Microwaving Does Not Harm Foods

A report from the nutrition department of Cornell University should convince you that microwaving food does not destroy its nutritional value. Dr. Gertrude Armbruster and her colleagues showed that fruits and vegetables lost the least vitamin C when microwaved, compared to other cooking methods. Vitamin C is a good indicator of the amount of nutrients lost because it is both water soluble and sensitive to heat (Newsweek, March 14, 2008).

Microwave ovens use electromagnetic waves that vibrate water molecules inside food to produce heat. Most nutrients in food are not destroyed by microwaving because they are not in the watery layer. An earlier study from Spain, widely reported in the news media, claimed that microwaving broccoli destroyed all of its antioxidants (Journal of Science in Food and Agriculture, November 2003). However, the researchers in this study cooked the broccoli in almost a cup of water for five minutes at full power. The antioxidants were destroyed by the long cooking in water at a high temperature, not by the microwaves. The length of time vegetables are exposed to hot water determines the amount of water-soluble nutrients lost, whether the cooking is done in a microwave oven, steamer, pot or pressure cooker. For nutrient- rich vegetables from your microwave, use very little water (no more than a tablespoon or two) and short cooking times.

Contrary to myths spread by a popular natural health newsletter, the radiation from microwaves is not harmful and has no effect whatever on food other than to heat it up. Once the food comes out of the oven, there are no lingering effects of the microwaves. If you are worried about chemical changes to the nutrients in your food, avoid broiling, grilling, frying or any other method that browns foods. The reason food cooked in a microwave oven is so bland is that the chemical changes caused by high surface temperatures don't happen. That's why most people use their microwave ovens to reheat food instead of for cooking. More