Between 2014 and 2021, there were 78 foodborne disease outbreaks linked to leafy greens (mainly lettuce) reported by the Centers for Disease Control and Prevention. So if you’ve noticed recalls for lettuce contaminated with E. coli and listeria, you might be wondering whether the salad in your bowl is safe to eat. The good news: You don’t need to give up lettuce; leafy greens are highly nutritious. You just need to take a few precautions. Here, CR’s experts answer some questions about the risks of bacteria in lettuce and how to minimize them.
Q. How Does Lettuce Get Contaminated in the First Place?
A. There are a few ways. Irrigation water, which is necessary to grow crops in areas that don’t get a lot of rain, creates a pathway for contamination, especially if the lettuce field is located near livestock farms. Cattle can carry deadly strains of E. coli, and their manure, which contains the bacteria, can seep into irrigation water and contaminate crops. Even when leafy greens are grown free of harmful bacteria, contamination can still occur during harvesting, processing, or packaging. And because packaged salad greens are processed at a small number of facilities across the U.S., bacteria such as listeria can easily spread from one batch to many.
Q. Does Washing Lettuce Remove Bacteria?
A. Not entirely. When bacteria such as E. coli come into contact with lettuce, they’re almost impossible to wash off completely. That’s often because bacteria can get inside the leaves of the greens as they’re growing, when contaminated water taken up by the roots is dispersed throughout the plant. What’s more, surface bacteria can adhere stubbornly to the wrinkles and grooves of leaves. So whether the packaging says “triple-washed” or you wash it yourself, bacteria could still be present—and even a small amount can make you sick.
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Q. What About Soaking Greens in Vinegar?
A. It won’t eliminate bacteria, but some experts say that soaking your greens in white vinegar (or a vinegar and water solution) for about 10 minutes, then rinsing them with water, may help reduce bacteria levels. Your greens may retain a slightly vinegary taste, but most salad dressings contain vinegar anyway.
Q. Are Some Types of Lettuce Safer Than Others?
A. Because contamination can happen anywhere from farm to table, no single type of leafy green is risk-free. But hydroponic lettuces (which are greenhouse-grown) are less likely to be contaminated by bacteria from animal droppings. Their cleanliness depends on the source of the water used to grow them and whether proper safety practices are followed by the people who handle the greens, says James E. Rogers, PhD, CR’s director of food safety research and testing.
Whole heads of lettuce (instead of bagged greens) may also be safer. While whole heads don’t necessarily have lower bacteria levels than packaged greens, their inner leaves are less exposed to sources of contamination and are handled less than bagged greens. This reduces the opportunities for contamination.
Q. What Else Can You Do to Make Your Lettuce Safer?
A. Bacteria multiply at room temperature, so it’s crucial to refrigerate bagged lettuce promptly. “As you would with meat and poultry, don’t let bagged lettucestay out of the fridgefor too long,” Rogers says.
In addition, the longer that lettuce sits in bags or containers, the more opportunity bacteria have to grow, so buy packages with expiration dates as far in the future as possible, and don’t buy more than you can eat in a few days. If even a few leaves look damaged, slimy, or bruised, don’t eat any of the greens in that package.
Another strategy: Opt for leafy greens that can be cooked, like spinach or kale. The heat will kill bacteria. This is particularly important for people who are more susceptible to the ill effects of food poisoning, such as those who are immunocompromised, pregnant, or elderly.
Editor’s Note: This article also appeared in the August 2023 issue of Consumer Reports magazine.
Kevin Loria
Kevin Loria is a senior reporter covering health and science at Consumer Reports. He has been with CR since 2018, covering environmental health, food safety, infectious disease, fitness, and more. Previously, Kevin was a correspondent covering health, science, and the environment at Business Insider. Kevin lives in Washington, D.C., with his wife and children. Follow him on Twitter @kevloria.
