Some weeks back there was a question about soy formula and studies of its
effect in baby boys. At the time I remembered reading something about this,
but couldn't locate it. I have just been going through my pile of 'to be
filed' papers on my desk and have found a photocopy of the article I
mentioned. It was a copy of an article from a Dec 95 Health Research
Council of NZ's publication, and reprinted in 'Issues', the NZLCA journal,
April 96.

It talked about the Health Research Council of New Zealand providing
funding to researchers in Christchurch to study absorption and excretion of
soy oestrogens in baby boys. They were to study 40 babies on soy milk and
20 on dairy milk from Auckland and Christchurch, and were going to measure
oestrogen compounds and testosterone (and other hormones) in babies' urine
samples.

Some of the background info in the article I found interesting:
"Soy oestrogens bind to mammalian oestrogen receptors, altering steroid
metabolism and other cellular processes. In male babies fed on breast or
dairy milk, the testosterone rises to adult levels between 20 days and 2
months after birth, before falling again. Stopping this rise in monkeys
leads to permanent changes in the regulation of regulating hormone
secretion, sexual behaviour and growth. These changes do not become obvious
until puberty.
"Ewes grazing on particular clover pastures become infertile, and soy
oestrogens are held responsible for infertility and liver disease in
captive cheetahs. A few small stuidies seem to indicate that consuming
certain amounts of soy oestrogens for more than a month causes changes in
vaginal cell growth, and may disturb menstrual cycles and hormone levels in
adult women.
"Soy is known to have some positive effects. (goes on to refer to adults
and other animals)
"Isoflavones, one of the plant oestrogens in soymilk, need to be broken
down by micro-organisms in the gut to have any effect. Babies develop these
micro-organisms in their first week of life, but no researchers have
investigated whether babies younger than four months can absorb
phytoestrogens. If soy oestrogens cannot be absorbed by infants up to two
months old, there is no chance that soymilk will affect their reproductive
development at this sensitive time."

The footnote to the article gives contact information for the researchers
for anyone interested:
Prof Cliff Irvine, Animal and Vetinary Sciences Group, Lincoln University,
PO Box 84, Christchurch, NZ. E-mail: <[log in to unmask]>

This looks like just one concern regarding the effects of phyoestrogens in
humans generally, but is an interesting start. There is also reference in
'Issues' to another study in Dunedin about the effects of phytoestrogens in
soy infant formula on neonatal breastbuds, that is also being funded by the
Health Research Council. I hope we can hear more about the results of these
sorts of studies.

Joy Anderson IBCLC, NMAA Breastfeeding Counsellor
Perth, Western Australia
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