Oh My Science: Exposing Microwave Myths

Your microwave turns on, molecules start to move around, and in a few minutes, you have a nice bag of popcorn or some lovely steamed veggies. Sounds nice, right? That story of the kid’s experiment with microwaved or boiled water on the plants tells us that we should be very afraid; the microwaved water killed the plant! Countless natural health oriented sites and magazines say microwaving removes nutrients and causes proteins to unfold in unhealthy ways. Other people point out the dangerous chemicals that can seep into our food because of the containers we use to microwave things. Is there any truth to this?

Only some.

Does it remove nutrients?
The evidence points mostly towards microwaving foods as one of the most healthy options for retaining nutrients. Microwaving a food with a little bit of water is like speed steaming your veggies, especially if you cover the bowl or plate. It keeps all the nutrients in as long as you don’t drown the vegetables with water, which, like boiling, can remove nutrients. For example, a study showed that microwaving spinach retained 101% folic acid compared to the 77% retained with boiling (Klein, Kuo, and Boyd, 1981). Another study pointed to the efficiency of properly microwaved vegetables, and that blanching vegetables in the microwave was BETTER for nutrient retention than other methods (Ramesh et al, 2002). A few studies have shown varying amounts of retention for a select few nutrients (like vitamin C), but most nutrients stay longer with microwaving.The overall verdict from the scientific community? The difference between microwaving and other conventional methods of cooking (steaming, boiling, etc) is minimal and doesn’t really matter significantly (Cross, Fung, and Decareau, 1982; Schardt, 2005).

The trick to get these benefits is to microwave food properly: don’t use too much water, cover it up to keep it steamy, and don’t cook it for too long.

Can it give me cancer?
When done right, NO, microwaving food will not raise your chances of getting cancer. However, plastic that is NOT microwave safe can contaminate your food. The packaging that is used in frozen dinners or microwaveable meals is meant to only be for one use, but is generally safe. Microwaving with plastic wrap is harmless, and unless you’re using plastic wrap from the 1980’s, the components of plastic wrap won’t contaminate your food either. General consensus: don’t microwave things in non microwave safe containers and you’ll be fine.

What should you be microwaving things in? Microwaveable plastic, glass and paper products like wax paper or plain paper plates. Avoid things like grocery bags, coated metallic bags, brown paper bags, and anything not approved for microwaving (Schardt, 2005).

What about the microwave itself? Can the radiation give me cancer?
Microwaves only emit radiation when they’re damaged, and even then they don’t emit enough to cause harm or increase cancer risk. New microwaves are engineered so that the microwaves generated only stay in the cooking chamber and don’t leak. Plus, the radiation waves that would sneak out dissipate so quickly that they likely wouldn’t do much anyway, especially compared to the amount of radiation you’re exposed to every time you step outside into the sun (unless you’re here in Seattle).

1. Klein, B.P., Kuo, C.H.Y., & Boyd, G. (1981). Folacin and ascorbic acid retention in fresh raw, microwave, and conventionally cooked spinach. Journal of Food Science, 46(2): 640-641.
2. Ramesh, M.N., et al. (2002). Microwave blanching of vegetables. Journal of Food Science, 67(1):390-398.
3. Cross, G.A., Fung, D.Y.C., & Decareau, R.V. (1982). The effect of microwaves on nutrient values of foods. Food Science and Nutrition, 16(4):355-381.
4. Schardt, D. (2005). Microwave myths. Nutrition Action Healthletter.

Extra resources:
Snopes.com on the microwaved water experiment: http://www.snopes.com/science/microwave/plants.asp

Alyssa Brandt

Alyssa Brandt is a senior and lead designer who loves all things brain-related. She likes illustrating and sugary cereals, and will eventually go to graduate school to pursue a PhD in neuroscience.

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