By Kris Gunnars, BSc
Cooking with a microwave oven is highly convenient.
It’s simple, doesn’t require stirring or flipping things, and is incredibly fast.
However, many people believe that this convenience must come at a cost.
Мicrowaves produce harmful radiation and cause damage to healthy nutrients.
This article takes a look at microwave ovens, and how they affect the nutrients and health effects of foods.
Microwave ovens are kitchen appliances that turn electric energy into electromagnetic waves, called microwaves.
These waves can stimulate molecules in the food, making them start to vibrate, spin around and clash with each other, which turns the energy into heat.
Microwaves primarily work on water molecules, but they can also heat up fats/oils and sugars, just to a lesser extent than water.
Because the waves are dispensed throughout the food, it can heat up much more evenly compared to other cooking methods like frying.
Bottom Line: Microwave ovens turn electric energy into electromagnetic waves. These waves stimulate molecules in the food, making them heat up.
Microwave ovens produce electromagnetic radiation.
You may find this concerning because of the negative connotation of the word “radiation.”
However, this is NOT the type of radiation associated with atomic bombs and nuclear disasters.
Microwave ovens produce non-ionizing radiation, which is similar to the radiation from your cellphone except that it is much stronger.
Don’t press your face against the window and keep your head at least a foot (30 cm) away from the oven. Radiation decreases rapidly with distance.
Also, make sure that your microwave oven is in good repair. If it looks old or broken, or if the door doesn’t close properly, then consider getting a new one.
Bottom Line: Microwaves are a form of electromagnetic radiation, similar to the radiation from cell phones.
Every form of cooking reduces the nutrient value.
The main factors that contribute to this are high temperatures, long cooking times, and using added water (which makes water-soluble nutrients leak out of the food).
There are actually a number of studies that have looked at this.
One study also compared the effects of cooking methods on the antioxidant content of 20 different vegetables.
One study found that just one minute of microwaving destroyed the cancer-fighting compounds in garlic, while this took 45 minutes in a conventional oven (4).
There’s also a study showing that microwaving destroyed 97% of flavonoid antioxidants in broccoli, while boiling only destroyed 66% (5).
It is not recommended to heat human milk in a microwave, because it can damage bacteria fighting agents in the milk (6).
Many plastics contain hormone-disrupting compounds that can cause harm.
For this reason, do not microwave your food in a plastic container unless it is labelled with “microwave safe.”
Keep in mind that this is not specific to microwaves. Heating your food inside a plastic container is a bad idea, no matter which heating method you use.
Bottom Line: Many plastics contain hormone-disrupting compounds like BPA, which can leak out when heated. Never heat your food in a plastic container.
One safety issue with microwaves, is that they may not be as effective as other cooking methods at killing bacteria and other pathogens.
The heat tends to be lower and the cooking time much shorter, and sometimes the food heats unevenly.
It’s also important to be careful when heating liquids. There are some reports of “exploding” cups when you heat them above boiling temperature, then as soon as you stir the liquid, the energy is released in a violent manner.