A2 Milk Infant Formula: Is It Better for Babies?
You may have noticed a newer type of product in the dairy aisle lately: A2 milk. Unlike ‘modified’ foods or milk alternatives, A2 milk is simply milk that contains a specific type of naturally occurring protein. In fact, all human breast milk contains A2 proteins (a big reason why A2 milk garners attention in the infant nutrition space).
But what exactly does ‘A2’ mean? Does choosing an A2 infant formula make a difference in your baby’s health? And what are the differences between infant formulas made with A2 milk versus those that aren’t?
As with many topics in infant feeding, the answer is nuanced. In this post, we’ll “digest” the science of A2 milk, explain how it differs from conventional dairy, and explore what research says about comfort A2 formula tolerance in babies. My goal is for you to feel better equipped to make the best choice for your baby.
What Are A2 Milk Proteins?
Cow milk contains several types of proteins, including beta-casein proteins in two primary forms: A1 and A2.
Most conventional dairy cows in the United States produce a mixture of A1 and A2 beta-casein proteins (A1/A2). However, certain breeds of cows are genetically predisposed to produce only A2 beta-casein (A2/A2). These cows are selectively bred to maintain the A2/A2 genetic trait.
Interestingly, thousands of years ago, before cattle domestication, all cows naturally produced A2 milk. Over time, genetic mutation in some cattle led to the development of the A1 protein gene variant.
Goats, buffalo, and humans naturally produce A2-dominant milk, which is a major reason why A2 dairy has become increasingly popular in infant formula development.
How do A1 and A2 Proteins Compare and Contrast?
Both A1 and A2 milk provide vital nutrients like protein, calcium, phosphorus, and fat to support infant growth and development. Nutritionally, they’re nearly indistinguishable.
The difference lies in how the proteins are broken down during digestion.
When A1 beta-caseins are digested, they release a compound called beta-casomorphin-7 (BCM-7). Research suggests that BCM-7 can slow down digestion and contribute to digestive discomfort in some individuals. This might look like gas, bloating, and abdominal discomfort (similar to the symptoms we see with lactose intolerance, which is a different issue).
A2 beta-caseins are structured differently, and in a way that prevents BCM-7 formation during digestion. Because of this, A2 milk proteins may be more tolerable for babies with a sensitive stomach.
Importantly, A2 milk still contains lactose and intact milk proteins. This means that A2 formula is not appropriate for babies diagnosed with a cow milk protein allergy (CMPA). Parents should always consult their pediatrician or allergy specialist to rule out allergies or food intolerances.
The Role of Protein Type in Infant Digestion
Breast milk is the gold standard when it comes to infant nutrition, digestion, and nutrient absorption; as a result, the goal of infant formula research is to develop products that mimic human milk as closely as possible. Since breast milk contains A2 proteins, it has been proposed that A2- based infant formulas offer a similar digestive experience to that of breastfed infants.
During the first year of life, the infant’s digestive system is still immature. Babies naturally produce lower levels of digestive enzymes and experience rapid development of the gut microbiome, which can make digestion more sensitive during infancy.
This may contribute to:
Gas
Fussiness
Spit-up
Constipation
Strained bowel movements
While these symptoms are common during infancy, protein composition often plays a role in how a baby tolerates formula. A recent study looking at the effects of A1 and A2 infant formulas noted some differences. Here are the main takeaways on the exclusively fed A2 formula infants:
No significant differences in growth metrics like body weight, length, body mass index [BMI], head circumference
A2 formula-fed infants had less digestive comfort and GI symptoms:
Less vomiting after feeding
Improvement of loose stool
Better digestion
A2 formula-fed infants had less parent-reported fussiness
A2 infant formula is one option families might consider when a baby struggles with formula intolerance. Several specialized formulas were developed to support infant digestion and feeding comfort, based on the underlying causes of digestive upset.
For more information on infant formulas for CMPA, you can find my previous blog post here.
Ultimately, the ‘best’ formula for a baby depends on a variety of factors, including whether and why a baby is experiencing discomfort in response to milk feeds. The following are other specialized formulas:
Partially hydrolyzed infant formulas
Milk proteins are broken down into smaller (“partially digested”) fragments, which may make them easier for some babies to tolerate.
Partially hydrolyzed formulas still contain larger milk fragments and are not safe for babies with a CMPA
Extensively hydrolyzed infant formulas
Milk proteins are broken down extensively into smaller pieces called peptides
Formulated to minimize the risk of an allergic immune response.
Most babies with CMPA can tolerate extensively hydrolyzed formulas, but a few babies may require amino acid-based formulas
Amino acid-based infant formulas
Milk proteins are broken down to their most basic building blocks: “amino acids”
May be best for infants with severe CMPA, multiple food protein allergies, or gastrointestinal disorders
Highly specialized formula that is typically used under medical supervision
**It is important to note that in Europe, the ‘hypoallergenic’ standard is defined differently than it is in the U.S. In the U.S., partially hydrolyzed formulas are not categorized as “hypoallergenic,” while in the EU, they can be and often are. If you have a baby with CMPA, note that partially hydrolyzed formulas are not appropriate for a CMPA because the proteins may still be large enough to provoke an allergic reaction in sensitive infants.
Who May Benefit Most from A2 Infant Formulas?
Babies with mild digestive discomfort without CMPA
Some babies with mild gas, stool discomfort, or feeding fussiness may respond well to an A2-based formula.
Combination feeding families
For families combining breastfeeding and formula feeding, A2 formulas may be appealing because the beta-casein profile closely resembles that of human milk.
Transitioning from breast milk to formula
Some parents may choose A2 formula while transitioning off breast milk and onto formula, with the intent of easing digestion throughout the process.
What brands of A2 infant formulas are available in the U.S.?
If you decide A2 infant formula may be right for your baby, there are a few nutritionally complete options available legally in the U.S., listed below.
Other European A2 infant formulas exist, but these can differ in cost, accessibility, and the method through which they arrive in the U.S., which can compromise their quality and integrity (it is highly recommended to avoid infant formula purchased from the gray market).
Other options to consider are FDA-reviewed goat milk-based infant formulas, which also contain predominantly A2 proteins.
Happy Baby Organic Infant Formula Stage 1 A2
This organic formula is made with A2 milk, and sourced from selectively bred cows that produce only A2 beta caseins. It is advertised as the first USDA organic formula with prebiotics and probiotics. Probiotics may help support your baby’s digestive health and may even help shape immune system development.
Baby’s Only A2 Organic Infant Formula
Baby’s Only organic formula is made with A2 milk and fortified with iron, a critical mineral for brain development and oxygen-carrying capacity in the blood.
Kabrita Goat Milk Infant Formula
Kabrita is a European-made formula that has completed the FDA review process and meets American infant formula requirements.
Aussie Bubs Goat Milk Infant Formula
Aussie Bubs Goat Milk Infant Formula is an FDA-compliant option made with whole goat milk sourced from Australian farms.
Kendamil Goat
Kendamil Goat Infant Formula is another European, FDA-reviewed formula made with whole goat milk and naturally occurring A2 proteins.
Final Thoughts
Keep in mind that every baby is different! As parents, the best we can do is become fully informed and work closely with our medical providers when choosing an infant formula that best meets the needs of our babies.
A2-based infant formulas may be best for babies who experience general digestive discomfort from regular dairy. They are not safe for babies with milk allergy. Although current research paints a promising picture for A2-formula and digestive comfort, every baby responds differently to formula feeding.
When considering switching formulas due to gas, constipation, or intolerance, always consult your baby’s pediatrician or a pediatric registered dietitian first to ensure your choice is safe for your child.
If you ever feel uncertain about your child’s nutrition, you’re not alone, and you don’t have to figure it out by yourself. If you have questions about supplements, portion sizes for your child, or special feeding needs, a pediatric dietitian or your child’s healthcare team can help you build a practical plan that fits your child and family. Please feel free to schedule a virtual one-on-one consult with me if you need additional support with specific nutritional concerns.
You can also find a free Allergen Intro Guide on my website when you’re preparing to introduce common allergens into your baby’s diet.
If you’re interested in learning more about how and when to integrate foods into your baby's diet, as well as how to reduce the risk of food allergies during infancy, check out my new baby-led feeding + food allergy prevention guide and cookbook.
Thank you to my dietetic intern, Katherine Lanca, for her contributions to this blog post.