Here is another article, this one published in LANCET (the other was in the
AM J. Cl Nutrition)

 Maximum Relevance:Exposure of infants to phyto-oestrogens from soy-based
infant formula [see comments]
Lancet 1997 Jul 5;350(9070):23-7   (ISSN: 0140-6736)
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, Ohio 45229, USA.
BACKGROUND: The isoflavones genistein, daidzein, and their glycosides, found
in high concentrations in soybeans and soy-protein foods, may have
beneficial effects in the prevention or treatment of many hormone-dependent
diseases. Because these bioactive phyto-oestrogens possess a wide range of
hormonal and non-hormonal activities, it has been suggested that adverse
effects may occur in infants fed soy-based formulas. METHODS: To evaluate
the extent of infant exposure to phyto-oestrogens from soy formula, the
isoflavone composition of 25 randomly selected samples from five major
brands of commercially available soy-based infant formulas were analysed,
and the plasma concentrations of genistein and daidzein, and the
intestinally derived metabolite, equol, were compared in 4-month-old infants
fed exclusively soy-based infant formula (n = 7), cow-milk formula (n = 7),
or human breast-milk (n = 7). FINDINGS: All of the soy formulas contained
mainly glycosides of genistein and daidzein, and the total isoflavone
content was similar among the five formulas analysed and was related to the
proportion of soy isolate used in their manufacture. From the concentrations
of isoflavones in these formulas (means 32-47 micrograms/mL), the typical
daily volume of milk consumed, and average bodyweight, a 4-month-old infant
fed soy formula would be exposed to 28-47 per day, or about 4.5-8.0 mg/kg
bodyweight per day, of total isoflavones. Mean (SD) plasma concentrations of
genistein and daidzein in the seven infants fed soy-based formulas were 684
(443) ng/mL and 295 (60) ng/mL, respectively, which was significantly
greater (p < 0.05) than in the infants fed either cow-milk formulas (3.2
[0.7] and 2.1 [0.3] ng/mL), or human breast-milk (2.8 [0.7] and 1.4 [0.1]
ng/mL), and an order of magnitude higher per bodyweight than typical plasma
concentrations of adults consuming soy foods. INTERPRETATION: The daily
exposure of infants to isoflavones in soy infant-formulas is 6-11 fold
higher on a bodyweight basis than the dose that has hormonal effects in
adults consuming soy foods. Circulating concentrations of isoflavones in the
seven infants fed soy-based formula were 13000-22000 times higher than
plasma oestradiol concentrations in early life, and may be sufficient to
exert biological effects, whereas the contribution of isoflavones from
breast-milk and cow-milk is negligible.
Comment in: Lancet 1997 Sep 13; 350(9080):815-6
 
   
--Chris Hafner-Eaton, PhD, MPH, CHES, IBCLC    [log in to unmask]
€€€INFANT CUISINE AND MOTHER CARE: LACTATION CONSULTING & PERINATAL CARE€€€
 

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