This is a resend with the correct subject (sorry)
Maximum Relevance:Isoflavone content of infant formulas and the metabolic
fate of these phytoestrogens in early life.
Am J Clin Nutr 1998 Dec;68(6 Suppl):1453S-1461S   (ISSN: 0002-9165)
Setchell KD; Zimmer-Nechemias L; Cai J; Heubi JE [Find other articles with
these Authors]
Clinical Mass Spectrometry Center, Children's Hospital Medical Center,
Cincinnati, OH 45229, USA. [log in to unmask]
***Isoflavones circulate at concentrations that are 13,000-22,000-fold
higher than plasma estradiol concentrations in early life. Exposure to these
phytoestrogens early in life may have long-term health benefits for
hormone-dependent diseases. ***

Soy-based infant formulas have been in use for >30 y. These formulas are
manufactured from soy protein isolates and contain significant amounts of
phytoestrogens of the isoflavone class. As determined by HPLC, the
isoflavone compositions of commercially available formulas are similar
qualitatively and quantitatively and are consistent with the isoflavone
composition of soy protein isolates. Genistein, found predominantly in the
form of glycosidic conjugates, accounts for >65% of the isoflavones in
soy-based formulas. Total isoflavone concentrations of soy-based formulas
prepared for infant feeding range from 32 to 47 mg/L, whereas isoflavone
concentrations in human breast milk are only 5.6 +/- 4.4 microg/L (mean +/-
SD, n = 9). Infants fed soy-based formulas are therefore exposed to 22-45 mg
isoflavones/d (6-11 mg x kg body wt(-1) x d(-1)), whereas the intake of
these phytoestrogens from human milk is negligible (<0.01 mg/d). The
metabolic fate of isoflavones from soy-based infant formula is described.
Plasma isoflavone concentrations reported previously for 4-mo-old infants
fed soy-based formula were 654-1775 microg/L (mean: 979.7 microg/L: Lancet
1997:350; 23-7), significantly higher than plasma concentrations of infants
fed either cow-milk formula (mean +/- SD: 9.4 +/- 1.2 microg/L) or human
breast milk (4.7 +/- 1.3 microg/L). The high steady state plasma
concentration of isoflavones in infants fed soy-based formula is explained
by reduced intestinal biotransformation, as evidenced by low or undetectable
concentrations of equol and other metabolites, and is maintained by constant
daily exposure from frequent feeding.

***Isoflavones circulate at concentrations that are 13,000-22,000-fold
higher than plasma estradiol concentrations in early life. Exposure to these
phytoestrogens early in life may have long-term health benefits for
hormone-dependent diseases. ***
   
--Chris Hafner-Eaton, PhD, MPH, CHES, IBCLC    [log in to unmask]
€€€INFANT CUISINE AND MOTHER CARE: LACTATION CONSULTING & PERINATAL CARE€€€

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