One of the most enduring outbreak warnings that comes back year after year is the warning that E. coli has infected leafy greens like spinach, lettuce, or collard greens. It’s so common, in fact, that numerous food chains have had to alter their intake processes for greens to avoid outbreaks of the troubling disease at their locations.
So, why does E. coli seem to favor leafy greens? After all, the last thing you’d think of making you sick is a nice, fresh salad. What’s going on with all of these E. coli outbreaks?
First, let’s take a closer look at E. coli. The bacteria is known scientifically as “Escherichia coli,” and is normally completely harmless. The vast majority of bacteria present in the gastrointestinal tract of warm-blooded animals, especially mammals, are E. coli strains. Right now, even if you’re healthy, the odds are good that you’ve got millions of E. coli bacteria living in your digestive tract, helping you break down your food.
Some strains of E. coli, however, are responsible for a number of damaging symptoms in humans. Humans suffering from virulent E. coli infection develop symptoms that result in anything from Crohn’s disease to gastroenteritis. The most common effect of ingesting virulent E. coli is colloquially referred to as “food poisoning,” with symptoms like diarrhea, vomiting, nausea, severe abdominal cramps, and even fever.
Much of the US’s supply of leafy greens comes from a small handful of corporate-run farms. Many of these farms are located near cattle-raising facilities. When cattle animals leave droppings on the ground, there is a chance of rainfall causing runoff into the local groundwater. If that runoff contains trace amounts of cattle droppings, this can lead to E. coli getting into the water that is used to raise leafy greens.
The kinds of E. coli that live in the intestinal tract of other mammals often don’t get along well with the strains that live naturally in human digestive systems. The resulting disagreement between your native gut flora and the invading E. coli is often manifested as “food poisoning,” a very unpleasant gastrointestinal condition that can keep even an otherwise healthy person out of commission for days.
The reason greens seem to be more prone to this than other produce is because greens don’t have skin like fruits, and they’re not commonly cooked, like vegetables. This is why thoroughly washing your greens before you eat them is so important!