Despite FDA inspection reports from 2023 that surfaced during the outbreak revealing food safety and hygiene violations at a now-closed ByHeart production facility, as well as the company receiving an FDA warning letter in 2023, FDA’s onsite investigation did not identify any such failures as contributing to the 2025–2026 outbreak.

The agency’s and ByHeart’s root cause investigations did identify Clostridium botulinum in a powdered milk ingredient, but no additional factors arose that could explain the cause of the outbreak.

Investigations into Contaminated Powdered Milk Ingredient

FDA also conducted an inspection at Dairy Farmers of America, the processor for Organic West Milk, which was a supplier to ByHeart. Whole genome sequencing (WGS) analysis of C. botulinum isolates, which were recovered from two samples of the same lot of organic whole milk powder, matched the strain to a clinical isolate and a positive infant formula finished product sample.

An ongoing root cause analysis, with a particular focus on ingredients, is still being conducted by FDA.

ByHeart to Implement Food Safety Action Plan

According to ByHeart, the company is working on an action plan to enhance food safety through improved processes and protocols, based on data and findings generated during the outbreak investigation.

These improvements will include a new C. botulinum testing protocol with heightened sensitivity, developed in collaboration with a third-party laboratory partner. A ByHeart representative told Food Safety Magazine that this testing protocol will be applied to “every dairy ingredient and to finished batches before they are released from [ByHeart’s] facilities.”

Updates about the developing action plan will be published on the company’s website.

FDA Initiates Work to Address C. botulinum in Infant Formula

In addition to FDA’s ongoing root cause analysis of the ByHeart infant botulism outbreak, the agency is undertaking other post-outbreak response actions and activities to help prevent future illnesses, including surveillance sampling to better assess the presence of C. botulinum in powdered milk.

Moreover, FDA is making an effort to better understand the risks associated with C. botulinum in infant formula and produce best practices for infant formula manufacturing.

For example, FDA recently advocated for the Joint Food and Agriculture Organization of the United Nations (FAO)/World Health Organization (WHO) Expert Meetings on Microbiological Risk Assessment (JEMRA) to conduct a risk assessment on spore-forming pathogens, including Clostridium botulinum and Bacillus cereus, in powdered infant formula.

The agency also supported the Codex Committee on Food Hygiene's request to JEMRA to:

• Update the existing risk assessment and scientific advice on Cronobacter and Salmonella in powdered infant formula
• Provide other relevant scientific advice that would inform recommendations on strengthened control measures across infant formula production, covering all stages, from primary production and packaging to the reconstitution of the product, and including environmental monitoring.

Update, June 11, 2026: ByHeart has published its action plan, which involves a new testing and verification protocol for C. botulinum, expanded supplier audits and increased ingredient testing frequency, QR-enabled batch traceability, and the formation of an independent Food Safety Advisory Council.

Update, June 24, 2026: ByHeart has developed a novel C. botulinum testing protocol that is reportedly 1,000 times more sensitive than SRC enumeration. Read more.