Best Soy-Based Baby Formulas: A Comprehensive Guide

When choosing the best baby formula for your little one, there are many options—which is great, but it can also be confusing. From cow’s milk formula to goat milk baby formula to soy infant formula, each choice offers unique benefits and considerations. 

Among the various options available, soy-based infant formulas have emerged as a fairly popular choice for many parents. Soy formula currently makes up about 12% of the infant formula market.

Whether you’re considering a switch from milk-based formulas or seeking an alternative due to dietary preferences, understanding the advantages of soy-based formulas can help you make an informed choice for your baby’s optimal nutrition.

In this blog post, we will explore the benefits of soy-based infant formulas, review some of the best options on the market, and provide guidance on choosing the right formula for your little one’s unique needs.

Why Choose Soy-Based Infant Formula?

While the American Academy of Pediatrics (AAP) recommends exclusive breastfeeding until 6 months of age (and longer if it is working for both mother and baby), breastfeeding can be challenging for many families. When breast milk is not an option (for whatever reason), infant formula is an excellent alternative and can also supplement breast milk. 

Soy-based formula is a popular alternative to traditional milk-based formulas for various reasons. It's made from soy protein but designed to be as similar to breast milk as possible in terms of nutrition.

For parents seeking a vegan baby formula or those concerned about lactose sensitivity, soy-based formulas provide a plant-based alternative well-tolerated by infants.

Benefits of Soy-Based Infant Formula

Soy formula can provide many benefits for babies. The American Academy of Pediatrics and ESPGHAN (European Society for Pediatric Gastroenterology, Hepatology, and Nutrition) recommend the use of soy formulas in limited circumstances:

• For babies with galactosemia (a rare condition where babies can’t digest galactose) and congenital lactase deficiency (a rare condition where babies are born without the enzyme needed to digest lactose)

• A safe and suitable choice for vegan/vegetarian babies or families seeking a plant-based option

• May be a good choice for babies with lactose sensitivity or IgE-mediated cow’s milk allergy

• May be considered in non-IgE mediated cow’s milk allergy if other formulas are not possible due to economic or cultural reasons

My Top Picks for Soy-Based Infant Formulas

When choosing a formula, be sure to look for reputable brands that adhere to strict quality control standards. Make sure that the can is sealed and not expired. Look for formulas that have been tested for safety and are compliant with relevant regulations and guidelines.

Make sure you choose an infant formula that is, in fact, for babies ages 0-12 months. “Toddler formulas" can look very similar to infant formulas but are not appropriate for infants! 

As a pediatric registered dietitian, here are some of my recommendations for the best soy-based infant formulas on the market, known for their quality ingredients and nutritional benefits:

1. Similac Soy Isomil

Similac Soy Isomil is a popular choice for parents seeking a dairy-free infant formula. It is affordable, is made with non-GMO ingredients, and contains vegan-sourced DHA from plant algae.

2. Enfamil ProSobee

Enfamil ProSobee is a plant-based infant formula that is easy to digest and provides a balanced nutritional profile with added DHA.

3. Earth’s Best Organic Soy Infant Formula

This formula is certified organic, meaning it is made with non-GMO ingredients and no artificial additives. It is also Kosher certified and contains vegan-sourced DHA. One downside is that it may be slightly more expensive than non-organic options.

4. Gerber Good Start Soy  

Gerber Good Start Soy is another reliable option for those needing a soy-based formula. It is also affordable, is made with non-GMO ingredients, and contains vegan-sourced DHA from plant algae.

**TOP TIP** It is not appropriate to replace breast milk or formula with soy milk, whole milk, or other plant-based milk alternatives for infants under 12 months of age as their primary milk source - they can, however, have it baked or added to different foods or recipes!

Can my baby with a milk protein allergy drink soy formula?

Extensively hydrolyzed formula (rather than soy) is the first-line formula for babies with suspected or confirmed cow’s milk allergy; however, soy can be an option in specific circumstances, especially in IgE-mediated cow’s milk allergy.

Unlike cow's milk formula, which contains casein and whey proteins, soy formulas use soy protein. Research shows that there is a risk of cross-sensitivity to soy proteins if a baby is also allergic to cow’s milk proteins, but the risk is much lower if they have an IgE-mediated cow’s milk allergy versus a non-IgE mediated allergy.

If you are interested in starting a soy-based formula for your baby with cow’s milk protein allergy, this decision should be discussed with your baby’s pediatrician, allergist, or dietitian. Soy-based products are typically introduced after 6 months of age.

Are soy-based infant formulas safe?

Soy can be a bit of a hotbed for myths and misconceptions, no matter how much evidence we have to the contrary. As long as you buy an infant formula sold in the US, it must adhere to the nutrition and safety standards outlined by the Infant Formula Act of 1980. The US Food and Drug Administration (FDA) requires certain nutrients, recall procedures, and inspection requirements, defines adulteration, and establishes quality controls.

Soy formula is rich in isoflavones, a type of phytoestrogen or plant compound with a similar structure to that of human estrogen. Concerns continue to circulate that soy formula causes reproductive and developmental abnormalities in babies, affects testosterone levels, and causes the development of breast tissue in males. 

The truth is that babies have been fed soy formulas for over 100 years, and these formulas continue to support proper growth and development. The majority of human research evidence hasn’t found any significant long-term negative effects with no significant reproductive, thyroid, brain, immune system development, or overall developmental differences in babies fed soy formula.

Can I breastfeed and give soy formula?

Yes! You can breastfeed and supplement your baby with soy formula if needed. Many parents choose to combine breastfeeding with formula feeding for various reasons, such as ensuring adequate nutrition if milk supply is low, addressing specific dietary needs, or providing flexibility in feeding.

Before introducing soy formula, it’s important to consult with your pediatrician. They can help you determine the best approach based on your baby’s health, nutritional needs, and any potential allergies or intolerances.

If you’re transitioning to or adding soy formula to your baby’s diet, consider doing so gradually. This can help your baby adjust to the new formula and allow you to monitor for any adverse reactions. While soy formulas are generally well-tolerated, it’s always a good idea to watch for any changes in your baby’s digestion or overall well-being.

Are there any contraindications to giving soy formula?

Soy formula is higher in aluminum and phytates and is, therefore, NOT designed or recommended for preterm infants due to the higher risk of osteopenia compared with preterm infants fed cow’s milk-based formulas.

It is also important to note that soy-based formula may interfere with the absorption of thyroid medications, so formula-bed babies with congenital hypothyroidism may need an alternative formula.

Starting solids soon?

Choosing the best soy-based baby formula involves considering your baby's health needs, dietary preferences, and any allergies or intolerances. Soy-based formulas offer a valuable alternative to cow’s milk-based options and can be an excellent choice for vegan families or those with special medical needs. 

If you’re interested in learning more about how and when to integrate foods into your baby's diet, as well as reducing the risk of food allergies for your baby, check out my new baby-led feeding cookbook!

It helps reduce the risk of developing food allergy during infant feeding and makes starting solids easy, joyful, and delicious for the baby and the entire family as well.

With a complete plan for allergen introduction, 8 weeks of baby-led feeding meal plans and 80 family-friendly recipes, you’ll never again have to wonder what to feed your baby!

For more information on infant formula feeding and other types of formula, be sure to check out my blog, or please schedule a virtual one-on-one consult with me if you need additional support with specific nutritional concerns. 

Thanks for reading!