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What do you think about microwaves?

While microwaves may be convenient for heating up foods, we actually prefer not to use them. We prefer stovetop and oven cooking, which can be used as quick cooking methods, and therefore you really don't have to spend much more time than you would cooking in a microwave. For example, it only takes a few minutes to boil, steam or healthy sauté greens such as spinach, kale, chard or collard greens.

The concern with microwave cooking is that, for such a widely used technology, it is so under-studied in terms of its health impact.

There are several aspects of microwave cooking that have been clearly researched. First, we know for certain that plastic packaging and microwaving are not a good mix, because small amounts of plastic migrate into the microwaved food. Glass/Pyrex containers or microwave-safe ceramics are recommended for microwave heating.

Second, we know that microwave heating can be fairly protective of vitamin and mineral content if foods aren't covered with water during the microwave process. To a certain extent, microwaving seems subject to the same rules as stovetop cooking. If you boil food in water for 10 minutes or more, instead of steaming it for 2-3 minutes, you get an enormous increase in nutrient loss. Heating briefly with a small amount of water (or no water) to reheat or defrost foods in the microwave corresponds to steaming on the stovetop.

What we don't know about microwaving involves the impact of this heating process on cellular structures in the food. We've seen no research in this area that convinces us that microwave heating is safe or unsafe, but we would definitely like to see more studies in this area.

Based upon all of this, given the choice, we much prefer to cook on the stovetop or in the oven rather than in a microwave. It doesn't really take much more time, and even if it does take a few additional minutes, we think that the price in terms of time is well worth it considering the unknown effects that may be associated with microwave cooking.

If you do decide to use a microwave oven, we would encourage you to follow our recommendations and use it for re-heating only (the industry calls it "re-thermalization"). And when re-heating, we would advise using the cookware (glass, Pyrex, and microwave-safe ceramics) as well as the re-heating techniques (limited addition of water, minimal re-heating times) described above.

From an environmental standpoint, we would add that microwave ovens are usually considered "hazardous waste" due to their content of metals like lead, cadmium, chromium, or copper and are problematic in terms of disposal. (It's the magnetron tube that is used to produce microwave radiation that's the key factor here.) Unlike conventional ovens, which are typically kept for dozens of years, the much more portable and affordable microwave ovens are often quickly discarded and replaced, creating problems for our environment.

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