What should I feed my baby? One of the most common questions every parent has. The one resounding answer that is clearly the best option is breastfeeding. Simply put, “breast is best”. While there are a multitude of reasons for why this is true, most of which I’m sure many of you have already heard or read, there are still many parents that turn to infant formulas for their baby’s nutrition. So which one should you choose? When should you switch?
Despite the large number of parents that use infant formulas, information regarding which to choose is difficult to wade through and quite confusing. When combined with misinformation about which is better and when to switch, parents are often confused or end up simply using a formula that is either inappropriate or unnecessary. Let’s try to change that.
Basics of Infant Formulas
As I stated above, no infant formula is comparable to breastmilk. While various brands attempt to replicate nature’s formula, it simply isn’t possible. That being said, all formulas marketed and sold meet a minimum nutritional requirement set forth by the FDA. Thus, there is no clear brand that is endorsed by the AAP and most every formula is sufficient to meet your baby’s nutritional needs. The only exception to this rule is any low iron formula—these are most definitely recommended against. So what’s the difference between some of these different types and brands? For the purposes of this article, there are 3 basic types of formulas:
- Cow’s milk formula
- Soy-based formula
- Elemental formula
To understand what to choose and why, I’m going to go into some Formula 101 (this is not to be confused with the racing car circuit). All formulas, no matter which group, are made up of 4 main components:
- Carbohydrate
- Protein
- Fat
- Electrolytes/minerals
Look vaguely familiar to food we eat? Well, it is. What differentiates each formula is what KIND of each of the above and in what ratio. So let’s look at each part.
Carbohydrate
This is just a big word for sugar. We’ve all heard of different kinds of carbohydrates like sucrose and fructose and glucose and dextrose, for example. Believe it or not, milk has “sugar” in it too. One of the ones we’ve all heard of before that we associate with milk is lactose. This is what is found in breastmilk and cow’s milk and it is important for many reasons. It helps to absorb calcium and iron effectively. It’s important in brain development in infants. It’s also important in helping to maintain a good environment for “good bacteria” to grow in the intestinal tract. Soy-based formulas are made with sucrose and corn syrup as their carbohydrate. Elemental formulas can vary, but most are made with a corn syrup and none contain lactose.
Protein
All milk is made up partially of protein as well. There are 3 main proteins that are relevant. The first two are called casein and whey. This is what is found in breastmilk as well as in cow’s milk formula. Soy milk has soy protein. Elemental formula may have some casein (in smaller amounts) or will simply have amino acids (the building blocks of proteins). This is what makes these formulas “elemental”.
Fat
All formulas have different types of fat. These are mostly made up of different types of oils such as coconut oil, soy oil, MCT oil, as well as various others. DHA and ARA fall into this category as well (I won’t go into this for the purposes of this article).
Electrolytes/Minerals/Vitamins
All formulas have varying amounts of sodium, potassium, calcium, phosphorus, iron, and vitamins.
Which formula to choose?
So this is the big question. This is why you’ve kept reading. The answer to this is that the vast majority of the time, you simply need to choose any brand of cow’s milk formula that you like. That’s it. You can choose based on advertising, you can choose based on price, you can choose based on how pretty the packaging is. The bottom line is that this is where most infants should start and where most infants should remain. While various brands have differing ratios of the above, the differences are negligible and all provide adequate nutrition for infants. This is the reason why the AAP does not endorse a specific brand. Enfamil, Similac, Carnation Good Start, etc all contain essentially the same ingredients. This is also the reason why switching from one brand of cow’s milk formula to another brand of cow’s milk formula (like Enfamil to Similac) for “tolerance” issues really doesn’t make much sense. It’s akin to preferring one brand of milk at the grocery store to another. They might be different cows but are essentially the same recipe.
When should I change from a cow’s milk formula to soy?
Unfortunately, parents will often change formulas for the wrong reasons. Essentially, there are very few reasons to change from a cow’s milk formula to either a soy-based formula or an elemental formula. I will detail those reasons below:
- Lactose intolerance
- Galactosemia
- Milk-protein allergy
That’s about it. Even better, I’m going to briefly explain each of those and how often you should expect to see these.
Lactose Intolerance
This is a common phrase that we hear and many of us either suffer from it or know someone that does. However, lactose intolerance in the sense that most of us know it is very, very rare in infants. This “congenital” form (i.e. born with) will show symptoms of diffuse diarrhea in the first few days of life. Fortunately, this is a very rare entity. “Acquired” lactose intolerance, or what we normally think of when we think of lactose intolerance, will almost always not develop until after 4 years of age (and often not until adolescence). Thus, it is highly unlikely that your infant has lactose intolerance and would need to be changed to a soy-based formula.
Galactosemia
This is also a very rare disorder (1 in 60,000 births) where infants cannot tolerate a cow’s milk formula. This disease is part of the newborn screen that is done on infants before they leave the hospital and is definitely a reason to switch to a soy-based formula. However, again, this is quite rare and not often encountered.
Milk-Protein Allergy
Milk protein allergy is a true food allergy much like people have allergies to shellfish, nuts, or eggs. Symptoms of this can include skin reactions (rash, hives, eczema), breathing problems (wheezing, cough, sneezing, persistent runny nose), abdominal symptoms (vomiting, profuse watery diarrhea, bloody stools, failure to gain weight), and behavior issues (persistent irritability, refusal to eat, poor sleeping). In other words, the symptoms are oftentimes quite serious. In particular, these infants usually do not gain weight well.
Unfortunately, some infants are given this diagnosis without truly having a milk-protein allergy based simply on spitting up, colic, or increased gassiness. In addition to this, up to 50% of infants with a true milk-protein allergy will also be allergic to the soy protein. Keeping in mind what was discussed above, this has nothing to do with lactose, which is a carbohydrate. Thus, changing an infant who has a milk-protein allergy to a soy-based formula is usually not the best choice. These children often require elemental based formulas until they outgrow their milk allergy (which most do by age 3-4).
So when should I switch to soy formula?
You’re probably asking yourself when am I finally going to get to the reasons to switch from cow’s milk formula to soy formula. Well, I’ve already covered them. That’s really about it. As you can see, there are very few medical reasons to switch to a soy formula and most of them are quite rare. So unless you are trying to raise your child as a vegetarian, there is really no reason to ever use anything but a cow’s milk formula unless your child has been diagnosed with one of the three above conditions (two of which are very rare). Is there any harm in using a soy formula? Well, actually there might be. First of all, soy-based formula lacks lactose. As described above, this is what is found in breastmilk and it has many helpful properties for developing babies. There are also questionable portions of soy formula such as phytoestrogens and increased aluminum that may lead to decreased immune system function, improper thyroid function, and decreased bone mineralization. In addition to this, soy milk has less fat than cow’s milk and fat is important for brain development in children up to 2 years old. So, while there is no official statement from the AAP at this time recommending against soy formulas or soy milk, there are no clear benefits and there may be potential risks involved.
So there are really not many reasons to switch formulas?
In short, no. Unless your child has a milk-protein allergy (which should include symptoms more severe than simple gassiness, fussiness, or spitting up), then changing formulas from one brand to another or from cow’s milk to soy milk really doesn’t make much sense. In addition to unnecessary added cost and inconvenience, these changes often cause infant’s digestive systems to readjust to different formulas, making the initial symptoms worse. If you feel that there may be a reason to change your formula, then you should do so in consultation with your pediatrician.
The article was written by Gian Musarra, MD, a pediatric hospitalist with St. Louis Children's Hospital and Washington University School of Medicine.