Soy has high amounts of phyto-estrogens, or plant based chemicals that mimic estrogen. They possess a wide range of hormonal and non-hormonal activities. The daily exposure of infants who consume soy formulas was 6-11 times higher than adults consuming soy foods.
The blood concentration of these hormones was 13,000 to 22,000 times higher than estrogen in the blood. The authors of this article speculate that this concentration may be sufficient to exert biological effects, whereas the contribution from breast-milk or cow-milk is negligible.
INSIGHT: As mentioned in issue #11, soy has many problems and it is not really designed to be consumed as a food unless it is fermented as in tempeh or misso. If you know someone who is using soy formula you might want to share this information with them and encourage them to consider other options.
Obviously, breast milk is best. I have found that even though it is from cow's milk, Carnation Good Start (under six months) seems to work well for most children as it is 80% hydrolyzed. This means that most of the protein is broken down and predigested to cause less of an allergic reaction.
Lancet July 5, 1997 350(9070) 23-27