Question
Asked 4th Jan, 2018

Microwave oven heated foods – are they safe?

We use Microwave ovens to save time in preparing foods, mainly fast foods.
Please read the mechanism of generation of the heat.
Microwave heating is the process in which a high-frequency alternating electric field, or radio wave or microwave electromagnetic radiation heats a dielectric material. At higher frequencies, this heating is caused by molecular dipole rotation within the dielectric materials…As the field alternates, the molecules reverse direction. Rotating molecules push, pull, and collide with other molecules (through electrical forces), distributing the energy to adjacent molecules and atoms in the material. The process of energy transfer from the source to the sample is a form of radiative heating….
Regular eating or drinking foods/ beverages prepared by microwave is a habit of many of us.
Do you think it as safe?

Most recent answer

24th Aug, 2021
Malcolm White
Creo Medical Ltd
Microwaves usually do not get foods with water in them much above 100 C because the boiling of the water at atmospheric pressure tends to stall the temperature increase at 100 C until the water has turned to steam. The time required to turn the water in food into steam, staying at 100 C, is the same as would otherwise have heated it another 540 C.
Once the water is gone, then the food gets hotter and tends to char.
1 Recommendation

All Answers (59)

Please have a look at this link...,
The research on microwave ovens reveals the following…
  • Microwaving prepared meats to ensure sanitary ingestion was found to provoke the formation of d-Nitrosodienthanolamines, a well-known carcinogen.
  • Microwaving milk and cereal grains was found to convert some of their amino acids into carcinogenic substances.
  • Swiss clinical trials have found that microwaving food increases cholesterol levels. It was also found to decrease red and white blood cell counts while decreasing hemoglobin and producing radiolytic compounds.
  • Thawing frozen fruits was found to convert their glucoside and galactoside containing fractions into carcinogens.
  • Even very short exposure of raw, cooked, or frozen vegetables to microwaves was found to convert their plant alkaloids into carcinogens.
  • Russian and Japanese studies have shown how food can lose nearly 60% to 90% of its food value when cooked or heated in a microwave oven. Significant portions of Vitamins B, C, E, and essential minerals have been found to be lost.
  • Food cooked in a microwave oven with a little water can lose up to 97% of its beneficial antioxidants.
  • Another issue with microwave ovens is that many people cook food in plastic and paper containers. Carcinogenic toxins can leach out of this packaging into your food. Studies have shown that chemicals such as polyethylene terpthalate (PET), benzene, toluene, and xylene can leach from the packaging of common microwavable foods such as pizzas, fries, and popcorn.
9 Recommendations
4th Jan, 2018
Neeran Jasim
University of Al-Qadisiyah
According of my reading I found :. The detrimental effects of microwaves and microwave cooking.
1- study found that broccoli when microwaved with a little bit of water loses up to 97% of its beneficial antioxidants. Steamed broccoli only lost 11% or less. Some amounts of phenolic compounds and glucosinolates were also lost. The study was published in the November 2003 issue of The Journal of the Science of Food and Agriculture.
2- Vitamin C in asparagus spears was lost during a 1999 Scandinavian study.
3-One study found 60 seconds of microwaving garlic depleted the food of it’s allinase, garlic’s primary cancer-fighting ingredient
4- Just 6 minutes of microwave heating turned 30-40 percent of the B12 in milk into a dead form, which was found in a Japanese study by Watanabe.
5- An Australian study recently conducted showed that microwaves cause a higher degree of “protein unfolding” than conventional heating.
6- A 1992 study found that breast milk lost lysozyme activity, antibodies, and became a more suitable environment for the potential growth of pathogenic bacteria after being microwaved
regards ...I follow to other answers ...
7 Recommendations
4th Jan, 2018
Najib Abou Karaki
University of Jordan
Although controversial, with strong negative presumptions, hence, one should apply the precautionary principle and avoid it as much as possible.
4 Recommendations
4th Jan, 2018
YOGESH CHANDRA TRIPATHI
Forest Research Institute Dehradun
As far as the nutritional value is concerned, it’s true that microwaving does destroy some of the nutrients in food, but any cooking method does that. Any type of heating will destroy some nutrients in food, especially Vitamin C, which is very heat-sensitive. Evidences either that microwaved food is less nutritious than food cooked by other methods or that the microwaves themselves cause any kind of health problems, are contradictory. I agree with Najib that "one should apply the precautionary principle and avoid it as much as possible."
4 Recommendations
4th Jan, 2018
Abiodun Olusola Omotayo
North-West University
They are fair.
2 Recommendations
4th Jan, 2018
Aderonke Abd'Quadri-Abojukoro
University of KwaZulu-Natal
Microwave ovens do not make foods radioactive. Microwave ovens heat food by producing radiation which is absorbed by water molecules in the food. This makes the water molecules vibrate and produce heat, which cooks the food. Microwaves heat food. They do not make any changes to food that aren’t made in any other cooking method. So they do not make food any more likely to cause cancer. If you follow the instructions for use for a microwave oven there is no known harmful effect on humans. For more information on radiation emissions from microwave ovens please refer to the Australian Radiation Protection and Nuclear Safety Agency Read more at https://www.cancercouncil.com.au/86089/cancer-information/general-information
4 Recommendations
4th Jan, 2018
Aderonke Abd'Quadri-Abojukoro
University of KwaZulu-Natal
Microwaves generated in microwave ovens cease to exist once the electrical power is turned off. They do not remain in the food when the power is turned off. They do not make the food or the oven radioactive. There is some evidence that nutritional content of some foods may be altered differently by cooking in a microwave oven, compared to conventional cooking, but there is no indication of detrimental health issues associated with microwaved food.( https://www.arpansa.gov.au/understanding-radiation)
5 Recommendations
4th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Dear Dr. Tripathi, Dr. Pal, Dr.Abojukoro,
Please read the answer of Dr. viji Viji and Dr. Jasim.
Generation of heat by molecular dipole rotation of food staffs is not comparable to any other kind of heating system!
1 Recommendation
4th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Yes . I am totally agree with you, Dr. Murthy.
We have to certify anything as 'safe' after studying their probable toxic effects at long term chronic use.
But contemporary research fails to develop such models and we are considering a new technology/ medicine/ food additives etc. as 'safe' after studying for a short period at controlled conditions.
2 Recommendations
4th Jan, 2018
Michael Issigonis
Brandon University
I am scared of that big magnet sitting in the microwave. The magnetic field generated with the electricity would be tremendous and will destroy the goodness of the food, I am sure. Will even give you leukaemia if you are standing near it.
2 Recommendations
4th Jan, 2018
Aamal Ghazi Mahdi Al-Saadi
University of Al-Qadisiyah
I agree with Michael
2 Recommendations
4th Jan, 2018
Dharmesh Chandra Sharma
Consultant Pathologist and Transfusion Medicine Specialist to Patankar Pathology, Laha Diagnostic , Madhur Pathology and Emergency Blood Bank , Gwalior, India
Doughtful
3 Recommendations
4th Jan, 2018
Isam Issa Omran
Al-Furat Al-Awsat Technical University
Not always, and depends on the amount of protection and safety on the specifications of manufacturing, which vary from one company to another.
2 Recommendations
4th Jan, 2018
Dickson Adom
Kwame Nkrumah University Of Science and Technology
Its not very safe.
2 Recommendations
4th Jan, 2018
Dennis Mazur
Oregon Health and Science University
A microwave user needs to be aware of hazards with pacemakers, defibrillators, and other electronic devices worn by patients to survive.
Dennis
Dennis Mazur
2 Recommendations
5th Jan, 2018
Faranack Nader Benz
Northcentral University, Arizona, United States
Through consulting with a physician, I could recommend to use for shorter time of 5-7 minutes for warming liquids and small non-liquids, ONLY. Because at the shorter times function of heat is much more than cell-damage, and our body could deal with those tiny pieces through different section of digestive system and variety of hormones... you & I can not win the competition with the related global industry, anyway... people will learn in hard ways.
3 Recommendations
5th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Right, Dr. Benz.
We can not fight with global marketing forces, we have to be alert and cautious about our own health!
1 Recommendation
5th Jan, 2018
YOGESH CHANDRA TRIPATHI
Forest Research Institute Dehradun
Microwaves are electromagnetic waves within a frequency band of 300MHz to 300 GHz. and belong to the non-ionising radiations. Microwaves are not forms of heat, but rather forms of energy that are manifested as heat through their interaction with materials. Microwaves initially excite the outer layers of molecules. The inner part of the material is warmed as heat travels from the outer layers inward. Most of the moisture is vaporized before leaving the material. In conventional or surface heating, the process time is limited by the rate of the heat flow into the body of the material from the surface as determined by its specific heat, thermal conductivity, density and viscosity. Surface heat is not only slow, but also non-uniform with the surfaces, edges and corners being much hotter than the inside of the material. Consequently, the quality of conventionally heated materials is variable and frequently inferior to the desired result. Microwaves cause water molecules in food to vibrate, producing heat that cooks the food. That's why foods that are high in water content, like fresh vegetables, can be cooked more quickly than other foods. The microwave energy is changed to heat as it is absorbed by food, and does not make food radioactive or contaminated. Microwave cooking can be more energy efficient than conventional cooking because foods cook faster and the energy heats only the food, not the whole oven compartment. Microwave cooking does not reduce the nutritional value of foods any more than conventional cooking. In fact, foods cooked in a microwave oven may keep more of their vitamins and minerals, because microwave ovens can cook more quickly and without adding water.
4 Recommendations
5th Jan, 2018
Hazim Hashim Tahir
Ministry of Science and Technology, Iraq
K. Karthik
We would like to know the source of your responses, otherwise it is pure plagiarism. Since you are a PhD holder should know that and you should teach the others the right things!!!
  • This is the source of your first response:
  • This is the source of your second response ( same as the first one - it was taken from the bottom part of the article):
  • This is the source of your third response"
  • This is the source of your fourth response:
  • This is the source of your last response ( The author name: Joshua Engel, Enthusiastic eater and adventurous cook .)
4 Recommendations
5th Jan, 2018
Oluwaseun Ruth Alara
Universiti Malaysia Pahang
This question and the answers that has been provided are informative.
2 Recommendations
5th Jan, 2018
Hazim Hashim Tahir
Ministry of Science and Technology, Iraq
Dear Colleagues, Good Day,
"How Your Microwave Oven Damages Your Health In Multiple Ways
......
How Microwaves Damage Your Health
You might not be aware of this, but microwave ovens operate on gigahertz frequencies very similar to most 4G cellular networks. So, the danger AND the justifications why are identical. Conventional science and industry are clinging to the concept that these microwaves from your cell phones, portable phones, Wi-Fi routers, smart meters and wireless computers and tablets are not harmful because they do not cause any thermal damage.
New research from Professor Emeritus Martin Pall, Ph.D., has provided us with the mechanism of how this low level nonthermal microwave exposure causes biological harm. It has to do with voltage gated calcium channels (VGCCs) that are embedded in the cell membranes. He determined this by evaluating over two dozen studies showing you can radically reduce biological microwave damage using calcium channel blockers.
This explains why the argument that the microwave radiation is not high enough to cause thermal damage is fatally flawed. The statement is partially correct, as the radiation does not cause thermal damage. However, it causes massive biological damage. Pall has compiled a list of 123 studies and papers documenting the various non-thermal health effects of EMFs for those who want to take a deep-dive into the research. The safety standards that have been established are off by a factor of over 7 million.
So just how does it cause damage? Well, once the VGCCs are activated by microwaves, about 1 million calcium ions per second, these ions then stimulate the release of nitric oxide, which combines with superoxide to form peroxynitrate. These peroxynitrates then create hydroxyl free radicals, the most destructive free radicals known to man, which decimate mitochondrial and nuclear DNA, membranes and proteins that lead to mitochondrial dysfunction, the core of most chronic disease.
Pall has calculated that these VGCCs are over 7 million times more sensitive to microwave radiation than the charged particles inside and outside the cell, which means the currently established safety standards are off by a factor of over 7 MILLION.
Interestingly, the tissues with the highest density of VGCCs are the brain and nerve tissue like the pacemaker in the heart, and also in the testes. This could explain why we are having an exponential increase in many diseases like autism, Alzheimer's, arrhythmias, anxiety, depression and male infertility. Indeed, in a 2016 paper, Pall documents how microwave EMFs produce "widespread neuropsychiatric effects including depression."7
Microwave radiation does not have enough energy to directly break covalent bonds and damage your DNA in the way that ionizing radiation from X- or gamma rays do. However, it can actually cause more DNA damage than ionizing radiation as a byproduct of the increased hydroxyl free radical production.
Failure to realize this and take steps to minimize exposure not only will damage your DNA and increase your risk of most chronic illness, but also seriously impair your body's ability to remove toxins, and significantly impair your immune response to address the large variety of pathogenic infectious assaults you regularly encounter, especially parasites.
It is important to understand that using your microwave oven will expose you to an energy density of milliwatts per square centimeter (the standard energy unit measurement in the U.S.). While that sounds like a small number that will not cause thermal damage, it is easily thousands if not millions of times higher than the energy density shown to cause biological damage in hundreds of studies, as biological damage typically shows up in the micro to picowatt range.
So, every time you turn on your microwave oven, you are exposing yourself to microwave radiation densities thousands of times higher than your cellphone. This is the primary reason why I strongly advise removing the microwave from your home. Next, I will review some of the evidence showing how microwaves damage your food. But remember, this is a relatively minor issue compared to the DIRECT biological damage it will cause you and your family every time you turn it on. The closer you are to the oven, the higher the energy density and the worse the damage will be.",...
Please, see the source for more details:
4 Recommendations
5th Jan, 2018
Gopikrishna Nidigonda
Chaitanya Engineering College
That's no good.. kills all proteins and vitamins..
2 Recommendations
6th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Thank you, Dr. Tahir for sharing information.
2 Recommendations
7th Jan, 2018
Malik N. Hawas
Al-Furat Al-Awsat Technical University
Good point
regards
1 Recommendation
Nice point made by dr. Tahir. Actually more findings should be available publicly for general awareness
1 Recommendation
8th Jan, 2018
Chris Deep
Lots of debate on this. Some interesting publications listed below.
Article below is a court case of someone being killed during a routine surgery due to microwave heated blood tranfusion.
So it's clear there are some very detrimental effects particularly where fluid foods are concerned (milk, etc...) . Most of this seems to come from the uneven heating caused by microwaves rather than the microwaves themselves.
Unlike conventional heating where the source of heat is first applied to the utensil and then to the food, microwaves use the food itself to generate the heat. In conventional heating the utensil is a high thermally conducting material which presents the food with a more even and gradual heat change while with microwaves the heat is applied directly to certain parts of the food while others can remain completely cold because natural convection and conduction don't have time to act. (Classic example is to try heating a bowl of thick soup).
In the world of fine cuisine utensils of varying thickness, shape and material are used for specific types of food. This is so that the application of heat can be controlled in a certain way depending on the type of food to give it a certain flavour. In microwave cooking the function of the utensil is merely as a holder for the food. The heat always gets applied directly so there is not much control except possibly to turn down the intensity. However most commercial microwaves do not do this! It simply turns the magnetron on and off giving spots of high intensity in the food.
Maybe this calls for the invention of some microwave utensil where the utensil gets heated and then conveys the heat to the food. This would however take away some of the efficiency in power (but you don't get something for nothing).
So the conclusion as far as I can see is that microwaves although efficient should be used with caution. They are probably not as bad as some articles on the internet would show. Personally I have stopped using microwave ovens altogether for foods of low viscosity and only occasionally for solid and highly viscous foods.
SOME PUBLICATIONS:
Chemical changes during microwave treatment of milk
Extracorporeal Hemolysis of Blood in a Microwave Blood Warmer
2 Recommendations
8th Jan, 2018
YOGESH CHANDRA TRIPATHI
Forest Research Institute Dehradun
In general, cooking methods that best retain nutrients are those that cook quickly – heating the food in the shortest amount of time and using as little liquid as possible. Microwaves heat foods so quickly. Vitamin C, a nutrient that is frequently lost in cooking, has been found to be well-preserved when microwaving. Research on nutrient quality of microwaved foods have shown that the nutritional effects of microwave cooking on protein, lipid and minerals seem to be minimal and nutrients like thiamin, riboflavin pyridoxine, folacin and ascorbic acid are retained
4 Recommendations
8th Jan, 2018
Amir W. Al-Khafaji
Bradley University
Yogesh provides good information.
1 Recommendation
9th Jan, 2018
Krishnakant Nainwal
Autoliv
There is simple explanation to this. Microwaves causes water molecules to vibrate. This high vibration of molecules heats up the food. Hence it is safe to have that food. When we say unsafe, it is due to the coking pot which we use to heat the food. If it is low grade plastic, then due to heat generated in the food, that plastic tend to degrade and may cause some bad effects on health.
1 Recommendation
9th Jan, 2018
Adil Osman Mageet
Mediclinic Middle East
It is unsafe if plastic containers are used, especially if the food is frozen and suddenly heated. Many scholar believe this will cause cancer?
1 Recommendation
9th Jan, 2018
Joseph Dubrovkin
Western Galilee College
Any heat treatment of food is to some extent dangerous. Why a person warms food ? Since it tastes better and it is better absorbed by the body. Thermo-treatment of meat has expanded the number of foods and has improved the protein balance of food. But see:
"Dangerous Health Risks of Meat—New Evidence"
1 Recommendation
9th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Dear Dr. Dubrovkin,
The article of your supplied link is related with safety of eating of meat.
It is a different issue.
Thanks.
9th Jan, 2018
Mohamed Gadallah
Qassim University
Microwave ovens are designed in a manner that the waves flow only when the oven is switched on. Thus, it does not pose any danger to the surroundings where it is placed. It is extremely important to maintain the functioning of the oven and it must be kept in a proper condition. It is only with poor maintenance and excessive damage, that the microwave oven poses serious threats. Overheating is a major reason why accidents occur in the kitchen.
2 Recommendations
9th Jan, 2018
Joseph Dubrovkin
Western Galilee College
Dear Shibabrata Pattanayak !
But we do not eat raw meat that is much more qualitative than heat-treated meat. For example, the famous explorer Ernest Thompson Seton ate raw mice as wolves did and did not suffer from a cold !
1 Recommendation
10th Jan, 2018
Pieter Willem Van der Walt
Stellenbosch University
If the answers above illustrate anything, it is that one should not believe everything you see on the internet, and to be especially vigilant if it is found on a website that sensationalises issues.
We live in the age of fake information, and fake information can cost lives, as the anti-vaccination campaign clearly illustrates.
Check information by correlating with reputable sources, such as ICNIRP, WHO and IEEE publications.
I agree with K. Karthik's replies. Microwaves heat food, and that is why you get chemical changes, as you would with any other heating mechanism. The way the heat spreads in the food with microwave heating differs from other methods of heating and that should of course be taken into account when cooking food.
Also see
2 Recommendations
11th Jan, 2018
Cyril Ogbuanu
Enugu State University of Science and Technology
The most important thing to note is that you do not use plastics in your microwaves oven because of the cancer causing chemicals released by hot plastics.
1 Recommendation
11th Jan, 2018
Varsha Dilip- Jadhav (Rathod)
Shivaji University, Kolhapur
Microwave food are not safe for daily purpose , majority 50-60% of nutrients lost during heating.
1 Recommendation
11th Jan, 2018
Shibabrata Pattanayak
Government of West Bengal
Dear Dr. Walt,
The article , so far I understand, is on mind set of people for pre -decision or pre - determination.
Thank you for sharing your view.
20th Feb, 2018
Hazim Hashim Tahir
Ministry of Science and Technology, Iraq
Dear Colleagues, Good Day,
"Microwave Ovens and Food Safety
.....
Do microwaves cook food safely? Bacteria will be destroyed during microwave cooking just as in other types of ovens, so food is safe cooked in a microwave oven. However the food can cook less evenly than in a conventional oven. Microwave cooking can be uneven just as with frying and grilling.
For that reason, it is important to use a food thermometer and test food in several places to be sure it has reached the recommended temperature to destroy bacteria and other pathogens that could cause foodborne illness.
To promote uniform cooking, arrange food items evenly in a covered dish and add some liquid if needed. Where possible, debone large pieces of meat; bone can shield meat from thorough cooking.
Cover the dish with a lid or plastic wrap. Allow enough space between the food and the top of the dish so that plastic wrap does not touch the food. Loosen or vent the lid or wrap to allow steam to vent. The moist heat that is created will help destroy harmful bacteria and ensure uniform cooking. Cooking bags also provide safe, even cooking.
Stir, rotate, or turn foods upside down (where possible) midway through the microwaving time to even the cooking and eliminate cold spots where harmful bacteria can survive. Even if the microwave oven has a turntable, it's still helpful to stir and turn food top to bottom.
Follow cooking instructions on product label (or recipe instructions). If a range of time is given, start with the fewest minutes recommended. Add cooking time if necessary to reach a safe internal temperature.
Observe the "standing time." Cooking continues and is completed during standing time. Most importantly, follow the manufacturer's instructions.",...
Please, see the source for more detail:
2 Recommendations
12th Nov, 2018
Claude Le Gressus
Atomic Energy and Alternative Energies Commission
I believe that one way of approaching the answer to your question is to start from the basic processes of breaking chemical bonds and to demonstrate that prolonged exposure to microwaves is not a cause of evolution of matter.
Some processes are described in JONSKER's books and in the following publication.
Electron-trapping and energy localization in insulating materials. Technological impact of space charge electron-beam characterization
AIP Advances 8, 095228 (2018); https://doi.org/10.1063/1.5047673.
Sincerely
2 Recommendations
19th Dec, 2018
Yijie Daniel Deng
Dartmouth College
The radiation issue should be minimum if use (a good) microwave correctly. I think the real issue is whether microwave can generate extremely high temperature ( > 150 °C) in food that could cause chemical reactions among food components, leading to some potential toxic chemicals. If the heat is transferred among food quickly, then there is no the issue. The amount of toxic chemicals it produces also depends on the cooking time. In reality, the amount should be very low to a safe level, if not impossible.
2 Recommendations
5th Jan, 2019
Catherine M G C Renard
French National Institute for Agriculture, Food, and Environment (INRAE)
There are three issues with this question:
- microbiological safety: when heating (or most often reheating) food using a microwave the temperature should be kept hot enough long enough to inactivate microorganisms. I.e. it still must be brought to a boil, not only reheated to eating temperature. This is actually the most frequent problem.
- food chemistry, with either degradation of typically vitamins or formation of neoformed compounds: there has been MANY articles in Food Chemistry journals about this. Results can still be contradictory but mostly what it look like is because of short duration there is relatively little vitamin degradation and because microwave needs water there is also limited Maillard reactions, acrylamide formation etc, certainly in the common domestic usages. Frankly from a food chemical safety point of view I would strongly prefer microwave over BBQ or grilling, which generates all kinds of polycyclic aromatic compounds.
- packaging and diffusion: I am not as familiar with this. Because of temperature definitely diffusion will be accelerated, but again duration of contact comes in play. Generally safe recommandation is to use an inert material for reheating (a plate, not plastic or paper).
7 Recommendations
23rd Aug, 2021
Jonathan Wayne Riddle
Walden University
Microwaves can cause oxidation, so are oxidized foods safe? First, it is understood the microwaves can be used to assist oxidative reactions (Tokala, & Shankaraiah, 2016). With that oxidants can damage molecules resulting in disease (NationalJewishHealth.org, 2021). A study conducted by Soumela, Tarvainen, and Kallio (2017) showed that canola oil produced more p-anisidine, which is a toxin.
1 Recommendation
24th Aug, 2021
Malcolm White
Creo Medical Ltd
Microwaves usually do not get foods with water in them much above 100 C because the boiling of the water at atmospheric pressure tends to stall the temperature increase at 100 C until the water has turned to steam. The time required to turn the water in food into steam, staying at 100 C, is the same as would otherwise have heated it another 540 C.
Once the water is gone, then the food gets hotter and tends to char.
1 Recommendation

Similar questions and discussions

Related Publications

Conference Paper
We present some results of microwave measurements at frequencies of about 110836.04 MHz, which are related to the ozone emission line generated in the middle atmosphere. Experiments were carried out on March 14-17, 2009 and March 27-28, 2011 under conditions when the lower ionosphere was modified using powerful high-frequency (HF) radio waves radia...
Got a technical question?
Get high-quality answers from experts.