A plain-language guide to a scary-sounding topic, with expert context from food safety scientist Dr. Kathy Glass.
If you have come across headlines about botulism and infant formula, you probably felt your stomach drop. When it comes to feeding a baby, these headlines land hard. So let us slow down and walk through what botulism actually is and how it relates to babies.
We sat down with Dr. Kathy Glass, a food safety scientist with more than 40 years of experience and one of the few people in the United States who has spent a career working with the bacteria behind botulism. Her message up front is the one worth holding onto.
“The sky is not falling. Infant formula is a really, very safe product.”Dr. Kathy Glass, University of Wisconsin–Madison
Here are all of your questions, answered in one place.
If you’re here because of a recent recall (updated June 2026)
If you landed here worried about a specific product, take a breath. As of June 2026, two infant formula recalls have been in the news. In June 2026, Nara Organics recalled all lots of its Whole Milk Organic Powdered Infant Formula after three infants were hospitalized with infant botulism. It followed the late-2025 recall of all ByHeart Whole Nutrition Infant Formula, which was linked to about 48 cases across 17 states. In both, the affected babies were hospitalized and no deaths have been reported.
If you have a recalled formula at home:
- Stop using it right away and switch to another brand. You do not need to wean gradually, and most babies do fine switching right away when needed.
- Save the can and photograph the lot number before storing it. Your health department may want to test it.
- Wash anything that touched the formula in hot soapy water or the dishwasher.
- Watch for early signs: constipation, weak feeding or sucking, a weaker cry, drooping eyelids or loss of head control. Call your pediatrician right away if you notice them.
Infant botulism is rare and treatable, and nearly all babies recover fully with prompt care. For the latest, the FDA and CDC outbreak pages are the source of truth, and your pediatrician is your best resource for your own baby.
What is botulism?
Botulism is a rare but serious illness caused by a toxin produced by a bacterium called Clostridium botulinum. The bacterium itself is common in the natural environment. The problem is not the bacterium sitting quietly. The problem is when it grows and produces its toxin, which can affect the nervous system.
Infant botulism is a specific version of this. It happens when the spores of Clostridium botulinum are swallowed by a baby, then settle and grow inside the baby’s gut and produce that toxin. In older children and adults, this almost never happens, and we will explain why below.
What are spores?
This is the part that sounds frightening and actually isn’t. A spore is simply the inactive, dormant form of a bacterium. Think of it like a seed.
“Spores might sound like the scary thing, but actually what they are is just an inert or inactive form of a regular bacteria.” Dr. Kathy Glass
Dr. Glass compares a spore to a bean. You can leave a dried bean outside through freezing temperatures, and nothing happens. Plant it the next spring with water, sunlight and nutrients, and it germinates into a plant. A bacterial spore behaves the same way. On its own it is harmless and stable. Put it in the right conditions and it can wake up, grow and, in the case of Clostridium botulinum, produce toxin.
It is also worth knowing that not all spores are bad. Some spore-forming bacteria are the good guys. Certain probiotics are spore formers that we actually want to germinate and grow in our gut. Spores are a normal part of the living world, not an automatic red flag.
Where do botulism spores come from?
Everywhere, essentially. Clostridium botulinum is found naturally in soil and sediment on every continent, and it turns up in dust, dirt and animal digestive systems. It is part of the environment we all live in.
“Microbes were here before we existed and will be here after we’re long gone.” Dr. Kathy Glass
The single most common known source of infant botulism worldwide is honey, which is exactly why honey is not recommended for babies under one year old. Other cases are linked to environmental exposure, like dirt and dust. Even so, the bacterium is relatively rare compared to the thousands of harmless microbes around it. As Dr. Glass put it, for every Clostridium botulinum out there, there may be a thousand other harmless clostridia.
How do babies get botulism?
A baby gets infant botulism by swallowing the spores, which then grow inside the gut. The most documented route is honey before 1 year of age. Environmental exposure, such as soil and dust, can also play a role. Babies explore the world with their hands and mouths, so some exposure is simply part of being a baby.
The reassuring context: there are fewer than 200 cases of infant botulism a year in the entire United States. When you consider how many babies are crawling on floors, dropping pacifiers and putting things in their mouths every single day, that number tells you how uncommon this actually is. Exposure is normal. Illness is rare.
Why are babies more vulnerable to botulism than adults?
The answer comes down to the gut. A newborn’s digestive system has not yet built up the community of microbes, the microbiome, that protects the rest of us. Over the first months of life, as a baby is exposed to caregivers, the environment and new foods, that protective microbiome develops.
Once it is established, swallowed spores have nowhere to take hold. They cannot compete with everything already living there, so they simply pass through. That is why adults are not at risk.
“You and I can drink honey in our tea that might have botulinum spores in it, and we’re just fine. However, if we gave that same honey to a one-month-old infant, they might not be fine.” Dr. Kathy Glass
At what age does botulism stop being a risk for babies?
Risk is highest in the first three to four months of life, when the microbiome is least developed. It drops steadily as a baby grows, and becomes very low as they approach their first birthday. After one year, children are generally considered safe, which is the same milestone behind the no-honey-before-one guidance.
This is also a reason a varied diet matters once a baby is ready for solids. Exposure to a range of foods helps build a diverse, resilient gut. Dr. Glass suggests a little caution with root vegetables early on, since foods grown in the soil are more likely to carry spores, and leaning on a wide variety of fruits and vegetables as a baby grows.
Can botulism spores survive pasteurization?
Yes, and this surprises a lot of people. Pasteurization is excellent at killing the harmful bacteria we worry about most, which is exactly why milk and infant formula are pasteurized. But spores are built to survive harsh conditions. They can make it through pasteurization, through the spray-drying step that turns formula into powder, and they can persist for years.
That does not mean formula is unsafe. It means a single step is not the whole safety story. Which brings us to testing.
What is SRC testing?
SRC stands for sulfite-reducing clostridia. It is a broad group of bacteria that includes, but is not limited to, Clostridium botulinum. Testing for the whole group works as an early-warning system. You are not necessarily finding botulinum itself, you are checking whether the broader family is showing up at levels that warrant a closer look.
Dr. Glass uses two everyday analogies. The first is a turn signal: when the car ahead of you flicks it on, you adjust, even though a signal is not a guarantee. The second, and maybe the most useful, is a smoke detector.
“Think of this as being a smoke detector. Just because your smoke detector goes off does not necessarily mean your house is on fire, but it does mean there’s smoke that may be coming in.” Dr. Kathy Glass
Looking for Clostridium botulinum directly is, in her words, a needle-in-a-haystack search. It can be present but so erratic that you test and test and never find it, and a negative result on one container does not promise the same for the next. Testing the broader SRC group casts a wider, more reliable net, and far more labs are equipped to run it, which keeps testing achievable and costs down.
What does an SRC test result actually mean?
About 15 years ago, the working benchmark was a level of 100 colony-forming units (CFU) per gram. Recent events and new research have pushed that thinking lower. Many infant formula makers are now moving toward 10 CFU per gram or below.
A higher reading does not automatically mean a product is unsafe. Dr. Glass notes that products with higher numbers have not been linked to illness. But low numbers do indicate a product is more likely to be safe, and the encouraging news from current research is that most formula on the market is testing very clean, often well under 10 CFU per gram.
Why testing alone is not enough
Here is the part Dr. Glass returns to again and again: a test is one piece of a much bigger system. Safety is built at every step, not bought with a single lab result.
“Everybody plays a role, every step of the process, from farm to bottle.” Dr. Kathy Glass
It starts on the farm with milk hygiene, cleaning udders, reducing places for microbes to collect, cooling milk quickly and moving it to pasteurization fast. It continues with manufacturers choosing quality ingredients, holding suppliers to standards and testing consistently. And it ends in the kitchen with the people preparing the bottle.
What can parents do at home to prepare formula safely?
The caregiver is the final, important step in the chain. A few simple habits cover it:
- Follow CDC preparation guidance. Using very hot water is can sometimes be recommended to kill other microbes like Cronobacter. Note that this step is not about botulinum spores, it is about other risks.
- Cool it, then use it promptly. Do not let prepared formula sit out for long stretches, which can give any spores a window to grow.
- Refrigerate right away and keep the fridge cold. Dr. Glass recommends keeping a thermometer in the refrigerator and holding it at 40°F or below.
- No honey before one year. The single clearest rule, since honey is the most common known source of infant botulism.
How Little Spoon thinks about all of this
Most food safety testing happens behind closed doors. Parents rarely get to see what a brand tests for, what limits it holds itself to, or what the results actually were. We think that is backwards.
- There is no worldwide standard yet for Clostridium botulinum in infant formula, and the science is still developing. So we set a voluntary standard for our infant formula that is ten times more stringent than the long-standing benchmark.
- We are also funding independent research at the University of Wisconsin–Madison to help build the baseline data this whole category has been missing.
- And we put the results where parents can see them. Our infant formula testing hub shows what we screen for, including heavy metals, pathogens, toxin-producing and spore-forming bacteria, hygiene indicators, pesticides, glyphosate and plasticizers, along with the standard each one has to meet to pass. Because saying you test is not the same as showing your work.
“Transparency is a way to build trust. I want to know that they aren’t just testing for testing’s sake, but they really do have a passion for the safety of their consumers.” Dr. Kathy Glass
That is the whole idea behind how we communicate hard topics. Facts over fear. The goal is never to scare you. It is to hand you the information so you can make the calls that feel right for your family.
About Dr. Kathy Glass
Dr. Kathy Glass is a Distinguished Scientist Emeritus at the University of Wisconsin–Madison Food Research Institute, where she spent more than 40 years specializing in food safety. She grew up on a small dairy farm in north central Wisconsin, which gave her an early, firsthand understanding of where food comes from, before earning her master’s degree and building a career studying foodborne pathogens across nearly every kind of food product.
She is one of the few researchers in the United States with deep experience in Clostridium botulinum, the bacterium behind botulism. She has served as co-chair of the National Advisory Committee for Microbiological Criteria for Foods, including its work on Cronobacter in powdered infant formula, sat on the executive board of the International Association for Food Protection, and chaired an FAO working group of worldwide experts on clostridia that examined infant botulism. Little Spoon is grateful for her guidance in bringing our infant formula to market and for sharing her expertise with our community.
