Are Microwave Ovens Safe for Our Health | Chris Kresser

Are Microwave Ovens Safe?

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Microwaving your food may not be as harmful as some health enthusiasts would lead you to believe.

are microwave ovens safe?
Microwave ovens are a convenient way to cook and reheat food. Maximkostenko/iStock/Thinkstock

Microwaves. These handy gadgets have been the source of much debate in the online health community, and it’s not hard to see why. The idea of “zapping,” “nuking,” or otherwise heating your food using microwave radiation can seem a little dubious.

In this article, I’ll take a look at the evidence behind some of the most common microwave concerns. Do microwaves leak radiation? Do microwaves destroy the nutrients in food? Do they denature proteins and make food toxic to our bodies? First, though, let’s start with the basics. How do they work?

How Do Microwave Ovens Work?

The aptly-named microwave oven uses microwave radiation to heat food. Electromagnetic (EM) radiation exists over a range of wavelengths, where shorter wavelengths (such as x-rays and gamma rays) have higher energy than longer wavelengths (such as radio waves). On the EM spectrum (pictured below), microwaves fall between radio and infrared waves.

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Image Source.

Each level of radiation has different effects on the molecules they interact with. Microwaves contain enough energy to induce molecular rotation, which is the lowest energy form of interaction, but they don’t have enough energy to induce molecular vibrations, electron excitation, or ionization. Microwaves have the greatest effect on water molecules, due to their polar structure, and these rapidly rotating water molecules transfer energy as heat to the other molecules in food.

Do Microwaves Leak Radiation?

One concern many people have about microwave ovens is the simple fact that they emit, well, microwaves. Hasn’t exposure to microwave radiation been linked to cancer and infertility? Evidence is mixed; most published research concludes that low-level microwave exposure doesn’t present a significant risk to human health. (1, 2, 3) Even if it did, this is only an issue if the microwaves inside the microwave somehow escape the microwave and encounter your body, which (as you’ll see below) is unlikely.

The FDA requires that microwaves emit no more than 5 mW/cm2 of radiation at a distance of 2 inches from the microwave. They also point out that microwave radiation dissipates rapidly as you move away from the source, so a measurement taken 20 inches from the microwave would be about 1/100 of the measurement taken at 2 inches. This is good news, because it means that to avoid radiation from your microwave, all you have to do is step away from it while your food is heating.

Are #microwaves as unhealthy as we are told?

The other good news is that in general, real microwave emissions seem to stay below the federally mandated maximum. A study published in 2013 on microwaves in Palestine found that the radiation leakage measured one meter from the microwave varied from 0.43 to 16.4 μW/cm2, with an average of 3.64 μW/cm2. (4) A 2001 survey of microwaves in Saudi Arabia concluded that with 95% probability, a microwave will be found to leak between 0.01 and 2.44 mW/cm2 at a distance of 5cm, and only one out of 106 microwaves surveyed was found to leak more than the FDA limit. (5)

For comparison’s sake, a 2013 study measured microwave radiation emitted by cell phones at a distance of 3.5cm from the phone, and found levels of 10 – 40 μW/cm2 during a call and 0.35 – 10.5 μW/cm2 on silent. (6) Based on these numbers, having a cell phone in your pocket on silent mode exposes you to roughly the same level of microwave radiation as standing one meter from your microwave while it’s heating food.

Honestly, just don’t press your face up against the door of the microwave while your food is cooking, and step a few feet away if you can. If you’re going to be concerned about exposure to microwave radiation, you’d probably be better off getting rid of your cellphone than your microwave oven. (But that’s a topic for a another day.)

Do Microwaves Make Proteins Toxic?

Now, let’s talk about the effect of microwave heating on food. One oft-cited claim is that microwaves can “denature” proteins, making them toxic to the human body. First of all, I think there are some misconceptions about what exactly “denaturation” is. Contrary to how the word is often used, it doesn’t mean that a protein has ‘changed’ in some unspecified way to make it more toxic. When a protein is “denatured,” that specifically means it has unfolded and lost its three-dimensional shape, but all of the amino acids in the protein are still bonded together.

Heat in general denatures proteins, so cooking your food (using any heating method) will denature the proteins. Cooking can even be defined as heating something enough to denature the proteins. (7) Changes in pH also denature proteins. In fact, guess what one of the functions of stomach acid is? Denaturing the proteins you ingest! Proteins need to be unfolded (denatured) before digestive enzymes can cleave them into individual amino acids to be absorbed in your small intestine. “Denatured proteins” don’t sound so scary any more, do they?

Perhaps what people have in mind when they refer to “protein denaturation” is actually isomerization of amino acids. This is a completely different process, but it is a change that actually affects the nutritive value of proteins. Without getting too into the chemistry, amino acids can exist in two configurations, termed D- and L-, and isomerization is the process by which an amino acid switches from one configuration to the other. Our bodies almost exclusively use the L- form of amino acids, but pH changes and heat can cause amino acids in food to isomerize to the D- forms, which can’t be efficiently digested or utilized by our body. (8)

A few studies where large amounts of isolated D- amino acids are fed to rodents show potential harmful effects, but there’s no evidence that the levels of D- amino acids normally found in food are harmful. (9) Plus, many foods (such as raw dairy from ruminants and some fruits and vegetables) naturally contain low levels of D- amino acids.

In any case, there doesn’t appear to be a significant difference in levels of D- amino acids in foods cooked in the microwave compared with foods heated conventionally. One study conducted in 1989 found higher levels of D- amino acids in microwaved formula compared with other heating methods (10), but several more recent studies have found no difference. (11, 12, 13, 14, 15) Additionally, the general consensus seems to be that if more D- amino acids are formed, it is due primarily to over heating or uneven temperature distribution, rather than a specific effect of microwaves themselves.

Do Microwaves Destroy Nutrients?

As far as vitamins, minerals, antioxidants, and plant phenols, retention does not appear to depend on cooking method. Levels of nutrient retention were sometimes higher in microwaved food, and sometimes lower, depending on time, temperature, and amount of water used in the cooking process. (16, 17, 18, 19, 20)

In general, nutrients are lost from food during any type of cooking, and more nutrients are lost when the temperature is higher or the food is cooked for longer. Water soluble vitamins are readily leached into cooking liquid (no surprise there), so boiling food tends to result in greater nutrient losses than microwaving it with a small amount of water (unless you drink the water you boiled the food in, in which case you’d still be getting most of the nutrients).

As a final interesting data point, one study published in 1995 used a rat model to look at the overall effects of a microwaved diet in vivo. The diet consisted of meat, potatoes, vegetables, and some oil, cooked either in the microwave or conventionally, and was fed to rats for 13 weeks. To magnify any adverse effects of microwave cooking, the study authors added two additional experimental groups that received “abused” food, which had been reheated and cooled a couple times either conventionally or in the microwave. (21) At the end of 13 weeks, they found no adverse effects of microwave cooking on the rats.

Don’t Fear the Microwave!

In conclusion, microwaves aren’t as scary as some people make them out to be. Yes, they’re another source of microwave radiation in your home, but the levels are extremely low, and can be almost entirely avoided by simply stepping away while your food is heating. And compared with microwave radiation from other devices (particularly cell phones), radiation from your microwave oven is negligible.

Additionally, there’s no evidence that microwaves adversely affect the nutrient profile of foods. Because microwaves are a relatively new device, I prefer to think of them as “guilty until proven innocent” rather than the other way around, but given what we know about EM radiation and its effects on food molecules, there isn’t really a mechanism by which microwaves could destroy nutrients other than heat. And heat, of course, is an issue regardless of cooking method!

If you’re still skeptical of microwaves after reading this, by all means – use whatever cooking method makes you comfortable. I might be one of the few freaks in the world now that still doesn’t use a microwave, but I can’t say that it’s because of any safety concern or scientific concern. I’ve just never liked what they do to the texture of certain foods, and for whatever reason, I’ve never gotten into using one.

But if you enjoy the convenience of a microwave, don’t be afraid to use it – especially if being able to microwave your food makes the difference between heating up leftover Paleo chili or grabbing a Nutri-Grain bar for lunch!

What do you think about microwaves? Did reading this article change your opinion of them? Let me know in the comments!

271 Comments

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    • Chris kresser is as reliable as they get, but of course you should still think critically and seek out many arguments.

    • This dude Chris is an absolute moron! Like the worst kind. Dr. Mercola is a very trusted source. This dude Chris who did this article is probably paid by all the agencies including the government and Big Pharma that are trying to keep us sick so they can make money. It’s called greed and depopulation. There is way more reliable evidence then this dude to prove microwaves are bad. Microwaves are unnatural!

  1. Microwave ovens are suppose to have shielding. Before the stringent safety regulations were tampered with, a test to see if your microwave oven is safe, you would place a mobile phone inside of the MWO, closed the door, then ring the phone. And in the olden days when safeguards was safeguard, the phone would not ring, and the radiation 2 inches from the door was 0.25mW/M2.

    Today, due to the cancellation of the stringent safeguards, from 100 milligauss to 1,000 milligauss and in other countries it could be 2,000 milligauss, the radiation 2 inches from the door is now 5-10mW/m2, and if you put your phone inside of the new MWOs the phone would ring, and I am sure if you stuck your face to the door, you will do some damage to your brain.

    Now, the author did make a rash statement, he said to put your face up against the door of the MWO, well if you want a brain tumour then go on and do that after all, the radiation from a MWO is at 100 times greater than a mobile phone, and the author said that a MWO is the same as a mobile phone and it’s safe. Well, I haven’t seen any government document categorily saying the microwave non-ionised radiation as being “safe”, and particularly if you had a mobile phone emitting above the SAR then that phone would be banned if it was emitting 5mW/m2.

    The “Controlled Offensive Behaviour-USSR” (ST-CS-01-169-72 July1972) and US DIA Medical Centre (DST-1810S-076-76 March 1976) tells a completely different story of a complete cover-up. Here are some extracts from these documents:

    The “Controlled Offensive Behaviour-USSR” (ST-CS-01-169-72 July1972):
    “Low frequency electromagnetic fields have been found…to generate sonic and ultrasonic oscillations in living organisms…these oscillations produce elastic deformation in the organism…if the frequency of the outside field corresponds to the oscillation frequency of the cells, the latter deteriorate as a result of the mechanical resonance.”
    Extracts of the declassified US DIA Medical Centre (DST-1810S-076-76 March 1976):

    (1) “A strict enforcement of stringent exposure standards (safety regulations) (to microwave non-ionised radiation) (Wi FI), there could be unfavourable effects on industrial output and military functions.”

    (2) “Personnel (military) exposed to microwave (non-ionised) radiation (Wi Fi) below thermal levels experience more neurological, cardiovascular, and haemodynamc disturbances that do their unexposed (military) counterparts.”

    (3) “Some of the effects attributed to exposure include bradycardia, hypotension, and changes in EKG indices.”

    (4) “Subjects (military personnel) exposed to microwave (non-ionised radiation) exhibited a variety of Neurasthenic disorders and the most common subjective complaints were headaches, fatigue, dizziness, menstrual disorders, irritability, agitation, tension, drowsiness, sleeplessness, depression, anxiety, forgetfulness and lack of concentration.”

    (5) “Recognition of the standard (stringent safety regulations of 1976) could also limit the application of new electronic technology by making the commercial exploitation of some products unattractive because of increased costs imposed by the need for additional safeguards (against microwave non-ionised radiation) (Wi Fi).”

    (6) “Alters the permeability of the blood-brain barrier, and this could allow neurotoxins in the blood to cross, as a result, an individual could develop severe neuropathological symptoms, either die, or become seriously impaired neurologically.”

    • Thank you George. I put a mobile phone inside my microwave oven, closed the door and called it. It rang. So if microwaves from the nearest o2 mobile phone tower can get in, maybe cooking microwaves can get out?

    • Aren’t words funny. It’s amazing how many people can see something like “does not present significant risk to human health” and take away that it presents no risk. Why is that? No significant risk? Well, first, how are these people defining “significant”? What happens just below significant? Negligible? Minor? It doesn’t mean nothing. Just as a person with Addison’s disease isn’t just fine one day and the next suddenly has adrenal gland failure, there is something in between. So what, here, is in between?
      How was this evidence compiled? Were there long-term studies? What were the parameters?
      You know, many people believe electricity causes no damage to health. But did you know that electricity causes positive ions (a waterfall produces negative ions, as do ocean waves and other things in nature. Positive ions come from electronics. People have had serious health problems from positive ions and have had to relocate themselves to places untouched by modern electronics, and people who go into Amish homes (or other homes without electric) often wonder why they feel so peaceful. That constant high-pitched, whining buzz of electricity is not without its harmful effects, moo matter what someone will say about “significant” risk.

  2. Ten Reasons not to Use Your Microwave Oven

    Based on Swiss, Russian and German clinical studies

    Continually eating food processed from a microwave oven causes long term, permanent, brain damage by “shorting out” electrical impulses in the brain [de-polarizing or de-magnetizing the brain tissue].

    The human body cannot metabolize [break down] the unknown by-products created in micro-waved food.

    Male and female hormone production is shut down and/or altered by continually eating micro-waved foods.

    The effects of micro-waved food by-products are residual [long term, permanent] within the human body.

    Minerals, vitamins, and nutrients of all micro-waved food is reduced or altered so that the human body gets little or no benefit, or the human body absorbs altered compounds that cannot be broken down.

    The minerals in vegetables are altered into cancerous free radicals when cooked in a microwave oven.

    Micro-waved foods cause stomach and intestinal cancerous growths [tumors]. This has been a primary contributor to the rapidly increased rate of colon cancer in the United States.

    The prolonged eating of micro-waved foods causes cancerous cells to increase in human blood.

    Continual ingestion of micro-waved food causes immune system deficiencies through lymph gland and blood serum alterations.

    Eating micro-waved food causes loss of memory, concentration, emotional instability, and a decrease of intelligence.

    https://www.health-science.com/microwave_hazards.html

    • @Imun known – Let’s cite European studies, that gets rid of American bias and governmental control. Except . . .

      The Russian studies were picked up by a “researcher” called Bill Kopp, he never cited the source (only “Russian research”), didn’t state which journal, university or other research centre, didn’t show the basis of testing or the results, just the conclusions.

      The German study was one by “Raum & Zeld”, only these authors do not exist, this is a missprint of “Raum & Zeid”, a German magazine (Space and Time) with conspiratorial leanings. It published the German version of a Swiss article by Hans Hertel.

      The Swiss study was by Hans Hertel where he tested 8 subjects on diets containing raw and pasteurised milk, raw and cooked vegetables, organic and non organic vegetables, frozen and fresh vegetables. To these already existing 4 factors he added a 5th, microwave cooking. As he was a subject himself and as everyone knew what they were eating there were no blinds. 5 factors and 8 subjects means that there were no controls. He has never published a detailed paper, nor results only conclusions. It has never been peer reviewed. The whole study is worthless.

      The rest of your comments come from Bill Kopp’s article which is one of the sources for “The Hidden Hazards of Microwave Cooking ” by Wayne and Lawrence which itself is a basis for Mercola.com’s site.

    • Oh my dear, but do you think that the processed food has something to do with your problem or the microwave? Cheers!

  3. What about fat oxidation? That has always been my concern, that the microwave would cause degradation for oils with lower smoke points.

  4. I’m interested in information about the container and materials in microwave cooking.

  5. “There’s no evidence”, “There’s no evidence”, “There’s no evidence”. Every time a claim is refuted, this glib mantra is chanted. For a long time there was “no evidence” that life was on Mars. “No evidence” doesn’t mean “non existent”.

    But anyway, since we’re on the subject, the author of the article wrote “without getting into the chemistry of things” which sounds like the writer wants to avoid any detail of the actual discoveries that have been made, which are as follows:

    -A degeneration and destabilization of the external energy activated potentials of food utilization within the processes of human metabolism.

    -A breakdown of the human “life-energy field” in those who were exposed to microwave ovens while in operation, with side-effects to the human energy field of increasingly longer duration.

    -Degeneration and circuit breakdowns of electrical nerve impulses within the junction potentials of the cerebrum [the front portion of the brain where thought and higher functions reside]

    -A long term cumulative loss of vital energies within humans, animals and plants that were located within a 500-meter radius of the operational equipment

    -A degeneration and destabilization of internal cellular membrane potentials while transferring catabolic [metabolic breakdown] processes into the blood serum from the digestive process

    -A degeneration of the cellular voltage parallels during the process of using the apparatus, especially in the blood and lymphatic areas

    -A destabilization and interruption in the production of hormones and maintenance of hormonal balance in males and females.

    -Loss of balance and circuiting of the bioelectric strengths within the ascending reticular activating system (the system which controls the function of consciousness)

    -Markedly higher levels of brainwave disturbance in the alpha, theta, and delta wave signal patterns of persons exposed to microwave emission fields.

    -Due to brainwave disturbance, negative psychological effects were noted, including deceleration of intellective processes, loss of memory, loss of ability to concentrate, suppressed emotional threshold, and interruptive sleep episodes in a statistically higher percentage of individuals subjected to continual range emissive field effects of microwave apparatus, either in cooking apparatus or in transmission stations.

    -A degeneration and breakdown of nerve electrical circuits and loss of energy field symmetry in the neuroplexuses, that is, in the nerve centers, both in the front and the rear of the central and autonomic nervous systems.

    -Long lasting residual effects of magnetic “deposits” were located throughout the nervous system and lymphatic system.

    Disclaimer: Mainstream science says “no evidence”.

    • Jay Barrelll – Please cite references for ALL that; 500 meters from a cell phone tower or a kitchen microwave? Just throwing out info without references is worthless.

    • Jay, I agree with Donna…I’d like to see your citations for the claims you’ve made.

      More importantly, however, I feel it necessary to point out the basic tenets of scientific inquiry: forming a hypothesis, weighing evidence or research results, and generating a conclusion based on the facts studied. If you aren’t forming an opinion based on evidence, what are you basing it on? Superstition? Conjecture? Folk knowledge?

      You’ve stated that “‘No evidence’ doesn’t mean ‘non-existent'”. I would argue that, in fact, the lack of evidence for a position should encourage us to doubt the veracity of that position. In other words, if I can’t find anything that leads me to believe something is true, I would be well advised to be very skeptical about it.

      This is the essence of scientific thinking.

    • Do you have any research that supports your claims or are they just anecdotal? If so, who is making those claims?

    • Perhaps he is not a major in biology but in electricity and radio frequencies.

      This technology is not like Einsteins feild of science(nuke), but rather more of Tesla’s concepts which is safer. and Im good with that.

      Well if microwave tech no good, then switch to natural gases. If fosil fuels no more, then use wood. If no more wood, no more oxygen.

      Anyways other feild of sciences are good and always are welcome to any rebuttals.
      I don’t have any sources to prove my statements.

  6. Just because it’s not as bad for you doesn’t mean it isn’t harmful. Using microwave instead of cooking with real fire is bad in general

    • That’s such an oxymoron. If you want to prove a point, please word it differently and provide cited evidence.
      (I understand your comment was from over 6 months ago, I just couldn’t ignore it.)

  7. You left out a major argument of the adverse effects of microwaves on food: the fact that they heat unevenly.

    When cooking on the stove, most types of food NEVER reach temperatures higher than 212 degrees Fahrenheit, because that is the temperature at which water boils at sea level.

    Microwaves, in contrast, use electromagnetic radiation. If a single molecule received all the energy from a single microwave, it’s reasonable to believe that the molecule could be heated to many thousands of degrees – hot enough to destroy it.

    There are two reasons this isn’t a problem. First, the fact that microwaves are very large – so large, in fact, that they can’t fit through the grid of holes in the microwave door. Microwaves might not heat food perfectly uniformly, but they cannot concentrate their energy on an area as small as a single molecule.

    Second… even if microwaves could destroy molecules through concentrated heating, they would only damage the molecules on the outside of the food. This is because microwaves don’t penetrate very deep into food. Substances like meat have a skin depth of about 2 centimeters in the microwave; that’s only 2 centimeters which could be damaged by the radiation. The rest of the food is unaffected (except by the natural transmission of meat from the outside to the inside).

    • I think you have it the wrong way around.

      MW ovens tend to heat to 100ºC (212ºF) because MWs work primarily on the water molecule which is a polar molecule (the 2 hydrogen atoms are both on one side giving a charge to that side which is what makes the molecule vibrate in an EM field, the friction from which is what heats the food). Yes, occasionally there are superheating effects.

      Conventional cooking (baking, frying, roasting, grilling) uses much higher temperatures from 180-240ºC. As heat and motion are linked (basically heat causes motion and motion causes heat), the molecules in food at 200ºC are vibrating far faster than in food in a MW oven.

  8. It is possible that microwaves are harmful because they allow us to cook in plastic. I remember when everyone had a stack of those cream-colored trays that frozen dinners made for the microwave came in. We used them over and over until they were totally caramelized! That’s really scary now that we know how bad some of the old plastics were.

  9. I avoid microwaving bc it alters the taste of the food…negatively imo.
    But my real concern is the potential dangers from cell phone radiation. Looking forward to your take on this….esp since unlike microwave ovens, cell phones are difficult to avoid.

    • The Non-ionizing radiation emitted by cell phones is extremely low frequency, there isn’t any scientific evidence showing that it causes serious illnesses.

      • bbsen comments that there isn’t any scientific evidence showing that cell phone radiation causes serious illness.
        I strongly disagree. There is too much evidence for me to list here. I refer anyone interested in reading about it to “A wellness guide for the digital age” by Dr. Kelly Crofton PhD.

  10. I have never been fond of using a microwave to heat or defrost food – simply because I find that it is very easy to over-cook the food, which affects the taste and texture… besides, I actually enjoy that tactile stimulation of stirring food in a pot on the stove…
    Having said that, it is great to see a well-written article about the safety of microwaves as they are certainly convenient at times…

  11. Chris: thank you for all your great information. Your website helps me educate people everyday in my community. Please let me return the favor in pointing you to one of the great scientists of our times: Mae Wan Ho. I highly suggest reading The Rainbow and the Worm(3rd edition) or visit her website The Institute for Science in Society. Granted there isn’t definitive evidence that microwaves are harmful, but there is so much exciting research going on in biophysics and the complex dynamics and role of water in organisms, that recommending microwaves doesn’t make sense anymore. She also has a book just on water now, but it is pretty dense and technical at parts and Rainbow and the Worm has an excellent chapter on water. I know you don’t like to jump ahead of the evidence, but it is pretty clear why microwaves could be harmful if you think about the implications of current research. There is more to life than biochemistry; understanding the biophysics is the future of science.

  12. I really wish you people would stop putting so many plugins and advertisements on your sites. They make coming to these sites unbearable as they take so long to load on phones through an email. You bandwith hogs are ruining The Internet. I am more concerned with that than microwaves.

  13. Really, what do you mean Palestine? Is an Israeli university? Or one in the West Bank?

      • Suggesting that a study occurred in Palestine is not remotely the same as suggesting that Israel does not exist. Perhaps a brush-up on basic geography and the history of the region is in order.

  14. “A study published in 2013 on microwaves in Palestine …” Do you mean Israel? If you do then call it Israel. This is 2015. I wouldn’t trust anything coming out of Gaza.

    • It would be a country if there was anything even close to fairness in the world. Palestine is a region, why do you feel upset about that? What arabs shouldn’t be allowed to do research? Are you racist?

    • You don’t have to “trust anything coming out of Gaza” because it’s someone else’s source. If you wish to pretend that a certain part of the world does not exist, despite numerous UN resolutions to the contrary, that’s your choice.

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