It hides in your lettuce. It makes the local news every other week. The CDC has over 40 documented outbreaks of it since 2006 alone. 

E. coli (short for Escherichia coli) may seem to be a terrifying pathogen that you hope to never encounter. 

But did you know that E. coli lives inside you?

Part Of A Balanced Gut

Your gut, which generally refers to your stomach and intestines, is full of different microorganisms. These microorganisms, collectively known as your gut microbiome, actually help your body in multiple ways.

For instance, certain bacteria can process fiber and produce molecules known as short-chain fatty acids. These molecules can help maintain your intestines and prevent colorectal cancer, and recent research shows they may even play a role in communication between your brain and gut. Most members of the microbiome, including E. coli, ensure that the intestines are properly digesting food.

Because there are so many different microorganisms—over 100 trillion, in fact—living in your body, this also prevents harmful invaders from taking space in your system. You can think of it like a plane trying to land in a busy runway; just as a plane may have to circle in the sky before it can land, a harmful pathogen may not be able to find a place to survive in the gut and is filtered out, keeping its host safe. 

Not All E. coli Are The Same

E. coli on a Petri Plate

adonofrio ( on Flickr

If E. coli is living inside of you, how can it make you sick? The answers lies in the different strains of this microbe.

When we talk about E. coli, we're not just referring to one single type of bacteria. There are many different types of the bacteria, some of which can cause the illnesses that we hear about a lot.

One of the main culprits in illnesses associated with the bacteria is E. coli O157:H7, which is also commonly referred to as a Shiga toxin-producing E. coli (or STEC, for short.) As the name implies, STEC can produce toxins that give you diarrhea and other harmful symptoms. 

There are other types of harmful E. coli that can cause a range of issues as well, but they are all similar in that they can enter the body through contaminated food or drinks.

Why Outbreaks Are So Common

According to the CDC, most STEC infections come from leafy green vegetables, followed by beef and dairy. So what makes these foods so susceptible to carrying this harmful bacteria? The FDA says that cows may be a key factor here.

"[T]he Outbreak A strain of E. coli O157:H7 was detected in a fecal-soil composite sample taken from a cattle grate on public land less than two miles upslope from a produce farm with multiple fields tied to the outbreaks by the traceback investigations," the organization stated in reference to the STEC outbreak from romaine lettuce in November 2019. 

Cows are not affected by the Shiga toxins produced by this strain of E. coli, which means that they may carry the bacteria and shed it through waste that can ultimately enter romaine lettuce and other crops. 

But our bovine counterparts are not entirely to blame, as contaminated water, soil, or hands of processors can all lead to an eventual contamination of the produce. And while it's important to keep your produce fresh and clean, such harmful pathogens may still find a way into your food. 

The Verdict

radicchio, salad, lettuce, purple lettuce, leaves, rinsing, sink, Kitchen
Julia Gilman

It might seem like yet another scary pathogen to be wary of, but E. coli can be an important part of your gut's health. Strains like STEC can lead to the harmful diseases we know about, which is why it's important to wash fresh produce before consumption.

But with more and more safeguards being implemented to predict and prevent E. coli outbreaks in vegetable crops, you should continue to include a sizable amount of vegetables in your diet. And, of course, sourcing those vegetables locally can reduce possibilities of harmful exposure among other benefits, so don't be afraid to shop local!