According to research published by the Harvard Medical School, you'll be pleasantly surprised to hear that microwaves actually do a a better job of preserving nutrients that break down when heated because cooking time is so quick.
In the case of boiling water, unfortunately you're worse off. "As far as vegetables go, cooking them in water robs them of some of their nutritional value because the nutrients leach out into the cooking water," says the research.
"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 find disgusting).
"Is steaming vegetables — even microwave steaming — better? In some respects, yes. For example, steamed broccoli holds on to more glucosinolate than boiled or fried broccoli," adds the research.
If you're looking to retain as much nutritional value as possible, the best way is one that cooks quickly with as little fluid as possible. "Using the microwave with a small amount of water essentially steams food from the inside out. That keeps in more vitamins and minerals than almost any other cooking method and shows microwave food can indeed be healthy."