Why does lettuce always make people sick?

Usually salad Synonymous with healthy eating. Except now, as the United States struggles with expansion Cyclosporiasis outbreak This has sickened more than 7,100 people in Michigan alone, likely caused by iceberg lettuce. Provided by Taylor Farms.

In fact, leafy greens are often implicated in cases of foodborne illness. There was a 2022 multi-state Escherichia coli The outbreak has been linked to romaine served in Wendy’s sandwiches and 173 norovirus cases have been linked to an Illinois DC Cobb’s restaurant. In 2021, BrightFarms recalled packaged salad greens sold in several states after 31 people became infected with salmonella. In 2019, a total of 167 people were infected Escherichia coli After eating romaine harvested from the Salinas Valley region of California. And this isn’t even the first Cyclospora outbreak linked to lettuce: In 2020, Fresh Express salad kits were linked to more than 700 cases of people infected with the parasite.

Centers for Disease Control and Prevention Estimates This product is responsible for nearly half of all reported cases of foodborne illness, with leafy green vegetables topping the list. So what makes lettuce a major source of food-borne stomach problems in America?

One big reason is simply because more people eat it. Lettuce is the second most consumed vegetable in the United States after potatoes. (The recent outbreak ensures that potatoes will remain the king of vegetables in the United States. Along with French fries.) Wraps, Subs, and Tacos—Name a fast-food sandwich and it’s almost certain to contain lettuce. Power rope chains They are installed throughout the United States. Grocery store coolers are filled with salad kits, over heads of unadorned iceberg lettuce and containers of spinach.

Ready-to-eat salads and spring mix mixes pose a particularly acute risk because they contain multiple types of leafy greens, which can come from different farms and locations. If one type of lettuce in the mix is ​​contaminated, it can contaminate the entire bag. Because this contaminated lettuce is packed into lots and lots of pre-packaged salads, it has the potential to spread germs far and wide.

How you grow lettuce can also expose it to a wide range of pathogens. A Study 2025 By researchers at Cornell University who studied Escherichia coli Romaine lettuce outbreaks have found that much of the contamination originates from irrigation with untreated surface water applied through overhead sprinkler irrigation systems. There are ways to reduce this risk, including switching to irrigation systems that do not contact the leaves directly, but this requires upgrading and downtime.

Lettuce’s sickly crunch is also what makes it vulnerable to pesky pathogens. Since it’s eaten raw – really, who wants wilted lettuce? – There is no chance of cooking any trapped contaminants. Like other raw fruits and produce, leafy greens do not go through what is known as a “kill step” — heating, pasteurization or freezing — which is intended to eliminate pathogens during the food manufacturing process.

The texture of lettuce is an additional factor in its ability to spread diseases. “Many types of lettuce have a lot of cracks and folds,” says Jane Marrazzo, CEO of the Infectious Diseases Society of America. “It’s very easy for small pathogens to get in there.”

Even pre-washing procedures in manufacturing facilities do not always remove microbes, which can adhere strongly to papers. In the case of Cyclospora, the parasite has thick outer walls, making it highly resistant to most food disinfectants. Experts say vigorous washing that includes scrubbing is the best way to get rid of Cyclospora.

“If you don’t wash these produce well, you’ll end up eating whatever’s in the lettuce,” says Amira Ross, an epidemiologist at George Mason University.