Microwaving food

Microwaving food

Last Updated November 3rd, 2022

No. There is no evidence to prove that foods cooked in microwaves are radioactive and cause cancer.
Microwaves heat the water in the food hence the food gets dry while reheating.
Reheating can affect the vitamins especially vitamin A and B in the foods.

The popularity of microwave cooking

A microwave is an integral part of most urban homes and they have added a lot of convenience to our lives. These devices generate high-frequency radio waves and as a part of the electromagnetic spectrum, they are used in various areas. Exposure to ionizing radiations like X-rays is harmful to organic cells but microwaves are non-ionizing and they do not have enough energy to alter the atomic structure of cells. These waves are used in TV broadcasting, radar for air and sea navigational aids, and telecommunications including mobile phones. While metallic surface reflects microwaves totally, glass and plastic materials are transparent to them. These waves are also absorbed by food items and water and result in the production of heat. Cooking through the use of a microwave is not only energy-saving but also a convenient and time-saving method.

A lot of people are concerned about microwaves breaking down the nutrients in food. The fact remains that all cooking processes break down the nutrients in food and some of the nutrients are used in the water that is used in the cooking process. Since a microwave oven performs the cooking within a relatively shorter time, it does a much better job of preserving the nutrients. In addition, it also uses a minimum amount of liquid that makes the food items retain a higher amount of nutrients. At the same time, the action of the energizing radiations on the food molecules can have an impact on their constitution and also on the health of the individual consuming it. This has raised a few concerns with some research acting on the area. But, there are safety standards set for leakage of radiation from microwaves, and the further a person stands away from a microwave, the lesser amount of radiation he or she absorbs.

How does microwave cooking work?

microwave cookingThe microwave was accidentally discovered by an American named Percy Spencer who launched the device in 1947. Microwave cooking works in an energy-efficient manner as the waves only heat the food materials and not the surrounding materials. The microwaves affect specific molecules like that of water, which have asymmetric electric properties and make them vibrate rapidly. These vibrations produce heat that cooks the food items. The microwave contains a device called a magnetron which converts electric energy into a waveform. The waves are passed into the heating chamber in which the food is kept on a rotating container so that it heats up evenly. These waves are reflected by the metallic walls of the chamber but are absorbed by the food which gets heated up due to the transfer of the energy. The friction between the vibrating food molecules results in higher levels of heat generation.

In a conventional oven, heat is passed through the methods of conduction and it transmits from the outside layers to the inside. While heating food in the microwave the liquid part of food first and hence some food items with a liquid element in the inside gets more heated on the outside than on the outside. This often leads to the idea that the microwave cooks from the inside out, which is not exactly true. The other important parts of a microwave oven are the transformer, diode, and capacitor. There is also a fan that blows air over the magnetron and keeps it cool. This is the element that produces the most amount of noise while the unit is in operation.

Disadvantages of microwave cooking

The microwave also has its drawbacks when it comes to cooking food. Typically the waves cannot penetrate more than two centimetres inside a food item and beyond that, they lose their energies. So while cooking bigger items in a microwave, the outer layers will be cooked fast while the inner parts may remain colder. This happens as heat is transmitted to the inner parts only through conduction. The process needs some getting used to or else one might end up with a food item that has been cooked well on the outside but remains uncooked in the middle. So the cooking process in such an oven ideally consists of a cooking time as well as a standing time. During the later stage, the heat is passed evenly through the food via conduction.

Safety factors while microwave cooking

Microwaving foodWhile some users have been concerned about the dangers of microwave cooking, the process is not dangerous. Microwave radiation can heat the body tissues and cause damage if exposure levels are high. The two areas that are most vulnerable to the damage are the eyes and the testes, as these two organs have a lesser number of blood vessels to carry away the heat. But these types of microwave-related health risks are caused when an individual is exposed to higher levels of radiation for prolonged periods. Such levels are much higher than the levels produced around a microwave used in a kitchen. In general, most microwave-related injuries are burns that result from improper handling of hot food. In some rare cases, improper servicing or damage to the sealing around the machine can cause wave leakage.

There were also concerns that microwaves can interfere with the working of pacemakers. But modern-day pacemakers are designed to remain unaffected by such interferences. The design of a microwave oven ensures that the microwaves are contained within the chamber and are produced only when the power supply is on and the door is shut. There can be some leakage arising from damaged, dirty, or modified microwave ovens. So a proper inspection of the machine while using is needed from the user’s end. On the other hand, the cooking process in a microwave depends on the power rating of the oven and the water content, density, and amount of food being heated. Thicker food materials do not allow the waves to pass through them and this can allow some microorganisms to survive in the food. This is the reason why a proper standing time is needed to allow the heat to get distributed throughout the food.

Tips on safe microwave cooking

The following tips are to be kept in mind while cooking or heating food in a microwave

  • It is necessary to follow the manufacturer’s instruction manual for recommended operating procedures and safety precautions for the model. The items including liquids should be heated for the time limit specified by the manufacturer.
  • Always use microwave-safe cookware specially manufactured for use inside the microwave oven.
  • Inspect an old machine regularly and do not operate it if the door does not close firmly or is bent, warped, or otherwise damaged. Check for any signs of leakage around the door area. In case the fan, light, or turntable operates when the door is open, you should stop using the oven.
  • Do not use a microwave oven if it continues to operate with the door remaining open.
  • As an added safety precaution, don’t stand directly against an oven or place your face against it for long periods of time while it is operating.
  • Do not heat water or liquids in the microwave oven for longer periods which can make them super-heated. Some liquids, including water, can get heated above the boiling point without showing any signs of boiling. In such cases, the slightest disturbance can cause the liquid to explode out of the container and cause major burns.
  • A few ovens should not be operated when empty. Refer to the instruction manual to check if your oven has the same requirements.
  • Regularly clean the oven cavity, the outer edge of the cavity, and the spaces around the door with water and a mild detergent. Be sure to not use scouring pads, steel wool, or other abrasives that may cause damage to the internal components.

Microwave health risks

In general, microwaves can cause several adverse effects on human health. These can include the following conditions.

  • chronic fatigue
  • somnolence
  • Troubles with concentration and memory
  • frequent headaches
  • An imbalance of the hormonal and nervous system may result in emotional instability and fertility problems

At the same time, a good quality microwave oven does not have any such detrimental effects as there is no leakage from it.

The waves also affect the immunity system which can result in increased susceptibility to the infections and development of cancerous cells in the body. In terms of degrading the food, research work shows that microwave cooking destroys 97% of flavonoid antioxidants in broccoli while boiling only destroyed 66% of the same. On average microwave cooking does not affect the nutrient levels more than conventional cooking mechanisms. But microwave cooking has been shown to destroy the powerful bacteria-fighting agents in breast milk and negative the positive effects of Vitamin B12. In addition, it is a good idea not to use plastic containers in a microwave as they contain hormone-disrupting compounds. When heated, these containers can leak into the food material rendering the food damaging for health and can also produce some carcinogens. The uneven heating of some food also makes microwave ovens less effective in killing harmful bacteria and other pathogens.

There are some researches that have pointed out that microwaves cause certain alterations in food molecules. The resulting changes can cause disorders in the digestive as well as the lymphatic system. These theories also state that microwaved food can result in the generation of more cancer-causing cells in the body. They also mention that microwaves can also cause a catabolic breakdown of plant and animal food when they are heated or thawed for short periods. But latest research indicates that there is no established relationship between radio-frequency energy emitted by microwaves and any cardiovascular, reproductive, immune, and other ailments in the human system.

Reheating food in microwave ovens

microwave reheatingThere are concerns that reheating food in a microwave oven will destroy all the nutrients in the food. The vitamin content in food items is definitely affected by any reheating process, especially that of vitamin C. At the same time, microwaves heat food more quickly, making it less susceptible to damage. It has been proved that microwave ovens did a better job of preserving the nutrients in fruits and vegetables as the moisture content in these materials is more than the rest.

Microwaving stuffed or whole poultry is not a good idea as the stuffing may not reach the right temperature level that makes it safe for consumption. Once these types of dishes are thawed in the oven, it is best to cook them completely. Preserving them again can spark the growth of harmful organisms like Salmonella Enteritidis, Staphylococcus aureus, Campylobacter jejuni, etc. To make sure that the food is good for consumption, a food thermometer can be used to check for even temperature distribution.

Advantages of microwave cooking

The following are the main advantages that cooking by microwaves provides:

  • The cooking temperature in a microwave oven is equal to that of boiling water and hence it produces far less harmful compounds in the food when compared to processes like baking or frying.
  • When food is pre-heated in a microwave oven and then placed on a grill or pan, the overall time and energy used for the cooking process are greatly reduced. It also generates lesser amounts of carcinogenic substances in the food. Items like potatoes and bacon, when cooked in by microwaves, generate lesser amounts of carcinogenic substances.
  • Due to the reduction in cooking time, more amount of nutrients is preserved in the food when it is cooked in a microwave oven.
  • These ovens make the process of cooking faster and it also occupies less space than the traditional cooking equipment.
  • The automatic turning off mechanism and the timer allow food to be cooked easily and it can be left unattended. The temperature settings also provide more control over the cooking process.


There is no doubt that microwave-based cooking and heating have added a lot of convenience to our daily lives. Apart from preserving the quality of food microwave cooking has the capability to lower your monthly energy bills. In addition, there are also some dishes that can be prepared in the best possible way only by a microwave. So, make sure that you use this device with all the right precautions and keep enjoying the benefits.


No. There is no evidence to prove that foods cooked in microwaves are radioactive and cause cancer.
Microwaves heat the water in the food hence the food gets dry while reheating.
Reheating can affect the vitamins especially vitamin A and B in the foods.

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