Need to Know

• The 2025–2026 ByHeart and Nara Organics infant botulism outbreaks exposed knowledge gaps and prompted new consideration of Clostridium botulinum as a powdered infant formula hazard
• Roundtable participants called for prevalence research across dairy farms, ingredient supply chains, and finished infant formula to better understand where C. botulinum spores are introduced or concentrated
• Limitations of traditional testing were discussed, as trace levels of C. botulinum spores may go undetected while still posing a risk to infants
• Participants called for validated preventive controls throughout dairy production, ingredient processing, and formula manufacturing, alongside improved industry data-sharing
• Participants also urged FDA to provide guidance on fit-for-purpose C. botulinum testing and thresholds.

The meeting occurred amid rapidly evolving understanding of C. botulinum as a powdered infant formula hazard. Prior to November 2025, the pathogen had not been demonstrated to cause outbreaks of infant botulism through its presence in infant formula. Since then, the outbreaks linked to ByHeart and Nara Organics formulas have challenged longstanding assumptions about the hazard and highlighted gaps in testing, prevalence data, and supply chain controls.

Roundtable participants emphasized the need for prevalence research, more sensitive and standardized C. botulinum testing, data-sharing, validated preventive controls, and coordinated action across the dairy and infant formula supply chains.

ByHeart, Nara Outbreaks Changed Understanding of C. botulinum Risk

The ByHeart and Nara outbreaks ended in February and August 2026, respectively. Investigations discovered that both companies had formulated their products using organic powdered whole milk supplied by Organic West Milk (OWM) and processed by Dairy Farmers of America (DFA). The powdered milk ingredient tested positive for the outbreak strain of C. botulinum, which whole genome sequencing (WGS) matched to clinical isolates from the Nara and ByHeart outbreaks, as well as ByHeart ingredient and finished-product samples.

Based on these findings, in combination with supply chain evidence, FDA concluded that the OWM/DFA powdered milk ingredient was the common source of contamination in both outbreaks. The agency has not yet determined whether contamination occurred before or during milk drying, however.

Against this backdrop, the Reagan-Udall roundtable was convened to establish a shared understanding of recent outbreak findings and research, identify factors that may increase C. botulinum risk, and explore improvements to preventive controls and testing.

Major Gaps Remain in Understanding C. botulinum Prevalence

One of the report's central conclusions was that significant knowledge gaps remain regarding the prevalence of C. botulinum throughout the infant formula supply chain.

Participants called for an initial assessment of prevalence on farms, throughout ingredient supply chains, and in finished products. Such information could help determine where spores are introduced or concentrated and where interventions would be most effective.

Among the unanswered questions identified by participants were the effects of regional, environmental, and climate conditions on C. botulinum prevalence; conditions that could allow low spore levels to increase; and whether changes in the powdered infant formula ecosystem, including changes in milk sources and ingredients, could affect contamination risk. Participants also considered potential farm-level contributors to bacterial spore loads in raw milk and possible processing interventions.

ByHeart Investigation Demonstrated Limitations of SRC Testing

Testing was another major focus of the report. Roundtable participants noted that there is no standardized industry method for detecting C. botulinum or its spores in infant formula, and relatively few laboratories can conduct such testing because of the biosecurity requirements associated with the organism and its neurotoxin.

Importantly, the report stated that findings from the ByHeart and FDA investigations showed that trace amounts of C. botulinum spores can occur at levels too low to be detected using traditional direct-plating sulfite-reducing clostridia (SRC) methods—considered to be the industry “gold standard”—while still being sufficient to cause illness in infants. Participants called for guidance on when enrichment SRC, polymerase chain reaction (PCR), and/or WGS should be used.

The shortcomings of SRC testing were evidenced through the Nara Organics outbreak. The company had already implemented the method prior to infants falling ill from its product. Nara reportedly tested raw ingredients, in-process formula powder, and finished packaged products to an SRC specification ten times stricter than international guidance; yet, this testing program still failed to prevent the outbreak.

Importantly, rather than recommending reliance on finished-product testing, roundtable participants stressed that testing alone cannot ensure infant formula safety, particularly when contamination is non-homogeneous and occurs at very low levels.

Calls for Better Data Collection and Sharing 

Other recommendations addressed data-sharing. Participants said there is limited understanding of how frequently C. botulinum has been detected across supply chains and manufacturing operations, and no centralized repository currently exists for such data.

The report recommended exploring the use of a trusted third party to house and safeguard industry data, supported by governance and confidentiality protections. Participants also called for greater sharing of both positive and negative testing results, as well as contextual information explaining why testing was conducted and which methodologies were used.

The Need for Validated Preventive Controls

On preventive controls, the report advocated a coordinated approach spanning farms, ingredient processing, and infant formula manufacturing. Participants recommended establishing and validating technologies and practices such as bacteria-removal separators, ultrafiltration, and on-farm interventions, while evaluating their effectiveness using measurable data.

At the same time, participants cautioned that increasingly costly or complex requirements could cause manufacturers to lose critical suppliers. The report therefore emphasized balancing additional risk-reduction measures with the need to maintain an ample and affordable infant formula supply.

Participants Seek FDA Guidance on Testing Methods and Thresholds

The roundtable also identified how FDA can play a role in resolving uncertainties surrounding C. botulinum testing.

Participants recommended that FDA provide guidance on fit-for-purpose tests and associated thresholds, establish standardized testing methods and requirements, and collaborate with other federal agencies to facilitate information-sharing.

Other proposed next steps included working toward laboratory accreditation and validation of fit-for-purpose testing methods; holding a similar forum with the dairy industry; examining lessons learned outside the U.S.; and assessing possible risks associated with other formula ingredients, including minerals, nondairy protein sources, and vitamins.

Beyond the roundtable, proposals have been made at the Congressional level for FDA to enforce mandatory C. botulinum testing and environmental monitoring at the infant formula manufacturer level, although such legislation has yet to advance.