ByHeart strengthens controls ahead of formula restart

ByHeart has detailed new ingredient-testing, supplier-assurance, sanitation, and manufacturing controls as it works towards restarting powdered infant formula production following the multistate botulism outbreak linked to its products in late 2025.

The company says it has submitted approximately 400 pages of investigation findings and corrective measures to the US Food and Drug Administration, covering its root-cause work, assessments by independent food-safety specialists, new Clostridium botulinum testing protocols, supplier controls, and preventive measures across manufacturing.

ByHeart reported on 28 August that FDA had no further questions on most of the submitted investigation and action plan, while two areas remained under review: a proposed sporicidal surface treatment and qualification of a new whole-milk ingredient supplier. That statement comes from ByHeart rather than a published FDA clearance, and production has not yet resumed.

The distinction is important because FDA’s wider investigation remains active. The regulator has independently confirmed that inspections at ByHeart’s own manufacturing facilities did not identify additional factors capable of explaining the outbreak and that its root-cause work is focused on ingredients and their production environments.

The original ByHeart outbreak affected 48 infants across 17 states between late 2025 and early 2026. CDC declared the outbreak over on 26 February, but laboratory work continued after C. botulinum was identified in powdered milk ingredient material used in formula production.

FDA and ByHeart collected dairy-ingredient samples associated with Dairy Farmers of America, which processed milk supplied by Organic West Milk. Two samples from one lot of organic whole-milk powder were subsequently shown by whole-genome sequencing to match a clinical sample and a positive infant-formula sample.

The investigation has gained further significance during 2026 because a separate infant-botulism outbreak involving Nara Organics formula has produced related findings. FDA’s 27 August update reported four confirmed cases in California, Pennsylvania, and Washington and said genetic analysis identified a match between an infant from the Nara outbreak, an infant from the earlier ByHeart outbreak, a powdered formula base sample, and four unopened cans of ByHeart formula.

The Nara formula lots involved were made using milk supplied by Organic West Milk and spray dried by Dairy Farmers of America — the same organisations associated with the organic whole-milk supply used for ByHeart formula.

FDA says the genetic results and supply-chain commonalities indicate a common contamination source between the two outbreaks. It has not, however, established whether contamination occurred before milk drying or during the drying process, and the root-cause investigation remains open.

That difference between identifying a common source and identifying the precise contamination route matters operationally. A processor cannot design an effective corrective action around a mechanism that has not been demonstrated, particularly where the possible entry point could sit at different stages of raw milk handling, drying, ingredient storage, transport, or subsequent formula manufacture.

ByHeart’s response therefore extends beyond its own factory environment. The company has set out tighter supplier qualification and verification, additional ingredient testing, manufacturing controls, sanitation measures, and changes to product-release procedures intended to detect or prevent extremely low-level contamination entering finished formula.

A central element is a testing protocol developed with IEH Laboratories. ByHeart says the method can detect C. botulinum down to 0.01 colony-forming units per gram in dairy ingredients and finished infant formula, a sensitivity it describes as 1,000 times greater than the standard SRC direct-plating methodology.

Those are company performance claims rather than an FDA endorsement of the method, and analytical sensitivity alone does not eliminate the wider sampling problem. Contamination present at very low concentration and distributed unevenly through a large powder lot can remain difficult to detect because only a small proportion of the material can practically be sampled.

The implication is that testing has to operate alongside preventive controls rather than become a substitute for them. Supplier history, process validation, lot segregation, sanitation, traceability, sampling design, ingredient specifications, and the ability to connect incoming materials to finished production all influence whether a low-level hazard can be contained.

That is particularly important in powdered infant formula because the product is intended for a vulnerable population and is not generally manufactured as a commercially sterile powder. Food-safety systems consequently have to manage hazards through a combination of ingredient control, hygienic manufacture, environmental monitoring, testing, traceability, and consumer preparation instructions.

FDA has already widened that message beyond the companies involved in the outbreaks. In July, the agency wrote to infant-formula manufacturers and their supply-chain partners calling for greater vigilance over ingredient sourcing after recent contamination events involving C. botulinum and cereulide.

The regulator explicitly pointed to the ByHeart and Nara Organics outbreaks as examples of risks entering through the supply chain. It also cited the international cereulide incident associated with contaminated arachidonic-acid oil, reinforcing the point that highly controlled final assembly cannot compensate indefinitely for hazards introduced through supplied ingredients.

A separate infant-formula recall involving a2 Milk earlier this year illustrated the same broad manufacturing problem from a different hazard. That incident involved cereulide rather than botulism and is not connected to ByHeart, but it again placed ingredient controls upstream of final formula packing at the centre of the response.

For procurement teams, stronger supplier oversight means more than collecting a current certificate of analysis. A manufacturer’s control system needs evidence about how a critical ingredient is produced, which hazards are reasonably foreseeable, which process steps reduce them, how lots are defined, what sampling plan is used, and what happens when a result falls outside specification.

The recent botulism investigations also demonstrate why trace-forward data matter. FDA disclosed that Organic West Milk initially provided an incomplete customer list during the 2025 investigation, with information later showing that its milk also entered the Nara Organics supply chain. Incomplete distribution information makes it harder to identify every product potentially exposed to a suspect ingredient when an incident is unfolding.

That creates a direct link between supplier approval and traceability. Knowing that a material passed specification at receipt is useful; knowing which other manufacturers, ingredient processors, and finished-product lots share the same upstream source becomes critical when investigators begin finding the same organism across apparently separate brands.

ByHeart’s proposed sporicidal surface treatment adds another layer to the control programme. FDA notes that C. botulinum spores occur naturally in the environment, including soil and dust, and can enter manufacturing environments on people, footwear, and other contaminated surfaces. A robust response therefore has to consider both ingredients and the environment even when evidence increasingly points upstream.

The company has also proposed qualifying a new whole-milk supplier. That is still under review according to ByHeart’s 28 August update, and changing supplier does not by itself resolve the wider technical question unless qualification establishes that the new production and drying controls adequately manage the relevant hazard.

ByHeart has committed to giving FDA 28 days’ notice before restarting production and to completing verification work and other pre-production commitments. The August update is therefore progress towards restart, not permission to resume manufacturing.

That nuance becomes more important now that the ByHeart outbreak is no longer an isolated formula event. FDA’s finding of a common contamination source with Nara Organics means the investigation has moved beyond one brand and towards an upstream ingredient chain serving more than one finished-product manufacturer.

For the wider formula sector, the uncomfortable lesson is technical rather than reputational. Increasing the sensitivity of finished-product testing can strengthen detection, but a manufacturing system cannot test its way out of an inadequately understood ingredient hazard.

The more durable response lies further upstream: establish where contamination can enter, qualify the process used to control it, retain enough traceability to follow every affected lot, and use testing to verify that those controls are working rather than asking a small sample to prove that an entire supply chain is clean.