I have toyed with the idea of buying a microwave for heating up food (stock etc) and cooking veg and fish. But I have read that it alters the nature of food and makes it, in effect, toxic. Is this just a prejudice against progress, or is there truth in the notion that heating using a microwave is a violent and destructive way of cooking?
Microwaves work by heating up water molecules and boiling them. It's not uranium in there.
It's actually interesting - take a glob of pure tallow, put it in a bowl, and microwave it. Nothing happens. It doesn't even get warm. Microwaves only work on water.
Additionally, microwaves use non-ionizing radation, which isn't harmful at all
Microwave ovens just heat up water, which heats the surrounding food. It seems different than "traditional" cooking because it doesn't sear or caramelize anything, but that's just because the energy is directed exclusively towards the water contained in the food instead of everything in the oven. That being said, every type of cooking "alters the nature of the food." That's why we cook it!
It's important to think about what you heat up the food in as well. Avoid plastic, of course. Although some expensive stuff (Tupperware makes a dedicated microwave range) is safe and designed not to leach chemicals - it's apparently 'invisible' to the waves.
I haven't read through this article in its entirety yet, but it seems like it may be worth considering: