So, a microwave doesn't blast your food, trying to ionize it. It does something smarter. It excites polar bonds like those present in water, and selectively feeds them energy. This energy is released as heat, which is then spread around.
Okay. Okay. Tell me if it is good or bad.
I am so glad you asked.
The quick answer is "it is not bad".
You have to realize that cooking per se robs food of its nutrients. So whether you boil, steam, grill or microwave food, its never going to be as good as it is when it is raw. Once you've decided, you want to cook, the answer sort of depends on what you are cooking.
A 2003 study on broccoli in the Journal of the Science of Food and Agriculture by Garcia-Viguera et al. concluded that microwave cooking lost the highest percentage of flavonoid antioxidants, about 97%. Pressure cooked and boiled broccoli lost 47% and 66%, respectively. With potatoes and tomatoes, the story turned upside down. Microwaving lost 45-65% of the nurtients, while boiling on a stove lost 60-80% of the flavonoids.
As a website with a harvard.edu suffix says:
So, as a general proposition, cooking with a microwave probably does a better job of preserving the nutrient content of foods because the cooking times are shorter.
As far as vegetables go, it’s cooking them in water that robs them of some of their nutritional value because the nutrients leach out into the cooking water. For example, boiled broccoli loses glucosinolate, the sulfur-containing compound that may give the vegetable its cancer-fighting properties as well as the taste that many find distinctive and some, disgusting.
Here, I have only touched upon the loss of nutrition. Some of the fears may be justified, since some of the first microwavable food leaked carcinogens like benzene, and I have heard of diacetyl leaching out of microwave popcorn. I'll probably look at that separately.
So what is the moral of the story:
- Raw is best!
- If that is not possible, minimize cooking time.
- Use as little water as possible in a microwave-safe container.
- Use the nutrient-rich water from boiled or microwaves vegetables