If you’ve ever been laughed at for your reliance on the microwave (a.k.a. it's the only appliance you use in the kitchen), go ahead and laugh right back. The microwave is one of the healthiest methods of cooking when it comes to preserving vitamins and nutrients.
“In general, there’s a huge difference in the retention of nutrients depending on the food and the way it’s cooked,” says Guy Crosby, Ph.D., a certified food scientist and science editor for America’s Test Kitchen.
For starters, just plain, dry heat, like that inside your oven, will destroy any nutrients that can’t withstand high temperatures—like vitamin C, which is highly sensitive to cooking. And then there are nutrients that are water-soluble. Say you boil vegetables. That water is going to leech out and dissolve those vitamins and minerals in fairly high quantities, and in some instances even chemically changes their nutrients, making them less wholesome (through a process called “hydrolysis”), Crosby says.
“You can lose anywhere from nothing to 80 or 90 percent of nutrients with conventional types of cooking like roasting, boiling, or frying, but with microwaves, you raise the temperature much faster, so the nutrients are subjected to heat for less time,” Crosby adds. So, aside from being more convenient, microwaves really do help protect the integrity of the food you’re cooking. Steaming, too, is a great method of cooking, he says; it retains about the same number of nutrients as nuking.
And while Cornell researchers found spinach retains nearly all its folate when cooked in a microwave—and loses about 77 percent when cooked on a stove—and bacon cooked by microwave has lower levels of cancer-causing nitrosamines than conventionally cooked bacon, Crosby says to take all research with a grain of salt. “Even with studies evaluating the same food, cooked by the same method, you’ll find variation in the nutrients lost in food because of the care with which it was done, how it was heated, and the way results were analyzed, so it’s not like you can pin the answer down to a single number.” However, most studies have found and reported that B1, B2, B6, vitamin C, and folic acid tend to be better retained in microwaves. So go ahead, nuke away.
And if you're concerned with the microwave’s potential to cause cancer, take solace in this info from the American Cancer Society: There is no evidence showing microwaves pose a health risk to people. They’re designed so the microwaves are contained inside the oven itself, and the federal standards limit the amount of radiation that can leak from a microwave oven to a level far below what would harm people.