The Guide to Infant Formulas: Part 1. What’s in formula, anyway?

The Pediatric Insider

© 2013 Roy Benaroch, MD

There used to be only a handful of infant formulas. The ordinary kind, made from cow’s milk; plus ones made from soy protein. There have also been extensively hydrolysed products with broken-down proteins available for babies with protein allergies. That was it. Three choices for bottle-feeding.

Not any more. There are dozens of formulas, each one claiming to address some kind of need—there are choices that “soothe”, or other ones that provide “comfort”. There’s even one specifically for supplementing. There are the top-tier name brands, then a cheaper name brand (with multiple choices), and the store brands. Which is best? Which one should you choose if you’d like to give your baby formula?

We at The Pediatric Insider are here to help. Presenting The Guide to Infant Formulas, untainted by commercial interests, with all of the marketing stripped away.

So what’s in that stuff, anyway? Commercial formula manufacturers all claim to make a product that’s closest to human milk—but by law, most of the nutrient components of these products are all the same. The net content of almost all of the significant nutrients has to fit within a narrow range dictated by the FDA, including the content of the macronutrients fat, protein, and carbohydrates. There are also vitamins, minerals, and nucleotides in specific amounts. Though the sources of these nutrients can vary, and there is a little bit of wiggle room, the bottom line for all of these formulas is that in almost every important respect, the nutrient quality and quantity is the same.

All the manufacturers can do is to tinker about at the margins, adding a little of this, a dash of that. All of the important decisions about what’s in there have already been made.

About the sources of these nutrients: there are some differences, though for most babies it doesn’t matter. For instance, most baby formulas get their proteins from cow’s milk, which contains both whey and casein proteins. The different companies use different proportions of whey and casein, or sometimes claim to break these proteins down into smaller fragments that are (they say) easier to digest. Some use only the whey portion. But there is no good evidence that any of these differences will make any difference to any babies—and certainly not your baby.

Some formulas are based on soy proteins rather than cow’s milk. This may be a selling point especially for vegans, but for most babies it makes no difference. Milk protein allergy does occur, but many babies who are allergic to cow’s milk protein are also allergic to soy, so switching from one to the other makes little sense.

The fat and carbohydrate sources can be different. Some manufacturers use palm-derived oils, or oils from other sources; some use lactose (which is abundantly present in human milk as well), and others use sugars more similar to cane sugar, or use a broken-down form of sugar. Again, the nutrient quality of these is the same. Some like to market their products as lactose-free (because so many parents are intolerant of lactose), but lactose intolerance is very, very rare in human babies. It really just doesn’t happen. These choices of carbohydrates are all about marketing, not about nutrition.

There are some formulas that are “extensively hydrolysed” to cut up the proteins into little bits. These are appropriate for babies with genuine milk protein allergy (which isn’t very common, and certainly isn’t a common cause of fussiness unless accompanied by other symptoms.) They’re expensive, but are crucial for those few babies who genuinely need them.

So fats, carbs, and proteins—very little important differences there, for most babies. What else can the formula companies add or change to distinguish their products from one another?

Many products now contain additives advertized to change the “intestinal flora”—that is, to help babies establish helpful, healthy bacteria in their guts. The additives include “probiotics—those are actual bacterial colonies that may or may not make their way to the colon—or “prebiotics”, which are compounds that provide nutrition for bacteria, or otherwise change the intestinal contents to be more supportive of healthy bacterial growth. An even newer word is “synbiotics”, which are a mix of probiotics and prebiotics. Though there is a lot of research on these going on, there’s currently very little to zero actual clinical evidence that these improve the health of babies when added to their formula. Available studies might show a change in the composition or quality of stool—but is that even important? We don’t know what kinds of pre- and probiotics are best, we don’t know the doses, we don’t know how they interact, and we certainly don’t know that routinely adding them to formula is a good thing. For what it’s worth, they seem harmless. But all of the marketing about the proportions and amounts and special kinds of pro- & pre- biotics is just that: marketing.

About ten years ago, formula manufacturers started adding long-chain fatty acids, often from chemical sources abbreviated “AHA” or “AA” or “DHA.” These compounds are found in varying amounts in human breast milk, and seem important for brain and eye development—though studies of their actual clinical benefits have not been impressive. We honestly don’t know the exact amounts of these nutrients that are ideal, especially because the amount in breast milk varies very much with mom’s diet. Still, it’s probably a good idea to have them in breast milk, and almost all available infant formulas in the US now contain them. Some claim to have more than others, but again, we don’t even know what the “best” amount is.

A few formulas have additives to help with spitting up. Typically, it’s a modified rice starch that makes the formula a little thicker, or one that thickens even more when in the acidic environment of the stomach. These are meant to be used instead of just adding rice cereal to the bottle—and there is an advantage over adding rice, because you don’t end up giving extra calories. But these products are seldom necessary. Spitting is normal, and all babies spit at least some. For most babies who spit up, the best solution is to feed less, or feed slower, and worry less about the spitting. Babies who genuinely have health problems because of regurgitation (such as poor growth or esophagitis or recurring pneumonias) need a thorough medical evaluation, not an “added rice” formula.

Next up: I’ll go through the products out there and tell you what you need to know. And then: my final recommendations!

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2 Comments on “The Guide to Infant Formulas: Part 1. What’s in formula, anyway?”

  1. Eileen Says:

    This guide is very helpful! Any chance you could add a bit about when added liquid vitamins, like Poly Vi Sol, are used and necessary, please? My daughter’s doctor told us to supplement with that stuff if she was getting less than 40 oz of formula per day (I was combo feeding), but I don’t know if that is a general recommendation or because she was a preemie. I find that, in general, there isn’t a lot of info out there on combo feeding, given all the rancor in the “breast or bottle” debate.


  2. Dr. Roy Says:

    Great question Eileen!

    For term infants, the AAP recommends vitamin D supplementation for breastfed babies, or for formula-fed or combo-fed babies getting less than 1 liter (about 32 oz) a day of formula. That really means a lot of babies– most even exclusively-formula fed babies won’t get up to 32 oz/day until 3-4 mos of age. And very few combo-fed babies will get up to 32 oz formula, ever.

    However, I will tell you that many practicing pediatricians don’t necessarily follow that AAP recommendation, because it is overly broad. Many babies get plenty of vitamin D from sunlight exposure, though that varies by skin tone, latitude, season, clothing, and family preferences. The AAP decided to disregard all of those considerations and make a recommendation that covers all babies, which is fine. But in practice, many of us don’t follow the one-size-fits-all vitamin D recommendation approach.

    The other micro nutrient that comes up in AAP recommendations is iron, which is also poorly delivered by human milk. The AAP recs that breast-fed (or half-breast fed) babies get an oral iron supplementation until iron-rich complementary foods like cereals are introduced. However, again, I think few practicing pediatricians are following this recommendation. Iron-deficiency is rarely seen in term infants until after 4 months, because of iron storage from pregnancy. And four months is when many families start complementary foods anyway.

    Other than iron and vitamin D, no supplements are recommended for breast fed term babies.

    For premature babies, there may be more need for iron, vitamin D, calcium, and maybe phosphorus and other micronutrients. The more premature, the more the need. That’s why preemie-specific formulas have a different composition.


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