Summer is officially here, which means our window to use the oven is quickly dwindling. Once it’s too hot to actually cook, we rely on salads for a fast and fresh meals. Whether you’re planning to eat a classic Cobb, a creamy caesar, or a something packed with seasonal produce (try our grilled plum & pancetta panzanella), your salad will likely start with some greens.
Each salad green brings its own unique flavor to the table. Arugula has a peppery bite, radicchio and endive have a delightful bitterness, and romaine offers unparalleled crunch. But let's be honest: washing lettuce can be a pain. Nobody genuinely enjoys breaking out the salad spinner and painstakingly wringing out excess water (and don’t even get us started on cleaning the spinner afterwards).
So it’s understandable that some people skip the lettuce-washing process entirely. But just how important is it, anyway? We consulted Dr. Matthew Landry, registered dietician and Assistant Professor of Population Health and Disease Prevention at University of California, Irvine, to unpack everything you need to consider when eating lettuce.
What Are The Risks Of Eating Unwashed Lettuce?
Any agricultural product can be exposed to environmental contaminants, and that's especially true for lettuce because it grows so close to the ground. Many heads of lettuce contain insects and dirt, but they can also harbor some more harmful microorganisms. Bacteria can come from the soil itself, the water, and from any of the materials used to harvest, process, and store the greens.
There are several different contaminants that can affect your greens, but Landry says the two most common are E. coli and listeria. Other foods that may be infected with E.coli, like meat and wheat flour, are often cooked enough to kill the bacteria. But because lettuce is typically served raw, the bacteria is still alive by the time you eat it.
The symptoms caused by these germs can vary. "Some people don't get sick at all, and others may have mild to severe gastrointestinal symptoms like vomiting and diarrhea," he says. "In rare cases, some people may become seriously ill." But most cases of lettuce-induced food borne illness resolve themselves in a matter of days.
Experts recommend washing greens in every scenario, regardless of how they're grown and packaged. Many salad bags advertise that the greens have been pre-washed (sometimes up to three times), but that doesn't necessarily mean they're clean. "Bacteria can still persist if the washing was done inefficiently, or bacteria may be stuck to grooves and folds in the leaves," Landry says.
An emerging market in the produce industry is hydroponically grown lettuce, which is grown indoors without soil. Landry says that this growing technology may reduce the risk of bacteria at the agricultural level, but doesn't eliminate it entirely. Harvesting, processing, and packaging all can introduce harmful microbes into your greens—regardless of how they were grown.
For those who are especially concerned about contaminated lettuce, Landry suggests buying whole heads of lettuce rather than bagged greens. The less handling that happens to your greens means there are fewer opportunities for contamination during the processing stage.
How Should We Wash Lettuce?
Now that you know just how gross lettuce can get, you might be tempted to wash your greens the second you get home from the grocery store. But the best time to clean your lettuce is right before you eat it. "Washing lettuce and then storing it can lead to excess moisture, which can promote the growth of bacteria and mold," Landry says.
Beyond the risk of food borne illness, washing lettuce ahead of time also can sacrifice its crisp texture. Your best bet is to store lettuce dry to maximize freshness and minimize microbial growth.
When it's time to clean your greens, Landry says it might be worth adding a splash of vinegar to your water. Letting your lettuce soak in a vinegar-water solution for about 10 minutes won't eliminate bacteria entirely. But Landry says that it can help reduce bacteria levels to some degree.
