Stetan utjecaj soje (na engleskom)
Martin Cotar @ Home
*****************************************************
Endocrine disrupters are chemicals in the environment that are similarin
structure to natural sex hormones and interfere with their normal functions,
usually by binding to the cell receptors and preventing the hormone from
binding to the receptor.
When hormones bind to their receptors, this triggers their biological
effects. Endocrine disrupters are found in plastics and foods.
Infertility is an emotive issue, and having children is a recognized
"right," so any implication that environmental pollution affects
reproduction has to be taken seriously.
When the causative agents might also be responsible for various cancers and
other diseases, then the level of interest that the issue attracts is
unsurprising hence the calls in the early 1990s for action in line with the
"precautionary principle."1
In men hypospadias, cryptorchidism (undescended testicles), cancer of the
prostate, testicular cancer, and semen quality and in women breast cancer,
cystic ovaries, and endometriosis have all been suggested as indicators of
adverse trends in reproductive health.2
The idea that these trends are real and are connected with environmental
pollution is gaining credence internationally. The effect on human health of
environmental chemicals that are mediated through the endocrine system
endocrine disrupters has generated huge interest and investment.
Why Is This, and What Is the Evidence for the Assumed Association?
Changes in the sexual morphology of fish exposed to sewage effluent have led
some scientists to conjecture that humans also live in a "sea of estrogens"
and that the apparent increases in the incidence of certain reproductive
conditions may be due to exposure to chemicals in the environment.
The so called Sharpe-Skakkebaek hypothesis offered a possible common cause
and toxicological mechanism for abnormalities in men and boys that is,
increased exposure to estrogen in utero may interfere with the
multiplication of fetal Sertoli cells, resulting in hormonally mediated
developmental effects and, after puberty, reduced quality of semen.3
It was postulated that synthetic chemicals in the environment are the prime
source of the excessive estrogenic stimulation, with exposure through food
and water being the primary route.
Further research has extended the concern to the role of antiandrogens and
has led to the recognition that a range of systems and processes may be
susceptible to hormonal modulation, including immune function, behavior, and
learning and memory, as well as reproduction.
The term environmental estrogen has given way to the more encompassing term
"environmental endocrine disrupter," defined as "an exogenous substance that
causes adverse health effects in an intact organism, or its progeny,
subsequent to changes in endocrine function."4
Endocrine disrupters are potentially present in food as natural
"phytoestrogens" and chemical contaminants, and there is a divide in the
perception of natural and synthetic substances.5
Hence the drive in some quarters to market "healthy" bread that is rich in
soy flour and linseed at the same time that other people are warning against
low levels of weak estrogenic synthetic chemicals as contaminants in food.
Perhaps this reflects the common view of natural things as good and
synthetic things as necessarily bad.
Two Questions Need To Be Addressed
? Do indicators of reproductive health truly reveal a worsening situation?
? Can exposure to environmental chemical contaminants conceivably be the
cause of any such temporal changes?
Baseline data on many of the implicated conditions are so poor that it is
not possible to say for sure whether trends are occurring. There is also the
issue of geographical variability in the measured indices, which can be
related to genetic differences in the population or to climatic differences
or changes in lifestyle, for example.
None the less, there is agreement that the incidence of testicular and
prostate cancer is increasing and that semen quality is probably worsening
in some regions of the world.
There is also some evidence for an increasing incidence of cryptorchidism
and hypospadias; and in women endometriosis and polycystic ovaries may be
more common.4-6
Perhaps the most controversial issues in research on endocrine disrupters
are the possible disproportionate effects of low levels of exposure, as
proposed by Vom Saal et al and recently accepted by the US national
toxicology program.
At least for a limited number of chemicals7-9; the question of synergism in
mixtures, which has become something of a no go area since the withdrawal of
the much quoted paper by Arnold et al10; and the development of appropriate
test methods.
Large amounts of resources have been invested in this last activity, through
the work of the endocrine disrupter screening and testing advisory committee
in the United States. Yet according to Ashby the developmental effects of
endocrine disruptors that are seen in rodent studies cannot be extrapolated
to humans.
This is not only because of the uncertainty of applying such results across
species but also because of the absence of an agreed control database in
rodents and the variability in test protocols and in the developmental
effects in test animals.11
Among specific chemicals </2001/mar/31/chemicals.htm> implicated as
endocrine disrupters phthalates may be of particular importance because of
their ubiquity.
Similarly bisphenol A </2001/may/19/canned_foods.htm> has been shown in both
in vitro and in vivo assays to have high potential for endocrine disruption
and potential for exposure to humans for example, through its use in can
linings.
These are issues of major interest, not least because of the possible
exposure of infants to these chemicals at critical stages of development.
Sharpe has argued that, until appropriate in vivo experiments are done,
phthalates and similar chemicals will continue to cause concern for
testicular development.12
British Medical Journal December 8, 2001;323:1317-1318
DR. MERCOLA'S COMMENT:
There is no question that one should avoid toxic chemicals like dioxin (a
toxic byproduct of chlorine) as it is a potent mimic of estrogen that can
cause very serious hormonal disruption.
The U.S. Environmental Protection Agency (EPA) has found dioxin to be
300,000 times more potent as a carcinogen than DDT. Dioxin is commonly found
in plastics that are made with polyvinyl chloride (PVC). This is one of the
reasons why you NEVER want to use a water bottle that is made from the
cloudy plastic bottles (commonly used to store milk). One should always use
the clear polyethylene bottles.
Bisphenol A, which is very common in canned foods is another potent
endocrine disruptor and is one of the reasons you want to keep canned foods
to an absolute minimum. You should NEVER regularly consume foods from cans.
Then we come to the issue of soy. Even the conservative US government has
recognized that soy formula is a potent endocrine disruptor
</2001/jul/11/pesticides.htm>. There is absolutely no reason to ever give
your child soy formula or soy milk. It is one of the worst foods you could
possibly give your child and the long-term health complications can be quite
significant.
Prostate and breast cancer, early puberty, endometriosis and infertility,
irregular and painful menstrual periods are only a few of the things your
children will have increased risk for if they are given soy formula or soy
milk.
If you have already given your child these foods the best way to reverse the
damage is to have them rigidly follow the eating plan </diet.htm>. The
nutrition from whole organic foods is the most potent corrective force for
these disruptions in hormones.
If you still aren't convinced of the dangers of soy you might want to review
the protest letter </2001/jun/30/soy_fda.htm> two FDA experts wrote earlier
this year which points to studies that show a link between soy and health
problems in certain animals.
Related Articles:
CDC Report States Exposure To Chemicals Higher Than Expected
</2001/mar/31/chemicals.htm>
Phthalate Plasticizers Dangerous, Especially to Children
</2000/dec/24/plasticizers.htm>
Nail Polish and Other Cosmetics May Cause Infertility
</2000/dec/31/cosmetics.htm>
Chemical Contamination Linked to Early Puberty
</2001/jan/21/chemicals_puberty.htm>
References
1. Colborn T, Clement C, eds. . Chemically-induced alterations in sexual
development: the wildlife/human connection. Princeton, NJ: Princeton
Scientific Publishing, 1992.
2. Harrison PTC, Holmes P, Humfrey CDN. Reproductive health in humans and
wildlife: are adverse trends associated with environmental chemical
exposure? Sci Total Environ 1997; 205: 97-106[Medline].
3. Sharpe RM, Skakkebæk NE. Are oestrogens involved in falling sperm counts
and disorders of the male reproductive tract? Lancet 1993; 341:
1392-1395[Medline].
4. European Commission. European workshop on the impact of endocrine
disrupters on human health and wildlife: report of the proceedings.
Brussels: European Commission, 1997. (EUR 17549)
5. Holmes P, Phillips B. Human health effects of phytoestrogens. In: Hester
RE, Harrison RM, eds. Issues in environmental science and technology. , Vol
12. Endocrine disrupting chemicals Cambridge, UK: Royal Society of
Chemistry, 1999:109-134.
6. Joffe M. Are problems with male reproductive health caused by endocrine
disruption? Occup Environ Med 2001; 58: 281-287[Full Text].
7. Vom Saal FS, Timms BG, Montano MM, Palanza P, Thayer KA, Nagel SC, et al.
Prostate enlargement in mice due to fetal exposure to low doses of estradiol
or diethylstilbestrol and opposite effects at high doses. Proc Natl Acad Sci
USA 1997; 94: 2056-2061[Abstract/Full Text].
8. Welshons WV, Nagel SC, Thayer KA, Judy BM, vom Saal FS. Low-dose
bioactivity of xenoestrogens in animals: fetal exposure to low doses of
methoxychlor and other xenoestrogens increases adult prostate size in mice.
Toxicol Ind Health 1999; 15: 12-25[Medline].
9. National Toxicology Program. Endocrine disruptors low-dose peer review.
http://ntp-server.niehs.nih.gov/htdocs/liason/LowDoseWebPage.html (accessed
24 May 2001).
10. McLachlan JA. Synergistic effect of environmental estrogens: report
withdrawn [retraction of Arnold SF, Klotz DM, Collins BM, Vonier PM,
Guillette LJ Jr, McLachlan JA. In: Science 1996;272:1489-92]. Science 1997;
277: 462-463[Medline].
11. Ashby J. Testing for endocrine disruption post-EDSTAC: extrapolation of
low dose rodent effects to humans. Toxicol Lett 2001; 120: 233-242[Medline].
12. Sharpe RM. Hormones and testis development and the possible adverse
effects of environmental chemicals. Toxicol Lett 2001; 120:
221-232[Medline].
13. Holmes P, Harrison PTC. Environmental and dietary endocrine disruptors
and women's health. J Brit Menopause Soc 2001; 7: 53-59.
Jasna
> Soy is an Endocrine Disrupter and Can Damage Your Child's Health
> *****************************************************
<.....>
> Endocrine disrupters are potentially present in food as natural
> "phytoestrogens" and chemical contaminants, and there is a divide in the
> perception of natural and synthetic substances.5
> Hence the drive in some quarters to market "healthy" bread that is rich in
> soy flour and linseed at the same time that other people are warning
against
> low levels of weak estrogenic synthetic chemicals as contaminants in food.
> Perhaps this reflects the common view of natural things as good and
> synthetic things as necessarily bad.
Ne cini ti se jako, jako neozbiljno (zuto-novinarski ;))) ) u cijelom
clanku soju i fitoestrogene tek spomenuti (o "argumentima" stetnog
djelovanja da i ne govorim), a staviti takav naslov ???
> None the less, there is agreement that the incidence of testicular and
> prostate cancer is increasing and that semen quality is probably worsening
> in some regions of the world.
.... tesko da su fitoestrogeni i soja uzrok .... Japanci i Kinezi jedu puno
vise soje od ostatka svijeta, a bas se ne primjecuju problemi s fertilitetom
;)))))
U svakom slucaju (AFAIK) nije da u iznimnim slucajevima fitoestrogeni
(uistinu pretjeranom konzumacijom, i to uglavnom u odredjenoj populaciji:
djeca, trudnice) nemaju stetno djelovanje, ali ne mogu se direktno
usporedjivati (sto je u clanku kojeg si ti poslao "zaboravljeno") sa
sintetičkim i industrijskim ksenoestrogenima (za koje se pretpostavlja da bi
mogli biti uzrok opazenog /u SADu i zapadnoj Europi/ smanjenja kvalitete
sjemena i porasta poremecaja reprodukcijskog sustava muskaraca).
Pozdrav.
Ako ce te vise zanimati procitaj:
http://ehpnet1.niehs.nih.gov/docs/1996/104-5/focus.html
Vesna Harni
"Martin Cotar @ Home" <martin...@pu.tel.hr> wrote in message
news:a24rns$6t46$1...@as201.hinet.hr...
> Soy is an Endocrine Disrupter and Can Damage Your Child's Health
> *****************************************************
> Endocrine disrupters are chemicals in the environment that are similarin
> structure to natural sex hormones and interfere with their normal
> functions, usually by binding to the cell receptors and preventing
> the hormone from binding to the receptor.
[...]
Navedeni clanak je revijalnog i senzacionalistickog karaktera, pri cemu se
nepravilno i u isti kos svrstavaju ksenoestrogeni i fitoestrogeni. Otuda je
i potencijalno stetan (clanak). Citirane reference odnose se prije svega na
ksenoestrogene, dok se ne navode znanstvene studije za izrecene tvrdnje,
osobito kako soja konzumirana u djetinjstvu moze izazvati endometriozu,
miom, rak dojke, rak prostate &stuff.
Ekspozicija zenskim spolnim hormonima estrogenima dovodi kod muskaraca
kako do pada kvalitete spermiograma, tako i do drugih bolesti muskog
reproduktivnog sustava (rak testisa, kriptorhizam i hipospadija). U zena je
u stanjima hiperestrogenemije ioli dugotrajnog neoponiranog djelovanja
estrogena poznat razvitak estrogenski ovisnih tumora (miom, endometrioza,
hiperplazija endometrija i poremecaji krvarenja, PMS, mastopatija i rak
dojke).
Izvori estrogena mogu biti endogeni i egzogeni.
Endogeni estrogeni u muskarca dolaze putem unosa odgovarajuce hrane
(porast tzv. enterohepaticke cirkulacije estrogena kod prehrane siromasne
biljnim vlaknima) ili kod povecane tjelesne mase (masno tkivo kao aktivni
endokrini organ koje je u stanju konvertirati druge steroide u estrogene), a
u zena se estrogeni pocinju prirodno ciklicki stvarati s pojavom prve
menstruacije.
Egzogeni estrogeni su sintetski estrogeni (npr. kontracepcijske tablete ili
aktivni anabolički steroidi) i ksenoestrogeni okolisa. Ksenoestrogeni
okolisa ukljucuju dioksine i furane, pesticide, PCBs i druge kemijske tvari
s hormonskim djelovanjem.
Osim eksperimentalnih saznanja iz animalnih pokusa, saznanja o djelovanju
dioksina i furana dolaze, nazalost, i iz preko 20 industrijskih katastrofa u
kojima je opisano ca. 1.000 slucajeva otrovanja dioksinima. Kada je u
pitanju akutna ekspozicija, za razlikovati su 'nespecificni' simptomi u koje
ubrajamo nadrazaj sluznice oka, nosa i zdrijela, vrtoglavicu, mucninu i
povracanje, od 'specificnih' simptoma - 'klorne akne' koje nastaju unutar 2
i vise tjedna od ekspozicije.
Daleko znacajnije posljedice za zdravlje ostavlja kronicna ekspozicija
dioksinima. Ovdje su svakako najznacajniji:
- kancerogeno djelovanje dioksina: pri cemu je pretpostavljeno djelovanje u
smislu 'tumorskog promotora'. Tumorski promotori nisu toksicni za genom,
ne izazivaju mutacije DNA, ali su u stanju snazno utjecati na pojacani
rast
spontano nastalih tumora. Kod industrijskih radnika izlozenih djelovanju
dioksina osobito cesto se registriraju tumori (sarkomi) mekih tkiva,
limfomi, kao i karcinomi zeluca.
- djelovanje na reproduktivne funkcije i teratogenitet, kao i
- djelovanje na imunoloski sustav.
Upravo su dioksini tvari koje se u novije vrijeme okrivljuju za nastanak
endometrioze.
[Mayani A. et al: 'Dioxin concentration in women with endometriosis';
Human Reproduction 1997; Vol 12: 373-375
Rier SE et al: 'Serum levels of TCCDD and dioxin-like chemicals in
Rhesus monkeys chronically exposed to dioxin: corelation of increased
serum PCB levels with endometriosis'; Toxicol Sci 2001 Jan; 59(1):147-59
http://ehpnet1.niehs.nih.gov/docs/1995/Suppl-7/rier.html
http://rachel.enviroweb.org/rhwn364.htm ]
Pesticidi su poznati kao kemikalije s priznatim hormonskim djelovanjem, koje
je slicno djelovanju zenskog spolnog hormona estrogena. Razgradni produkt
DDT - DDE, osim estrogenskog djelovanja posjeduje i antiandrogensko
djelovanje - djelovanje suprotno muskom spolnom hormonu testosteronu. Visoke
koncentracije DDT i DDE u eksperimentima na zivotinjama dovode do
feminizacije muskih zivotinja, smetnji u razvitku seksualnih organa i
odlika, kao i smetnji u plodnosti mnogobrojnih zivotinjskih vrsta kao sto su
to razlicite vrste ptica i aligatora u prirodi, odnosno eksperimentalno kod
pacova.
[Bell EM et al; A case-control study of pesticides and fetal death due to
congenital anomalies
Epidemiology 2001; 12(2):148-56 ISSN: 1044-3983
Daniels JL et al; Residential pesticide exposure and neuroblastoma
Epidemiology 2001; 12(1):20-7 ISSN:1044-3983
Loffredo C, Silbergeld EK, Ferencz C, Zhang J. Association of Transposition
of the Great Arteries in Infants with Maternal Exposure to Herbicides and
Rodenticides.
Am J Epidemiol 2001 November, Vol 153 (6): 529-536
http://www.aje.oupjournals.org/cgi/content/abstract/153/6/529
http://www.acoem.org/pubs/joem/1000abs.htm
http://www.hc-sc.gc.ca/hpb/lcdc/publicat/farmfam/vol7-2/ff7-2h_e.html ]
Poliklorirani bifenili (PCB) imaju slicno djelovanje na zdravlje ljudi i
zivotinja kao i dioksini. Najpoznatija ekoloska katastrofa, u kojoj je
stradalo oko 2.000 ljudi je katastrofa koja se odigrala u japanskom gradu
Yusho ('Yusho sindrom'). Osim teskih akutnih posljedica s kloraknama,
ostecenjima organa, osobito sredisnjeg zivcanog sustava, opisane su i
promjene kod novorodjencadi i male djece koja su u kontaktu s PCBs
pokazivala zastoj u rastu, kao i razvitku, kako tjelesnom, tako i dusevnom i
seksualnom. Osim izravnog ostecenja sredisnjeg zivcanog sustava
pretpostavljaju se i ostecenja na razini hormonske regulacije razvitka
djece.
PCBs posjeduju hormonsko djelovanje slicno estrogenima, te utjecu na
razvitak i funkciju kako seksualnog sustava, tako i plodnosti. Osobito
negativno djelovanje PCBs uoceno je u djecaka majki izlozenih visokim
koncentracijama PCBs. Smatra se takodjer da veliku ulogu u problemu
smanjenja broja i motiliteta spermija u muskaraca igra upravo PCBs. U
mnogobrojnih parova koji se lijece od neplodnosti pored DDT i PCP u sjemenoj
tekucini, odnosno u folikularnoj tekucini kod zena izolirani su i PCBs.
Od ostalih kemijskih tvari s hormonskim (estrogenskim) djelovanjem za
spomenuti su UV zastitni filteri (kreme za suncanje) i bisphenol A.
U ispitivanjima UV zastitnih filtera zapanjajuća konstatacija je bila kako
vecina ispitivanih filtera (svih 5 'UV B' zaątitnih filtera) posjeduje
estrogensko djelovanje, te uzrokuje brzi rast tumorskih stanica, a pojedni
od njih i smetnje u razvitku. Jedan od najcesce koristenih zastitnih filtera
'4-MBC: methylbenzyliden camphor' pokazuje osobito snazne efekte. U
ekperimentima s laboratorijskim misevima, nanosenje mjesavine 4-MBC i
maslinovog ulja kozu laboratorijskih miseva izaziva dva puta brzi rast
maternice zenskih miseva. Iznenadjenje je bilo tim vece, jer je
upotrijebljena ista koncentracija 4-MBC koja je dozvoljena u zastitnim
kremama za suncanje!
Bisphenol A se primjenjuje u izradi konzervi i djecijih bocica (unutrasnji
zastitni sloj), umjetnih materijala, raznog stomatoloskog materijala, te za
recikliranje papira. Putem otpadnih voda BPA dospijeva u okolis. Podaci
njemackog ministarstva za zastitu okolisa su egzaktni: godisnje se preko
otpadnih voda oslobodi 410.000 tona BPA u okolis. Iako kemijska industrija
odbacuje optuzbe, kao i moguca estrogenska djelovanja BPA: povecanje
prostate, pad koncentracije spermatozoida i prerani pubertet, intenzivno se
traga za novim tvarima koje bi nadomjestile BPA, a njemacki
'Umweltbundesamt' uputio je zahtjev za povlacenje BPA iz uporabe, prije
svega iz sastava djecijih bočica i konzervi.
[ http://www.newscientist.com/dailynews/news.jsp?id=ns9999641
Markey CM; Michaelson CL et al; The Mouse Uterotrophic Assay: A Reevaluation
of its Validity in Assesing the Estrogenicity of Bisphenol A.
Environ Health Perspect 2001 Jan;109(1):55-60 ISSN: 0091-6765
Sun Y; Wada M; Al-Dirbachi O et al; High performance liquid chromatography
with peroxyoxalate chemiluminescence detection of bisphenol A migrated from
polycarbonate baby bottles using 4-(4,5-diphenyl-1H-limidazol-2-yl)benzoyl
chloride as a label.
J Chomatogr B Biomed Sci Appl 2000 Nov;749(1):49-56 ISSN: 1387-2273
http://www.yavivo.de/News/0_Archive/20001120/20001120_3.html ]
... slijedi Part II: Phytoestrogens
--
__
Vesna Harni
Fitoestrogeni su nesteroidalne tvari biljnog podrijetla, koje u različitoj
mjeri, a sveukupno vrlo slabo kompetitivno konkuriraju ľenskom spolnom
hormonu estradiolu na njegovim receptorskim mjestima. Za razliku od
ksenoestrogena, fitoestrogeni ispoljavaju osim svojstava slabog vezivanja na
estrogenski receptor i slabog estrogenskog efekta, i _antiestrogenski_
učinak slično tamoksifenu, kao i antagonistička djelovanja na viruse,
bakterije, gljivice i kancerogene.
Najpoznatiji fitoestrogeni su izoflavoni i lignani. Za razliku od
ksenoestrogena koji su bez razlike industrijski nusprodukti, fitoestrogeni
se nalaze prirodno u viąe od 100 različitih biljaka, osobito u mahunarkama,
a među kojima prednjače soja i sojini produkti, leća, zrnevlje ľitarica, i
određene vrste graąka i graha. U biljnom svijetu se fitoestrogeni nalaze u
vezanom obliku, i tek djelovanjem enzima glukozidaze iz crijevne flore
postaju aktivni.
Eksperimentalni podaci ukazuju da izoflavoni i lignani mogu modificirati
aktivnost mnogobrojnih enzimskih sustava, koji imaju centralno mjesto u
metabolizmu estrogena. Stimuliraju stvaranje SHBG ('Sexual Hormon Binding
Globulin') koji je plazmatski 'nosač' estrogena i na taj način smanjuju
razinu i djelovanje slobodnog estrogena u krvi. U eksperimentima in vitro
inhibiraju angiogenezu, kao i proliferaciju i diferencijaciju određenih
staničnih linija raka modificirajući djelovanje faktora rasta. Inhibiraju
enzime tirozinkinazu, topoizomerazu i histidinkinazu, koji igraju značajnu
ulogu u proliferaciji i transformaciji stanica raka dojke.
['Medline' - www.medsite.com
Boersma BJ; Barnes S et al; Soy isoflavonoids and cancer - metabolism at the
target site. Mutat Res 2001 Sep 1;480-481(1-2):121-7
Lu LJ et al; Effects of an isoflavone-free soy diet on ovarian hormones in
premenopausal women. J Clin Endocrinol Metab 2001 Jul;86(7):3045-52
Dai Q; Shu XO et al; Population-based case-control study of soyfood intake
and breast cancer risk in Shanghai. Br J Cancer 2001 Aug;85(3):372-8
Shu XO et al: Soyfood intake during adolescence and subsequent risk of
breast cancer among Chinese women. Cancer Epidemiol Biomarkers Prev 2001
May;10(5):483-8
Jin-Rong Z et al; Soybean Phytochemicalis Inhibit the Growth of
Transplantable Human Prostate Carcinoma and Tumor Angiogenesis in Mice. J
Nutrition 1999; 129: 1628-1635 ]
Eksperimenti in vivo potvrđuju da izoflavonoidi inhibiraju kancerogenezu
provociranu kemikalijama ili radijacijom, kao ąto signifikantno smanjuju i
broj estrogenskih receptora u tumorskom tkivu raka dojke.
[Hakkak R; Korourian S; Soy protein isolate consumption protects against
azoxymethane-induced colon tumors in male rats.
Cancer Lett 2001 May 10;166(1):27-32
Kamei H; Koide T et al; Tumor cell growth-inhibiting effect of melanoidins
extracted from miso and soy sauce. Cancer Biother Radiopharm 1997
Dec;12(6):405-9
Davis JN; Kucuk O et al; Soy isoflavone supplementation in healthy men
prevents NF-kappaB activation by TNF-alpha in blood lymphocytes. Free Radic
Biol Med 2001 Jun 1;30(11):1293-302
Pietinen P. et al; Serum enterolactone and risk of breast cancer: a
case-control study in eastern Finland. Cancer Epidemiol Biomarkers Prev
2001 Apr;10(4):339-44 ]
Dobro je znan i kardioprotektivni efekat fitoestrogena, baziran na padu
razine serumskih triglicerida, ukupnog kolesterola i LDL kod dnevnog unosa
> 47 g sojinih proteina (metaanaliza 38 kontrolirane studije). Istodobno je
nađen porast HDL frakcije kao i dilatacija aterosklerotično promijenjenih
koronarnih arterija.
[Alexandersen P; Haarbo J; Dietary phytoestrogens and estrogen inhibit
experimental atherosclerosis. Climacteric 2001 Jun;4(2):151-9
Kim H; Xu J et al; Actions of the soy phytoestrogen genistein in models of
human chronic disease: potential involvement of transforming growth factor
beta. Biochem Soc Trans 2001 May;29(Pt 2):216-22 ]
Obzirom da sam potroąila ovoliko prostora, a tek sam stigla do uloge
fitoestrogena i njihovog potencijalnog ątetnog djelovanja u djetinjstvu,
ovaj dio onda ostavljam za Part III: Infants and Phytoestrogens ;)
--
__
Vesna Harni
Problem stetnog djelovanja fitoestrogena u dojencadi prvi puta je postao
aktualan tijekom kasnih 90. ih godina, nakon clanaka objavljenih u
Lancet-u i Am J of Clinical Nutrition.
[Setchel KDR; Zimmer-Nechemisa L et al. Exposure of infants to
phyto-oestrogens from soy-based infant formula. Lancet 1997; Vol 350, Number
9070.
Setchel KD; Zimmer-Nechemias L et al. Isoflavone content of infant formulas
and the metabolic fate of these phytoestrogens in early life. Am J Clin
Nutrition 1998; Vol 68: 1453-1461]
Ovdje se prvi puta iznose rezultati mjerenja koncentracije izoflavona u
serumu dojencadi hranjene adaptiranim sojinim mlijekom. Prosjecna
koncentracija genisteina u plazmi iznosila je 684 ng/ml i daidzeina 295
ng/ml, sto je u poredjenju s dojencadi na humanom mlijeku (2.8 ng/ml
genistein i 1.4 ng/ml daidzein) ili adaptiranom kravljem mlijeku (3.2 ng/ml
genistein i s.2 ng/nl daidzein) statisticki znacajno visi rezultat.
Prosjecna koncentracija totalnih izoflavona u odnosu na tjelesnu masu
dojencadi iznosila je 4.5 - 8.0 ng/kg tjelesne mase. Istrazivaci zakljucuju
da je u odnosu na tjelesnu masu, dnevna ekspozicija fitoestrogenima kod
dojencadi hranjenje adaptiranim sojinim mlijekom 6 - 11 puta veca od
ekspozicije odraslih, a cirkulacija totalnih izoflavona je u slucaju
adaptiranog sojinog mlijeka 13.000 - 22.000 puta veca od koncentracije
estradiola u plazmi u ranom zivotu.
Uskoro slijedi eksperimentalni radovi na misevima, gdje se ispituje
kancerogeni
efekat genisteina.
[Newbold RR; Banks EP et al. Uterine adenocarcinoma in mice treated
neonatally with genistein. Cancer Res 2001; 61 (11):4325-4328]
U ovom radu su zenski misevi tretirani visokim dozama genisteina (50
mg/kg/dan) i poznatog kancerogena dietilstilbestrola (0.001 mg/kg/dan)
tijekom prvih 5 dana zivota. 18 mjeseci kasnije, ucestalost adenokarcinoma
maternice iznosila je 35% u grupi miseva tretiranih s fitoestrogenom i 31% u
grupi s dietilstilbestrolom.
Usporedo s ovim radovima nastajala su daljnja istrazivanja i objasnjenja
efekata fitoestrogena u ovom osjetljivom razdoblju zivotu.
Osnovna zamjerka navedenim istrazivanjima je mjerenje ukupne koncentracije
fitoestrogena u plazmi, dakle koncentracije i nakon hidroliziranja ili
konjugiranja fitoestrogena, a ne koncentracije slobodnih fitoestrogena koja
je zapravo odgovorna za aktivaciju estrogenskog receptora. U ovom radu je
upravo prikazano kako su dojencad u stanju intenzivno metabolizirati
izoflavonoide iz soje u glukuronide i sulfatne konjugate, koji ne posjeduju
biolosku aktivnost. Iako je u skupini dojencadi ispitivane u ovom radu
nadjena gotovo ista koncentracija totalnog genisteina i daidzeina u plazmi,
razina slobodnih izoflavona u plazmi iznosila je 0. Slican rad potjece s
Novog Zelanda, gdje je kod dojencadi potvrdjena sposobnost digestije,
apsorpcije i ekskrecije genisteina i daidzeina.
[Huggett, Pridmore S et all. Phyto-oestrogens in soy-based infant formula.
Lancet 1997; Vol 350; Number 9080
Irvine CH; Shand N et al. Daily intake and urinary excretion of genistein
and daidzein by infants fed soy- or diary-based infant formulas. Am J Clin
Nutririon 1998; Vol 68: 1462-1465.]
Ipak najznacajniji rad na ovu temu objavljen je koncem prosle godine u
uglednom casopisu JAMA. Americki znanstvenici su pratili klinicke:
endokrinoloske i reproduktivne parametre u djece hranjene adaptiranim
sojinim mlijekom (248 djece) i djece hranjene adaptiranim kravljim mlijekom
(563 djece) tijekom dojenacke dobe i to u razdoblju izmedju 1965 - 1978.
godine. Pretragama ispitanika tijekom 1999. godine, u njihovoj dobi od
24 - 30 godina, registrirani su prijevremeno nastupanje puberteta, povijest
menstrualnog ciklusa i reproduktivna povijest, visina i uobicajena tezina,
opce zdravstveno stanje. Rezultati studije ukazuju ne nepostojanje
statisticki znacajnih razlika obzirom na navedene parametre, a zakljucak
studije nedvojbeno ukazuje na nepostojanje klinickih razlika u opcem
zdravlju i reproduktivnim funkcijama odraslih ljudi koji su u ranoj zivotnoj
dobi konzumirali adaptirano sojino mlijeko.
[Atrom BL; Schinnar R. et al. Exposure to soy-based formula in infancy and
endocrinological and reproductive outcomes in young adulthood. JAMA 2001;
286 (7):807-814.]
U cilju definicije i boljeg razumijevanja utjecaja potencijalnih modulatora
endokrine funkcije, u novije vrijeme definira se pojam HBMOS (Hygiene-based
margin of safety) za ksenoestrogene i fitoestrogene. U tu svrhu u BRD je
osnovana SKLM (The Senate Commission on the Evaluation of Food Safety), cija
su preporuke za sigurnu dozu dnevnog unosa fitoestrogena reda veličine 1
mg/kg TT.
Najbolji uvid u odnos izmedju fitoestrogena i ksenoestrogena daje izravna
usporedba djelovanja ovih tvari na uterus (oznaceno kao estrogensko
djelovanje), a koja potjece iz eksperimentalnih studija. Ukoliko se
estrogenska aktivnost daidzeina oznaci s 1, tada ovi odnosi izgledaju ovako:
Daidzein 1
octylphenol 2
DDT 4
nonyphenol 250-500
bisphenol A 1000
etinil-estradiol
(kontracepcijske tablete) 40 000
[Bolt HM; Janning P et al. Comparative assessment of endocrine modulators
with oestrogenic activity: I. Definition of a hygiene-based margin of safety
(HBMOS) for xeno-oestrogens against the background of European developments.
Arch Toxicol 2001; 74 (11):649-662]
I konacno, teoretski potencijalno stetno estrogensko djelovanje
fitoestrogena u djece nije niti jednim eksperimentalnim niti klinickim
znanstvenim radom dokazano. Adaptirano sojino mlijeko moze se primjenjivati
u dojenackoj dobi bez ikakovih nezeljenih posljedica, stav je dvije
najznacajnije udruge: 'The American Dietetic Association' i 'The American
Academy of Pediatrics'. U prvih 4 -6 mjeseci zivota dobra alternativa
adaptiranom kravljem ili majcinom mlijeku je adaptirano sojino mlijeko. Tofu
ili drugi izvori sojinih proteina mogu se poceti davati djeci u uzrastu od
7-8 mjeseci. Komercijalno sojino mlijeko se ne preporuca davati djeci ispod
1 godine zivota.
Mlijeko dojilja koje se hrane vegetarijanski moze sadrzavati manjak vitamina
B12, a u kasnijoj dobi i relativni manjak cinka, zeljeza ili vitamina D sto
se preporuca dodati prehrani, kako dojilje tako i dojenceta.
[Mangels AR; Messina V. Considerations in planning vegan diets: infants. J
Am Diet Assoc 2001; 101(6):670-677]
Za kraj, samo za Martina:
sta ti bi da postas ovakav bombaski tekst? ;)
--
__
Martin Cotar @ Home
> sta ti bi da postas ovakav bombaski tekst? ;)
Sad to mogu reci i ja... :)))
Daj, dozvoli mi kojih tjedan-dva da procitam sve ovo i malo porazmislim pa
se (mozda) javim svojim kopljima protiv tvoje teske artiljerije... B-))
--
---
martin
**
Do or do not. There is no try!
Stjepan Mikuliæ
> > Za kraj, samo za Martina:
> > sta ti bi da postas ovakav bombaski tekst? ;)
>
> Sad to mogu reci i ja... :)))
>
> Daj, dozvoli mi kojih tjedan-dva da procitam sve ovo i malo porazmislim pa
> se (mozda) javim svojim kopljima protiv tvoje teske artiljerije... B-))
>
Nemoj!!!! Zensko je zensko, uvjek te moze poklopiti kolicinom teksta.
:-))))))
--
------------------------------------------------------------
To beer or not to beer, SHAKESBEER
stjepan...@zg.tel.hr
Vesna Harni
> > sta ti bi da postas ovakav bombaski tekst? ;)
>
> Sad to mogu reci i ja... :)))
>
> Daj, dozvoli mi kojih tjedan-dva da procitam sve ovo i malo porazmislim
> pa se (mozda) javim svojim kopljima protiv tvoje teske artiljerije... B-))
>
nemoj previse ostriti koplja, uplasices me ;-)
--
__
Vesna Harni
"Stjepan Mikuliæ" <stjepan...@zg.tel.hr> wrote in message
news:a339fr$eltd$3...@as201.hinet.hr...
> "Martin Cotar @ Home" <martin...@pu.tel.hr> wrote in message
> news:a334pp$f9jk$1...@as201.hinet.hr...
> > > Za kraj, samo za Martina:
> > > sta ti bi da postas ovakav bombaski tekst? ;)
> >
> > Sad to mogu reci i ja... :)))
> >
> > Daj, dozvoli mi kojih tjedan-dva da procitam sve ovo i malo porazmislim
> > pa se (mozda) javim svojim kopljima protiv tvoje teske artiljerije...
> > B-))
> >
>
> Nemoj!!!! Zensko je zensko, uvjek te moze poklopiti kolicinom teksta.
> :-))))))
>
he he he :))
... na vrijeme ste se zaustavili ;-)
--
__
Daemon Weird
ako ne pretjeraą sa soyom, isto ko i bez nje
soja je samo vrsta graha, a ova sranja koja rulja radi od nje
to je za vola ubit, a kamo li čovjeka
--
L.L.E.
:-) your life
http://www.inet.hr/skysleeper
http://www.spirit-ri.hr