Cooking in a microwave, when done properly, keeps more vitamins and nutrients in foods than almost any other cooking method. The healthiest cooking methods use the least amount of liquid, cook quickly and have least exposure time to heat.
Using microwave-safe cookware and a small amount of water is one of the best methods to steam vegetables and retain their nutrients. Microwaves can actually enhance the nutritional value of foods such as tomatoes and carrots by making the carotenoids in them easier to digest. Meats such as bacon produce fewer cancer-promoting nitrosamines when cooked in a microwave, as opposed to fried to crispness in a skillet.