It’s a scary time to eat a salad, given the news of a vast E. coli outbreak in the U.S. spread by contaminated romaine lettuce. If the outbreak has you worrying about your produce-washing habits, you’re not alone. But washing your produce won’t protect you from E. coli.
A recent study in Food Science & Nutrition found that rinsing or submerging leafy vegetables in water doesn’t meaningfully reduce their burden of E. coli bacteria. Another study, this one from the University of Georgia, found specially designed produce washes were even less effective than a water rinse at clearing away E. coli. (In fact, the FDA recommends skipping those produce washes altogether.)
That’s the bad news. The good news is that you’re very unlikely to encounter E. coli on your fresh produce. “We see occasional outbreaks, but the risk of getting sick from eating produce is very, very low,” says Linda Harris, a department chair and food-safety researcher at the University of California, Davis.
But even though you can’t wash away E. coli, Harris says there are compelling reasons to clean your produce. “Produce is sold out in the open where anyone can handle it, and it comes from the soil, so there could be dirt on it,” she says.
When it comes to removing that dirt, grime or anything else that could make you sick—including the pathogens sloughing off on your produce from other shoppers’ fingers—a simple rinse and, when feasible, rubbing and drying your fruits and vegetables is usually the most effective cleaning method, she says.
Of course, the advice differs a bit from item to item. “Something like an apple with a smooth outer surface, you can rub it as you rinse it,” she says. “We’ve done some studies that show doing this and then drying it with a clean towel can achieve significant reductions of microorganisms.”
While this method works for apples, pears and other hard-skinned items, Harris says it’s unreasonable with soft fruits like berries. “It’s impossible to rub a raspberry and still end up with a raspberry,” she says. With these delicate foods, a good rinse just before eating is best.
That “just before eating” part is important. “Moisture can encourage bacterial growth,” says Marisa Bunning, an associate professor of food science and human nutrition at Colorado State University. So you don’t want to wash anything until you’re ready to eat or cook it, she says.
Also, be sure your hands, colander, salad spinner and anything else you use to rinse or prepare your produce are clean. If you don’t take these precautions, you’re as likely to spread something onto your produce as wash it off. “This is why we follow the FDA’s guidance not to wash the bagged and pre-washed greens,” she says. (You’re more likely to de-sterilize these items than to further clean them.)
Some steps you don’t need to take include scrubbing your produce with a brush, submerging it in a sink full of water or using baking soda to clean away pesticides. The first two methods are more likely to contaminate your produce than disinfect them. And while there is evidence that baking soda really can remove pesticide residues from contaminated fruit, Harris says she’s seen little evidence that pesticide levels in store-bought produce are a health risk. “There’s a lot of regulation on pesticide levels in the U.S., so the levels [that cause harm] just aren’t there,” she adds. (If you’re still concerned about pesticide residues, there’s evidence that switching to organic will significantly reduce your exposures.)
To sum all this up, don’t wash items that are labeled “pre-washed” and/or “ready to eat.” For everything else, give your produce a good rinse and, when possible, use your fingers to rub away dirt or other residues. Dry your produce with a clean towel or paper towels. Do that, and you can feel confident your fruits and vegetables are safe to eat.