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Food Poisoning: Protecting Your Family

Food poisoning occurs when food is not prepared or handled correctly. Harmful microorganisms such as bacteria, viruses, or parasites get in the food, causing illness. All foods have the potential to cause food-borne illness. Food-borne microorganisms often cannot be seen, tasted, or smelled.

The consequences of eating contaminated foods can be very serious.

Symptoms of food poisoning may include:

  • nausea
  • vomiting
  • diarrhea
  • stomach cramps
  • fever

Young children, pregnant women, and the elderly are more at risk for very serious health problems from food poisoning. 

Tips to reduce the risk of food-borne illness

Wash hands and surfaces

Always wash your hands with soap and warm water for at least 20 seconds before and after handling food. Wash all utensils, dishes, cutting boards, and counter tops with hot soapy water before and after preparing food.

Cook food to proper temperatures

Cook foods to their safe internal temperatures. This kills harmful microorganisms that cause food poisoning. Use a food thermometer to measure the internal temperature of cooked foods.

Different foods have slightly different safe minimum cooking temperatures:

  • Seafood, veal, lamb, and fresh beef should be heated to 60°C (about 140°F).
  • Eggs, egg dishes, and pork should be heated to 70°C (about 160°F).
  • Leftovers, casseroles, ground beef, and poultry should be heated to 75°C (about 170°F).

Thaw frozen foods properly

Frozen raw meat should never be left on the counter to thaw at room temperature. Thaw frozen meat in the refrigerator, in a microwave oven, or in cold water. If thawing in cold water, replace the water every 30 minutes.

The temperature danger zone

Perishable foods should not be kept at temperatures between 4°C and 60°C (about 40°F to 140°F) for more than two hours. Microorganisms can grow quickly at these temperatures.

Keep hot food hot

Keep the food hot (above 60°C or about 140°F) if it is not going to be eaten right away. Use a hot plate, wrap food in tinfoil, or use insulated containers to keep food hot.

Keep cold food cold

Foods that need refrigeration should always be kept cold (below 4°C, less than about 40°F). If allowed to warm, microorganisms may start to grow. Separate large portions of leftover food and divide them into small, shallow containers less than 8 cm (3 inches) thick for quicker cooling in the refrigerator. When travelling with cold foods, bring a cooler with ice or freezer packs.

Don’t cross-contaminate

Separate meats and their juices from other foods during storage and preparation. Microorganisms from raw meat and poultry can spread to other foods. These meat juices can drip from packages or can be transferred through hands or utensils. Clean all surfaces that may have come in contact with meats or their juices.

When in doubt, throw it out!

  • Never sample food that has expired or that you suspect may be spoiled.
  • If you are unsure whether or not a food is safe to eat, throw it out.
  • Do not eat canned food if the can is bulging, dented, or appears to have a leak.
  • Do not re-heat leftover food that you suspect is spoiled in the microwave. This will not destroy the microorganisms if a food has been handled incorrectly.
  • If a food looks, smells, or tastes off, throw it out!

Reporting a food safety concern

If you are concerned that a food product may pose a health or safety risk, report the product to your local board of health or food inspection agency.

Common food poisoning illnesses


A bacterial infection caused by Listeria monocytogenes. Listeriosis is rare and usually affects newborns, the elderly, and people with weakened immune systems. Symptoms include:

  • nausea
  • stomach cramps
  • vomiting
  • diarrhea
  • headache
  • constipation
  • fever
  • convulsions

Foods that may cause listeriosis include contaminated fruits, vegetables, meats, and dairy products.


A bacteria that normally resides on the surface of the skin. Staphylococcus can cause a wide variety of diseases when ingested in food through either toxin production or bacterial colonization. Staphylococcal toxin is a common cause of food poisoning and symptoms include nausea, vomiting, and diarrhea.

Common foods that can be sources of staphylococcus bacteria include milk and cheese.

E. coli

A bacteria commonly found in the lower intestine of mammals. Most E. coli strains are harmless, but some can cause serious food poisoning and can be life-threatening. Symptoms include:

  • bloody diarrhea
  • cramps
  • fever
  • nausea
  • vomiting

Common foods that may be sources of E. coli bacteria include ground beef, unpasteurized milk and cheese, spinach, alfalfa sprouts, and water.


Salmonella is a bacteria that can cause serious infection in humans. Most often, the bacteria is transferred to humans when partly cooked eggs are eaten. Symptoms of an infection include:

  • vomiting
  • diarrhea
  • fever
  • abdominal cramping 12 to 72 hours after exposure

Key points

  • Most food borne illness can be prevented by proper cleaning and cooking.
  • If you believe a food may be contaminated, throw it out.
  • Food poisoning can be very serious. The young, the old, and the sick are most at risk.

Cristina Cicco, RD

This article was written by the registered dietitians at the Specialty Food Shop at Toronto's SickKids Hospital.