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Our concierge doctors absolutely recommend a diet high in vegetables, especially leafy greens, for optimal health. But a new study released this month highlights a problem with this otherwise beneficial food: E. coli.

The report, published in the journal Emerging Infectious Diseases, found leafy greens are a common source of food-borne illnesses. It notes that they’ve been implicated in 40 outbreaks of a serious strain of E. coli between 2009 and 2018. These outbreaks resulted in 1,212 illnesses, 420 hospitalizations, and eight deaths.

Products to look out for

As you might suspect from the frequent reports in the news, romaine lettuce was involved most often. In of the outbreaks related to leafy greens studied for E. coli contamination, romaine lettuce was responsible for 54 percent of cases. Spinach and iceberg lettuce caused 17 percent each. Kale, cabbage, and green leaf lettuce were linked for four percent of the outbreaks.

The study also found outbreaks linked to mixed greens. This included three romaine and iceberg mixes, a butter lettuce and radicchio mix, and a spinach and spring mix.

Researchers were uncertain why romaine lettuce was so often involved in E. coli contamination. They speculated the green’s growing popularity over the study period accounted for some of the increase. Also the shape of the leaf itself contributed to contamination. Because romaine’s crinkled leaves grow in an elongated rosette shape, it’s difficult to wash it sufficiently to remove all of the surface contamination.

What’s causing the bacteria growth

Agricultural practices in this country have also been implicated in contamination outbreaks in leafy greens, but especially romaine lettuce.

Nearly all romaine lettuce grown in the U.S. originates from two main areas: the Salinas Valley in California and the Imperial and Coachella valleys in Southern California and around Yuma, Arizona.

E. coli is common in animals, including goats, deer, feral pigs, and especially cattle. One recent widespread outbreak in 2018 was attributed to contamination of surface water possibly used to irrigate and harvest the crop (with high-pressure water knives, which are used to cut the vegetables, as opposed by slicing them from the roots by hand).

Perhaps not surprisingly, many of the outbreaks have occurred within weeks of the time when nearby farming operations fertilize their fields.

“We know from earlier outbreaks that a little bit of contamination in the field can lead to cross-contamination,” Benjamin Chapman, a professor and food safety specialist at North Carolina State University, told NBC News. Chapman was not involved in the current study.

Once the plant is contaminated, it’s “very difficult to remove,” he explained. Even though produce is triple-washed in processing plants and once at home, the consumer maybe be able to rinse off 90 to 99 percent of what remains. That may not be enough to ensure complete safety, he added.

Symptoms of an infection

Symptoms of E. coli bacterial infection include stomach pain or non-bloody diarrhea that worsens over several days. It can take up to 10 days to begin feeling symptoms after consuming affected food. This makes outbreaks so difficult to track down.

An E. coli infection is normally self-limiting, meaning the body fights it off with no complications other than feeling fairly miserable for a few days. But it can also lead to more severe complications, especially for infants and children under five, older adults, and those with compromised immune systems.

Reducing the risk

As we said earlier, we still encourage consumption of leafy greens. They’re an excellent source of fiber, vitamins, minerals, and phytonutrients. They’ve also been linked to a reduced risk of heart disease, some cancers, macular degeneration and type 2 diabetes.

So how can you keep your family safe? First, always assume leafy greens are contaminated, and rinse them thoroughly if you plan to eat them raw.

The Center for Disease Control and Prevention (CDC) provides the following advice to minimize the chances of contamination.

Check to see if your prepackaged leafy greens are labeled “ready to eat,” “triple washed” or “no washing necessary.” These leafy greens do not need to be washed again. Thoroughly wash all other leafy greens before eating, cutting or cooking.

Consumers should follow these simple steps:

• Wash your hands for 20 seconds with soap and water before preparing leafy greens.
• Discard outer leaves and any torn or bruised ones.
• Rinse the leafy greens under running water and use your hands to gently rub the surface of the leaves.
• Don’t soak leafy greens in a sink filled with water. They can become contaminated with germs in the sink.
• Don’t soak leafy greens in a bowl filled with water, which can spread contamination through the water to other leaves.
• Dry leafy greens with a clean cloth or paper towel.
• Do not wash vegetables with soap, detergent, or produce washes.
• Do not use bleach solution or other disinfectants to wash produce.

If you think you have become ill from eating contaminated foods, be sure to talk to us. While food poisoning may result in nothing more than a few days of misery, it can also be dangerous. We can advise you on the best ways to recover.