FDA – ByHeart is Source of Botulism Outbreak – Tainted Ingredient Likely

The FDA and CDC, in collaboration with the California Department of Public Health (CDPH), Infant Botulism Treatment and Prevention Program (IBTPP), and other state and local partners, continue to investigate a multistate outbreak of infant botulism. Epidemiologic and laboratory analyses indicate that ByHeart Whole Nutrition infant formula is the source of this multistate outbreak of infant botulism. No new cases have been added to the investigation since December 10, 2025.

Product sampling and testing is being conducted by FDA, CDC, state partners, and ByHeart. Additionally, FDA collected ByHeart ingredient samples for analysis, as part of the investigation.

As of January 23, 2026, two samples collected by FDA tested positive for Clostridium botulinum (toxin), Type A. One is a ByHeart powdered infant formula closed product sample that matches a clinical isolate from an infant included in this outbreak according to whole genome sequencing (WGS) analysis. These samples also match two isolates of organic whole milk powder, an ingredient that ByHeart uses in the production of ByHeart Whole Nutrition powdered infant formula, which were collected and tested by ByHeart. 

The second organic whole milk powder sample was collected by FDA at a processor for a supplier to ByHeart and analyzed by the New York Wadsworth Laboratory. WGS analysis showed that the Clostridium botulinum found in the sample of organic whole milk powder is a genetic match to the Clostridium botulinum detected in the finished product sample of ByHeart’s infant formula according to analysis conducted by ByHeart.

While these results advance FDA’s understanding of the outbreak, FDA’s investigation is ongoing to determine the source of contamination.

Previously, on December 23, 2025, ByHeart publicly reported positive test results for Clostridium botulinum in six of 36 samples of finished product. These six samples were taken from two batches (Batch 251261P2 and Batch 251131P2), which were both included in the initial product recall.

Sample analysis is ongoing, and results will be reported as they become available. The detection of Clostridium botulinum in infant formula, or ingredients, is complex, and confirmation of results can take several weeks. This in part is due to the heat-resistant spores which require special activation before they can be detected. Additionally, testing for C. botulinum in infant formula requires specialized testing and lab equipment. While initial screening tests are performed, a preliminary positive result requires confirmatory tests. This complex process can take two or more weeks for final results. There are a limited number of labs that have the specialized equipment and resources to conduct these tests, which further reduces testing capacity. FDA is working with partners to improve and update these methods, so that results can be confirmed and compared across stakeholders more easily.  

FDA’s investigation is focused on gaining a clearer understanding of contributing factors in this outbreak. This is the first documented outbreak of botulism in the United States attributed to contaminated infant formula and there are fundamental differences between spore-forming bacteria like Clostridium botulinum and vegetative bacteria such as Cronobacter and Salmonella. These are important considerations as FDA continues to respond to this outbreak and implement risk reduction strategies going forward. FDA has established the FDA’s Actions to Respond to Clostridium botulinum Illnesses Associated with Consumption of Powdered Infant Formula page to capture ongoing efforts to ensure the safety of powdered infant formula, including general information about formula safety.

All ByHeart infant formula products have been recalled, and these products should not be available for sale in stores or online. This includes all formula cans and single-serve “anywhere pack” sticks.

FDA continues to receive reports that recalled formula is still being found on store shelves, despite the ongoing recall of all ByHeart infant formula products. FDA continues to work with state partners and retailers to ensure an effective recall and immediate removal of these products from store shelves across the country. On December 15, 2025, FDA issued a press release and reminded industry about its legal duties regarding food recalls under the Federal Food, Drug, and Cosmetic Act. FDA asked companies to follow best practices when carrying out recalls. This is especially important for recalls involving foods for infants and young children, who are among our most vulnerable populations.

FDA’s investigation is ongoing and this advisory will be updated as information becomes available.  

Republished with permission from Bill Marler and Marler Clark. Copyright (c) Marler Clark LLP, PS. All rights reserved.