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Harvard Commentaries
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Reviewed by the Faculty of Harvard Medical School

Food for Thought Food for Thought

How To Avoid Foodborne Illnesses

June 05, 2013

By Marc C. O'Meara, R.D., L.D.N, C.D.E.
Brigham and Women's Hospital

Every year, there are about 9.4 million episodes of foodborne illnesses in the United States, according to the Centers For Disease Control and Prevention (CDC). These illnesses can be caused by bacteria, viruses, toxins, chemicals and parasites.

In 2009 and 2010, 1,184 people were hospitalized and 23 people died from foodborne illnesses. In that short period of time, 1,527 foodborne illnesses caused 29,444 people to become sick. The most common causes of foodborne illness during that time were norovirus, salmonella and E. coli.

Two salmonella outbreaks have occurred so far in 2013. More than 80 people have become sick in each case. One outbreak was caused by imported cucumbers. The other outbreak was from food at a Las Vegas restaurant named Fire Fly.

E. coli sickened more than 30 people from Farm Rich frozen meals this year. There were 3 deadly outbreaks in 2011, including a listeriosis outbreak from cantaloupes that led to 30 deaths, the second-deadliest outbreak in U.S. history since 1970.

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Which Foods Are Risky?

When a food is suspected of causing people to become ill, it can be recalled, or taken off the market. Since 2009, there have been recalls for the following foods: cheese or cheese-containing products, oysters, raw milk, salami, bison, sirloin steak, peanut butter, cookie dough, cantaloupes, papaya, salmon, strawberries, hazelnuts, Romaine lettuce, ground turkey, tuna steak, unpasteurized dairy, eggs, beef and frozen entrées.

Any food that is handled by people or processed near sewerage can become contaminated. In 2009 and 2010, the largest number of foodborne disease outbreaks was due to beef, dairy (mostly unpasteurized), fish and poultry.

Experts can often identify the microorganism that caused an outbreak. The most common microorganisms are bacteria: Campylobacter sp. in unpasteurized dairy foods, Salmonella sp. in eggs and shiga-toxin producing E. coli in beef.

Other foods that can cause illness are:

  • Leafy greens, such as spinach and lettuce
  • Sprouts (bean and alfalfa)
  • Unpasteurized juices and cider

That's because these foods:


  • Grow close to the ground or fall to the ground (apples)
  • Are not cooked before eating
  • Are not acidic (foods like citrus fruits are acidic and can fend off bacteria better than produce that is neutral or basic)

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Symptoms of Foodborne Illnesses

Symptoms usually show up 1 to 4 days after eating contaminated food. The most common symptoms of infection are:

  • Severe abdominal cramps
  • Bloody stools
  • Fever
  • Vomiting
  • Body aches
  • Headaches

If diarrhea is bloody or doesn't resolve in 3 days, or if there is also a fever over 101.5° F, it's time to call the doctor. Most illnesses and outbreaks (when two or more people become ill) never get reported to the CDC because people think they just have the flu and they don't go to the doctor.

More severe outcomes can occur, such as:

  • Kidney failure
  • Red blood cell damage (hemolysis)
  • Blindness
  • Paralysis
  • Death

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Safety Tips

The tips below may help you get the health benefits of eating fresh fruits and vegetables while avoiding foodborne illnesses.

  • Wash hands with warm water and soap for 20 seconds before preparing food.
  • Wash surfaces or utensils after each use.
  • Refrigerate or freeze leftovers within 2 hours of cooking.
  • Thaw foods in the refrigerator, not on the counter or in the sink.
  • Be sure all dairy products and juices are pasteurized.
  • Eat refrigerated leftovers within 4 days or throw them out.
  • Reheat foods to 165° F and reheat soup until boiling.
  • Keep meat, poultry, seafood and eggs separate from each other and other food items in the refrigerator.
  • Use separate surfaces and utensils when preparing raw meat or eggs.
  • Always use a food thermometer to make sure you have cooked food to the right temperature:
    • 145° for meat (whole cuts of pork, veal, lamb, beef)
    • 160° for ground meat (beef, veal, lamb, and pork
    • 165° for poultry (including ground turkey and chicken)
  • Egg yolks should be firm, not runny.
  • Keep the food hot, above 140° F and refrigerate leftovers right away.
  • Remove outer leaves of lettuce and cabbage before preparing.
  • Don't eat raw sprouts (bean or alfalfa).
  • Wash produce even if you are going to just peel it or slice it. The knife can transfer bacteria from the outside to the inside as it slices through.
  • Wash fruits and vegetables under running water just before eating, cutting or cooking. (Washing fruits and vegetables with soap, detergent or commercial produce washes is not recommended.)
  • Remove the outer leaves of leafy vegetables. Processing plants wash leafy greens three times in chlorinated water before bagging them. But bacteria are sticky, so even thorough washing may not remove all contamination.
  • Organically grown produce is not necessarily safer than conventionally grown produce.
  • Canned and frozen spinach are safe to eat.

For more information on food safety go to the U.S.D.A.'s Food Safety and Inspection Service.

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Marc O'Meara, R.D., L.D.N., C.D.E. is a senior nutritionist at the Brigham and Women's Hospital and the Roxbury Heart Center, and also works in the lipid clinic at Children's Hospital Boston. He graduated from the University of Vermont in 1991 with a bachelor of science in dietetics. He completed his dietetic internship at Beth Israel Deaconess Medical Center in 1992.

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