Guess What Cookie Dough Ingredient Can Give You E. Coli?

When you’re rolling out the dough for holiday cookies, think twice before taking a bite. A report released by the journal Clinical Infectious Diseases attributes a 2009 E. coli outbreak to raw cookie dough and not because of raw eggs, which can contain Salmonella, but from… raw flour.

Teenage girls and their parents should especially take note as the researchers observed that “consumption of cookie dough appears to be a popular practice, especially among adolescent females.”

In the 2009 E. coli outbreak, 77 people from 30 states were affected. 35 were hospitalized but there were no deaths. The Centers for Disease Control and Prevention and local public health officials found that raw cookie dough could be the culprit by interviewing those who had contracted E. coli and asking them what foods they had eaten.

Among the foods eaten frequently were strawberries, ground beef, poultry, apples, leafy greens–and raw, pre-packaged cookie dough. Studying 36 patients and 36 controls from 18 states, researchers found that eating a particular brand of cookie dough was the only thing significantly linked to illness. Although not named in the study, news reports at the time identified Nestle Toll House cookie dough.

After some cookie dough product samples turned up positive for E. coli after testing there was a voluntary recall.

The 2009 E. coli outbreak was the first in which packaged raw cookie dough was found to be the cause. Researchers ruled out food handling, safety violations or intentional contamination as possible causes, then considered a number of ingredients: molasses, unpasteurized eggs, sugar, margarine, chocolate chips and baking soda.

Karen Neil, an epidemiologist at the CDC who investigated the outbreak, notes that molasses, sugar and margarine are all processed to kill pathogens, so those were ruled out. So were eggs, as the eggs in the Nestle cookie dough had been pasteurized. Chocolate was the next ingredient considered as it has spread Salmonella in the past, but some of those who had fallen ill had eaten cookie dough without chips and people who had eaten Nestle chocolate chips from the bag had not.

The only ingredient left was flour, which is not processed to kill pathogens and which is “purchased in large quantities and could have been distributed to a number of lots.” As it’s a “raw agricultural product,” it can still come into contact with “dirt, animal feces, and other unpleasant substances between field and grocery store shelf.”

Adolescent females in particular should pay heed to the study’s findings:

In the 2009 outbreak, 66 percent of the people who got sick were under age 19, and most were female. An earlier study of college students found that more than half said they ate unbaked cookie dough. A fair number of those people have no intention of ever turning on the oven; they’re eating it all right out of the package.

Nestle has announced that it will begin to heat-treat the flour it uses in packaged cookie dough. But the study’s findings — like the advice of mothers shooing their children from sneaking in bites of raw dough — are well worth noting: Cookies don’t take long to bake so wait till after they come out of the oven to sneak a taste. What’s a few minutes to finding yourself in the hospital with E. coli for days?

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Photo by Vix Walker


Sonny Honrado
Sonny Honrado4 years ago

Cook your cookie before eating.

Duane B.
.4 years ago

Thank you for sharing.

ANA MARIJA R.4 years ago

Thank you for sharing!

KARLOLINA G.4 years ago


Paulina L.

quite scary

rene davis
irene davis4 years ago


Anne F.
Anne F.4 years ago

Easy to mix up your own cookie dough and bake the cookies. Mass manufactured food just isn't good enough to eat.

colleen p.
colleen p.4 years ago

We need a safe friendly bacteria to eat our e.coli! How do we. Ecome friends?

Zdenko S.
Zdenko Sirca4 years ago

Use DIY flour. Buy organic grain/corn, wash it, dry it, grind it. You need a tabletop dryer and grinder, but this is a long lasting investment in your health. And don't use any animal ingredients!

Be veg, go green to save your health and our planet!

Barbara G.
Barbara Goheen4 years ago

I would never have guessed raw flour. Nothing is safe today. Tomorrow it will be something different.