There are those who express concerns about microwaving their food. While there is much legitimate concern with the effects of the new 5G wireless technology coming out and the problems associated with electromagenetic exposure that will consistently radiate human beings to levels we have never seen before, those concerns are not the same as heating food in a microwave. The levels of radiation in a microwave don’t hurt you unless you walk into the microwave and are cooked along with the food. The radiation is self-contained in a metal box so very little energy seeps out. Microwaving food does not alter the food any more than cooking it on the stove or in the oven. The radiation does not get in the food to harm us. It is not like eating meat from a sick cow who hasn’t been raised or fed properly…that harms us. However, any time we heat food it will always lower the nutritional value no matter how it is done so it is always best to eat food as raw as you can to maintain the maximum healthy benefits of your whole foods. Let me provide a history and the science behind the microwave. If that doesn’t interest you, just skip to the last paragraph for my conclusion.

The microwave has been around for a long time. When the vacuum tube radio transmitters were invented around 1920, scientists discovered it was possible to heat things. At the 1933 Chicago World’s Fair, scientists from Westinghouse demonstrated they could cook foods between two metal plates. Foods like steaks and potatoes were cooked in minutes. But it wasn’t until the invention of the cavity magnetron at the beginning of World War II, that electromagnetic waves with a small enough wavelength (microwaves) were able to be generated. These microwaves were used to develop the radar systems crucial to winning the war. British physicists created the first systems. They brought the magnetron to the U.S. in 1940 and contracts were awarded to companies like Raytheon to mass produce the magnetron.

After the war, a Raytheon employee, Percy Spencer accidentally discovered the heating effect of high-power microwave beams. He was working on an active radar site and noticed his chocolate bar in his pocket starting to melt. Intrigued, he conducted experiments. The first food he cooked was popcorn. The second was an egg which actually exploded in the face of one of his colleagues. Spencer built a metal box to keep the microwave energy contained and found the food cooked even faster. He filed for a patent and Raytheon built the first microwave unit commercially sold and called it the Radarange in 1947.

Most of the early microwaves were big. The purchasers were large industrial and military complexes. It was the Japanese companies like Sharp and Samsung in the late 1970s and 1980s who successfully penetrated the residential market by developing low-cost microwaves. By 1997, over 90% of American households had a microwave.

The microwave oven uses energy waves at a frequency higher than ordinary radio waves but lower than infrared waves (2.45 gigahertz with a wavelength of 4.8 inches). Water, fat, and other substances in food absorb energy from the microwaves in a process called dielectric heating. There are many molecules like water that are electric dipoles meaning they have a partial positive charge on one end and a partial negative charge at the other. As the microwaves pass through them, these molecules rotate and try to align themselves with the alternating electric field. Rotating molecules hit other molecules and put them into motion. All of this motion raises the temperature of the food in a process similar to heat transfer by contact with a hotter body (stove cooking). Microwaves can operate at many frequencies–the misconception that they operate at a special resonance with water molecules is not true.

Microwave ovens produce heat directly within the food. They do not cook from the inside out because 2.45 GHz microwaves can only penetrate about 1 centimeter (0.39 in) into most foods. The inside portions of thicker foods are cooked by heat conducted from the  outer 1 centimeter. Any form of cooking involving heat will destroy some nutrients in food. The key variables are how much water is used in the cooking, how long the food is cooked, and at what temperature. Nutrients are mostly lost by leaching into cooking water. This fact tends to make microwave cooking healthier, given the shorter cooking times required. As in the case of other heating methods, microwaving will also convert vitamin B12 from an active to inactive form. Spinach retains nearly all its folate when cooked in a microwave but loses 77% when boiled due to leaching out nutrients. Eating raw is always the best alternative regardless of microwaving or conventional heating.

Bacon cooked by microwave has significantly lower levels of carcinogenic nitrosamines than conventionally cooked bacon. Steamed vegetables tend to maintain more nutrients when microwaved than when cooked on a stove top. Microwave blanching is 3–4 times more effective than boiled water blanching in retaining water-soluble vitamins like folic acid, thiamin and riboflavin, but not ascorbic acid (28.8% is lost vs. 16% with boiled water blanching). Microwaving human milk at high temperatures is definitely not recommended as it causes a huge decrease in anti-infection factors.

There is a good article with some scientific references that further document concerns with microwaved food (overheating is the big problem). To read it, click here.

As you can see, any discussion of microwaving gets complicated. Depending upon what is emphasized, different conclusions can be reached. The bottom line seems to be that there is nothing inherently evil about microwaves. They don’t alter your food any more than conventional heating. When radiation is mentioned it does not mean radioactive radiation. Microwave heating is no more dangerous than thermal radiation (heat from a stove top). All electromagnetic waves are a form of radiation just like seeing sunlight and color–there is nothing harmful unless overdone to the extreme. So, reheating food with a microwave for a short time is definitely the least risky way to use this convenient technology. Don’t overheat your food–this is where problems occur but they occur no matter how you cook your food. Definitely do not use plastic or plastic wrap in the microwave (or a stove top for that matter!) as that can release plasticizers into the food. The chemicals from plastic will create havoc with your endocrine system which is topic for another day.

 

 

 

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