In one way or another, all forms of cooking remove nutrients from food. For example, boiling carrots and broccoli causes them to lose some of the cancer-fighting compounds like beta carotene (carrots) and glucosinolate (broccoli) which is washed away in the water.
Both boiling and poaching can also cause water soluble vitamins like vitamins B and C to be washed away with the water. On the other hand, protein becomes easier to digest and more available when meat is cooked, and heating makes vitamin A, iron, and calcium more available in spinach.
So yes, the microwave causes a food to lose some nutrients during the heating process, but no, it does not cause nutrient losses greater than normal from any other cooking method. It does not “zap” those nutrients out of the food, and nutrient losses are not any greater than they might be from boiling or frying something. In fact, some think the microwave might actually cause less nutrient losses because the cook time is shorter.
When The Microwave Is A Good Idea
In our world, it can be very difficult to eat healthy without a microwave. At least I would find it difficult to eat out or eat cold food everyday at work. So, sometimes a microwave can help us stick to our healthy habits. Microwaves are a good idea when:
- You are heating up leftovers of a fresh, healthy meal you made from whole food ingredients
- You are heating up unprocessed foods like frozen broccoli or a sweet potato
- You are heating up water for tea
When The Microwave Is A Bad Idea
Hey, sometimes microwaves make us lazy. If all of your meals come from square boxes or the frozen section of Trader Joe’s, and you haven’t used a stove or oven in the past month, it might be time to cut back on microwave use and spend a little more time on your food preparation.
Bottom line: as long as the microwave is a secondary method of cooking (i.e. you use it to reheat home cooked meals) or a way to cook unprocessed foods (like potatoes or frozen vegetables) then nuke away! If you use the microwave daily because your diet consists of nothing but Smart Ones or Hungry Man, it’s time to consider a more unprocessed, whole foods approach and Eat Like It’s 1899.
Harvard School of Public Health http://www.health.harvard.edu/fhg/updates/Microwave-cooking-and-nutrition.shtml
University of Florida IFAS Extension: Eating Defensively http://edis.ifas.ufl.edu/fy1395