Are Microwaves Bad For Your Health? (Part 1 of 2)

Story at a Glance.

  • Microwaving your food has been shown in several studies to denature the vitamin and molecular structure of the food.
  • The agitating affect on the water molecules chemically alters the food at the same time.
  • Studies show that microwaving vegetables such as broccoli and asparagus, as well as heating up breast milk, significantly alters the nutritional value of the product.

It’s such a staple in our kitchens these days. And it probably ranks right up there with the kettle and the toaster for getting the most workout during the day. But is our drive for convenience and efficacy doing us more harm than good?

Microwaves work by agitating the water molecules in your food at a molecular level. It vibrates these molecules at a very, very high rate, heating the food as it does so. Whilst it is rapidly vibrating the water molecules in your food, the concern is, that it is also chemically altering it at the same time.

The Journal of the Science of Food and Agriculture published a study1 on broccoli to see what happened to it after it had been steamed and microwaved.

“Clear disadvantages were detected when broccoli was microwaved, namely high losses of flavonoids (97%), sinapic acid derivatives (74%) and caffeoyl-quinic acid derivatives (87%),” noted the study

“On the other hand, steaming had minimal effects, in terms of loss, on both flavonoid and hydroxycinnamoyl derivative contents.”

Another vegetable study was conducted in 1999 and published in the journal Acta Agroculturae Scandinavica B 2. It found microwaving asparagus caused a reduction in vitamins, specifically vitamin C. Vitamin C and vitamin B, are water-soluble vitamins, which means they are more likely to be affected by the agitation of the water molecules employed by microwave technology.

Bottles of baby’s breast milk warmed up in microwave don’t pass muster either. A study published in the journal Paediatrics3 looked at the effects of microwave radiation on human breast milk. The microwaved milk had E coli growth that was five times that of control human milk. Microwaving at low temperatures (20 degrees C to 53 degrees C) significantly decreased lysozyme and specific IgA to E coli serotype 06.

“Microwaving appears to be contraindicated at high temperatures, and questions regarding its safety exist even at low temperatures,” noted the study.

The Swiss scientist Hans Ulrich Hertel a Lausanne University professor published a study in 1991 stating microwaves significantly decreased the nutritional value in food and that food cooked in microwave ovens could pose a greater risk to health than food cooked by conventional means.

The article appeared in Issue number 19 of the Journal Franz Weber. In it stated that the consumption of food cooked in microwave ovens had cancer- type effects on the blood.

The study explored how microwaves change the molecular structure of food and the effects of that food on the human body. In his study, he found that individuals who consumed the microwaved foods experienced a decrease in HDL cholesterol (good cholesterol), a reduced red blood cell count, and fewer white blood cells.

The study was never released as the The Swiss Association of Manufacturers and Suppliers of Household Appliances swiftly brought action against this report and the Swiss court issued a ‘gag order.’ In 1998 that decision was overturned by the European Court of Human Rights in Stasbourg and the ‘gag order’ issued by the Swiss courts was lifted. The court ruled that the Bern scientist, unable to publish his study was contrary to the right to freedom of expression.

Now whilst this is intriguing in itself, we are still left with few studies about the nature of food and it’s deterioration under microwaved conditions. Surprising considering it’s one of the most ubiquitous cooking tools in our contemporary existence.

However what we do know is that it’s not just food that changes through the microwaving process.

In part 2 of our follow up article, we cover the nature of toxic chemicals that leak out of the containers you use to microwave your food.


[1] Phenolic compound contents in edible parts of broccoli inflorescences after domestic cooking. F Vallejo, FA Tomás-Barberán andC García-Viguera. Journal of the Science of Food and Agriculture Version of Record online: 15 OCT 2003 DOI: 10.1002/jsfa.1585

[2] Changes in Texture and Nutritional Quality of Green Asparagus Spears (Asparagus officinalis L.) during Microwave Blanching and Cryogenic Freezing. Ulla Kidmose & Karl Kaack. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, Pages 110-116 Published online: 05 Nov 2010

[3] Effects of microwave radiation on anti-infective factors in human milk. Quan R, Yang C, Rubinstein S, Lewiston NJ, Sunshine P, Stevenson DK, Kerner JA Jr. Pediatrics. 1992 Apr;89(4 Pt 1):667-9.

[4] Low-dose exposure to bisphenol A and replacement bisphenol S induces precocious hypothalamic neurogenesis in embryonic zebrafish. Cassandra D. Kinch, Kingsley Ibhazehiebo, Joo-Hyun Jeong, Hamid R. Habibi, and Deborah M. Kurrasch. PNAS   vol. 112 no. 5

[5] Iatrogenic hemolysis: a complication of blood warmed by a microwave device. McCullough J, Polesky HF, Nelson C, Hoff T. Anesth Analg 1972;51:102-106.

[6] Extracorporeal hemolysis of blood in a microwave blood warmer. Staples PJ, Griner PF. N Engl J Med 1971;285:317-319.

[7] Indicators of Erythrocyte Damage after Microwave Warming of Packed Red Blood Cells. Jan Hirsch, Axel Menzebach, Ingeborg Dorothea Welters, Gerald Volker Dietrich, Norbert Katz, Gunter Hempelmann. Clinical Chemistry DOI: 10.1373/49.5.792 Published May 2003

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