Overview of Soy Milk Baby Formula

Woman feeding milk to her daughter

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The use of soy-protein based baby formula is popular with some parents because they think it will help relieve gas, fussiness, or colic. However, switching baby formula usually doesn't relieve these symptoms. And since soy baby formulas usually cost more than cow's milk-based formulas, parents shouldn't be quick to try them unless they are medically indicated.

According to the American Academy of Pediatrics, "Soy protein-based formulas in the United States may account for nearly 20% to 25% of the formula market."

The rate of soy formula use may be higher than it needs to be; there are few medical conditions for which a baby actually needs a soy formula. Most newborns and infants who aren't breastfeeding will do just fine on a regular cow's milk-based formula, such as Enfamil Infant, Similac Advance, or Parent's Choice Advantage.

When to Switch to Soy Formula

Pediatricians usually recommend soy formula for those babies who need it, including infants with:

  • Galactosemia
  • Primary lactase deficiency (a rare condition in which a baby is born without the enzyme to digest the sugar lactose)
  • Diarrhea and a temporary lactase deficiency (switching babies to soy formula when they have diarrhea alone is controversial and usually not recommended)

A soy formula can also be a good choice if parents wish to raise their baby as a vegetarian and the mother isn't breastfeeding. Since there are no completely vegan baby formulas, organic soy formula may be a good choice for vegan parents who want to raise their baby as a vegan, too.

If your pediatrician does think that a change to soy formula is necessary for your baby, be assured that these are just as good as other formulas and are readily available wherever baby formula is sold. Soy baby formula options include:

  • Enfamil ProSobee
  • Similac Soy Isomil
  • Gerber Good Start Soy
  • Parent's Choice Soy (Wal-Mart brand baby formula)
  • Earth's Best Organic Soy Infant Formula

When to Avoid Switching to Soy Formula

Soy formula is usually not recommended for infants who have:

  • Colic or fussiness, since the switch will likely not be helpful
  • A cow's milk protein allergy, since many of these infants can also be allergic to soy proteins and should drink an extensively hydrolyzed protein formula instead, such as Nutramigen or Alimentum
  • A high risk for food allergies, since soy is among the most common allergens (If not breastfeeding, babies at high risk for food allergies should likely drink Nutramigen or Alimentum and not soy- or cow's milk-based formula)
  • Been born premature, since soy formula can lead to decreased bone mineralization, even when babies are given supplemental calcium

Unless there is a good reason to start your baby on soy formula, if you stop breastfeeding before your baby is 12 months old or need to supplement, you can likely use a cow's milk-based formula instead of soy formula.

Is Soy Formula Harmful?

Soy formula can be harmful to premature babies, but the American Academy of Pediatrics (AAP) states that "there is no conclusive evidence from animal, adult human, or infant populations that dietary soy isoflavones may adversely affect human development, reproduction, or endocrine function."

One of the concerns is that phytoestrogens, especially isoflavones, may have estrogen-like activity. Some experts question the effect that soy products influence on a child's immune function and thyroid function, although again, the AAP says that research has not shown any risks or long-term adverse effects from drinking soy baby formula.

One last concern is that soy-protein formula contains a relatively high level of aluminum as compared to breast milk and cow's milk-based formula. This exposure is not thought to be a problem for full-term infants but may lead to reduced bone mineralization in preterm babies.

Soy Milk vs. Cow's Milk

Like soy baby formula, soy milk is becoming popular with older children, both for children with milk allergies and for parents who are simply trying to avoid cow's milk. But although some sources recommend giving whole-fat soy milk to toddlers under two years old, no brands of soy milk have the equivalent amount of fat per serving as whole milk.

Whole cow's milk has 8 grams of fat per serving, while 2% reduced-fat milk has about 5 grams of fat. Most brands of soy milk only have 4 grams to 5 grams of fat per serving or less. In fact, low-fat soy milk only has about 2.5 grams of fat per serving, which is the equivalent of 1% cow's milk.

Soy milk can be a good substitute for cow's milk, but it is reduced or low fat and so is not usually a good choice until a child is at least 2 years old.

The American Academy of Pediatrics states that "young children need calories from fat for growth and brain development," and that "this is especially important in the first two years of life." So if you do give your toddler reduced-fat milk, make up for that missed fat in other parts of your child's diet.

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Article Sources
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  • American Academy of Pediatrics. Guide to Your Child's Nutrition.
  • American Academy of Pediatrics Clinical Report. Use of Soy Protein-Based Formulas in Infant Feeding. PEDIATRICS Vol. 121 No. 5 May 2008, pp. 1062-1068.