Why uncooked flour can make you sick

Researchers say last year's E. coli outbreak wasn't a fluke.

Most of us are aware that eating cookie dough is risky, due to the raw eggs. But did you know that the flour in the recipe can be just as dangerous?

The dry, harmless-looking white powder was the source of a 24-state E.coli outbreak last year. No one died, but at least one person developed kidney failure, and others suffered from crippling symptoms like abdominal pain, fever, vomiting and diarrhea.

A study published this week in the New England Journal of Medicine details the investigation that was launched by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). Researchers warn that the findings show the outbreak wasn't a fluke.

"We’re not trying to ruin people’s holidays but we want them to be aware of the risks,” Samuel J. Crowe, the lead author of the study told the New York Times.

At first, researchers say they suspected chocolate chips were the source of the outbreak. But by the end of June, the FDA was warning Americans not to consume raw cookie dough, because the illnesses were linked to flour produced at a General Mills facility in Kansas City, Missouri.

The company recalled 10 million pounds of flour sold under three brand names: Gold Medal, Signature Kitchen’s, and Gold Medal Wondra.

When the CDC closed its investigation in Sept. 2016, 63 people had been infected and 17 were hospitalized. The agency warned that illnesses were expected to continue for some time, since flour has a long shelf life and consumers who didn't know about the recalls could continue to eat the products and get sick.

Now that it's been over a year since the investigation closed, hopefully most of the recalled flour is long gone. But that doesn't mean this couldn't happen again.

Researchers say the Shiga toxin-producing E. coli – the kind involved in the 2016 outbreak – doesn't need a damp environment to thrive.

How do they know? Because no contamination was found at the General Mills facility in Kansas City. 

Instead, researchers speculate that the bacteria had most likely spread earlier. If an animal goes to the bathroom in a field, bacteria from animal waste can contaminate the grain. That grain is then harvested and milled into flour.

Which means any raw flour, regardless of the brand, can contain bacteria that cause disease.

"Although it is a low-moisture food, raw flour can be a vehicle for foodborne pathogens," the study concluded.

Don't panic – when the flour is boiled, baked, roasted, microwaved or fried, the bacteria gets killed making it safe to eat.

But unfortunately that means you have to wait for the cookies to bake.

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