It had been thought for 20 years that microwaved food may not have all its nutrients. According to most studies, however, the reality is quite the opposite. Every cooking method can destroy vitamins and other nutrients in food. The factors that determine the extent are how long the food is cooked, how much liquid is used and the cooking temperature.
Since microwave ovens often use less heat than conventional methods and involve shorter cooking times, they generally have the least destructive effects. The most heat-sensitive nutrients are water-soluble vitamins, like folic acid and vitamins B and C, which are common in vegetables.
In studies at Cornell University, scientists looked at the effects of cooking on water-soluble vitamins in vegetables and found that spinach retained nearly all its folate when cooked in a microwave, but lost about 77 percent when cooked on a stove. They also found that bacon cooked by microwave has significantly lower levels of cancer-causing nitrosamines than conventionally cooked bacon.
When it comes to vegetables, adding water can greatly accelerate the loss of nutrients. One study published in The Journal of the Science of Food and Agriculture in 2003 found that broccoli cooked by microwave — and immersed in water — loses about 74 percent to 97 percent of its antioxidants. When steamed or cooked without water, the broccoli retained most of its nutrients.
Some scientists feel that much of the benefit of food is due to vibration of energy. Microwaves cause isomerization which is the rearrangement of electrons which morphs into another form such an amino acid going from L. lysine to D lysine. Living tissue recognizes the L. but not the D form. This is much more in theory than proof.
However, microwaved heating of banked blood has reportedly caused at least one death. Also, people who were given microwaved foods were shown to have depletion of some vital enzymes. It may be years before the truth is known. But for now I use the microwave mostly to heat water and not food. I am still moderately concerned about the devitalization of the micronutrients in food. Study after study has shown that the more any food is cooked by any method, the less nutrition it has "if it's not raw don’t eat it at all".