Read on to learn about the benefits of protein in infant formula, the difference between milk and plant-based proteins, and various formula options to choose from based on babies’ needs.
Why do babies need protein?
Protein provides amino acids, which are essential building blocks for proper infant growth, hormone health, brain development, and the developing immune system.1 Babies grow quickly in the first 6 months and less quickly after that, so the amount of protein they need changes over their first year of life. The Daily Reference Intake (DRI) for protein in newborns is 2.2g/kg body weight, and from 6 months through one year it decreases to 1.2g/kg body weight.2 In fact, to meet these changing protein demands, breast milk—the gold standard for infant nutrition—is more concentrated in protein during those early months, and then decreases proportionally over time. Infant formulas are crafted with a target protein amount in the middle of this range to ensure that babies receive enough protein to promote growth and development throughout the entire first year of life.
What kind of protein is used in formula?
Cow’s milk is the protein source most commonly used in routine infant formulas, and it contains two different types of proteins: whey and casein.
Similar to breast milk, our routine cow’s milk-based infant formulas contain a combination of both whey and casein proteins, however the ratios may vary depending on the ingredients used. Additionally, the whey and casein proteins in cow’s milk have different amounts of amino acids than those in breast milk. But infant formulas are specially designed to adjust for those differences, so your baby gets all the essential amino acids they need. All of Abbott formulas include protein blends that have been extensively studied to verify that they support normal growth.
Are some protein sources better than others?
In specialty and certain tolerance formulas, the protein composition may differ depending on the intended population. While cow’s milk protein is well-tolerated by most infants, mild tolerance and specialty formulas containing different protein sources are available for babies who may benefit from them. The following alternate protein sources are available and may be recommended by your pediatrician:
- Partially hydrolyzed cow’s milk protein: Formulas like Similac Total Comfort® where the milk proteins are broken down into smaller pieces, making them easy to digest.
- Extensively hydrolyzed cow’s milk protein: Similac® Alimentum® contains protein that’s been extensively broken down into small pieces to virtually eliminate allergic reactions in most babies allergic to cow's milk protein.
- Soy protein: A plant-based alternative containing protein derived from soy, such as Similac® Soy Isomil®. Soy protein-based infant formulas are options for babies with galactosemia and for families with plant-based preferences.
- Amino acid-based formulations: Formulas made with free amino acids, rather than intact or hydrolyzed proteins. These are designed for babies with food allergies or GI disorders who cannot tolerate intact or hydrolyzed protein. Your doctor may recommend EleCare® if your little one falls into this category.
All of these formula types provide the necessary nutrients for a baby’s growth and development. Contact your healthcare provider to discuss the best option to feed your baby based on their needs.
Will plant-based formula meet my baby’s needs?
The use of plant-based formulas is based on personal preference, tolerability, and individual nutrient needs.
All infant formulas in the U.S. – whether dairy-based or plant-based – are strictly regulated by the FDA and provide a complete source of nutrition to ensure proper growth and development over the first year of life.
You’ve got this, and we’re here to help
Protein plays a vital role in your baby’s growth, brain development, and immune health.1 While breast milk is the ideal source of infant nutrition, formula can provide sufficient nutrition, including protein, for babies who are not breastfed. Similac offers a range of safe, science-backed formulas—including cow’s milk, hydrolyzed, soy, and amino acid-based options—designed to support digestion, absorption, and normal growth. Each product is carefully formulated to meet the nutritional needs of different infant populations. Always consult your pediatrician to choose the best feeding option for your baby.
References:
- Greer, F. R., & Abrams, S. A. (Eds.). (2025). Protein. In Pediatric Nutrition (9th ed.). American Academy of Pediatrics.
- Institute of Medicine. (2005). Protein and amino acids. In Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids (macronutrients) (pp. 593–594). National Academies Press.
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