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Recent recalls of leafy greens, key ingredients in a healthy diet, have made the issue of food safety impossible to ignore.

Last month, confirmed cases of E. coli-related illness in Ontario, Quebec, New Brunswick and several U.S. states were traced to romaine lettuce harvested in California.

This week, kale was identified as a source of Listeria contamination, prompting the Canadian Food Inspection Agency (CIFA) to recall Eat Smart’s salad kits, Salad Shake Ups – Sweet Kale. (Despite the recall, there have been no reported illnesses associated with eating this product.)

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While cooking vegetables (and meat) can kill harmful bacteria, many leafy greens are eaten raw, making them especially vulnerable.

If the recent news has left you scared to eat salad, or cooked greens, here’s what you need to know.

I’ve heard about E. coli, but what is Listeria?

Listeria monocytogenes live in soil, the intestines of animals (and, therefore, are excreted in their feces) and untreated water. Unlike many bacteria, Listeria can grow in the cold temperature of the refrigerator. It’s killed by cooking and pasteurization.

People can become infected by Listeria bacteria by eating contaminated fresh produce, deli meats, refrigerated pâté, undercooked meat, poultry and fish, refrigerated smoked seafood and unpasteurized dairy products including soft and semi-soft cheeses (e.g. brie, Camembert, blue-veined cheese).

Symptoms of Listeria poisoning can begin a few hours after eating a contaminated food or as long as one month afterward and include fever, muscle aches, nausea and diarrhea.

Listeria infection can be serious, even life-threatening, for pregnant women and their babies, as well as people with weakened immune systems.

E. coli 0157:H7, the bacteria species linked to recent illness caused by eating romaine lettuce, can cause abdominal pain, nausea, vomiting and diarrhea, including bloody diarrhea.

Should I worry about other fresh kale products?

At this time, the CFIA has no evidence that bunches of kale or other kale salad kits are a concern for Listeria contamination, besides the recalled Eat Smart’s salad kits, Salad Shake Ups – Sweet Kale.

The agency’s investigation is ongoing. If other high-risk products are recalled, the CFIA will notify consumers on the food recall warnings page of its website.

How do Listeria and E. coli get into leafy greens?

Illness-causing bacteria can contaminate leafy greens (and other produce) if contaminated water is used on crops. Runoff from cattle farms can also contaminate fields where fresh produce is grown.

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Listeria and E. coli in soil and manure-based fertilizers can also contaminate crops.

Bacteria can get into food from contaminated processing equipment or when food is handled improperly, leading to cross-contamination.

The CFIA has not yet determined the source of the Listeria contamination in Eat Smart’s salad kits, Salad Shake Ups – Sweet Kale. The source of E. coli O157:H7 contamination of romaine lettuce has also not been identified.

Is romaine lettuce now safe to eat?

The recent outbreak of E. coli infections tied to romaine lettuce has been traced to romaine lettuce harvested in California’s Central Coast growing regions – Monterey, San Benito, San Luis Obispo, Santa Barbara, Santa Cruz and Ventura.

Romaine lettuce grown in Canada, including hydroponic lettuce and lettuce grown in greenhouses, is not associated with this E. coli outbreak and is considered safe to eat.

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The Public Health Agency of Canada has implemented new actions to ensure that romaine lettuce is not imported from affected growing regions in California.

Even so, the government continues to advise residents of Ontario, Quebec and New Brunswick to avoid eating romaine lettuce and salad mixes containing romaine, unless it’s clearly identified that the lettuce did not come from an affected growing area. (Last month, the U.S. FDA announced new voluntary labelling for romaine lettuce disclosing date of harvest and harvest growing region.)

Should I rinse “prewashed” greens to be safe?

No. Cleaning prewashed greens at home can actually increase the likelihood of food-borne illness. Additional handling could introduce bacteria from your hands, the cutting board, the sink or nearby raw foods.

If packaged salad greens are not labelled “prewashed” or “ready to eat;” wash them thoroughly under cold running water just before you intend to use them. Washing leafy greens before storing could promote bacterial growth and enhance spoilage.

Do not buy prepackaged greens that contain spoiled leaves. Damage to greens can stimulate bacteria to grow and multiply, especially when they’re stored in packages.

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If you buy whole heads of lettuce or other greens, discard the outer leaves and wash the rest.

To minimize your risk of food poisoning from leafy greens and other foods, practice safe food-handling and preparation at home.

Leslie Beck, a Toronto-based private practice dietitian, is Director of Food and Nutrition at Medcan.

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