tan et al., 2006).

Using the marmoset monkey as an animal model, the

group of Richard Sharpe investigated the effects of soy-

based formula on testicular development and function

(Sharpe et al., 2002; Tan et al., 2006). Seven co-twin sets

of male marmoset infants were fed during the first

6 weeks of age either with a standard or a soy-based

formula. Like human male infants, marmosets exhibit a

Table 2 Animal studies evaluating the adult effects of gestational and post-natal exposure to isoflavones on male reproduction

Species and strain

Period of

exposure Dose

Serum

isoflavone

levels

No.

animals

Litter

size

Sperm

production

Testis

weight

Seminal

vesicle

weight

Blood

hormone

levels Reference

Oral gavage of genistein

Mice mg ⁄ kg ⁄ day

B6D2F1

(C57BL ⁄ 6 · DBA ⁄ 2)

E12 to P20 0.1–10 ND ND ND No effect No effect No effect ND Fielden et al.,

(2003)

Rats

Sprague–Dawley E6 to P20 0.4 ND ND ND No effect Increased Increased ND Kang et al.,

(2002)

4.0 ND ND ND No effect No effect No effect ND

Rabbits

New Zealand E0 to P29 10–20 ND 12 (12) ND No effect No effect ND ND Cardoso & Bao,

(2008)

Dietary supplementation with aglycone genistein

Mice mg ⁄ kg ⁄ day

NIH ⁄ S E0 to P21 8 ND ND ND ND No effect No effect ND Ryokkynen et al.,

(2006)

C57BL ⁄ 6 mice E0 to P21 5; 300 (ppm) ND 7 (10) ND No effect No effect No effect T: No

effect

Wisniewski et al.,

(2005)

Mink mg ⁄ kg ⁄ day

Wild type E0 to P21 8 ND ND ND No effect +11% ND T: No

effect

Ryokkynen et al.,

(2005)

Rats ppm

Sprague–Dawley E15 to P10 20–1000 ND 5 (5) ND ND No effect ND ND Masutomi et al.,

(2003)

Long Evans E0 to P21 5 ND 12 (12) ND No effect No effect No effect T: )52% Wisniewski et al.,

(2003)

300% ND 12 (12) ND No effect No effect No effect T: )40%

Rabbits

New Zealand E0 to P29 18% ND 12 (12) ND No effect No effect ND ND Cardoso & Bao,

(2008)

Drinking solution of resveratrol

Rats lM

Sprague–Dawley E0 to P22 5–100 ND 9 (11) ND ND +9% ND )60% Henry & Witt,

(2006)

For control groups, the number of individuals (n) is shown in parentheses.

ND, not determined; ppm, parts per million; E, embryonic day; P, post-natal day; T, testosterone.



similar period of neonatal testicular activity (Lunn et al.,

1994). Feeding with soy-based formula initially attenuated

the neonatal testosterone rise (Sharpe et al., 2002), but no

adverse reproductive consequences were observed in

adulthood. More precisely, no significant effects were

reported on the timing of puberty, on fertility, on penis

development and length, and on the weight of the pros-

tate and seminal vesicles. Surprisingly, testicular weight

and Sertoli and Leydig cell number were significantly

increased in marmosets fed with soy-based formula as

infants (Tan et al., 2006). Although these aforementioned

studies did not measure isoflavone levels, several

reports indicate that primates, including humans, are

able to produce equol (Adlercreutz et al., 1986; Musey

et al., 1995; Clarkson et al., 2001; Blair et al., 2003).

However, the relevance of this particular isoflavone in

affecting mammalian reproductive health remains to be

investigated.

Even though soy-based formula has been consumed by

millions of infants over the past decades without apparent

detrimental effects, caution should prevail. Infancy is a

very sensitive period for endocrine disruption, and expo-

sure to significant levels of phyto-oestrogens may ulti-

mately lead to adult onset diseases. More generally, as a

result of the scarcity of human data available, evidence

linking soy ⁄ isoflavone consumption with adverse effects

on semen quality and the reproductive hormonal profile

is lacking.

In this regard, paediatric and health organizations usu-

ally consider that there is no conclusive evidence from

animal, adult human or infant populations that isoflav-

ones or soy-based formula may adversely affect human

development, reproduction, or endocrine function (COT

Report, 2003; National Toxicology Program, 2006; Bhatia

& Greer, 2008). Although no long-term detrimental

effects to growth or sexual maturation were identified, it

should be noted that recently a review panel from the

Center for the Evaluation of Risks to Human Reproduc-

tion (CERHR, established by the National Toxicology

Program, NTP and the National Institute of Environmen-

tal Health Sciences, NIEHS) failed to issue a conclusive

recommendation on the reproductive and developmental

toxicity of soy protein-based formula because of the lim-

ited utility of available humans studies (National Toxicol-

ogy Program, 2006). It is thus very important that this

issue of developmental or reproductive toxicity of soy

infant formula is examined further, ideally in randomized

trials.

Reproductive and hormonal effects of soy andphyto-oestrogens in rodents

The initial recognition and identification of phyto-oestro-

gens as bioactive compounds were made in the 1940s

when it was found that formononetin, an isoflavone pres-

ent in red clover (Trifolium pratense L.), caused a devas-

tating infertility syndrome in sheep grazing in clover

pasture (Bennetts et al., 1946). In another study, high

levels of phyto-oestrogens were found in the leaves of

stunted desert annuals in a dry year, leading ultimately to

impaired reproduction when ingested by the California

quail (Lophortyx californicus). In wet years, these quails

bred normally and phyto-oestrogens were largely absent

in these herbs (Leopold et al., 1976).

Table 3 Animal studies evaluating the adult effects of post-natal exposure to isoflavones on male reproduction.

Species

and strain

Period of

exposure Dose

Serum

isoflavone

levels

No.

animals

Litter

size

Sperm

production

Testis

weight

Seminal

vesicle

weight

Blood

hormone

levels Reference

Subcutaneous injections of single isoflavones

Mice (mg ⁄ kg ⁄ day)

ICR P1–P5 0.1 genistein ND 5 (5) ND ND No effect ND ND Adachi et al.,

(2004)

Rats

Sprague –

Dawley

P1–P5 0.1

coumestrol

ND 8 (8) ND No effect No effect ND No effects on

LH, FSH, T

Awoniyi et al.,

(1997)

Wistar P2–P18 4 gesnitein ND ND No

effect

ND )8% (P18) ND FSH: )35% Atanassova

et al., (1999)

Oral gavage of genistein

Sprague –

Dawley

P1–P5 12.5–100 ND 23 (31) No

effect

No effect No effect No effect T: No effect Nagao et al.,

(2001)

Wistar P1–P75 4 ND ND ND ND Increased ND ND Fisher et al.,

(1999)

For control groups, the number of individuals (n) is shown in parentheses.

ND, not determined; P, post-natal day; T, testosterone.




Tab

le4

Anim

alst

udie

sev

aluat

ing

the

effe

cts

of

adult

chro

nic

exposu

reto

isoflav

ones

on

mal

ere

pro

duct

ion

Spec

ies

and

stra

in

Period

of

exposu

reD

ose

Seru

m

isoflav

one

leve

ls

No.

anim

als

Litt

er

size

Sper

m

pro

duct

ion

Test

is

wei

ght

Sem

inal

vesi

cle

wei

ght

Blo

od

horm

one

leve

lsRef

eren

ce

Subcu

taneo

us

inje

ctio

ns

of

gen

iste

in

Mic

em

g⁄k

g⁄d

ay

NM

RI

M10

for

7day

s

2.5

ND

5(5

)N

DN

DN

DN

DT:

)80%

LH:)

40%

Stra

uss

etal

.,(1

998)

Ora

lgav

age

of

gen

iste

in

Mic

em

g⁄k

g⁄d

ay

ICR

mic

eP1

toP5

62.5

ND

10

(10)

ND

No

effe

ctN

oef

fect

ND

ND

Jung

etal

.,(2

004)

ICR

mic

eP2

1to

P56

2.5

–5.0

ND

10

(10)

ND

No

effe

ctN

oef

fect

ND

ND

Lee

etal

.,(2

004a)

ICR

mic

eM

6fo

r

5w

eeks

2.5

ND

10

(10)

ND

No

effe

ctN

oef

fect

ND

ND

Lee

etal

.,(2

004b)

Die

tary

supple

men

tation

with

gen

iste

in

Rat

sppm

Spra

gue–

Daw

ley

P21

toP3

5250

1785

8(8

)N

DN

DN

oef

fect

ND

T:N

oef

fect

Fritz

etal

.,(2

003)

1000

9640

8(8

)N

DN

DN

oef

fect

ND

T:N

oef

fect

NIH

⁄SA

dult

8N

D10

(10)

ND

ND

No

effe

ctN

DT:

+25%

Ryo

kkyn

enet

al.,

(2006)

Wis

tar

W7

for

52

wee

ks

5BLD

30

ND

ND

No

effe

ctN

DN

DM

cCla

inet

al.,

(2007)

50

177

30

ND

ND

No

effe

ctN

DN

D

500

1108

30

ND

ND

No

effe

ctN

DN

D

Die

tary

supple

men

tation

with

isoflav

ones

agly

cone

Mic

em

g⁄d

ay

(Gen

:Dai

d)

ApoE-

null

W6

toW

16

120

(10:1

)G

:927

D:

142

10

(10)

ND

ND

No

effe

ctN

oef

fect

T:N

oef

fect

Clin

eet

al.,

(2004)

120

(2:1

)G

:241

D:

191

10

(10)

ND

ND

)41%

)73%

T:)

90%

120

(1:1

0)

G:

51

D:

736

10

(10)

ND

ND

No

effe

ct)

73%

T:)

85%

Rat

sppm

Wis

tar-

Unile

ver

W8

for

12

month

s

200

aN

DN

DN

DN

oef

fect

No

effe

ctN

DN

DFa

qiet

al.,

(2004)

2000

aN

DN

DN

DN

oef

fect

No

effe

ctN

DN

D

Monke

ys

Cyn

om

olg

us

mac

aques

Adult

94

a799

a30

(30)

ND

No

effe

ctN

oef

fect

ND

T:N

oef

fect

Perr

yet

al.,

(2007)

1188

a1458

a30

(30)

ND

No

effe

ctN

oef

fect

ND

T:N

oef

fect



To date, there are no experimental studies evaluating

the effects of gestation-only exposure to soy ⁄ isoflavones

on adult male reproduction. However, some reports have

evaluated the long-term effects of exposures encompass-

ing both foetal and post-natal life in rodents (Table 2).

For instance, rats exposed to maternal dietary genistein

(300 ppm) through gestation and lactation exhibited a

decrease in the anogenital distance, testis size and

serum testosterone levels (Wisniewski et al., 2003). By

contrast, perinatal exposure to genistein (from 0.1 to

10 mg ⁄ kg ⁄ day by oral gavage), had no effect on testis and

seminal weight, or on sperm abundance (Fielden et al.,

2003). Similarly, oral gavage of genistein at 4 mg ⁄ kg ⁄ day

during gestation and lactation had no consequences on

testis and seminal vesicle weight or on sperm abundance

in rats (Kang et al., 2002).

Exposure to soy ⁄ isoflavone exclusively during post-natal

life also yielded conflicting results (Table 3). Wistar rats

exposed to genistein from post-natal day 2 (P2) to P18

only, through subcutaneous injections at 4 mg ⁄ kg ⁄ day,

showed reduced FSH levels and testis weight (Atanassova

et al., 1999). By contrast, oral gavage of genistein in Spra-

gue–Dawley rats from P1 to P5, at doses ranging from

12.5 to 100 mg ⁄ kg ⁄ day, did not reveal any detrimental

effects on male reproductive parameters such as litter size,

sperm production, testosterone levels, testis and seminal

vesicle weights (Nagao et al., 2001). Using the same win-

dow of exposure and experimental model, subcutaneous

injections of coumestrol at 100 lg ⁄ kg ⁄ day had no effects

on sperm abundance, testis weight, LH, FSH or testoster-

one levels (Awoniyi et al., 1997).

Despite the known long-term effects on testicular func-

tion of foetal exposure to endocrine disruptors (Phillips &

Tanphaichitr, 2008), only two studies have evaluated, by

means of toxicogenomic analyses, the effects of in utero

exposure to phyto-oestrogens on the foetal testis. Subcuta-

neous delivery of genistein at 100 mg ⁄ kg ⁄ day in rat dams

from gestational day 11 (GD11) to GD20 shows only a

modest effect on testicular gene transcription, with an

alteration in expression for only five genes [‡2-fold; (Nac-

iff et al., 2005)]. This includes a 3.0-fold reduction of Star

transcripts and a 2.9-fold increase in transcripts coding for

the progesterone receptor. Unfortunately, these variations

have not been validated by qRT-PCR. Similarly, transcrip-

tional changes were also absent in the testes of newborn

pups whose mothers were fed with dietary soy during

the gestation (Cederroth, Beny, Zimmermann, Schaad,

Combepine, Doerge, Pralong, Vassalli, Nef, submitted).

Some of the studies that have evaluated the effects of

lifelong exposure to phyto-oestrogens also assessed for

reproductive efficiency in vivo (Table 5). Atanassova

et al., (1999) have shown that litter size is not affected in

male Wistar rats exposed throughout life to dietary soy.Tab

le4

(Continued

)

Spec

ies

and

stra

in

Period

of

exposu

reD

ose

Seru

m

isoflav

one

leve

ls

No.

anim

als

Litt

er

size

Sper

m

pro

duct

ion

Test

is

wei

ght

Sem

inal

vesi

cle

wei

ght

Blo

od

horm

one

leve

lsRef

eren

ce

Die

tary

supple

men

tation

with

die

tary

soy

Rat

sppm

isoflav

one

ng

⁄ml

Spra

gue–

Daw

ley

Adult

600

a2224

a57

(57)

ND

ND

No

effe

ctN

DT:

)50%

LH:

No

effe

ct

Web

eret

al.,

(2001)

Soy

form

ula

milk

die

tary

Monke

ysm

g⁄L

(agly

cone)

Mar

mose

tP4

toP4

525.5

aN

D15

(15)

ND

ND

No

effe

ctN

D)

55%

Shar

pe

etal

.,(2

002)

Mar

mose

tP4

toP4

525.5

aN

D7

(7)

No

effe

ctN

D+

14%

No

effe

ctT:

No

effe

ct

(fro

mW

40)

Tan

etal

.,(2

006)

For

contr

olgro

ups,

the

num

ber

of

indiv

idual

s(n

)is

show

nin

par

enth

eses

.

ND

,N

ot

det

erm

ined

;P,

post

-nat

alday

;W

,w

eek;

M,

month

;BLD

,bel

ow

the

limit

of

det

ection.

aTo

talis

oflav

one

conte

nt.

Seru

mgen

iste

inva

lues

are

expre

ssed

inn

M.




Tab

le5

Anim

alst

udie

sev

aluat

ing

the

adult

effe

cts

of

lifel

ong

exposu

reto

isoflav

ones

(fro

mges

tation

untilad

ulthood)

on

mal

ere

pro

duct

ion

Spec

ies

and

stra

in

Period

of

exposu

reD

ose

Seru

m

gen

iste

in

leve

ls

No.

anim

als

Litt

er

size

Sper

m

pro

duct

ion

Test

is

wei

ght

Sem

inal

vesi

cle

wei

ght

Blo

od

horm

one

leve

lsRef

eren

ce

Ora

lgav

age

of

gen

iste

in

Rat

sm

g⁄k

g⁄d

ay

Wis

tar

Han

E0onw

ard

1N

D‡1

5)

45%

No

effe

ctN

oef

fect

No

effe

ctN

oef

fect

sfo

r

LH,

FSH

,T

Eust

ache

etal

.,(2

009)

10

ND

‡15

)40%

Dec

reas

edN

oef

fect

No

effe

ctFS

H:

no

effe

ct

LH:

no

effe

ct

T:)

40%

Die

tary

supple

men

tation

with

gen

iste

in

Rat

sppm

Spra

gue–

Daw

ley

E0onw

ard

200–1

000

ND

6(6

)N

DN

DN

oef

fect

ND

ND

Cas

anova

etal

.,(1

999)

Spra

gue–

Daw

ley

E17

onw

ard

5N

D8

(8)

ND

No

effe

ct)

14%

No

effe

ctLH

:)

67%

T:N

oef

fect

Rober

tset

al.,

(2000)

Spra

gue–

Daw

ley

E7onw

ard

5–1

250

ND

ND

ND

ND

No

effe

ctN

oef

fect

ND

Del

clos

etal

.,(2

001)

Die

tary

supple

men

tation

with

die

tary

soy

Mic

eppm

C57BL

⁄6C

RSl

cE0

onw

ard

0.0

5%

aN

D10

(21)

ND

ND

)5%

ND

ND

Taka

shim

a-Sa

saki

etal

.,

(2006)

CD

-1E0

onw

ard

600

a�

10

a20

(18)

)21%

)25%

No

effe

ct)

30%

T:N

oef

fect

Ced

erro

thet

al.,

(2009)

CD

-1E0

onw

ard

ND

ND

22

(24)

ND

ND

+8%

+22%

ND

Ruhle

net

al.,

(2008)

Rat

s Wis

tar

E0onw

ard

15.5

%a

ND

ND

No

effe

ctN

D)

10%

ND

FSH

:+

12%

Ata

nas

sova

etal

.,(1

999)

For

contr

olgro

ups,

the

num

ber

of

indiv

idual

s(n

)is

show

nin

par

enth

eses

.

ND

,N

ot

det

erm

ined

;E,

embry

onic

day

;T,

test

ost

erone.

aTo

talis

oflav

one

conte

nt.

Seru

mgen

iste

inva

lues

are

expre

ssed

inl

M.



By contrast, two studies have come to the conclusion that

lifelong exposure to isoflavones may affect reproductive

success. Wistar Han rats exposed by gavage to genistein

at 1 or 10 mg ⁄ kg ⁄ day from conception through to adult-

hood displayed reductions in sperm production, motility

and abnormal motion parameters (Eustache et al., 2009).

When mated with untreated females, male fertility was

reduced at both doses, as reflected by an increased rate of

post-implantation losses and a decrease in litter size.

Corroborating such findings with another experimental

design, CD-1 male mice exposed throughout life to

dietary soy, and by inference phyto-oestrogens

(� 20 mg ⁄ kg ⁄ day), had decreased sperm abundance and

seminal vesicle weight, and smaller litter sizes after mating

(Cederroth et al., 2009). Curiously both studies are the

exception, among some twenty others, in reporting signif-

icant negative effects of phyto-oestrogen exposure in

males on reproductive success (Tables 2–5). Such discrep-

ancies may reflect differences in experimental design, spe-

cies and strains, formulations, doses, routes of exposure,

time and duration of exposure and measurements to eval-

uate the testicular and reproductive effects. The negative

effects described above may reflect additive detrimental

effects as a result of life-long exposure to phyto-oestro-

gens, which encompasses all developmental periods (ges-

tation, lactation and adulthood). This could explain, for

example, the absence of negative reproductive effects in

animals exposed post-natally to dietary soy and ⁄ or phyto-

oestrogens (Table 3). In addition, potential multigenera-

tional effects would require further consideration as a

recent study from the National Toxicology Program

reported a decrease in litter size at the F2 generation of

parent rats exposed to 500 ppm of genistein during adult-

hood (National Toxicology Program, 2008).

Hormonal changes after exposure to soy-derivedphyto-oestrogens

LH levels and testis weight are both decreased in Spra-

gue–Dawley rats exposed from embryonic day 17 (E17)

onwards to a dietary supplement containing 5 ppm geni-

stein (Roberts et al., 2000). In ApoE-null mice exposed

during adulthood to both dietary genistein and daidzein,

testosterone levels are lower and also correlate with a

decrease in testis weight (Cline et al., 2004). By contrast,

other studies have shown an absence of effect in testis

weight despite a decrease in hormonal levels in various

species of mammals with differing routes and time of

exposure (Strauss et al., 1998; Sharpe et al., 2002;

Wisniewski et al., 2003). Strikingly, some reports mention

an increase of testis and seminal vesicles weights, but with

no differences in sexual hormone levels (Fisher et al.,

1999; Kang et al., 2002; Ryokkynen et al., 2005; Tan et al.,

2006). Overall, these studies indicate that hormone levels

and testis weight cannot serve as an indicator for disrup-

tion of reproductive functions.

Interference with spermatogenesis upon lifelongexposure to phyto-oestrogens

The potential mechanisms by which soy and isoflavones

adverserly affect the male reproductive system remain

poorly characterized. Potential mechanisms of spermato-

genesis disruption by dietary phyto-oestrogens have been

recently proposed (Cederroth et al., 2009). Life long expo-

sure to dietary phyto-oestrogens decreased epididymal

sperm abundance, which correlated with a reduction in

the number of haploid cells in the testis of CD-1 mice,

without altering testosterone levels in the serum. The

authors have shown by quantitative real-time PCR that

Sertoli cell maturation and function appears to be unaf-

fected, and that markers that cover the various stages of

early and mid-spermatogenesis remain unchanged

(Cederroth et al., 2009). However, the spermatid specific

marker Gapd-s (glyceraldehyde 3-phosphate dehydroge-

nase-s), which encodes for a protein that regulates glycoly-

sis in the spermatozoa and is required for sperm motility

and fertility (Miki et al., 2004), was downregulated in the

testis of mice exposed to dietary phyto-oestrogens. This

result indicates that late spermatogenesis is affected.

Interestingly, androgen receptor regulated genes (i.e. Pem,

Testin and tPA) were also downregulated, suggesting that

androgen sensitivity is perturbed upon exposure to phyto-

oestrogens. These data suggest that spermatogenesis is

unaffected until the round-spermatid stage and that

phyto-oestrogen exposure might interfere with the

androgen receptor pathway and affect the late steps of

spermatogenesis. A recent study investigated changes in

the adult testis transcriptome of rats exposed to genistein

from conception to adulthood (Eustache et al., 2009). In

this study, the number of modified genes at a ‡2-fold

threshold, was over 100 at 1 mg ⁄ kg ⁄ day but markedly

lower at 10 mg ⁄ kg ⁄ day. Generally, different genes were

modified in the two groups, although for the genes which

were modified at both doses, the magnitude of the effects

was more pronounced for the higher dose. Although this

analysis was performed with RNAs extracted from

whole testis – a very heterogenous population of cells – a

functional classification of genes revealed a slight upregu-

lation of genes implicated in the GnRH pathway.

Potential reproductive effects of a low-dosemixture of EDCs including phyto-oestrogens

The sources of exposure to EDCs are diverse and vary

widely around the world. As our environment contains




numerous pollutants, it is likely that individuals or popu-

lations are exposed to a mixture of endocrine disrupting

compounds with potential additive or synergistic effects.

However, the consequences of simultaneous exposure to

phyto-oestrogens and other EDCs are only beginning to

be investigated. Recently, it was reported that the rela-

tively weak alterations in reproductive function of males

exposed to low doses of genistein (1 mg ⁄ kg ⁄ day) were

exacerbated when co-exposed with a low dose of the fun-

gicide vinclozolin (1 mg ⁄ kg ⁄ day), an ubiquitous anti-

androgenic food contaminant (Eustache et al., 2009).

Indeed, the genistein ⁄ vinclozolin mixture induced greater

alterations on the male reproductive tract and fertility

endpoints when compared with the exposure to each

compound in isolation, at the same dose. Interestingly,

the effects were greater in the low dose mixture

(1 mg ⁄ kg ⁄ day for both compounds) than in the high

dose mixture (10 mg ⁄ kg ⁄ day genistein +30 mg ⁄ kg ⁄ day

vinclozolin), and mimicked the effects of vinclozolin

exposure alone at 30 mg ⁄ kg ⁄ day. Such results emphasize

the need for further studies to assess the synergistic effects

of natural and chemical EDC mixtures at low doses on

male reproductive success.

Conclusion

Exposure to endocrine disruptors (e.g. BPA or dioxins)

during critical periods of reproductive development

increases the incidence of reproductive disorders. Given

the popularity of soy-based formula, isoflavone supple-

ments and soy-derived products, a better understanding

of the influence of phyto-oestrogens on male develop-

ment is needed. To date, there has been a lack of consis-

tency in human and animal studies examining the effects

of soy and phyto-oestrogens on reproductive parameters.

These discrepancies certainly reflect the variety of experi-

mental designs, the differences between the specific end-

points measured but also inadequate descriptions or

insufficient sample size to permit confidence in the

observed results. In humans for example, it would be

important to investigate adult male reproductive and

endocrine functions of healthy full-term infant fed soy-

based formula compared with breast-fed or cow milk for-

mula-fed infants. These studies should investigate puber-

tal development and reproductive endpoints such as adult

testicular function (testicular volume, spermiogram) and

endocrine parameters (testosterone, DHT, oestradiol, LH,

FSH, IGF1, INSL3, etc). The cohorts should be large

enough to ensure statistical power to detect meaningful

differences. Concerning animal studies, the choice of the

animal model and nutritional differences in animal diets

need to be considered carefully when designing experi-

ment. It would be relevant to assess dose response

relationships, mutigenerational studies and evaluation of

both reproductive and post-natal endpoints. Finally, most

studies are designed to investigate the effects of a single

endocrine disrupting chemical. Although straightforward

in term of scientific design, this approach fails to appreci-

ate the chemical soup that is more typical of the human

or animal environment. Thus further investigation is

needed to evaluate the consequences of simultaneous

exposure to phyto-oestrogens and other EDCs on fertility

and testicular function.

Acknowledgements

S.N. is supported by the Foundation Gertrude von Meissner and

The Sir Jules Thorn Charitable Overseas Trust Reg., Schaan.

C.R.C. is supported by the Ernst & Lucie Schmidheiny Founda-

tion. Serge Nef declares is a founder of Amazentis S.A. and a

member of its scientific advisory board. J.A. and F.E. have been

supported in part by the French Program on Endocrine Disrup-

tion (PNRPE; contract MEDD CV 05147).

References

Adachi, T., Ono, Y., Koh, K. B., Takashima, K., Tainaka, H., Matsuno,

Y., Nakagawa, S., Todaka, E., Sakurai, K., Fukata, H., Iguchi, T.,

Komiyama, M. & Mori, C. (2004) Long-term alteration of gene

expression without morphological change in testis after neonatal

exposure to genistein in mice: toxicogenomic analysis using cDNA

microarray. Food Chemical Toxicology 42, 445–452.

Adlercreutz, H., Musey, P. I., Fotsis, T., Bannwart, C., Wahala, K.,

Makela, T., Brunow, G. & Hase, T. (1986) Identification of lignans

and phytoestrogens in urine of chimpanzees. Clinica Chimica Acta

158, 147–154.

Adlercreutz, H., Fotsis, T., Lampe, J., Wahala, K., Makela, T., Brunow,

G. & Hase, T. (1993a) Quantitative determination of lignans and

isoflavonoids in plasma of omnivorous and vegetarian women by

isotope dilution gas chromatography-mass spectrometry. Scandina-

vian Journal of Clinical and Laboratory Investigation. Supplement

215, 5–18.

Adlercreutz, H., Markkanen, H. & Watanabe, S. (1993b) Plasma con-

centrations of phyto-oestrogens in japanese men. Lancet 342, 1209–

1210.

Akiyama, T., Ishida, J., Nakagawa, S., Ogawara, H., Watanabe, S., Itoh,

N., Shibuya, M. & Fukami, Y. (1987) Genistein, a specific inhibitor

of tyrosine-specific protein kinases. Journal of Biological Chemistry

262, 5592–5595.

Atanassova, N., McKinnell, C., Walker, M., Turner, K. J., Fisher, J. S.,

Morley, M., Millar, M. R., Groome, N. P. & Sharpe, R. M. (1999)

Permanent effects of neonatal estrogen exposure in rats on

reproductive hormone levels, sertoli cell number, and the efficiency

of spermatogenesis in adulthood. Endocrinology 140, 5364–5373.

Atkinson, C., Frankenfeld, C. L. & Lampe, J. W. (2005) Gut bacterial

metabolism of the soy isoflavone daidzein: exploring the relevance

to human health. Experimental Biology and Medicine (Maywood)

230, 155–170.

Awoniyi, C. A., Roberts, D., Chandrashekar, V., Veeramachaneni, D.

N., Hurst, B. S., Tucker, K. E. & Schlaff, W. D. (1997) Neonatal



exposure to coumestrol, a phytoestrogen, does not alter spermato-

genic potential in rats. Endocrine 7, 337–341.

Badger, T. M., Gilchrist, J. M., Pivik, R. T., Andres, A., Shankar, K.,

Chen, J. R. & Ronis, M. J. (2009) The health implications of soy

infant formula. American Journal of Clinical Nutrition 89, 1668S–

1672S.

Barrett, J. R. (2006) The science of soy: what do we really know?

Environmental Health Perspectives 114, A352–A358.

Bennetts, H. W., Underwood, E. J. & Shier, F. L. (1946) A specific

breeding problem of sheep on subterranean clover pastures in

western Australia. Australian Veterinary Journal 22, 2–12.

Bhatia, J. & Greer, F. (2008) Use of soy protein-based formulas in

infant feeding. Pediatrics 121, 1062–1068.

Blair, R. M., Appt, S. E., Franke, A. A. & Clarkson, T. B. (2003) Treat-

ment with antibiotics reduces plasma equol concentration in cyno-

molgus monkeys (Macaca fascicularis). Journal of Nutrition 133,

2262–2267.

Cardoso, J. R. & Bao, S. N. (2008) Morphology of Reproductive

Organs, Semen Quality and Sexual Behaviour of the Male Rabbit

Exposed to a Soy-containing Diet and Soy-derived Isoflavones dur-

ing Gestation and Lactation. Reproduction in Domestic Animals

doi: 10.1111 ⁄ j.1439-0531.2008.01121.x

Casanova, M., You, L., Gaido, K. W., Archibeque-Engle, S., Janszen,

D. B. & Heck, H. A. (1999) Developmental effects of dietary

phytoestrogens in Sprague-Dawley rats and interactions of

genistein and daidzein with rat estrogen receptors alpha and beta

in vitro. Toxicological Sciences 51, 236–244.

Cederroth, C. R. & Nef, S. (2009) Soy, phytoestrogens and metabolism:

a review. Molecular and Cellular Endocrinology 304, 30–42.

Cederroth, C. R., Beny, J. L., Zimmermann, C., Schaad, O., Combe-

pine, C., Doerge, D. R., Pralong, F., Vassalli, J. D. & Nef, S. (2009)

Potential detrimental effects of a phytoestrogen-rich diet on male

fertility in mice. Submitted.

Chavarro, J. E., Toth, T. L., Sadio, S. M. & Hauser, R. (2008) Soy food

and isoflavone intake in relation to semen quality parameters among

men from an infertility clinic. Human Reproduction 23, 2584–2590.

Clarkson, T. B., Anthony, M. S. & Morgan, T. M. (2001) Inhibition of

postmenopausal atherosclerosis progression: a comparison of the

effects of conjugated equine estrogens and soy phytoestrogens. Jour-

nal of Clinical Endocrinology and Metabolism 86, 41–47.

Cline, J. M., Franke, A. A., Register, T. C., Golden, D. L. & Adams, M.

R. (2004) Effects of dietary isoflavone aglycones on the reproductive

tract of male and female mice. Toxicologic Pathology 32, 91–99.

COT Report (2003) Phytoestrogens and Health. Consumer Products

and the Environment, Food Standards Agency, Department of

Health, Committee on Toxicity of Chemicals in Food, United

Kingdom, 1–444.

Coward, L., Kirk, M., Albin, N. & Barnes, S. (1996) Analysis of plasma

isoflavones by reversed-phase hplc-multiple reaction ion monitor-

ing-mass spectrometry. Clinica Chimica Acta 247, 121–142.

Delclos, K. B., Bucci, T. J., Lomax, L. G., Latendresse, J. R.,

Warbritton, A., Weis, C. C. & Newbold, R. R. (2001) Effects of diet-

ary genistein exposure during development on male and female CD

(Sprague-Dawley) rats. Reproductive Toxicology 15, 647–663.

van Erp-Baart, M. A., Brants, H. A., Kiely, M., Mulligan, A., Turrini,

A., Sermoneta, C., Kilkkinen, A. & Valsta, L. M. (2003) Isoflavone

intake in four different european countries: the venus approach.

British Journal of Nutrition 89(Suppl. 1), S25–S30.

Eustache, F., Mondon, F., Canivenc-Lavier, M. C., Lesaffre, C., Fulla,

Y., Berges, R., Cravedi, J. P., Vaiman, D. & Auger, J. (2009) Chronic

dietary exposure to a low-dose mixture of genistein and vinclozolin

modifies the reproductive axis, testis transcriptome and fertility.

Environmental Health Perspectives 117, 1272–1279.

Faqi, A. S., Johnson, W. D., Morrissey, R. L. & McCormick, D. L.

(2004) Reproductive toxicity assessment of chronic dietary exposure

to soy isoflavones in male rats. Reproductive Toxicology, 18,

605–611.

Fielden, M. R., Samy, S. M., Chou, K. C. & Zacharewski, T. R. (2003)

Effect of human dietary exposure levels of genistein during gestation

and lactation on long-term reproductive development and sperm

quality in mice. Food and Chemical Toxicology 41, 447–454.

Fisher, J. S., Turner, K. J., Brown, D. & Sharpe, R. M. (1999) Effect of

neonatal exposure to estrogenic compounds on development of the

excurrent ducts of the rat testis through puberty to adulthood. Envi-

ronmental Health Perspectives 107, 397–405.

Fraser, L. R., Beyret, E., Milligan, S. R. & Adeoya-Osiguwa, S. A.

(2006) Effects of estrogenic xenobiotics on human and mouse sper-

matozoa. Human Reproduction 21, 1184–1193.

Fritz, W. A., Cotroneo, M. S., Wang, J., Eltoum, I. E. & Lamartiniere,

C. A. (2003) Dietary diethylstilbestrol but not genistein adversely

affects rat testicular development. Journal of Nutrition 133,

2287–2293.

Goldman, L. R., Newbold, R. & Swan, S. H. (2001) Exposure to soy-

based formula in infancy. JAMA 286, 2402–2403.

Habito, R. C., Montalto, J., Leslie, E. & Ball, M. J. (2000) Effects of

replacing meat with soyabean in the diet on sex hormone concen-

trations in healthy adult males. British Journal of Nutrition 84,

557–563.

Henry, L. A. & Witt, D. M. (2002) Resveratrol: phytoestrogen effects

on reproductive physiology and behavior in female rats. Hormones

and Behavior 41, 220–228.

Irvine, C., Fitzpatrick, M., Robertson, I. & Woodhams, D. (1995) The

potential adverse effects of soybean phytoestrogens in infant feeding.

New Zealand Medical Journal 108, 208–209.

Irvine, C. H., Fitzpatrick, M. G. & Alexander, S. L. (1998a)

Phytoestrogens in soy-based infant foods: concentrations, daily intake,

and possible biological effects. Proceedings of the Society for Experimen-

tal Biology and Medicine 217, 247–253.

Irvine, C. H., Shand, N., Fitzpatrick, M. G. & Alexander, S. L. (1998b)

Daily intake and urinary excretion of genistein and daidzein by

infants fed soy- or dairy-based infant formulas. American Journal of

Clinical Nutrition 68, 1462S–1465S.

Jung, E. Y., Lee, B. J., Yun, Y. W., Kang, J. K., Baek, I. J., Jurg, M. Y.,

Lee, Y. B., Sohn, H. S., Lee, J. Y., Kim, K. S., Yu, W. J., Do, J. C.,

Kim, Y. C. & Nam, S. Y. (2004) Effects of exposure to genistein and

estradiol on reproductive development in immature male mice

weaned from dams adapted to a soy-based commercial diet. Journal

of Veterinary Medical Science 66, 1347–1354.

Kang, K. S., Che, J. H. & Lee, Y. S. (2002) Lack of adverse effects in the f1

offspring maternally exposed to genistein at human intake dose level.

Food and Chemical Toxicology 40, 43–51.

King, R. A. & Bursill, D. B. (1998) Plasma and urinary kinetics of the

isoflavones daidzein and genistein after a single soy meal in humans.

American Journal of Clinical Nutrition 67, 867–872.

Kuiper, G. G., Carlsson, B., Grandien, K., Enmark, E., Haggblad, J.,

Nilsson, S. & Gustafsson, J. A. (1997) Comparison of the ligand

binding specificity and transcript tissue distribution of estrogen

receptors alpha and beta. Endocrinology 138, 863–870.

Kuiper, G. G., Lemmen, J. G., Carlsson, B., Corton, J. C., Safe, S. H.,

van der Saag, P. T., van der Burg, B. & Gustafsson, J. A. (1998)




Interaction of estrogenic chemicals and phytoestrogens with estro-

gen receptor beta. Endocrinology 139, 4252–4263.

de Lamirande, E., Leclerc, P. & Gagnon, C. (1997) Capacitation as a

regulatory event that primes spermatozoa for the acrosome reaction

and fertilization. Molecular Human Reproduction 3, 175–194.

Lee, B. J., Jung, E. Y., Yun, Y. W., Kang, J. K., Baek, I. J., Yon, J. M.,

Lee, Y. B., Sohn, H. S., Lee, J. Y., Kim, K. S. & Nam, S. Y. (2004a)

Effects of exposure to genistein during pubertal development on the

reproductive system of male mice. Journal of Reproduction and

Development 50, 399–409.

Lee, B. J., Kang, J. K., Jung, E. Y., Yun, Y. W., Baek, I. J., Yon, J. M.,

Lee, Y. B., Sohn, H. S., Lee, J. Y., Kim, K. S. & Nam, S. Y. (2004b)

Exposure to genistein does not adversely affect the reproductive sys-

tem in adult male mice adapted to a soy-based commercial diet.

Journal of Veterinary Science 5(3), 227–234.

Leopold, A. S., Erwin, M., Oh, J. & Browning, B. (1976) Phyto-

estrogens: adverse effects on reproduction in california quail. Science

191, 98–100.

Lunn, S. F., Recio, R., Morris, K. & Fraser, H. M. (1994) Blockade of

the neonatal rise in testosterone by a gonadotrophin-releasing hor-

mone antagonist: effects on timing of puberty and sexual behaviour

in the male marmoset monkey. Journal of Endocrinology 141, 439–

447.

Masutomi, N., Hibutani, M., Takagi, H., Uneyama, C., Takahashi, N.

& Hirose, M. (2003) Impact of dietary exposure to methoxychlor,

genistein, or diisononyl phthalate during the perinatal period on the

development of the rat endocrine ⁄ reproductive systems in later

life. Toxicology 192, 149–170.

McClain, R. M., Wolz, E., Davidovich, A., Edwards, J. & Bausch, J.

(2007) Reproductive safety studies with genistein in rats. Food and

Chemical Toxicology 45, 1319–1332.

Michael McClain, R., Wolz, E., Davidovich, A., Pfannkuch, F.,

Edwards, J. A. & Bausch, J. (2006) Acute, subchronic and chronic

safety studies with genistein in rats. Food and Chemical Toxicology

44, 56–80.

Miki, K., Qu, W., Goulding, E. H., Willis, W. D., Bunch, D. O.,

Strader, L. F., Perreault, S. D., Eddy, E. M. & O’Brien, D. A. (2004)

Glyceraldehyde 3-phosphate dehydrogenase-s, a sperm-specific

glycolytic enzyme, is required for sperm motility and male fertility.

Proceedings of the National Academy of Sciences of the United States

of America 101, 16501–16506.

Mitchell, J. H., Cawood, E., Kinniburgh, D., Provan, A., Collins, A. R.

& Irvine, D. S. (2001) Effect of a phytoestrogen food supplement on

reproductive health in normal males. Clinical Science (London) 100,

613–618.

Morton, M. S., Wilcox, G., Wahlqvist, M. L. & Griffiths, K. (1994)

Determination of lignans and isoflavonoids in human female plasma

following dietary supplementation. Journal of Endocrinology 142,

251–259.

Musey, P. I., Adlercreutz, H., Gould, K. G., Collins, D. C., Fotsis, T.,

Bannwart, C., Makela, T., Wahala, K., Brunow, G. & Hase, T.

(1995) Effect of diet on lignans and isoflavonoid phytoestrogens in

chimpanzees. Life Sciences 57, 655–664.

Naciff, J. M., Hess, K. A., Overmann, G. J., Torontali, S. M., Carr, G.

J., Tiesman, J. P., Foertsch, L. M., Richardson, B. D., Martinez, J. E.

& Daston, G. P. (2005) Gene expression changes induced in the

testis by transplacental exposure to high and low doses of

17{alpha}-ethynyl estradiol, genistein, or bisphenol A. Toxicological

Sciences 86, 396–416.

Nagao, T., Yoshimura, S., Saito, Y., Nakagomi, M., Usumi, K. & Ono,

H. (2001) Reproductive effects in male and female rats of neonatal

exposure to genistein. Reproductive Toxicology 15, 399–411.

Nagata, C., Inaba, S., Kawakami, N., Kakizoe, T. & Shimizu, H. (2000)

Inverse association of soy product intake with serum androgen and

estrogen concentrations in japanese men. Nutrition and Cancer 36,

14–18.

Nagata, C., Takatsuka, N., Shimizu, H., Hayashi, H., Akamatsu, T. & Mur-

ase, K. (2001) Effect of soymilk consumption on serum estrogen and

androgen concentrations in japanese men. Cancer Epidemiology,

Biomarkers and Prevention 10, 179–184.

National Toxicology Program (2006) NTP-CERHR Expert Panel

Report on the Reproductive and Developmental Toxicity of soy For-

mula. U.S. Department of Health and Human Services, Center for

The Evaluation of Risks to Human Reproduction, Research Triangle

Park, NC, 1–214.

National Toxicology Program (2008) Multigenerational reproductive

study of genistein (cas no. 446-72-0) in sprague-dawley rats (feed

study). National Toxicology Program Technical Report Series TOX79,

1–98.

Perry, D. L., Spedick, J. M., McCoy, T. P., Adams, M. R., Franke, A. A.

& Cline, J. M. (2007) Dietary soy protein containing isoflavonoids

does not adversely affect the reproductive tract of male cynomolgus

macaques (Macaca fascicularis). Journal of Nutrition 137, 1390–1394.

Phillips, K. P. & Tanphaichitr, N. (2008) Human exposure to endo-

crine disrupters and semen quality. Journal of Toxicology and Envi-

ronmental Health. Part B, Critical Reviews 11, 188–220.

Roberts, D., Veeramachaneni, D. N., Schlaff, W. D. & Awoniyi, C. A.

(2000) Effects of chronic dietary exposure to genistein, a

phytoestrogen, during various stages of development on repro-

ductive hormones and spermatogenesis in rats. Endocrine 13,

281–286.

Ruhlen, R. L., Howdeshell, K. L., Mao, J., Taylor, J. A., Bronson, F. H.,

Newbold, R. R., Welshons, W. V. & vom Saal, F. S. (2008) Low

phytoestrogen levels in feed increase fetal serum estradiol resulting

in the ‘‘fetal estrogenization syndrome’’ and obesity in CD-1 mice.

Environmental Health Perspectives 116, 322–328.

Ryokkynen, A., Nieminen, P., Mustonen, A. M., Pyykonen, T., Asikai-

nen, J., Hanninen, S., Mononen, J. & Kukkonen, J. V. (2005)

Phytoestrogens alter the reproductive organ development in the

mink (mustela vison). Toxicology and Applied Pharmacology 202,

132–139.

Ryokkynen, A., Kukkonen, J. V. & Nieminen, P. (2006) Effects of diet-

ary genistein on mouse reproduction, postnatal development and

weight-regulation. Animal Reproduction Science 93, 337–348.

Sacks, F. M., Lichtenstein, A., Van Horn, L., Harris, W., Kris-Etherton,

P. & Winston, M. (2006) Soy protein, isoflavones, and cardiovascu-

lar health: an american heart association science advisory for profes-

sionals from the nutrition committee. Circulation 113, 1034–1044.

Setchell, K. D. (1998) Phytoestrogens: the biochemistry, physiology,

and implications for human health of soy isoflavones. American

Journal of Clinical Nutrition 68, 1333S–1346S.

Setchell, K. D., Zimmer-Nechemias, L., Cai, J. & Heubi, J. E. (1997)

Exposure of infants to phyto-oestrogens from soy-based infant

formula. Lancet 350, 23–27.

Setchell, K. D., Zimmer-Nechemias, L., Cai, J. & Heubi, J. E. (1998)

Isoflavone content of infant formulas and the metabolic fate of these

phytoestrogens in early life. American Journal of Clinical Nutrition

68, 1453S–1461S.



Sharpe, R. M., Martin, B., Morris, K., Greig, I., McKinnell, C.,

McNeilly, A. S. & Walker, M. (2002) 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. Human Reproduction 17, 1692–1703.

Skakkebaek, N. E., Rajpert-De Meyts, E. & Main, K. M. (2001) Testic-

ular dysgenesis syndrome: an increasingly common developmental

disorder with environmental aspects. Human Reproduction 16, 972–

978.

Strauss, L., Makela, S., Joshi, S., Huhtaniemi, I. & Santti, R. (1998)

Genistein exerts estrogen-like effects in male mouse reproductive

tract. Molecular and Cellular Endocrinology 144, 83–93.

Strom, B. L., Schinnar, R., Ziegler, E. E., Barnhart, K. T., Sammel, M.

D., Macones, G. A., Stallings, V. A., Drulis, J. M., Nelson, S. E. &

Hanson, S. A. (2001) Exposure to soy-based formula in infancy and

endocrinological and reproductive outcomes in young adulthood.

JAMA 286, 807–814.

Takashima-Sasaki, K., Komiyama, M., Adachi, T., Sakurai, K., Kato,

H., Iguchi, T. & Mori, C. (2006) Effect of exposure to high isofla-

vone-containing diets on prenatal and postnatal offspring mice.

Bioscience, Biotechnology, and Biochemistry 70, 2874–2882.

Tan, K. A., Walker, M., Morris, K., Greig, I., Mason, J. I. & Sharpe, R.

M. (2006) Infant feeding with soy formula milk: effects on puberty

progression, reproductive function and testicular cell numbers in

marmoset monkeys in adulthood. Human Reproduction 21, 896–904.

Tham, D. M., Gardner, C. D. & Haskell, W. L. (1998) Clinical review

97: potential health benefits of dietary phytoestrogens: a review of

the clinical, epidemiological, and mechanistic evidence. Journal of

Clinical Endocrinology and Metabolism 83, 2223–2235.

Toppari, J. (2002) Environmental endocrine disrupters and disorders

of sexual differentiation. Seminars in Reproductive Medicine 20, 305–

312.

Vedavanam, K., Srijayanta, S., O’Reilly, J., Raman, A. & Wiseman, H.

(1999) Antioxidant action and potential antidiabetic properties of an

isoflavonoid-containing soyabean phytochemical extract (spe). Phyto-

theraphy Research 13, 601–608.

Watanabe, S., Yamaguchi, M., Sobue, T., Takahashi, T., Miura, T., Arai,

Y., Mazur, W., Wahala, K. & Adlercreutz, H. (1998) Pharmacokinetics

of soybean isoflavones in plasma, urine and feces of men after inges-

tion of 60 g baked soybean powder (kinako). Journal of Nutrition 128,

1710–1715.

Weber, K. S., Setchell, K. D., Stocco, D. M. & Lephart, E. D. (2001)

Dietary soy-phytoestrogens decrease testosterone levels and prostate

weight without altering LH, prostate 5alpha-reductase or testicular

steroidogenic acute regulatory peptide levels in adult male Sprague-

Dawley rats. Journal of Endocrinology 170, 591–599.

Wisniewski, A. B., Klein, S. L., Lakshmanan, Y. & Gearhart, J. P.

(2003) Exposure to genistein during gestation and lactation dema-

sculinizes the reproductive system in rats. Journal of Urology 169,

1582–1586.

Wisniewski, A.B., Cernetich, A., Gearhart, J.P. & Klein, S.L. (2005)

Perinatal exposure to genistein alters reproductive development and

aggressive behavior in male mice. Physiology & Behavior 84,

327–334.

Xu, X., Wang, H. J., Murphy, P. A., Cook, L. & Hendrich, S. (1994)

Daidzein is a more bioavailable soymilk isoflavone than is genistein

in adult women. Journal of Nutrition 124, 825–832.




Soy, phyto-oestrogens and male reproductive function: a review

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