Powdered whole milk could be a culprit in the ByHeart botulism outbreak, tests show

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This article was published 23/01/2026 (251 days ago), so information in it may no longer be current.

Powdered whole milk used to make ByHeart infant formula could be a source of contamination that led to an outbreak of botulism that has sickened dozens of babies, U.S. health officials indicated Friday.

Testing by the U.S. Food and Drug Administration found the type of bacteria that can cause the illness in two samples linked to the formula, officials said.

The agency found that bacteria in an unopened can of formula matched a sample from a sick baby — and it also matched contamination detected in samples of organic whole milk powder used to make ByHeart formula and collected and tested by the company.

FDA testing also found contamination in a sample of whole milk powder supplied to ByHeart — and it matched the germ in a finished sample of the company’s formula.

The findings are not conclusive, and the investigation continues “to determine the source of the contamination,” the agency said in a statement.

In a statement, ByHeart officials said the new finding “suggests that we are significantly closer to determining the root cause of the contamination.”

Neither FDA nor ByHeart named the supplier of the powdered whole milk.

At this time, there is no indication of a broader problem in the infant formula supply, the FDA said.

New York-based ByHeart has been at the center of a food poisoning outbreak that has sickened 51 babies in 19 states since December 2023. The problem was identified in November after officials with the California program that supplies the sole treatment for infant botulism detected a surge in cases in babies who consumed ByHeart formula.

No new cases in the outbreak have been identified since mid-December, the U.S. Centers for Disease Control and Prevention said.

ByHeart initially recalled two lots of formula, but it expanded the recall to all products days later. Federal health officials later said they could not rule out contamination of all products made since the company launched in March 2022.

That followed company testing, announced in November, that found six of 36 samples of formula from three different lots contained the dangerous type of bacteria that causes infant botulism.

Illnesses caused by botulism bacteria in infant formula are rare, and the size and scope of the ByHeart outbreak is unprecedented, food safety experts said.

Some formula companies do test raw materials and finished formula for evidence of the contamination, but such testing should be required, said Sarah Sorscher, director of regulatory affairs for the Center for Science in the Public Interest, an advocacy group.

“FDA has not announced a plan to do testing, and that’s what we really want to see them do,” she said.

Even if the contamination was traced to a milk supplier, the company remains responsible for the harm caused by its product, said Bill Marler, a Seattle food safety lawyer who represents more than 30 families of babies who fell ill.

“Just because they are able to point the finger at dried powder as the ingredient that may have been contaminated, it doesn’t take any of the legal or moral responsibility away from ByHeart,” Marler said.

ByHeart, which accounted for about 1% of the U.S. infant formula market, previously sold about 200,000 cans of the product per month. It was marketed as an option close to human breast milk, one that used “organic, grass-fed whole milk.” Parents of babies sickened in the outbreak said they chose the formula, which cost about $42 per can, because of its touted health benefits.

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