Re: Do microwave ovens effect food nutrients?

Yes, a microwave oven, as a heat  source, affects some food nutrients. 
But, microwaves are just a heat source generated by a fancy electronic 
tube.  True, those heat waves have special properties such as instant 
availability (you don't have to wait for the griddle to heat up) and 
microwaves can penetrate food better than some other heat sources.  
Microwaves are also selectively absorbed by some food components, e.g, fat 
and salt solutions. 
But beyond the simple heat effect, there's little solid evidence of adverse 
nutritional effects (selective food absorption by microwaves caused some 
errors in interpreting earlier data). 

On the beneficial side, a microwave oven, by not charring (or crisping) the 
food when reheating it, destroys fewer heat labile nutrients. 
One negative effect could be if the food is not throughly cooked (or 
reheated), any food borne disease could reduce nutrient absorption because 
of emesis or diarrhea (good words to look up for when you're speaking of 
gross things in polite company).