Is the microwave damaging our health?

The microwave oven can be summed up in one word: “convenience”. This modern marvel, beloved for its speed and ease of use, is now a prominent fixture on many kitchen worktops, throughout Scotland.

According to a national survey on UK food buying habits, consumption of ready meals has increased five-fold over the last 40 years. No doubt, a positive correlation exists between the rise in popularity of the microwave and the demand for these conveniently prepared meals. From a nutritional point of view, they come with a whole host of concerns and the internet is full of myths and urban legends about them, but what are the possible health hazards of using a microwave to heat your food?

Like most great inventions, the microwave was discovered by accident by an American engineer Percy Spencer after the Second World War. While testing military radar technology, he suddenly realised the snack in his pocket had melted. Further investigation showed that the microwaves emitted from the radar had caused the water molecules in snack to vibrate, resulting in heat which raised the internal temperature of the food far more rapidly than a conventional oven. However the first counter-top microwave oven didn’t appear in household kitchens until about 1967 and now their use has spread into commercial and residential kitchens around the world.

One thing is for certain, food cooked in a microwave oven does not taste as good as food cooked by traditional means. The key to much of the flavour of conventionally cooked food is a sequence of chemical events known as the Maillard reaction, which results browning and caramelisation of the sugars and gives bread a brown crust for example. Researchers of the University of California found that flavours produced by microwaves are chemically different to those produced by conventional thermal cooking. They found that cooking times are too short and temperatures too low to bring about the Maillard reaction, in turn affecting the taste.

What about carcinogens?

Microwave cooking does alter the chemical composition of food. Any heating process does. Higher cooking temperatures can create chemical reactions that may produce dangerous compounds that can damage our DNA. Microwaves heat food from the outside in, very similar to other heating methods. Cooking meat products with microwaves produces less nitrosamine than conventional cooking. Nitrosamine is a carcinogenic compound produced when nitrogenous compounds in meat are heated in the presence of carbohydrates. This heating causes moisture to leach from microwaved products which helps to flush out the nitrosamine. However, it also causes the product to lose flavour.

How about nutrition?

Every cooking method can destroy vitamins and other nutrients in food. In a 2010 study published in the Journal of Food Biochemistry, researchers observed that microwave cooking and pressure cooking were actually better than boiling in retaining maximum nutrients in some foods. As in any type of cooking, nutrients are leached from food especially when the food is cooked for a long period of time with high amounts of water.

Is heating food in plastic containers safe?

Many plastic containers when heated release toxic and hormone-disrupting compounds due to chemical migration from the plastic into your food. This movement of chemicals between plastics and heated foods can be easily seen when someone heats food in a styrofoam container in the microwave. So don’t microwave food in plastic containers especially one that doesn’t say “microwave-safe” or carry a microwave icon on it. And don't allow plastic wrap-prepared meals to touch your food during heating. Some experts would go as far as to say no plastic containers should be used in the microwave “ever”. If you’re unsure, just use glass or ceramic dishes marked “heatproof” or “microwave-safe”.

Other things than you should never use to cover microwaved food include aluminium foil, brown paper bags, cold-storage plastic containers (such as butter, cottage-cheese, and yoghurt tubs), one time-use plastic containers, dishes with metallic paint or trim and foam-insulated cups, bowls, plates or trays.

Perhaps, after all, the microwave oven is not the real problem here. Perhaps the real damaging problem to our health is what people put in them.