How bad are microwaves, really?

Posted on February 13th, 2014

In my list of Top 100 Hairy Chestnuts I Get Confronted With When I Talk About Cooking, “But aren’t microwaves bad?” comes in at about #25. I’m a fan of getting more people cooking, first and foremost. For some this involves using a microwave. Thus, my short answer to the above question is: If it gets you cooking with real food, go ahead, use a microwave. Indeed, I use a microwave from time to time. We have one at the office for heating our lunch, for instance. The longer answer, however, follows here…

Paleo Choc Muggin: a one-minute microwave meal

Julie Van Rosendaal’s 2-minute microwave mug brownie. I have a sugar-free Paleo Choc Muggin (a muffin in a mug!) version, available from I Quit Sugar For Life

Microwaves don’t radiate you

Microwave ovens use radio/microwaves to make the water molecules in food vibrate, which produces friction, which heats the food. It uses a form of non-ionizing radiation (it can’t directly break up atoms or molecules). This means it can’t damage your DNA like, say, X-rays do.

But they do emit EMFs

Building biologist Nicole Bijlsma says: Microwaves do emit EMFs three types of electromagnetic fields: electric field (minimal), magnetic field (can be high from the digital clock and also where the transformer is located) and radio/microwaves. The electric and magnetic field (from the digital clock) will be present even when the microwave oven is not heating. The magnetic field will increase when the microwave oven is in use and will drop off to background levels within one metre. The World Health Organisation has classified radio/microwaves and magnetic fields in 2011 and 2002 respectively as “possibly carcinogenic to humans”. However, unlike the pulsing nature of the radio/microwaves used in the telecommunications industry (mobile phones and Wi-Fi), the microwave oven uses continuous wave fields so the biological effects are not likely to be as bad.

Do microwaves kill nutrients?

Any cooking will change the nutrients in food in some way. Low and slow cooking preserves the most nutrients, as I’ve shared before. The faster you cook (or heat) your food, the more nutrients and enzymes you destroy.

A study published in The Journal of the Science of Food and Agriculture found that the amount of nutrients lost depends on the duration and way in which the food is cooked – steaming broccoli in the microwave for 90 seconds is better than zapping it for 4-5 minutes.

Research from the University of Oslo found that microwaving carrots, spinach, mushrooms, asparagus, cabbage, green and red capsicums and tomatoes led to an increase in the antioxidant content of the foods (in that the antioxidants become more available for absorption).

Some sources also claim microwave ovens can cause issues because:

  • They can heat food beyond their natural boiling point, thus scalding it.
  • They can leave cold spots from uneven heating, causing bacterial growth.
  • Overheating dairy can destabilise proteins

I tend to take these claims with a grain of …salt…or something. I think any kind of cooking can cause these issues if you’re hasty or lazy.

How to use microwaves safely

* Stand back. Because the radiation diminishes quickly over distance, standing further away from the microwave during operation cuts your exposure even more significantly. One metre is about right. And keep your distance even when the microwave isn’t in operation.

* Don’t put plastic in your microwave. All plastics leech chemicals (hormone disrupting chemicals such as phthalates and BPA, benzene, acrylamide) and/or metals (such as antimony, if PETE or number 1 plastics are used) into the food the hotter they become. Says, Nicole, “When the Milwaukee Journal Sentinel tested plastics labeled “microwave-safe” and advertised for infants, they were found to release “toxic doses” of Bisphenol A. The amounts detected were at levels that scientists have found cause neurological and developmental damage in laboratory animals.”

* Use glass or ceramics instead.

* Keep the microwave clean, especially around the seal.

* Don’t be hasty and lazy. Cook food low and slow.

The upshot, I ‘spose, is this: as with everything in life we have to weight up costs and benefits. Me, personally, I use other methods of cooking when I can (in part because I prefer to be able to see and smell and touch food as it cooks, to keep an eye on it). When I can’t, a microwave is fine, but I take the precautions (I always stand back, cook in ceramic etc.). No big deal.

We can get a bit too worked up about these kind of “hot topics”, but then forgot bigger and dirtier pictures. Like, who really knows how the food at their local cafe is cooked? Which oils? How much sugar? Who really  gets fired up about how their banana bread is made? I’d be far more concerned about these factors than the small impacts of microwave cooking.

Do you agree?

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