There’s probably no household appliance that sees more use than a microwave. For people who don’t have the time or inclination to prepare dinners from scratch or heat meals in a conventional oven, zapping food has become the ultimate method of time management in the kitchen.
Some people harbor the belief that a price has to be paid for that convenience—specifically, that food loses nutritional value by being subjected to a quick nuking.
The truth? Microwaving doesn’t harm a food’s nutrients. In fact, it may preserve them more than some slow-cook methods do.
The reason is found in how microwaves work. The appliances heat food by blasting it with waves of energy not unlike radio waves. These waves target water and other molecules in the food. Thermal energy quickly builds up, and dishes come out heated in a relatively short period of time. This process avoids two of the factors that can lead to nutrient loss: cooking duration and high temperatures. Typically, the longer and hotter food is cooked, the more its nutritional value dissipates.
The other advantage is that microwaves don’t require water for heating. If you boil broccoli, for example, the hot water allows nutrients to leach out of the vegetable. (While that makes for a good stock, your broccoli may be robbed of some of its healthy benefits.) A quick steam in the microwave leaves broccoli relatively intact.
That’s not to say that microwave cooking is superior to a stovetop. Cooking foods at reasonable temperatures and durations shouldn’t result in significant nutrient loss, though some is inevitable for any manner of cooking. But microwaving isn’t going to erase nutrients via some mysterious microwave alchemy, either.