Everything You Need to Know About Choosing Baby Formula

Lots of parents rely on formula as a way of feeding their baby, whether they formula feed right out of the gate or decide to combo-feed later. For some families, making the switch happens due to unforeseen supply issues or breastfeeding simply not working out. Whatever the reason, choosing a formula can feel like a huge decision. And with all the options—formulas that claim to be gentle on tummies, formulas that ease gas, formulas that promise to help eye or brain development—it can be a lot to take in on three hours of sleep. 

That’s why we tapped Dr. Devon Kuehn, mom and Chief Medical Officer at ByHeart, to help you navigate the formula aisle with answers to some of the most-asked questions about infant formula. When they entered the market, ByHeart was the first new infant formula manufacturer in the US in 15 years (and one of only five in the entire country). And they basically created a whole new recipe from scratch using organic, grass fed whole milk. So suffice to say, combined with her experience as a pediatrician and neonatologist, Dr. Kuehn knows a thing or two about the science behind formula.

From making sense of nutrition labels (see that at 0:48) to simply knowing if your baby likes the formula you've chosen for them (more on that at the 02:20 mark) or why soft baby poops are a good thing (jump to 03:40 to find out), here’s everything you need to know about infant formula. Watch the video above for the complete conversation between Dr. Kuehn and Babylist mom of two, Julie, or read on for the highlights. 

How do you choose one formula over another?

The first thing to know when choosing a formula is that, at the end of the day, it’s food. The same way you’d look at ingredients and nutrition labels for your own food is how you should approach formula, too. So when making your formula decision, Dr Devon says to consider the building blocks of baby nutrition: “If you think of it in that way, you can remember that there's protein, there's fats and there are carbohydrates,” she says. All formulas will include these nutrients in varying amounts, but how they do that can differ. For example, the formulas you might find on shelves in the baby aisle could include: 

• Whole cow’s milk: A whole cow’s milk formula like ByHeart retains the natural fats found in cow’s milk like naturally-occurring MFGM—a complex blend of fats and proteins also found in breast milk that’s crucial for a baby's brain development and growth. Dr. Kuehn says this is because whole milk “has some really important fats for babies that you lose when you skim milk…cholesterol is one. Milk fat globule membrane…has really important lipids and proteins that all help with baby's brain development. So for us it was really, really important when we think about supporting baby and the development to include these animal fats or these whole milk fats in our formula.”

• Skim cow’s milk: These formulas are made with cow's milk protein that has been changed to be more like breast milk. They contain lactose (a type of sugar in milk) as a source of carbs and minerals from the cow's milk.

• Partially hydrolyzed formula: In these formulas, milk protein is broken down into smaller pieces which makes it easier to digest. Compared to cow’s milk formula, these can sometimes have a reduced amount of carbohydrates—aka less lactose. You might also see it labeled “predigested.”

• Soy-based formulas: If you're worried your baby might have a dairy allergy, you could go completely dairy-free with a soy-based formula (soy provides protein without the lactose), but always check with your pediatrician first. 

• Hypoallergenic formulas: These formulas (also called hydrolysate formulas) are used when  a baby has allergies to milk proteins, has special digestive needs or has serious health conditions like galactosemia. If your pediatrician recommends a specialized formula for your infant, follow their guidance about feeding requirements. 

How do you know if a formula is actually similar to breast milk? 

First, let’s start with what breast milk is. As the original source of nutrition for babies, it's the blueprint for how formula has developed and includes essential nutrients, like carbohydrates, proteins and fats, as well as water to keep your baby hydrated. In specific terms, that’s about:

• 87% water

• 3–5% fat 

• 6.9–7.2% lactose (think: sugar) 

• 0.8–0.9% protein (early milk is 80% whey and 20% casein; mature milk is 60% whey and 40% casein)

There are also minerals and fat-soluble vitamins like A, D, E, and K and water-soluble vitamins such as vitamin C, riboflavin, niacin and pantothenic acid.

Dr. Kuehn says what makes ByHeart’s patented protein blend closest to breast milk is the kind of proteins it includes. There are two, she says, that are important: alpha-lactalbumin and lactoferrin. 

“Lactoferrin is really high in colostrum and sort of stays high, and then alpha-lactalbumin is the highest protein in mature breast milk,” she says. “We purposely focused on these two proteins.”

What are alpha-lactalbumin and lactoferrin? 

“Alpha-lactalbumin is really important because it's high in essential amino acids…[which] are the building blocks of protein, Dr. Kuehn explains. And essential means that you can't make them. 

“You have to get them from your diet, “ she continues. And so by having alpha-lactalbumin at breast milk levels, we were able to sort of match those essential amino acids for baby, which is really, really exciting. And lactoferrin drives a lot of benefits. It's actually really important in the microbiome and carries iron to baby. And so we focused on these two, making us the closest to breast milk when you focus on these two proteins.” 

How do you know if your baby likes the formula?

Since babies can’t talk, parents are left trying to interpret cries, gassiness, fussiness and poop quality to gauge how a formula works with their infant. One thing Dr. Kuehn says to know: babies are born with a preference for sweet things.

“Lactose, which is the primary sugar in breast milk and the primary sugar in ByHeart formula, is sweet tasting,” she says. Comparatively, many other brands rely on ingredients like corn syrup to use as the primary carb source in their formulas.

Other things that parents use to see if their baby's tolerating formula is stool consistency. She says observing “how soft it is, how many times a day [they poop], whether they're gassy, whether they seem fussy, whether they're spitting up a ton” can help. 

Some things to look for in your baby’s post-feeding response: 

• A formula that agrees with your newborn will result in soft or pasty poops regularly after feeding. 

• Dr. Kuehn says all babies spit up, so it doesn’t necessarily mean a formula isn’t the right choice, but monitoring when it happens and how much is important. Generally, spit up happens right after feeding or 1–2 hours later and you should expect no more than one or two mouthfuls at a time, though this can vary. 

Can formula cause constipation?

In short, yes. While every baby is different, there are certain ingredients that tend to cause it more than others, Dr. Kuehn says. “Palm oil is one that has fatty acids that can lead to sort of calcium stones in poop.” There are also things you can include in a formula that can combat constipation, like prebiotics.

“...GOS (galacto-oligosaccharide)—which is what ByHeart has—can help with softening stools because it changes the microbiome,” she says. “Another thing, lactoferrin, can help with microbiome development. So depending on the bacteria your baby has, depending on certain ingredients and formula, it can change the stool consistency for babies.”

Softer poops was actually one of the things ByHeart noticed when they ran their clinical trial.*

Is it okay to mix breast milk with formula or should you keep them separate?

For parents who supplement, the rules about mixing breast milk with formula can be unclear. Dr. Kuehn says it’s totally fine to mix, but how you mix is what matters. Start by making your formula just as instructed on the can and then mix in breast milk after.

“What we don't want is people adding the powdered infant formula to breast milk,” she says. You will get far too many nutrients for your baby, so make the formula the way it should be made, have your breast milk, and then you can mix them together…If you can, start with 75% breast milk, add a little formula and sort of titrate up over time. The reality is babies will adjust to whatever you're feeding them. And so I think it really comes down to parent comfort on how to sort of do that mix or add in a formula when they're supplementing.”

How long can a baby stay on formula? 

“Infant formulas in the US are made to meet the nutritional needs of the baby from 0 to 12 months, which is great,” Dr. Kuehn says. “If you choose to continue on infant formula after 12 months, I always recommend that you check with your pediatrician because the nutrient needs of your baby after that time period might be different.”

For more insight on what’s really going on in the formula aisle, watch our full interview with Dr. Kuehn here. And if you’re curious for more on how ByHeart is made, check out their ingredient breakdown and take a deeper look at their clinical trial results. 

*Clinically proven vs. a leading infant formula

This information is intended for healthy, full-term infants from 0-12 months and is not intended as medical advice or to replace guidance from your baby’s healthcare provider. As always, please discuss all medical concerns and possible interventions directly with your baby’s healthcare provider, before implementing any information contained in this video.

This post is sponsored by ByHeart. Babylist’s free site, apps and emails are made possible by our sponsors. We limit our sponsored content to relevant partners that offer products and services we believe in and use ourselves.