Nuking Your Food's Nutrional Value

A reader writes The Green Guide:

I am interested in knowing more about what happens to food when it is heated and or cooked in the microwave. I would like to know both sides of the argument as I have been told both that it has a negative effect on one's health and that there is no scientific basis to that contention.

The Green Guide responds:

Microwaves heat food by heating the water within the food you're cooking. The electronically generated microwaves are absorbed by the food's water molecules, and heating the food's water heats the rest of the food indirectly. You shouldn't be concerned about being exposed to dangerous radiation, ala nuclear radiation, because the microwaves come from electromagnetic energy, not radioactive sources.

There are quite a few Internet sites devoted to the health hazards of microwaving food, ranging from claims that microwaves cause loss of vitamins and other vital nutrients to claims that microwaving food alters the chemical makeup of food such that carcinogenic compounds are formed as a result. There have been no studies verifying the truth of these claims. Scientists at the U.S. Department of Energy and those at Health Canada (the equivalent to the U.S. FDA) attest that microwaving food has no different effect on the food's chemical makeup than any other method of heating, such as boiling or baking, and that heating food in any manner is going to cause some loss of nutritional value. Health Canada officials actually state that microwaves, due to the shorter cooking times, allow food to retain more nutrients than other methods of cooking. Nevetheless, if you want to preserve as much nutrition as possible, don't heat your food, unless, of course, you're dealing with meat products.

The health concerns you should consider when microwaving food deal mostly with food safety and packaging. Both agencies recommend against heating meat products in the microwave simply because microwaves may heat them unevenly, creating the risk of exposure to harmful bacteria. In terms of packaging, you should avoid using plastics and plastic wraps in the microwave. While a "microwave-safe" or "microwavable" label on plastic containers only means that they shouldn't melt, crack or fall apart when used in the microwave, the label is no guarantee that containers don't leach chemicals into foods when heated. Also, you may want to avoid eating microwaved popcorn, as a study published last year revealed that the interior linings of microwave-popcorn bags are coated with Teflon, a chemical considered a "likely carcinogen" by the Environmental Protection Agency.