A: Believe it or not, microwave cooking may actually retain nutrients better than traditional methods. That’s because the longer your cook food, particularly in water that’s discarded before eating, the more nutrients are lost. For example, one study found that spinach retained 100 percent of its folate — a water soluble B-vitamin — when cooked in a microwave, vs. 77 percent when stove-top boiled. Moreover, briefer cooking of meats produces lower levels of potentially cancer-causing chemicals.
At the same time, microwaving tends to heat foods unevenly, so that outer portions may not get hot enough. To help ensure germ-killing temperatures throughout, cover the food, and leave a hole for steam to escape. (Waxed paper is preferable to plastic wrap, which might transfer possibly harmful amounts of plastic to the food). For the same reason, use only containers labeled, “microwave safe.” Stir and turn the food during cooking and let it stand for a while afterwards, as directed. And check its temperature in several places with a food thermometer.