>Penny Lane <[log in to unmask]> posted:
>
>Dear Kathy,
>
>You reminded me of a point, concerning baby boys and their mother's
>hormones, that I was informed of recently and would like to investigate
>further.  A professor mentioned that young adult males, with mothers
>suffering from hyperemesis through their pregnancy, were at increased risk
>of testicular cancer because of her excessively increased estrogen level
>through their fetal growth.
>
>I would be interested in hearing your comments and reading any additional
>information that any of you may have on this issue, particularly
>concerning soy and estrogen for breastfed children.
>
>God Bless,
>Penny Lane RN, IBCLC

This topic doesn't appear to have been much-studied, but I did find a few
articles in my files; hence, it has captured the attention of at least some
researchers! A PubMed search using the terms "isoflavone, breast, milk"
turns up a page worth of studies, a few of which I have in my files.
Probably the most informative one I've got is by Setchell et al.: Setchell,
KDR, et al. Isoflavone content of infant formulas and the metabolic fate of
these phytoestrogens in early life. American Journal of Clinical Nutrition
1998; 68(suppl):1453S-61S.

Although the article focuses on soy formula, data on the phytoestrogen
content of breastmilk are included for comparison. The study shows that
phytoestrogens are found in breastmilk and indicates that they are
glucuronide conjugates versus the glycosidic conjugates of soy milk or soy
formula (i.e., metabolized versus unmetabolized). However, it's unknown how
that might affect bioavailability. The data also show that the amount of
isoflavones (e.g., the phytoestrogens genistein and daidzein) found in the
milk of a soy-consuming mom is trivial compared to what babies fed soy
formula receive (0.005-0.01 mg isoflavones per day versus 22-45 mg
isoflavones per day).

Concerning phytoestrogens in breastmilk, Setchell et al. conclude:

" ... the available data provide little reason to be concerned about
maternal-infant transfer of phytoestrogens from human breast milk, even in
women consuming phytoestrogen-rich diets while breast-feeding; on the basis
of the weak estrogenic activity of isoflavones, it is doubtful that the
dietary intake from human milk is sufficient to exert biological effects."

The potential effects of phytoestrogens on infants is a pretty
controversial topic. Dr. Setchell is considered a leading expert in the
field of phytoestrogen research and based on his research and interviews
with him, my impression is that he isn't alarmed by the measured levels of
phytoestrogens taken in by infants. However, other researchers, notably
Clifford Irvine in New Zealand (sorry, I don't have his current
affiliation) and Retha Newbold of the National Institute of Environmental
Health Sciences (NIEHS), are alarmed, at least when it comes to soy formula
and soy foods.

A relevant study is Irvine, CHG, et al. Daily intake and urinary excretion
of genistein and daidzein by infants fed soy- or dairy-based infant
formulas. American Journal of Clinical Nutrition 1998; 68(suppl):1462S-5S.
This study included 11 breast-feeding moms, five of whom consumed soy; only
two on the level of the women in Setchell's study. Irvine and his
co-researchers did not detect any isoflavones in the mothers' breastmilk,
but they cite other studies that do. Based on those studies, he estimated
that breastfed babies would consume only about 1/1000 the isoflavones
ingested by soy formula-fed babies.

But, as I said earlier, it's not a particularly well-researched topic. I'll
see if I can dig up anything else later. Right now, my 10-week old is
starting to get impatient. Supper time! :-)

regards,
Julia

Julia R. Barrett
Freelance Science Writer
Madison, Wisconsin
608-238-8409; [log in to unmask]

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