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Soy Baby Formula and Phytoestrogens

Expert Q&A


Updated February 09, 2005

Q. I have been reading on the internet all the "so-called" negative long term effects of giving your child soy-based formula. How true are the allegations about the amount of estrogen in these products? Have there been studies done on fertility of children having consumed these formulas?

I am very upset because I have 3 boys who have had to take soy as infants on the advice of my pediatrician and a daughter 2 mos old currently who is having feeding problems while breastfeeding presumably secondary to dairy in my diet and is on soy presently. Please let me know where the AAP stands on their opinion of formulas. Janet, Cedar Grove, WI

A. The American Academy of Pediatrics, in their policy statement on Soy Protein-based Formulas: Recommendations for Use in Infant Feeding, states that 'in term infants whose nutritional needs are not being met from maternal breast milk or cow milk-based formulas, isolated soy protein-based formulas are safe and effective alternatives to provide appropriate nutrition for normal growth and development.'

The issue you are talking about concerns the effects of phytoestrogens or isoflavones, which are present in soy baby formulas. Unfortunately, there is very little research that describe the risks or benefits to babies drinking soy formula, even though soy based baby formula has been in use for over 40 years.

The AAP also states that there is also some concern that babies 'absorb calcium and some other minerals less efficiently from soy formulas than from milk-based formulas.' Soy formulas have more calcium than milk based formula to help offset this though.

Because of these concerns, soy based baby formula should only be used when indicated, including:

  • babies who have galactosemia or hereditary lactase deficiency
  • parents who wish to raise their term baby as a vegetarian
  • infants with true lactose intolerance (a lactose free formula might be a better alternative in this case though)
  • infants who have an IgE mediated allergy to cow milk proteins (although these babies may need a hypoallergenic formula if they are also allergic to soy formula)
So basically, as the AAP states, 'healthy full-term infants should be given soy formula only when medically necessary,' but soy formula is still 'safe and effective' when needed.

Soy formula should not be used simply because a baby has a stomach virus or colic. It should also not be used to try and prevent food allergies, in which case a hypoallergenic formula would be a better choice, or for preterm infants who weigh less than 1800 grams. However, when it is needed, the benefits of using soy formula likely outweigh any potential risks.

If you are still concerned, you might consult a lactation consultant to see if there is another cause for your baby's feeding problems. A lactation consultant might also be able to help you get to where you can exclusively breastfeed your daughter, so that you don't have to supplement at all.

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