Caution when steaming foods in the microwave

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I am a big fan of the microwave. Now that I am cracking down for my finals, I am cooking less and just "nuking" more.

The microwave is an amazing device for quick meals... healthy or otherwise. I opt to microwave my veggies with a wet paper towel over them for ~90 seconds rather than wait 5 minutes to steam them on a stovetop.

What is the downside of the microwave?
Researchers found that microwaving foods decreases the amount of vitamin B12 present.

Appreciable loss (approximately 30-40%) of vitamin B12 occurred in the foods during microwave heating due to the degradation of vitamin B12 molecule by microwave heating.

You also need to be careful of flash boiling your cup of hot water. You can actually superheat the water above 100deg celcius and it will bubble over and scald you with a tiny nudge, a spoon or a bag of tea!

What are some of the myths of microwave cooking?
One of my favorites is the "dioxin" theory. Dioxins are chemicals, labelled as potential carcinogens by the FDA. KHON-2 news (I'm somewhat ashamed that misinformation was spread via a station my dad used to work at) in Hawaii had a health alert that it was bad to microwave plastic. Dioxins have not been shown to be present in plastics, nor is there any evidence that it leaches out from microwave-safe plastic containers. The reason why some containers (like styrofoam take-out containers and margarine tubs) are not microwave-safe is because they melt and warp in a microwave.

Uhm... well, that's about the only myth I can think of.

I read something else on the nets (i.e. from a .com website rather than a .gov or .edu site) about anemia -- but vitamin B12 deficiency does give you anemia. It also can cause peripheral neuropathy (numbness and tingling in extremities, loss of vibration sensations and clumsiness) and dementia.

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Reference:
Effects of Microwave Heating on the Loss of Vitamin B12 in Foods. Fumio Watanabe. Journal of Agricultural and Food Chemistry 1998 46 (1), 206-210

Snopes.com: Microwaving Plastic Releases Cancer Causing Agents: False! last updated 3 April 2007

Food Safety.gov: FDA Consumer - Plastics and the Microwave

USDA: Cooking Safely in the Microwave Oven - Fact Sheet Nov-Dec 2002