There’s no question about it! By far, vegetables are a vital part of a healthy meal. And millions of portions of leafy vegetables are eaten safely every day.
However, leafy vegetables are occasionally contaminated enough to make people very ill.
Contamination of Leafy Vegetables
Leafy vegetables, like kale, spinach, lettuce, bok choy, and cabbage, provide nutrients that help protect us from some cancers, stroke, and heart disease. Nevertheless, similar to other fruits and vegetables, leafy vegetables are at times contaminated with harmful germs.
Washing leafy vegetables doesn’t remove all germs, because germs can adhere to the surface of leaves. Germs can also find their way inside vegetables.
According to estimates by the Centers of Disease Control and Prevention (CDC) germs on produce eaten raw cause a large percentage foodborne illnesses, sometimes called food poisoning.
List of Foodborne Illnesses
- Leafy vegetables and other vegetable row crops are a major source of E. coli O157 infections.
- Other harmful germs found on leafy vegetables include Salmonella, Cyclospora, Norovirus, and Listeria.
Anyone can get a foodborne illness. However, some groups of people are more likely to get one and to have a serious illness. These groups include:
- People who have health problems
- People who take medicines that weaken their immune system
- Adults age 65 and older
- Pregnant women
- Children younger than 5 years
Safely Handling and Preparing Leafy Greens
Prewashed vegetables sometimes cause illness. But the commercial washing process removes most of the contamination that can be removed by washing.
Therefore, prewashed greens do not need to be washed again. You don’t need to wash the vegetable if the label on a leafy greens package says any of the following:
- No washing necessary
- Triple washed
All other leafy greens should be thoroughly washed before cutting, cooking, or eating. No washing method can remove all germs. Nevertheless, the best way to wash leafy vegetables is by rinsing them under running water. Studies show that this step removes some of the germs and dirt on leafy vegetables and other vegetables and fruits
Follow these steps to wash leafy vegetables that you plan to eat raw:
- Wash hands for 20 seconds with soap and water before and after preparing leafy vegetables.
- Remove and dispose any bruised or torn leaves. Also, remove and dispose the outer leaves of lettuce heads and cabbages.
- Rinse the remaining leaves under running water. To help get rid of dirt and germs gently rub the remaining leaves with your hands.
- Dry leafy greens with a paper towel or clean cloth.
Do not soak leafy vegetables. The best way to wash leafy greens is by washing them under running water. If you soak them in a sink, germs in the sink can contaminate the greens. If you soak them in a bowl, germs on one leaf can spread to the other leaves.
Additionally, do not wash leafy vegetables or other produce with soap, detergent, or produce wash. Above all, do not use a bleach solution or other disinfectant to wash produce.
Selecting, Storing, and Preparing Leafy Vegetables and Other Produce
- Make sure pre-cut produce, such as bagged salad or cut vegetables and fruits, is refrigerated or on ice at the store.
- Select leafy vegetables and other fruits and vegetables that aren’t damaged or bruised.
- Separate produce from eggs, poultry, seafood, and raw meat in your shopping cart, grocery bags, and refrigerator.
- Store leafy vegetables, salads, and all pre-cut and packaged produce in a clean refrigerator with the temperature set to 40°F or colder.
- Use separate cutting boards and utensils for produce and for eggs, poultry, seafood, and raw meat.
- Prepare produce before working with raw meat.
- Wash utensils, cutting boards, and kitchen surfaces with hot, soapy water after each use.
- Cook thoroughly or throw away any produce that touches raw meat, poultry, seafood or their juices.
- Refrigerate cut or cooked produce, including salads, within 2 hours (one hour if the food is exposed to temperatures above 90°F, like a picnic or hot car).
How Vegetables Get Contaminated With Germs
Germs that make people ill are found in many places — including on kitchen surfaces, in refrigerators, in the soil, in the feces of animals.
Germs can contaminate leafy vegetables at many points before they reach your plate. For example, germs from animal feces can get in irrigation water or fields where vegetables grow.
Germs can also get on leafy greens in packing and processing facilities, in trucks used for shipping, from the unwashed hands of food handlers, and in the kitchen.
Keeping the Garden Safe to Eat
Home gardens can be an excellent source of fruits and vegetables. Follow these tips to help prevent food poisoning:
- Plant your garden away from compost bins, manure piles, and animal pens.
- Water your garden with clean, drinkable water.
- Keep dirty water, including storm runoff, away from the parts of plants you will eat.
CDC is not aware of any evidence that organic greens are safer. And, most foodborne illnesses are not part of a recognized outbreak. The nearly 2,000 illnesses reported in 2014–2020 outbreaks linked to leafy greens represent only a small part of illnesses caused by contaminated leafy greens during those years.
Moreover, the CDC typically communicates only about outbreaks that affect people in more than one state. In addition, most sources of foodborne outbreaks are never identified.
A variety of produce, including organic leafy vegetables, can be contaminated with harmful germs. To prevent contamination, leafy vegetables should be grown and handled safely at all points from farm to fork.