Man is the only animal that cooks its food. Over 400,000 years ago, our ancestors were using fire for cooking. In the process, humans created a new ecological niche. Man can eat vastly more different types of foods than any other animal. Even very primitive tribes in arid environments have a minimum of a few hundred different foods to eat. More typically, tribal people might have a few thousand foods, about 100 times the variety available to a typical animal. About 98 percent of the vegetable matter in a lush tropical jungle falls to the ground uneaten, even by insects, because of contained toxins—most of which can be destroyed by cooking.
Cooking food accomplishes five different things.
1. Inedible components in foods become edible after being cooked. An example is potatoes. Raw potatoes cannot be digested by humans because their tough cell walls are composed of cellulose, a polysaccharide straight-chain polymer of glucose (the glucose molecules are linked to each other). When potatoes are cooked, however, the polysaccharide is broken down into monosaccharides and disaccharides, which we can digest. (Undigested polysaccharides can be of value in the diet as fiber but not as a source of energy.)
2. Cooking releases or creates flavor elements in foods. When vegetables are cooked, for example, some of the RNA (ribonucleic acid) they contain is broken down into the nucleotides inosinate and guanylate, which are important flavor elements in vegetables, as well as in meats and dairy products.
3. Cooking denatures (destroys the chemical structure of) both protein toxins and proteins in microbes required for their survival.
That's the good news. The bad news is that cooking can also do the following:
4. It destroys nutrients in the food, either by oxidation, heat, or leaching. An example of all three is the loss of vitamins that takes place when vegetables are boiled in water.
5. Cooking can create carcinogens (cancer-causing agents). That delicious-tasting scorched exterior on your charbroiled steak contains potent carcinogens called polynuclear aromatichydrocarbons, also found in cigarette smoke and smog. In addition to the carcinogens in the food itself, the use of a gas range or oven releases large amounts of carcinogenic nitrogen oxides and other harmful gases (such as carbon monoxide) into the air of your home. In fact, enough nitrogen oxides are released during typical home use of gas ovens to surpass the five-minute maximum exposure limit per day allowed in chemical manufacturing plants by the US Occupational Safety and Health Administration.
Microwave cookery offers a number of advantages in terms of the discussion above: It is fast and convenient. More nutrients are retained because of the fast cooking, relatively low peak temperatures, and lack of leaching. Far fewer carcinogens are created in the food, and carcinogens are not released into the air.
Microwave cookery does have some dangers (nothing is perfectly safe):
1. Some foods, such as poultry, may be inadequately cooked, especially in older microwave ovens that do not mix the microwaves well or when the cook does not rotate the food properly. Salmonella bacteria and parasites such as trichinella (found in pork) are a particular hazard in such undercooked foods. This danger applies to any method of cooking.
2. A person might be injured by thermal (heat) effects of microwaves leaking out of a badly damaged microwave oven and cooking part of you instead of the food. In microwave ovens manufactured during the past 10 years, this is not a problem. A gas or electric oven is far more dangerous in this respect. In fact, microwave ovens offer by far the safest means of cooking for persons with mental or physical impairment. For example, microwave ovens cannot burn your house down. With the exception of browning-dishes, the food is the hottest part of the oven.
Many people confuse microwave radiation with nuclear radiation (such as gamma rays or x-rays). Sunlight (solar radiation) is closer to x-rays in its properties than it is to microwave radiation. Radiation comes in discrete chunks called quanta. Energy per quanta of x-rays is very high and can break any chemical bond and can alter any molecule. This is why high-energy radiation can damage our DNA and cause cancer. Quanta of sunlight contain less energy and can break some chemical bonds but not others. (It can damage DNA in skin, for example, producing skin cancer.) Microwaves, however, contain very low energy and can break no chemical bonds. All the chemical changes produced by microwaves are due to heating.
Microwave radiation is very similar to the infrared heat radiation given off by a heat lamp or a hot-steam radiator and is about as hazardous as these infrared radiations. It is much easier, however, to accidentally burn yourself by contact with a hot, exposed steam radiator or heat lamp than with a cool microwave oven door, which, in all such units made within the past 10 years, is equipped with several built-in safety devices to automatically shut off the oven when the door is opened.
Cooking was a giant step forward in the evolutionary history of man. Done with proper care, microwave cookery makes it possible to avoid or minimize traditional cooking's "bad news."
Durk Pearson and Sandy Shaw are consulting scientists and authors of Life Extension.