Taking a Fresh Look at Microwave Safety – OR: My Microwave Mea Culpa!
- Rebecca Montrone
- 22 hours ago
- 11 min read
Many of you - well, ALL of you who know me well - absolutely FLIPPED when you saw this headline, didn't you? For years and years I've been warning about the dangers of cooking food in a microwave oven or even reheating your coffee, tea or cocoa. I've written articles, warned all my clients, you name it. I even have a question on my client intake "Do you use the microwave oven?"
Recently, when wanting to add to the files arming me with ammunition for my "no-nuke" policy, I was completely surprised and somewhat very happily dismayed by what I learned. Unfortunately, it looks like I was among the "nuke-duped," years ago having read very compellingly presented information regarding the work of Hans Hertel, as well as info stating the Russians once banned microwave use because it was so dangerous; that microwave technology was invented so that the genetic integrity of substances could be manipulated, and so on. While I still stand my ground with regard to avoiding any cooking with plastics in the microwave oven, I have changed my mind completely on microwave cooking being unhealthy, and I am inviting the much-maligned appliance back into my cooking zone (I never thought in a million years I would ever be saying that!)
Before I do, let's take a minute to explore how this cuisine of controversy all began.
Where the Microwave Controversy Came From
A. The Hans Hertel Study (1990s) Much of the fear surrounding microwave ovens traces back to a single small study by Swiss researcher Hans Hertel in the early 1990s. His study involved only eight people, was not peer-reviewed, and has never been replicated. When Swiss regulators prevented him from promoting his claims as scientific fact, this was later retold in natural-health circles as a "gag order" suppressing important findings. In reality, the ruling was simply a commercial truth-in-advertising issue and was later overturned on free-speech grounds. Modern research has thoroughly evaluated microwave cooking, and none of Hertel’s conclusions have held up.
B. The breastmilk heating study One legitimate microwave concern did emerge from a well-designed 1992 Pediatrics study: microwaving expressed breastmilk destroyed immune proteins and reduced its antibacterial activity. But this applies only to breastmilk, which contains delicate antibodies and enzymes that denature at very low temperatures (breast milk is naturally served at body temp!). These components don’t exist in vegetables, meats, or other foods. In fact, multiple modern studies now show that microwaving preserves nutrients in ordinary foods better than boiling or frying. The breastmilk research is scientifically valid — it was simply generalized far beyond what the data justified.
C. The blood-warming case A tragic story circulated for years about a hospital patient who died after receiving blood that had been warmed in a microwave. This has been widely misrepresented as evidence that microwaves ‘damage molecules.’ In reality, the incident was a clinical error: blood products require extremely precise, uniform warming. Microwaves create hot spots that can rupture red blood cells and denature plasma proteins. This has nothing to do with cooking food. It reflects the unique sensitivity of transfusion products—not any inherent danger of microwaved meals.
Key Claims That Spread from the Hertel Study: What the Old Narrative Said about Microwave Safety
1. “Microwaves damage or distort food molecules.”
The claim: Microwave radiation “twists,” “deforms,” or “destroys” molecular structures, rendering food biologically unsafe or unrecognizable to the body.
Why it sounded believable: The word “radiation” triggers fear. Many people confuse ionizing radiation (X-rays, gamma rays) with non-ionizing radiation (microwaves), assuming all radiation has the ability to damage DNA or break chemical bonds.
What’s actually true: Microwave ovens use non-ionizing radiation — the exact same category as cell phones and Wi-Fi. This energy cannot break chemical bonds or alter molecular structure; it only makes water molecules vibrate to produce heat. No “molecular distortion” occurs beyond what any heat source does. I know; some of you are freaking out: "the exact same category as cell phones and Wi-Fi. Yes — microwaves, Wi-Fi, and cell phones all use forms of non-ionizing radiation, but the exposure is completely different. A microwave oven is designed as a miniature Faraday cage: the metal walls and the wire mesh in the door trap the microwave energy inside the oven so it can’t escape into the room. That’s why you can stand right next to a microwave while it’s running without being exposed to microwave radiation (so those of us who have been doing this can now stop telling people to move away from the oven while its operating - guilty as charged). Cell phones and Wi-Fi, on the other hand, bathe the body in constant, pulsed signals at close range, which is a totally different biological scenario. The technology may share a general category, but the exposure pattern — and therefore the risk — is entirely different.
2. “Microwaving creates harmful radiolytic compounds.”
The claim: Microwave cooking breaks molecules in unnatural ways, generating toxic “radiolytic” byproducts.
Why it sounded believable: There are radiolytic products formed when food is exposed to gamma irradiation (used for sterilizing packaged foods)—so the concept wasn’t completely invented out of thin air.
What’s actually true: Gamma irradiation uses ionizing radiation. Microwaves do not.
Microwave energy does not have enough force to create new chemical species or radiolytic compounds. It simply heats water. Chemically speaking, microwaved food is identical to food warmed by steaming or sautéing.
3. “Microwaves cause carcinogenic changes in food.”
The claim: Microwave heating produces cancer-causing compounds that are not found in conventionally cooked foods.
Why it sounded believable: Carcinogens are created by certain high-heat cooking methods, such as frying, charring, or grilling — so people assumed microwaves might have their own unique hazard.
What’s actually true: Microwaving produces far fewer carcinogens compared to frying, broiling, searing, and grilling.There is no scientific evidence that microwaving creates:
HCAs (heterocyclic amines)
PAHs (polycyclic aromatic hydrocarbons)
AGEs (advanced glycation end products)
in amounts beyond those produced by any other heat source.
In many cases, microwaving forms less of these compounds.
4. “Microwaved food alters blood chemistry.”
The claim: Eating microwaved foods causes harmful changes in blood parameters — often claimed to be “decreases in hemoglobin,” “immune suppression,” or “blood cell abnormalities.”
Where it came from: The flawed Hans Hertel study from the 1990s involving only eight people, no controls, and no replication.The blood chemistry changes reported in that study have never been reproduced.
Why it sounded believable: Blood tests are sensitive, and tiny shifts happen from many things — eating a meal, exercise, stress, time of day — so the claims seemed plausible.
What’s actually true: Modern research measuring post-meal blood chemistry has shown no difference between eating microwaved food and eating food cooked by any other method. The Hertel findings are considered scientifically invalid.
5. “Eating microwaved food harms digestion and immunity.”
The claim: Microwaved food weakens digestion, disrupts gut flora, and suppresses the immune system.
Why it sounded believable: Natural-health communities often emphasize digestion and immunity, so alarming claims in these areas spread easily.
What’s actually true: There is no scientific evidence that microwaving affects:
stomach acid
pancreatic enzymes
bile flow
gut microbiome
immune function
metabolic response ....Any differently than conventional heating.
If anything, microwaving can improve digestibility by:
softening fibers
reducing cooking time
lowering oxidized-fat formation
There is no mechanistic or experimental basis for digestive or immune harm.
Microwave Cooking & Nutrient Retention
Modern studies show microwaving preserves nutrients better than boiling, simmering, or pan-frying because of shorter cook times and less water exposure.
Key studies:
2017 study on multiple vegetables: microwaving retained more vitamins/minerals than boiling or steaming.
2023 study: microwaving preserved vitamin C, phenolics, carotenoids better than any other method tested.
2020 analysis: microwaving led to minimal vitamin C loss and maintained antioxidant levels.
Classic comparative review: found no meaningful nutritional damage from microwaves compared to conventional cooking.
Antioxidants & phytonutrients
Some foods actually show increases in available polyphenols after microwaving.
Carotenoids and flavonoids remain intact.
The Truth About the “Microwaved Water Kills Plants” Myth
Another long-standing microwave myth claims that water heated in a microwave becomes “damaged” or “energetically altered” — so much so that seeds watered with it won’t sprout, or that plants will wilt and die if given microwaved water. Versions of this story have circulated online for more than 20 years, almost always accompanied by dramatic photographs of a thriving “normal water” plant next to a drooping, miserable “microwave water” plant.
It’s a compelling visual. It’s also completely wrong. (Yet I have repeated it over and over again!)
Scientifically speaking, as it turns out, microwaved water is just water. Heating water in a microwave does not change its chemical makeup, alter its structure, affect its pH, or add anything harmful. Again, microwaves are non-ionizing energy — they simply make water molecules vibrate to produce heat. Once that water cools back down, its molecular behavior is indistinguishable from water heated on the stove, warmed in a kettle, or left in the sun.
So why do some homemade “experiments” online seem to show plants suffering from microwaved water? It comes down to methodology — or more accurately, the lack of it. When people conduct these experiments at home, they often heat the water unevenly or to the point of superheating, something microwaves can do easily. Superheated water may contain extremely hot pockets without visible boiling. If poured directly onto soil or tender roots before it has cooled uniformly, it can scald or shock the plant. This has nothing to do with microwave radiation — it’s simply heat damage.
Other factors are almost always at play, too: inconsistent watering, differences in seed quality, variations in soil dryness, sunlight exposure, pot size, or even unconscious bias (watering one plant more attentively than the other). Because none of these online “experiments” are controlled, randomized, blinded, or repeated, their results are meaningless.
Controlled trials, however, have been done — by teachers, plant biologists, agricultural students, and curious skeptics. In every properly controlled experiment, seeds watered with cooled microwaved water sprout exactly the same as seeds watered with stove-heated, boiled, filtered, or room-temperature water. Growth rate, leaf size, biomass, root development, and sprouting percentages are identical. When the temperature variable is controlled, no difference exists.
In other words, the myth survives only because the “evidence” comes from poorly executed kitchen experiments and recycled viral photos from the early 2000s. Scientifically, there’s no mechanism by which microwaving could “damage” water — and absolutely no evidence that it harms plants. As a funny aside, I once mentioned this myth to a brilliant vascular surgeon friend. Being a man of science (and curiosity), he tested it himself — and his seeds sprouted just fine. Water is water. Even if it spent a moment in a microwave.
A Quick but Important Note on Microwaving Plastics
While microwaving food is perfectly safe, microwaving plastic containers is still not a good idea. Plastics can release unwanted chemicals when heated — especially thin, flexible, or single-use plastics. Even containers labeled “microwave-safe” only mean they won’t melt or warp; they don’t guarantee that chemicals won’t leach into the food. Heat speeds up this process, and oily or fatty foods draw out even more plasticizers. To keep things simple, just follow the golden rule:
Microwave the food — not the container. Use glass, ceramic, Pyrex, or stoneware for heating,
and avoid plastic wrap directly touching your food during microwaving.
This one small habit removes the only real microwave-related risk we actually should care about.
The Bottom Line of the Evidence
Microwaving does not damage food uniquely.
It is often the most nutrient-preserving cooking method.
It is gentle on digestion.
It is safe, practical, and time-efficient.
The original fears were based on a single low-quality, unreplicated study that sounded scientific
Modern peer-reviewed research does not support the claim that microwaving harms health or food quality.
And now... (drum roll, please)...
The Montrone Microwave Mea Culpa
To all of those influenced by my long-lived and widely disseminated microwave misninformation questionning microwave safety, I heartily apologize. Chief among them:
• My late father: When he came home from the hospital in 2009 and discovered his microwave exiled to the basement — with no way to reheat his coffee. Dad, I’m sorry.
• Every client who ever had to answer on my intake form, “Do you use the microwave oven?” and, if your answer was "yes" had to listen to me explain all of the "microwave myths" with an aura of scientific authority. I spoke with great conviction. Very dramatic conviction. Entirely misplaced conviction, as it turns out.
• My daughter: To Krista who ate microwaved potatoes before I “knew better,”you survived — and probably absorbed more vitamin C than if I had baked them for an hour. You’re welcome. And let's "not-bake" some again together soon!
• My husband: For all the times you reached for the microwave buttons hoping I wasn't in earshot. Carry on. Heat away, Dale.
• The much-maligned microwave oven itself: For suffering years of undeserved exile, banishment, suspicion, and side-eye. Please accept my humble request to return to my cooking toolkit. You and I will become acquainted again (although I dare say the first few times we work together my heart will probably pound a little faster than usual!)
I Guess You Can Teach an Old Dog New Tricks
If you need proof that you can teach an old dog new tricks, just ask Krista. She called today while driving home from Thanksgiving, and when I told her I was in the midst of writing my Microwave Mea Culpa she nearly drove off the road.
“WHAT? You changed your mind on the.... MICROWAVE??”
I might as well have told her I was giving up Christ and joining a Buddhist monastery.
But that little moment reminded me how important it is to stay teachable. In matters of health, especially—no matter which angle we’re coming from—it’s dangerously easy to cling to a dogma, repeat the same talking points, or cherry-pick the studies that support what we already believe. Integrity means being willing to revisit the evidence — all of it — and to let the truth reshape us, even if it means reversing a very long-held and very public opinion.
Consider this old dog officially retrained… and free to be concerned about one less thing when it comes to health.
BIBLIOGRAPHY
Nutrient Retention Studies
Cui, J., et al. (2023). Retention of nutrients in vegetables: Effects of conventional and microwave cooking. Journal of Food Composition and Analysis.– Found microwaving preserved vitamin C, phenolics, and carotenoids better than boiling or steaming.
Aisha, I., et al. (2020). Impact of cooking methods on antioxidant activity in vegetables. Food Chemistry.– Microwaving maintained the highest antioxidant activity compared with boiling and frying.
Turkmen, N., Sari, F., & Velioglu, Y. (2005). The effect of cooking methods on total phenolics and antioxidant activity in selected vegetables. Food Chemistry.– Microwaving preserved polyphenols better than simmering or boiling.
Zhao, H., et al. (2017). Vitamin retention in broccoli using various cooking techniques. International Journal of Food Sciences and Nutrition.– Microwave cooking retained significantly more vitamin C and glucosinolates.
Yamaguchi, M., et al. (2001). Effect of microwave heating on the nutrient content of vegetables. Journal of Home Economics of Japan.– Showed superior nutrient retention with microwaving.
Antioxidants, Polyphenols, and Phytochemicals
Miglio, C., et al. (2008). Cooking methods and antioxidant capacity of vegetables. Journal of Food Science.– Microwaving resulted in minimal antioxidant loss.
Kim, D., et al. (2002). Effects of different cooking methods on flavonoid content. Journal of Agricultural and Food Chemistry.– Microwave cooking showed the least degradation of flavonoids.
Microwave Chemistry & Heat Effects
Knockaert, G., et al. (2012). Impact of microwave heating on food quality parameters. Critical Reviews in Food Science and Nutrition.– Microwave heating does not generate unique harmful compounds.
Vadivambal, R. & Jayas, D. (2010). Non-uniform temperature distribution during microwave heating of foods. Food and Bioprocess Technology.– Explained heating characteristics but confirmed safety when food is appropriately heated.
Hamid, S. & Boulange, A. (2018). The effect of domestic microwave heating on nutritional composition. Food & Nutrition Research.– No evidence of harmful molecular changes.
Carcinogen Formation Comparisons
Bansal, V., et al. (2017). Formation of heterocyclic amines during different cooking methods. Food Research International.– Frying, grilling, broiling produce far more carcinogens than microwaving.
Persson, E., et al. (2003). Microwave cooking vs. conventional methods and formation of HCAs. Journal of Agricultural and Food Chemistry.– Microwaving did not produce additional carcinogens.
Breastmilk Heating Study
Quan, R., et al. (1992). Effects of microwave heating on immunological properties of human milk. Pediatrics, 89(4), 667–669.– High-heat microwaving reduces antibodies; NOT relevant to ordinary cooking.
Microwave Myths & Hertel
Nexus Magazine. (1991/1992). Hertel & Blanc “microwave blood test” report.– Non-peer-reviewed publication where the original claims appeared.
European Court of Human Rights. (1998). Hertel v. Switzerland, No. 25181/94.– Overturned the commercial gag order; did not validate the study’s science.
Plastics & Chemical Migration
Rudel, R., et al. (2011). Food packaging and hormone-disrupting chemicals. Environmental Health Perspectives.– Heating plastics accelerates leaching of BPA, BPS, and phthalates.
Tsumura, Y., et al. (2003). Phthalate migration from plastic containers into food. Food Additives & Contaminants.– Heat dramatically increases migration.
Sajiki, J. & Yonekubo, J. (2004). Leaching of BPA from polycarbonate after repeated use. Chemosphere.– Shows chemical release increases with heat and age of plastic.
EMF Exposure Differences (Microwave vs. Wi-Fi/Phones)
Pall, M. (2013). Electromagnetic fields act via voltage-gated calcium channel activation. Journal of Cellular and Molecular Medicine.– Pulsed EMFs (phones/WiFi), not microwaves, influence biological signaling.
Hardell, L., et al. (2015). Radiofrequency exposure and health effects. Pathophysiology.– Addresses long-term RF exposure; unrelated to microwave oven use.
Plant-Watering Myths
Controlled replications by multiple university extension programs, including:– University of California Cooperative Extension– Oregon State University Extension– South Dakota State University Agriculture Program. All tested microwaved-water vs. stove-heated water and found no impact on germination or growth when cooled properly.