Novel C. Botulinum Test for Infant Formula Developed After ByHeart Study Reveals Industry Standard Falls Short
On June 14, 2026, a ByHeart-commissioned study was published in Frontiers in Microbiology, suggesting that sulfite-reducing clostridia (SRC) enumeration, which is recommended as a general indicator of spore contamination by the International Commission on Microbiological Specifications for Foods (ICMSF), may not be enough to ensure powdered infant formula is free of Clostridium botulinum.
As a result, ByHeart, in collaboration with a third-party laboratory, developed a novel testing protocol for C. botulinum that is designed to be more sensitive than SRC enumeration.
A ByHeart spokesperson told Food Safety Magazine that the company has already shared the details of the novel testing protocol with the U.S. Food and Drug Administration (FDA), and plans to share this information with the wider scientific community and industry.
ByHeart Formula Outbreak Prompts Closer Look at C. botulinum Detection Methods
The ByHeart-commissioned study was conducted as a part of ByHeart’s investigation into the 2025 infant botulism outbreak linked to its product, which closed in February 2026 with 48 infants falling ill in 17 states. C. botulinum was detected in an organic powdered milk ingredient (produced by Organic West Milk and processed at a Dairy Farmers of America facility) used in ByHeart's formula.
ByHeart engaged a third-party laboratory, IEH Laboratories and Consulting Group, to screen, detect, and characterize C. botulinum from finished products, using a tiered analytical approach combining anaerobic enrichment, molecular screening, culture confirmation, and genomic analysis.
The researchers concluded that “indicator-based screening (such as SRC enumeration), even if it had been in place before the [ByHeart] outbreak, would not have prevented its occurrence.”
‘Gold-Standard’ Test Failed to Stop Infant Botulism Outbreak
SRC enumeration is used by several competitors to ByHeart—that is, smaller, independently owned organic formula brands that market their products as "wholesome" and "clean"—including Nara Organics, which is now embroiled in its own, ongoing infant botulism outbreak (and which shared a powdered milk supplier with ByHeart). In fact, Nara tested to ten times the international best practice recommended by ICMSF, which set a maximum level of less than 100 colony forming units per gram (CFU/g). Nara had set its specification at less than 10 CFU/g, and went as far as to test each batch of formula for SRC at three stages: raw ingredients, formula powder during production, and finished product. Still, SRC enumeration was unable to prevent the Nara Organics outbreak.
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As of June 15, three babies who were fed Nara Organics formula contracted botulism, and the company recalled its product out of an abundance of caution based on early epidemiologic evidence. Product testing for C. botulism in Nara products is still ongoing.
The use of SRC enumeration is promoted by several infant formula manufacturers who use it as a voluntary effort to strengthen the safety of their products.
Novel Test Method is 1,000 Times More Sensitive
ByHeart’s new testing protocol layers two testing methods at three stages of production. It is built on the foundation of an ISO Standardized Method combined with a novel, fit-for-purpose test method that was developed by IEH Laboratories specifically to aid ByHeart’s outbreak investigation. Both test methods are polymerase chain reaction (PCR)-based.
The new testing protocol detects C. botulinum to 0.01 CFU/g, which is 1,000 times more sensitive than the limits of SRC enumeration, according to ByHeart.
The company says the new protocol has been essential in verifying the contamination and helping trace the root cause of the outbreak. The test protocol is part of the company's recently introduced action plan to enhance formula safety, which also involves expanded supplier audits and increased ingredient testing frequency, QR-enabled batch traceability, and the formation of an independent Food Safety Advisory Council.
ByHeart to Share Findings with Industry, Food Safety Stakeholders
In a statement to Food Safety Magazine, ByHeart said, "We have gained significant insights and data during the investigation over the past seven months, and in addition to using it to inform our next steps, we have and will continue to share this knowledge openly with the scientific, medical, and industry community. To that end, we have already shared our research and the details of the testing protocol with the FDA and are committed to working with industry groups, research institutions, and our peers to advance this science further. We plan to convene a group next month to discuss this very topic. We aim to do all we can to prevent something like this from happening again."
“Science evolves, and so must we. While we utilized the industry-standard direct-plating SRC methodology, based on the best information available at the time, this outbreak shows that protecting babies means continuously reassessing our methods and strengthening them when needed. This new evidence shows that a long-used test, like SRC, is not a reliable indicator for Clostridium botulinum; we have a responsibility to acknowledge that openly and act on it,” said Devon Kuehn, M.D., ByHeart’s Chief Medical Officer and Chief Scientific Officer.
