What No One Is Telling You About Infant Formula

Who needs another article about infant formula?

Is infant formula a safe substitute for breast milk? What formula is best for my baby? Do I really have to boil water or sterilize bottles? What are the dos and don'ts in preparing powdered formula?

You may be reading this article because you’re concerned about safety and want to know if you are unknowingly putting your baby at risk. Maybe your knee jerk reaction is to assume you’re about to read a super judgy blog post from some know-it-all, holier-than-thou doula shaming you for your choice to supplement or cease breastfeeding. Maybe you’re a healthcare professional or birth worker rolling your eyes about yet another breast is best campaign that fails to take into account the vast and complex needs of modern families or the many valid reasons why parents may choose commercial infant formula to feed their babies.

Before I tell you the secret about infant formula...

Let me put a couple of things to rest outright. As a professional doula that has been practicing for a decade, with extensive ongoing education and certifications, including Certified Lactation Counselor and a Bachelor’s Degree in Education, I fundamentally believe the following:

  1. Breast is best. There really is no disputing the fact that human milk is best for human babies. It’s pretty logical, actually, not to mention the extensive research supporting this fact. Nutritionally, physiologically and psychologically, breastfeeding is hands down, the superior method of nourishing human babies [1].

  2. Fed is best. There really is no disputing this either. We all do the best we can with what we have available, and for many parents that means making the choice to supplement or completely replace breast milk with commercially prepared infant formula. There are so many factors that can contribute to this, including but not limited to: infant prematurity and/or NICU stay, maternal medications that interfere with breastfeeding, postpartum complications in mother that inhibit ability to breastfeed, breast augmentation of any kind, maternal illegal drug use, infant or maternal anatomical/physiological limitations (inadequate milk glands, infant oral restrictions), lifestyle stress, prior or present physical and/or sexual abuse, traumatic birth experience, perinatal mood disorders (depression, anxiety, etc.) and many more. Your baby needs to eat, period. Even if you plan to breastfeed long-term but need to supplement until you get back on track, your baby does not need to starve for you to reach your goals [2]!
  3. Parents have a fundamental right to make informed choices, which means they must have access to as much information as possible and the information must be accurate. How can one be expected to make quality choices when he/she does not have all the information? I have ZERO stake in your choices or the outcome of your choices and have no intention of swaying you towards some secret agenda. I want you to make the best choices for your family, which means you deserve the best, most accurate and complete information available. That’s why I created Your Birth Experience (YBE), to reduce fear and increase confidence by combatting myths with facts and equipping parents with the tools and resources they need to make informed decisions and take action!

So, what’s this about an infant formula secret?

Here it is, the big, bad, dirty, scary secret about infant formula (specifically powdered infant formula or PIF): it is not sterile. The follow up secret to that is that the safest way to prepare PIF is by adding it to water that has been boiled and cooled to no less than 158° F. Premixed formula in liquid form IS sterile and is safe for consumption without warming, but powdered formula must be mixed with water hot enough to eradicate dangerous contaminates.

I know you’re thinking, “Uh, okay…and what’s so scary about formula being unsterile?” The questions we need to ask revolve around whether or not we need the food we eat to be sterile and why unsterile infant formula in particular poses a problem. The truth is, it’s a perfectly normal and healthy reality that we do not live in sterile environments or consume sterile foods. Our bodies and environments are full of germs and microbes that all create a sustainable ecosystem. Each of our bodies has its own microbiome that contributes to our immunity and overall health.

I also know that you’re probably going to ask your mother, sister, friends and healthcare provider about this and they will probably all look at you like you’re crazy for suggesting anyone needs to boil water to prepare PIF. Cue the eye rolls and scoffs! They’re going to look at you like you’re crazy because just about no one does this. I’m not sure when exactly people stopped boiling water and sterilizing their bottles when preparing and feeding babies formula (because ask your mom; it used to be the norm), but it’s not the norm anymore. So, since you’re probably questioning how serious this is, and everyone around you will be as well, and frankly since I’ve had enough people look at ME like I’m crazy, I’m going to go above and beyond to provide you the complete and accurate information so you can make an educated decision about what to do for your family.

It’s actually not a secret, but it IS confusing.

To further complicate things, while PIF containers clearly state the product is not sterile, the labels also do not include information on the safest way to prepare the formula AND they usually advise you to ask your doctor about the proper way to prepare formula. There is also a ton of conflicting advice and downright misinformation online and perpetuated by professionals and well-meaning individuals, advising parents in some cases to use regular tap water, boiled then cooled purified water, nursery water, or lukewarm water just to name a few. So, what’s a parent to do?

First, let’s establish what the real problem is.

Many people are misinformed about whether or not to boil water in preparing PIF thinking that the issue is the water. This can be the case in situations where clean drinking water is a concern, but if you have access to clean and safe drinking water, the water isn’t the issue. The FORMULA is the issue.

Why? The problem with infant formula not being sterile is that it is quite easily contaminated. This contamination can come from your environment, your countertops that haven’t been adequately disinfected, or from your own hands that you reach into the container to scoop out the powder. If it is not prepared as safely as possible, you could be feeding your baby food containing highly dangerous and potentially deadly bacteria. The formula itself is what needs to be sterilized and the only way to insure this is by adding it to water hot enough to kill harmful bacteria. The top two harmful bacteria that cause concern are Cronobacter and Salmonella. Salmonella can cause gastroenteritis (food poisoning) and Cronobacter can be fatal.

Are you starting to think I’m the crazy one? Want proof? Here you go:

  • “PIF preparers should be aware that PIF is not sterile and can contain pathogenic organisms (e.g., Cronobacter spp.). Preparers also should be aware that PIF can be contaminated extrinsically,” meaning contamination came from YOUR environment, after you opened the factory sealed container and the contamination did not come from the manufacturer, “and that bacteria can multiply rapidly in reconstituted PIF. Consequently, WHO has developed guidelines for preparation of PIF, including reconstitution with water hot enough to inactivate Cronobacter organisms” [3].
  • “PIF is not a sterile product; it can be intrinsically, that is before the tin is opened for use, contaminated with bacteria” [4].
  • “Based on available information in 50-80% of cases, powdered infant formula is both the source and the vehicle of E. sakazakii induced illness…mortality rates between 20 and 50 percent had been reported with lasting damage, including neurological disorders, among survivors” [5].
  • “Using current mix technology, it does not seem possible to produce commercially sterile powders or to completely eliminate the potential of contamination” [5].
  • “Although sometimes erroneously believed to be low risk because they are unable to support microbial growth, all of these food matrices remain susceptible to microbial contamination and may pose a risk to consumers. This misconception can lead to manufacturers releasing unsafe products and also inappropriate preparation practices that can render the product unsafe for consumption due to microbial proliferation. An example of the latter includes the storing of reconstituted PIF at room temperature for extended periods of time…Salmonella are one of the most challenging bacteria for food manufacturers, and are a major cause of gastroenteritis. Furthermore, an estimated 155,000 deaths are reported annually due to Salmonella infection. The majority of reported food-borne illness outbreaks related to low-moisture products occur as a result of Salmonella contamination” [6].

To drive this home, I want to clarify that it’s very possible powdered infant formula may be contaminated before you even open it, and can easily be contaminated from the bacteria in your home environment once you open it. This means that no matter how clean your water is, if you add PIF that is contaminated to the water, you’re contaminating the water with the formula. Then, to add insult to injury, once that bacteria hits the water (especially at the temperatures most parents use), the bacteria grows rapidly, and the longer it sits out before you feed your baby, it’s basically a breeding ground for harmful bacteria that could make your baby sick or at the very least very uncomfortable! Gives new insight to fussy/gassy/colicky babies, eh?

Let's hear from an expert, shall we?

Heather Hanson, M.S. is an accomplished infectious disease epidemiologist with over a decade of experience leading outbreak investigations and communicable disease surveillance at the NYC Department of Health and Mental Hygiene.  She has a bachelor’s degree in Biological Anthropology from Harvard University and a Master’s of Science in Public Health and Nutrition from Columbia University.  She also has over 18 publications in infectious disease, including two as first author. Currently, she is living in Toronto, Ontario and working at Public Health Ontario. I asked her to shoot me straight and here’s what she said,

“For Cronobacter, the CDC mentioned 4-6 cases per year. Sure they don’t hear about all cases, but that number is extremely tiny so thus very rare. However a lot of the general messaging about hand hygiene etc. is good to emphasize to parents and caregivers for a whole host of diseases. I found in NYC that more formula fed infants got salmonella than breast-fed. It wasn’t the formula, but cross contamination in the kitchen. We got hundreds of infants with this each year, though rarely fatal. Compared to Cronobacter, which we never heard about in my 10 years there, but clearly scarier if you do. I would emphasize boiled water and hand hygiene” [7].

4-6 deaths a year may be small number, but it doesn't feel like a small issue if it's YOUR baby.

Why is this so dangerous for babies?

The infant’s immune system is not yet fully mature at the time of birth. In the womb, babies are protected by the parent’s immunity; once outside the womb, they have to start developing their own immunity. This happens in a couple of ways:

  1. For babies born vaginally, they are inoculated with their mother’s microbiome found in the naturally occurring bacteria in the secretions of the birth canal. This is like nature’s probiotic. Although babies born via cesarean do not typically have exposure to this microbiome, the relatively new practice of “seeding the microbiome” is one possible way to decrease the susceptibility of babies born via cesarean to potential illness [8].
  2. For babies who are breastfed, breast milk contains tons of antibodies and “good bacteria” that coats the lining of the baby’s gut to initiate the formation of healthy flora to aid in digestion and build the child’s immunity. ANY amount of breast milk your baby gets goes a LONG way in protecting your baby from any kind of bacteria and illness, whether it comes from infant formula or any other source!

Because of this, many sources will state that infants under a certain age or with compromised immune systems should only be fed premixed formula.

How big of a problem is this?

As recently as April 13, 2016, the CDC reported, “Getting sick from Cronobacter does not happen very often, but it is often deadly in young infants. It usually occurs in the first days or weeks of life. Typically, CDC is informed of about 4-6 cases of sickness from Cronobacter in infants each year, but reporting isn't required…” [9]

In one 2008 study from Italy, “sixty-two percent of parents had been instructed on PIF preparation by health professionals, mostly in the hospital; the remaining parents were using the instructions found in the labels to prepare the product…only 11% prepare PIF safely…the fact that just over 10% of 131 parents with a medium to high level of education comply with the safety criteria set by WHO is a matter of concern. On the other hand, how could parents act differently if those were the instructions they got from health professional and/or read in the labels…”

So, while it is a rare occurrence, it is almost completely preventable by the simple act of boiling water before adding PIF in preparation to feed your baby!

Here’s what else I know. Parents have it TOUGH. The early postpartum period, heck ALL of parenting is a whirlwind. For most new parents, it’s a miracle if they remember to brush their teeth and find time to have a decent meal or take a shower let alone remember to wash their hands and sanitize their kitchen properly. Most parents I know can barely squeeze some hand sanitizer on their hands after every diaper change, let alone exercise proper hand washing to insure their hands are clean before reaching into the formula container to scoop out formula. So if you can be 100% positive that all your kitchen surfaces are contaminate free, AND your hands are properly washed AND the bottle you’re mixing the formula in is perfectly sterile, AND the powdered formula is 100% contaminate free, then by all means mix it with water cooler than 158°. But when you think of it that way, isn’t it a quicker fix to just boil the water?

I can hear your complaints, and formula companies have resisted stating drawbacks of potential scalding and that this extra step is too difficult or time consuming for parents. Let me ask you this, are you not already adding extra steps by having to prepare and clean bottles for each feeding for your baby? I timed it. Heating 4oz of water in my electric teakettle took all of one minute and twenty seconds. Is it really that big of a hassle? Seriously, 1.5 minutes to just safeguard against any germs you missed by being human seems like a quick fix to me. You can even mix it with boiled water ahead of time and store in the refrigerator for up to 24 hours to make it easy on yourself.

“The expectation in most societies is that adults can simultaneously manage a source of heat for cooking and keep babies and small children safe from it. Half a century ago when artificial feeding became commonplace in Western countries, parents and even the older children in the family were trusted to manage the complex and heat-intensive process of sterilization. The implication that adults are no longer capable of doing this is patronizing and ludicrous…The technology is not out of range, the skills involved are not difficult to learn and the costs are minimal compared with other public health interventions and treatment of the illnesses that result from contaminated feeds. The necessary and all-too-often missing ingredient is commitment to the highest possible standard of health care and nutrition available for all children everywhere” [5].

Parents, I believe in you. You are totally capable of safely preparing your child’s formula.

So, what are the guidelines? 

The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) agree on the following practices for the safe preparation of powdered infant formula:

  • Clean up before preparation
    • Wash your hands with soap and water
    • Clean bottles in a dishwasher with hot water and a heated drying cycle, or scrub bottles in hot, soapy water and then sterilize them
    • Clean work surfaces, such as countertops and sinks
  • Prepare safely
    • Keep powdered formula lids and scoops clean (be careful about what they touch)
    • Close containers of infant formula or bottled water as soon as possible
    • Use hot water (158° F/70° C and above) to make formula
    • Carefully shake, rather than stir, formula in the bottle
    • Cool formula to ensure it is not too hot before feeding your baby by running the prepared, capped bottle under cool water or placing it into an ice bath, taking care to keep the cooling water from getting into the bottle or on the nipple
    • Before feeding the baby, test the temperature by shaking a few drops on your wrist
  • Use quickly or store safely
    • Use formula within 2 hours of preparation. If the baby does not finish the entire bottle of formula, discard the unused formula.
    • If you do not plan to use the prepared formula right away, refrigerate it immediately and use it within 24 hours. Refrigeration slows bacterial growth and increases safety.
    • When in doubt, throw it out. If you can't remember how long you have kept formula in the refrigerator, it is safer to throw it out than to feed it to your baby [10].

My Quick and Easy Tips:

  1. Purchase an electric teakettle. They are inexpensive, boil water quickly, don’t require a stove that can burn little hands (or big hands) or be accidentally left on by a potentially exhausted parent, AND have an automatic shut off switch once the water boils. That’s like a win, win, win.

  2. Prepare a bowl of ice water. If you’ve ever wanted to cool down some beer bottles quickly, you know that an ice bath is the quickest way to do it. Multitask to make the most of your time by filling up a bowl with ice water while your teakettle is heating up. Then after you shake up the bottle of formula, set it in the bowl and it will cool down to body temperature for your baby to safely drink it in no time!

  3. Purchase steam bags to easily and quickly sterilize bottles, nipples and accessories. This eliminates the whole stove debacle once again. My favorites are the Medela Quick-Clean Micro-Steam Bags.

With those three steps, you’re adding maybe 5 extra minutes to your formula prep routine!

How I Put This Into Action

At a local level, I work with Tulsa Family Doulas as a birth a postpartum doula, childbirth educator, lactation counselor and placenta encapsulation specialist. As stated above, I have no vested interest in how my clients choose to birth and parent their babies; however, I am passionate about doing everything I can to equip my clients with comprehensive and accurate information. It’s my belief there are many times parents make what they believe are well-educated decisions, when in fact they are ill informed. My heart breaks when I hear parents say, “If I had known xyz, I would have done things so differently,” and this vital information about safe formula feeding is one of those categories! 

I’m proud that the doula agency through which I serve families is committed to the highest standards of care for Tulsa families. My clients may make any choice they wish, and when I am in their homes, if they make the choice to nourish their babies with commercial formula, I will not only support them, but I will do everything I can to assist and support them in safely feeding their babies and preventing illness.


  1. Breastfeeding. (2015, January 14). Retrieved March 09, 2017, from http://onlinelibrary.wiley.com/doi/10.1111/1552-6909.12530/full

  2. About. (n.d.). Retrieved March 09, 2017, from https://fedisbest.org/about/

  3. Leggiadro, R. J. (2010). Cronobacter Species Isolation in Two Infants—New Mexico, 2008. The Pediatric Infectious Disease Journal,29(2), 114. doi:10.1097/inf.0b013e3181cb86c9
  4. Carletti, C., & Cattaneo, A. (2008). Home preparation of powdered infant formula: is it safe. Acta Pdiatrica,97(8), 1131-1132. doi:10.1111/j.1651-2227.2008.00846.x
  5. Hormann, E. (2010). Reducing the Risk for Formula-Fed Infants: Examining the Guidelines. Birth,37(1), 72-76. doi:10.1111/j.1523-536x.2009.00381_1.x
  6. Finn, S., Condell, O., Mcclure, P., Amézquita, A., & Fanning, S. (2013). Mechanisms of survival, responses and sources of Salmonella in low-moisture environments. Frontiers in Microbiology,4. doi:10.3389/fmicb.2013.00331
  7. Hanson, H. (2016, August 22). Personal interview August 22, 2016.
  8. Dominguez-Bello, M. G., Jesus-Laboy, K. M., Shen, N., Cox, L. M., Amir, A., Gonzalez, A., . . . Clemente, J. C. (2016). Partial restoration of the microbiota of cesarean-born infants via vaginal microbial transfer. Nature Medicine,22(3), 250-253. doi:10.1038/nm.4039
  9. Learn About Cronobacter Infection. (2016, April 13). Retrieved March 08, 2017, from https://www.cdc.gov/features/cronobacter/
  10. World Health Organization. (2007). Safe preparation, storage and handlingof powdered infant formula Guidelines. Source: http://www.who.int/foodsafety/publications/micro/pif_guidelines.pdf