
A Rare Disease With a Strange Mechanism
Infant botulism is rare, and it does not work like the botulism most people have heard of. In foodborne botulism, an adult eats food, often badly home-canned vegetables, in which the bacterium Clostridium botulinum has already produced its toxin. Botulinum toxin is one of the most lethal substances known. It blocks the signals between nerves and muscles, and it paralyzes from the top down.
In infant botulism, the baby does not swallow the toxin. The baby swallows the spores of the bacterium, which are tough, dormant forms that survive drying, heat, and time. In an adult’s gut, the spores pass harmlessly through, crowded out by mature intestinal bacteria. In a young infant’s gut, which has not yet developed those defenses, the spores can germinate and multiply. The baby’s own intestine becomes the place where the toxin is made.
The signs come slowly and then quickly. Constipation is often first. Then come weak sucking, poor feeding, a soft or altered cry, drooping eyelids, a flat face, and a body that goes limp, the classic “floppy baby.” In the worst cases, the muscles that control breathing fail, and the baby needs a ventilator. Because the early signs look like so many ordinary infant problems, the disease is easy to miss.
There is a treatment, and it works. BabyBIG, an antitoxin made from human plasma, neutralizes toxin still circulating in the blood. In a California trial, it cut the average hospital stay from 5.7 weeks to 2.6. But it cannot undo the toxin already bound to nerves. Those nerve endings have to regrow, and that takes weeks. Babies need feeding tubes, intensive care monitoring, and often months of physical, occupational, and feeding therapy afterward. In the ByHeart outbreak, CDC’s preliminary data found that about two-thirds of the infants evaluated needed physical therapy or feeding support after they left the hospital.
Most cases of infant botulism are isolated. Spores live in soil and dust everywhere, and in most cases no source is ever found. The one well-known food source is honey, which is why pediatricians tell parents never to give it to a baby under a year old. For decades, surveys of commercial dried milk and infant formula almost never found C. botulinum.
That is why, when the outbreak investigation was over, the numbers were so striking. Public health officials counted 48 infants, 28 confirmed and 20 probable cases, in seventeen states, from Arizona to Rhode Island. Every one of the 48 babies was hospitalized. No baby died. The earliest illness onset was December 24, 2023. The last was November 29, 2025.
“The More You Control the Process”
ByHeart was founded in 2016 by a brother and sister, Ron Belldegrun and Mia Funt. Belldegrun, who came from venture capital and hedge funds, became chief executive. Funt, who came from marketing and business development, became president. They raised hundreds of millions of dollars from investors. In the spring of 2025, a financing round valued the company at more than $900 million. Before the recall, ByHeart sold roughly 200,000 cans a month at about $42 a can.
The founders built their brand on control. Instead of hiring an established contract manufacturer, ByHeart bought its own plants: a factory in Reading, Pennsylvania, converted from toddler food to infant formula for $21.6 million; a plant in Allerton, Iowa, bought in January 2023 from a subsidiary of Dairy Farmers of America; and a blending and canning plant in Portland, Oregon.
They talked about that control constantly. In June 2021, before ByHeart sold its first can, Belldegrun told Fast Company: “We believe that the more you control of the process, the more you control the quality of the formula.” At launch in March 2022, Funt told Forbes that ByHeart had “acquired our own manufacturing facility, sourced every ingredient, and applied rigorous quality standards, from farm to formula,” and that she was proud the company had kept its promise of “no shortcuts and no compromises.”
The founders made the same promises directly to parents on ByHeart’s Instagram account. In December 2021, the company posted a quote from Funt telling parents that “every parent deserves to feel confident when feeding baby.” In June 2022, standing in the Reading plant with Pennsylvania’s governor, Funt said the founders had set out “to own our supply chain — own and oversee our supply chain,” which “meant acquiring our manufacturing facility, hand-selecting every ingredient.” In a March 2025 video, she told parents that it took “nine months to go through our rigorous ingredient selection process” and that ByHeart ran “over a thousand tests on our ingredients and throughout every step of the process” for “contaminants and heavy metals and bacteria.” “What really matters,” she said, “is the testing protocols.”
In June 2025, Belldegrun made the same point on camera: “We own our supply chain, we own our manufacturing, and we directly handpick all of our ingredients.” He promised “incredibly rigorous testing — like, every step, from the ingredients, to while we’re running, to before we release product.” He also explained why the stakes were so high. For a baby who is not breastfed, he said, formula “is the only nutrition that a baby consumes in that first year of life, when all of their systems are developing.”
That idea, that formula is a baby’s sole source of nutrition, is the reason infant formula is held to a higher standard than any other food. It is also the foundation of the families’ cases.
The Ingredient
What set ByHeart apart was its milk. Most formulas are made from skim milk, with vegetable oils added for fat. ByHeart used organic, grass-fed whole milk. Belldegrun promoted the choice in a June 2025 op-ed and took credit for it in his video: “Prior to our work, you could only use skim milk here.”
The whole milk powder came through a brokered supply chain. According to the complaints, liquid whole milk from about twenty organic dairies was delivered to a Dairy Farmers of America plant in Fallon, Nevada, and spray-dried into powder. Organic West Milk, acting as a broker, sold the powder to ByHeart and shipped it to the Allerton plant, where it went into the base mix for the formula.
Powdered infant formula is not sterile. Pasteurization and spray-drying kill Salmonella and Cronobacter, the bacteria the formula industry usually worries about. They do not reliably kill C. botulinum spores, which are built to survive heat. Spores are common in soil, manure, bedding, and silage, and they can travel from those places to a cow’s udder and into the milk tank. On organic dairies, where cows spend time on pasture, weather can make that more likely.
The complaints allege that ByHeart never required testing for C. botulinum in its whole milk powder, its base powder, or its finished formula before release. Finished lots were tested for Cronobacter, Salmonella, Listeria, Staphylococcus, E. coli, and Bacillus cereus, but not for botulism. ByHeart relied instead on a general indicator test for “sulfite-reducing clostridia,” a broad family of related bacteria. That test could not do the job. ByHeart later reported that every sample in which its lab detected C. botulinum by genetic testing, 33 in all across finished product, base powder, and ingredients, had indicator counts below the level that would have raised a flag.
None of this was unknowable. In 2003, the international food standards body known as Codex named C. botulinum among the pathogens of concern that may be present in powdered infant formula. A 2010 study by California’s infant botulism program found spores of related clostridia in seven of nine unopened, store-bought powdered formulas. In March 2023, the FDA wrote to every formula maker warning that ingredient suppliers are an extension of the manufacturing process and that the historical links between powdered formula and Clostridium botulinum “should be considered when designing and implementing controls.” At least one major competitor, Mead Johnson, the maker of Enfamil, has said it tests every lot of its dairy ingredients for infant botulism contamination.
The Clean Label Project “Purity Award” that ByHeart displayed on its cans, and that Funt cited when she told parents in a November 2024 video that ByHeart was made with “certified-clean ingredients,” never involved testing for pathogens like the one that causes infant botulism.
Warning Signs
ByHeart’s own history, as described in FDA records, showed trouble long before the outbreak.
In July and August 2022, months after launch, ByHeart’s contract laboratory repeatedly found Cronobacter sakazakii in the processing environment of the Reading plant. In October, the same bacterium turned up in a batch of finished formula made with Reading base powder. ByHeart’s own analysis blamed lab error. The laboratory rejected that conclusion, writing that “laboratory error was not found or supported.”
In December 2022, ByHeart recalled five batches. Belldegrun and Funt sat side by side in a video posted to Instagram. Belldegrun told parents that the company had built its own plant in Reading “to be accountable to quality,” that “we own our entire manufacturing supply chain, except for final packaging,” and that the recall was “not related to ByHeart’s own manufacturing facility in Reading, Pennsylvania, in any way.” The company blamed a third-party packager. It told parents whose babies had already finished the recalled formula that there was “no reason for concern.”
The FDA saw it differently. In August 2023, it sent ByHeart a Warning Letter, addressed to Belldegrun. The FDA found that ByHeart had not done the investigation needed to eliminate the hazard, had not compared the genetic fingerprints of the bacteria from its plant and its product, and had let potentially contaminated formula reach customers without notifying the agency.
The problems continued. When FDA investigators returned to Reading in December 2023 and January 2024, they found mold in a tank meant to hold clean water, a leaking roof, flies over a sensitive production area, and more than 2,500 dead insects near light traps. The plant had also broken its own rules on the temperatures needed to kill bacteria in the formula base. The FDA gave the inspection its most serious classification, “Official Action Indicated.” At Allerton in February 2025, investigators found twelve Cronobacter positives in environmental samples over thirteen months, rusted surfaces, peeling epoxy, and repeated rodent activity. They also found that ByHeart had more than once released an ingredient from a shipment that showed rodent excreta and torn bags. ByHeart’s senior food safety director told the FDA that rodents were not a food safety concern because the process had a “kill step.” The kill step, the complaints point out, does not kill botulism spores.
ByHeart was also hearing from parents. Between April 2024 and March 2025, according to FDA records, ByHeart received 3,247 complaints, 2,167 of them health-related. At least seven reported infants diagnosed with Salmonella. ByHeart closed each of the investigations after a records review.
After each of these findings, the families allege, Belldegrun and Funt decided to keep producing and selling formula without changing how ByHeart qualified or tested its dairy ingredients for spore-forming bacteria.
The Recall
The California program’s alert in October 2025 set off an investigation by the FDA, the CDC, and state health departments. On November 7, the FDA asked ByHeart to recall two lots of formula. ByHeart announced the recall the next day.
In its November 8 press release, ByHeart quoted Funt: “The safety and well-being of every infant who uses our formula is our absolute highest priority.” The release also said that “no ByHeart product has tested positive for any contaminants” and that “botulism is extremely uncommon in dairy products or infant formula.” The company called the recall a step taken out of “an abundance of caution.”
That weekend, Funt recorded a video for parents and posted it on ByHeart’s social media. “There is no reason to believe that infant formula can cause infant botulism,” she said, “and multiple regulatory bodies such as Codex have come to this conclusion.” She said that “the FDA has never found a direct connection between infant formula and infant botulism, and no related toxin has been found in ByHeart.” ByHeart, she said, was committed to “real transparency, real safety.” ByHeart later deleted the TikTok version of that video. Codex had concluded no such thing. More than twenty years earlier, it had named C. botulinum among the pathogens of concern in powdered infant formula.
On November 9, after the California Department of Public Health reported C. botulinum in an opened can fed to a sick baby, the founders published an update to families signed “Mia & Ron.” It said that testing an opened can “lacks scientific basis to establish causation,” and that “no U.S. or global infant formula company tests for Clostridium botulinum.” The families allege that statement was false, because Mead Johnson had been testing its dairy ingredients for years. “We, along with our own families, friends, and team members, use ByHeart every day,” the update said, “and continue to do so.”
On November 10, the FDA asked ByHeart to recall everything. On November 11, ByHeart announced a recall of all its products, while again stressing that “no unopened ByHeart product has tested positive.” The same day, ByHeart posted on Instagram recommending another organic whole-milk formula, Nara Organics, and offering its customers a 20 percent discount code to help them switch. That post was later deleted too.
By November 19, ByHeart’s own testing had found C. botulinum in five of 36 unopened cans from three lots. On December 3, six samples of ByHeart formula tested positive, and they came from two batches: 251261P2 and 251131P2. Those were the batch numbers printed on the two opened cans that A.B.’s parents had handed to California health officials in early November. Their third can, from batch 251131P2 and still sealed, remains in their possession.
What the Science Found
Through the winter, the investigators followed the genetic trail. Whole-genome sequencing, which reads an organism’s entire DNA, can show whether bacteria from a sick child, a can of formula, and a factory ingredient are the same strain. In the ByHeart investigation, the trail led back to the milk.
The FDA collected samples of organic whole milk powder at Dairy Farmers of America, the processor for Organic West Milk, which supplied ByHeart. Two isolates from one lot of that powder matched a cluster that included a sick infant, an unopened can of ByHeart formula, a sealed can tested by New York’s Wadsworth Center, and isolates from milk powder that ByHeart itself had tested. Other clusters linked sick babies to opened cans, to finished formula, and to the base powder used to make it. The FDA inspected all three ByHeart plants and found no facility problem that could explain the outbreak. Its root-cause investigation turned to incoming ingredients, especially the dairy supply chain.
The FDA has been careful. It has said that testing for C. botulinum is complex, that sequencing has identified seventeen different strains across patient, product, and ingredient samples, and that it has not formally declared a root cause. The complaints acknowledge that. But they point out that for decades, surveys almost never found C. botulinum in commercial dried milk or formula. This time it was found in the ingredient, in the base, in finished formula, and in babies in seventeen states.
On February 26, 2026, the CDC declared the outbreak over: 48 babies, all hospitalized, none killed.
Four months later, it happened again. In June 2026, the FDA and CDC opened a second infant botulism investigation, this one tied to Nara Organics whole-milk formula, the same brand ByHeart had pointed its customers toward. Four babies in California, Pennsylvania, and Washington were confirmed with type A botulism. C. botulinum was found in an open can of Nara formula fed to one of them. Nara and ByHeart shared the same dairy suppliers: Organic West Milk and Dairy Farmers of America. Genetic sequencing matched a Nara case to a ByHeart case, to ByHeart base powder, and to four unopened ByHeart cans.
In July 2026, the FDA wrote to the entire infant formula industry. It said a manufacturer’s responsibility for safety extends to every ingredient, every supplier, and every link in the supply chain. It said its investigation had found Clostridium botulinum contamination in a dairy-based ingredient linked to both formulas. The agency, along with international food safety bodies, began a formal review of spore-forming bacteria in powdered infant formula.
ByHeart changed its testing. In a letter signed “Ron & Mia,” the founders wrote that “we now know that the existing safeguards are insufficient,” and committed to testing every batch of finished formula and its supply chain for C. botulinum. In August 2026, ByHeart announced “new testing protocols specifically designed to detect C. botulinum in dairy ingredients and finished infant formula.” That testing, the families argue, was always possible, and nothing stopped the company from doing it before it sold its first can.
After
The families have sued ByHeart, the companies that supplied and processed its milk powder, and the stores that sold it to them. The FDA sent warning letters to four major retailers, including Target, after recalled ByHeart formula stayed on store shelves for weeks. In Arkansas, state inspectors found recalled ByHeart “anywhere pack” sticks on a Target shelf under a “Sale!” sign. Now the families are amending their complaints to add Belldegrun and Funt personally.
They allege that the founders made the decisions that mattered: choosing the ingredient, approving the suppliers, setting the testing program, continuing production after each warning, and deciding what to tell parents when the outbreak came. They also allege that the founders left ByHeart with only $10 million in products liability insurance, coverage that shrinks with every dollar spent defending the company, for a business that raised more than $330 million and sold formula to babies nationwide. In October 2026, a spokesperson for the founders’ new company, MeridianMade, said ByHeart had been discontinued and would not relaunch. MeridianMade, led by Belldegrun and Funt, has agreed to buy Perrigo’s infant formula business for up to $175 million.
Some facts are not in dispute. Forty-eight babies were hospitalized. The formula their parents chose was marketed as the cleanest and safest they could buy. The milk in it carried a bacterium that is rare in dried milk but has been known for decades to be a risk in infant formula. And during those years, nobody at ByHeart was testing for it.
“For parents who can’t or choose not to breastfeed,” Belldegrun said in June 2025, five months before the recall, “this is the only nutrition that a baby consumes in that first year of life, when all of their systems are developing.”
He was right. That is why what happened matters.
And, you have to love social media.
1. Funt on TikTok, the weekend the outbreak was announced (November 2025)
“There is no reason to believe that infant formula can cause infant botulism, and multiple regulatory bodies such as Codex have come to this conclusion… no related toxin has been found in ByHeart.”
It was posted as babies were being hospitalized. Within days ByHeart recalled everything, and C. botulinum was found in opened and unopened ByHeart cans. Codex said the opposite: it flagged C. botulinum in powdered formula in 2003. ByHeart then deleted the video. That’s three problems in one statement: it was false, it misrepresented a regulator, and it was taken down.
2. The founders’ “Update for Families,” signed “Mia & Ron” (November 9, 2025)
“No U.S. or global infant formula company tests for Clostridium botulinum.”
“We, along with our own families, friends, and team members, use ByHeart every day—and continue to do so.”
The first line was false. Mead Johnson (Enfamil) tests every lot of its dairy ingredients for infant botulism contamination. The second line told parents it was safe to keep feeding ByHeart. The FDA had it recalled the next day, and ByHeart announced that recall on November 11.
3. Funt on Instagram (March 21, 2025)
“It takes nine months to go through our rigorous ingredient selection process… We have over a thousand tests on our ingredients… for unwanted things like contaminants and heavy metals and bacteria.”
“What really matters is the testing protocols.”
She held up testing as the standard to judge ByHeart by. None of those thousand tests was for C. botulinum, and the ingredient selection process she was praising approved the milk powder that carried it.
4. Belldegrun on Instagram (June 5, 2025)
“We own our supply chain, we own our manufacturing, and we directly handpick all of our ingredients.”
“Incredibly rigorous testing — like, every step, from the ingredients… to before we release product.”
The CEO says on camera that he personally picked the ingredients, which is direct proof of personal participation. He promises testing at “every step” five months before the recall, and the testing never looked for the hazard.
5. “Ron & Mia” letter after the outbreak (January 2026)
“We now know that the existing safeguards are insufficient.”
They admitted the safeguards failed and committed to C. botulinum testing they could have done from the start.
6. Belldegrun in the December 12, 2022 recall video
“We own our entire manufacturing supply chain, except for final packaging. This recall is not related to ByHeart’s own manufacturing facility in Reading, Pennsylvania, in any way.”
ByHeart’s own lab had found Cronobacter at Reading that summer. The lab rejected ByHeart’s “lab error” explanation, and the FDA’s Warning Letter to Belldegrun said ByHeart hadn’t done the investigation needed to eliminate the hazard. This shows a pattern: blame someone else and tell parents not to worry.
7. Belldegrun on control (Fast Company, June 2021)
“We believe that the more you control of the process, the more you control the quality of the formula.”
Funt said the same thing at launch: “the more you control the process, the more you can control the quality of the product” and “no shortcuts and no compromises.” These close off the “we didn’t know what our supplier was doing” defense.
8. Funt on Instagram (November 8, 2023)
“The ingredients are tested before they even ever enter the facility… there’s no rushing this and no shortcuts, ever.”
“Bacteria is something that naturally exists in the environment.”
She vouched for ingredient testing that didn’t cover the risk, and she acknowledged that environmental bacteria were a known risk.
9. Belldegrun during the 2022 formula shortage (Fox Business)
“This is a category where we cannot make mistakes.”
10. Belldegrun on Instagram (June 2025)
“For parents who can’t or choose not to breastfeed, this is the only nutrition that a baby consumes in that first year of life, when all of their systems are developing.”
Sources
- FDA, Outbreak Investigation of Infant Botulism: Infant Formula (November 2025)
- CDC, Infant Botulism Outbreak Linked to Infant Formula, November 2025
- CDC, Investigation Update: Infant Botulism Outbreak, November 2025
- FDA, Post-Outbreak Response Activities: Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula
- FDA, FDA’s Actions to Respond to Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula
- FDA, Outbreak Investigation of Infant Botulism: Powdered Infant Formula (June 2026)
- FDA, FDA Calls on Infant Formula Industry to Better Safeguard Against Contaminants (July 2026)
- FDA, Warning Letter to ByHeart, Inc. (Aug. 30, 2023)
- Wadsworth Center, Biodefense Laboratory Identifies Contamination Source in Multistate Infant Botulism Outbreak
- CDC, Infant Botulism: Clinical Overview
- CDC, EIS Conference Abstract: Infant Botulism Outbreak Caused by Powdered Infant Formula
- NEJM Evidence, Multistate Infant Botulism Outbreak Associated with Powdered Infant Formula (2026)
- Journal of Pediatrics, Clostridial Spores in Powdered Infant Formula (2010)00070-3/fulltext)
- ByHeart Press Release (Nov. 8, 2025)
- ByHeart Press Release, ByHeart Broadens Voluntary Recall While Investigation Continues (Nov. 11, 2025)
- STAT, ByHeart Response to Infant Formula Botulism Outbreak Draws Criticism (Nov. 14, 2025)
- Fast Company, Can This Startup Engineer a Better Baby Formula? (June 1, 2021)
- Forbes, ByHeart’s Mia Funt on the Launch of Its Next-Generation Infant Formula (Mar. 23, 2022)
- RealClearHealth, Ron Belldegrun, Beyond the Bottle (June 3, 2025)
- Senate HELP Committee, Letter to ByHeart on Infant Formula Recall (Dec. 18, 2025)
- ByHeart Update: FDA Confirms Review of ByHeart’s Root Cause Investigation and Action Plan (Aug. 28, 2026)
- Healthbeat, Nara Baby Formula Recall, Botulism Cases Raise Safety Oversight Questions (June 15, 2026)
- ByHeart’s Instagram and TikTok videos and posts quoted above (Dec. 14, 2021; June 3, 2022; Dec. 12, 2022; Nov. 19, 2024; Mar. 21, 2025; June 5, 2025; Nov. 2025), transcribed by Marler Clark.













