Is microwave food unhealthy?
You can quickly thaw a frozen meal or warm up something you cooked the day before, thanks to the microwave radiation inside the oven, which has a frequency of 2.45 gigahertz.
It does not add anything to the food apart from heat.
"Microwaved food is harmless for your health," says nutrition expert Margret Morlo.
Ina Stelljes, of the German Agency for Radiation Protection, agrees.
Theoretically, you could rely solely on a microwave to heat up all your food and drinks every day.
However there is a catch. We need raw fruit and vegetables in our diet, and if you think you can freeze raw vegetables in portions,
bring they back to room temperature in the microwave and still eat vitamin-rich food, you would be wrong.
"Most vitamins are very sensitive to heat," says Morlo.
Temperature, light and oxygen reduce foodstuffs' vitamin content. The maximum vitamin loss is usually between 40 and 80 per cent. Folate and vitamin C, however, can be completely depleted.
"People who often warm up or cook their meals in the microwave should also eat raw fruit and vegetables on a daily basis in order to optimize their vitamin intake," Morlo recommends.
Microwaves work with a so-called magnetron, Morlo explains. This generates electromagnetic waves. Those waves move inside the device and are reflected by the walls of the cooking space and distributed around that area as uniformly as possible.
"Electromagnetic waves cause major oscillations, particularly in the water molecules in food," Morlo notes.
These oscillations generate heat, which is why foodstuffs with a high water content warm up faster than those that are rather dry.
Choosing the right container is important while warming up food in the microwave.
"Containers that have been especially produced for microwave use are of course the best, but porcelain and glass are fine too," says Annabel Oelmann, who leads a consumer advice centre in the German city of Bremen.
However, you should never use plastic bowls made of melamine to roast, cook or heat up anything in a microwave, says Andreas Hensel, head of the German Institute for Risk Assessment, a government agency that offers bias-free advice on food safety.
The reason is that when melamine is subjected to high temperatures inside the device, melamine or formaldehyde can pass from them to the food, which can be harmful if eaten.
Oelmann notes that microwave ovens often fail to warm up food uniformly.
"That means that your cocoa may only feel lukewarm when you start to drink it and burn your mouth a second later," the expert says.
This is why it is important to stir it before drinking.
In order to prevent food and drinks from splashing all over the microwave or becoming dry on the surface, you should cover them for heating.
In principle, microwave users should let their food stand in the microwave for a few minutes after heating or cooking it.
"That is the best way to distribute the heat around the food," Morlo says.
"Safety mechanisms ensure than only very little radiation gets out of the microwave while it is running," Stelljes says.
Still, she notes that there can be a little bit of so-called leakage radiation in the area around the microwave's screen and door. Safety rules set a required maximum leakage of 5 milliwatts per square centimetre in the region of up to 5 centimetres from the device.
An overwhelming majority of microwaves are indeed within those limits, tests in Germany have shown.
"Technically flawless devices pose no health risks, even to people like pregnant women or young children," Stelljes assures.