Healthy or Not? 3 Microwave Myths

Cynthia Ross Cravit | August 17th, 2016
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A microwave oven is a convenient way to thaw, cook and reheat food. But just how healthy is it?

Many of us are dependent on our microwave ovens for thawing, cooking or reheating food. But just how healthy is “zapping” your food compared to cooking in a conventional oven or skillet?

Here, we debunk three popular myths.

Myth #1: Cooking your food in the microwave removes the risk of food poisoning.

Many people rely on microwave ovens to kill dangerous bacteria in food. Good idea? Not always, health experts say.

A study by the U.S. Centers for Disease Control and Prevention looked at a salmonella outbreak following a picnic where dozens of people ate reheated roast pork. The study, published in The American Journal of Epidemiology, found that of all 30 people involved, those who used a microwave oven became sick. On the other hand, those who used a conventional oven or skillet were not affected.

The reason may have to do with how microwave ovens work. Food is heated from the outside in — not from the inside out — which can result in “cold spots” where pockets of bacteria can thrive.

The bottom line: Don’t assume that “zapping” your food means you’re necessarily killing bacteria. Health Canada makes these recommendations:

– If you’re using the microwave to defrost or partially cook food, be sure to refrigerate or finish cooking the food by some other method right away. Do not let perishable foods remain in the “danger zone” for longer than 2 hours.

– Heat your food evenly to avoid “cold spots” where bacteria might multiply and cause food poisoning. Follow these steps to heat food evenly:

* Cut food into small pieces and arrange items in a uniform manner
* Add a liquid (such as water, juice or gravy) to solid foods
* Stop mid-way through cooking to stir foods or rotate trays or containers
* Cover food with a microwave-safe lid or with microwave-safe plastic wrap to trap steam
* Follow directions for “standing times”. This helps ensure that heat is distributed uniformly, even after cooking.

– Use a food thermometer to check that your food has reached a safe internal temperature. Take the temperature at several locations, especially in the thickest area of the meat, ensuring that the thermometer is inserted away from bone, fat or gristle. For example:

* All ground beef products should be cooked to 71 degrees C (160 degrees F).
* Food mixtures containing poultry, eggs, meat and fish should be cooked to 74 degrees C (165 degrees F).
* Leftovers should be heated to 74 degrees C (165 degrees F).
* Never cook whole poultry, including turkey, in the microwave.

Myth #2: Microwave cooking reduces the nutrients in food.

While all cooking methods have some effect on the nutrients in food, the effect is worse if you over-cook the food.

For this reason, microwave cooking tends to be less harsh on nutrients than conventional cooking methods, because the cooking times are shorter and less water is used.

The bottom line: To help preserve nutrients when microwaving food, use techniques that promote the even distribution of heat. This will help prevent the formation of “hot spots” where portions of the food could be over-cooked.

Myth #3: Microwave ovens present a risk of radiation.

Microwaves are a form of radio-frequency electromagnetic energy. They are generated electronically. They do not come from radioactive sources and they do not cause food or the oven itself to become radioactive.

When microwaves penetrate food, they cause water molecules in the food to rotate. The rotation causes friction between the molecules and the result is a rapid rise in temperature. This is why the cooking time with microwave ovens is shorter than with conventional ovens. When you shut the microwave oven off, the microwaves disappear.

The bottom line: Microwaves do not change the chemical components in food and so the formation of new compounds, like carcinogens, is not expected. Some studies have been conducted to investigate any possible negative health effects of microwaving foods. These studies, which have been reviewed by Health Canada scientists, have found no evidence of toxin or carcinogens.