Microwave ovens and the Plant Program

Microwave ovens and the Plant Program

A friend of mine with cancer told me recently about the Plant Program(me), after it was recommended to her by an oncologist.

The Plant Programme is essentially a diet that dramatically reduces the levels of growth hormones and other dietary factors that may cause the growth of certain types of cancer, specifically breast and prostate cancer. It was put together by Professor Jane Plant, a respected scientist. Professor Plant attributes her rapid remission from breast cancer, and subsequent non-recurrence, to the diet.

For the most part, what Professor Plant says is supported by a growing amount of evidence. Breast and prostate cancers are sensitive to a range of chemicals that increase cell proliferation. And as well as there being certain foods that promote cancer growth, other foods may reduce or prevent it, like the phytoestrogens in soy, which may act by blocking estrogen receptors in the body. I wasn’t surprised by all of that. Jane Plant is a well established researcher in a field in which I have worked myself, and, as expected, her evidentiary base was good.

But she doesn’t like microwaving.

That did surprise me, because the people that tend to not like microwaving are the same people that eschew not just that one piece of technology, but also many of the gifts of the Enlightenment, from evidence based reasoning to modern medicine. A quick look around the wonderful world wide web revealed an abundance of supposition and nonsense about microwaving, with nary a good, published, paper in sight. So why doesn’t Professor Plant like microwaving? Here is what she wrote about it (in: ‘Prostate Cancer: understand, prevent & overcome prostate cancer’, p.242 and 245, and ‘Your Life in Your Hands, understanding, preventing and overcoming breast cancer’, p. 202.)

“Never use a microwave cooker because free radicals are formed in the food.”

“I do not own a microwave and try to avoid food cooked or heated in one. Unlike normal heating, microwaving food works by vibrating water molecules in food. This generates free radicals and I suspect would not destroy as many ‘bad’ chemicals as ordinary cooking (although I have been unable to find any data on this).”

Let’s break these statements down.

1. The mechanism by which a microwave oven cooks food (by vibrating water molecules) generates free radicals.

2. The mechanism by which a microwave oven cooks food ‘would not destroy as many bad chemicals as ordinary cooking’

Claim 1. Free radical production

This should be straightforward to verify, but with this claim, I straightaway hit an obstacle. The quotes in the book were provided as is, sans footnotes or references. That shouldn’t be a problem, because I’m fairly sure that Professor Plant and I hang out in the same databases, read the same kind of books, kind of thing. Yet after several hours searching on Google Scholar, Pubmed, and ISI Web of Science, I couldn’t find any support for the notion that microwaving creates free radicals in food. I could have missed something, but given that the only people claiming microwaving creates free radicals are the cranks, and the usual science databases are quiet on the subject, I do not know where to find good evidence to support this claim.

So who does say that microwaving produces free radicals in food? The Atlantis Rising Educational Center in Portland, Oregon, I’m told. As the story goes, the Soviets investigated microwave ovens and decided they were dangerous, and pulled them off the market for two years in the 1970’s. Good luck finding any proof that really happened, because I couldn’t. Anyway, in a fit of largesse, the Soviets shared their findings with the world, the world in this case, apparently, being the Atlantis Rising Educational Center in Portland, Oregon, and not it seems, for what I am sure were sound political reasons, the World Health Organisation. Among their findings were the alarming notion that microwaving produces free radicals in food, especially root vegetables.

If I come across as snarky, it’s because none of this stuff has citations. Trying to find out why Professor Jane Plant has encouraged potentially thousands of cancer sufferers to unplug their microwaves has led me way down into a veritable rabbit hole of woo. I thought it would be simple, but actually I can’t find a single, credible, reliable source for the idea that microwave ovens produce free radicals. Not a one. I can find plenty of ‘references’ to the Soviet research from the 1970’s, and lots of pointers to the Atlantis Rising Educational Center, the unlikely repository for 1970’s Soviet research. So by all means, if you have a good reference, an original citation, or indeed access to the Soviet research, dear reader, then please share it in the comments.

Lets take a different approach. Is it even possible that microwaves produce free radicals in food? Microwave ovens work by heating water and other polar molecules in food, like fat. They do this through rapid rotation of these molecules in the presence of an alternating electromagnetic field, which creates friction and heat. The heated molecules in turn will distribute the energy to the remainder of the food. Microwave ovens are actually pretty simple, in terms of the chemistry that they can affect. Water molecules, because they are polar, are affected by the microwaves – in fact, much more efficiently than other polar molecules –  and all that will happen is that they become very hot. Most other effects on microwaved food are indirect, and caused by heating from proximity to the water molecules. In contrast, an oven will produce a smorgasbord of chemical reactions. A conventional oven can be used to brown food. Maillard reactions occur between sugar molecules and proteins, as when meat is fried. Caramelization occurs when carbohydrates are heated, like when coffee beans are roasted. But you can’t fry food in a microwave. You can’t roast coffee beans in a microwave. You can’t bake bread in a microwave, at least, not in a way that will give you tasty bread. Microwaves really just heat water molecules, which in turn heat the food. At what point in this process could free radicals be produced? Could it be as a result of the rapid oscillation of water molecules in the presence of microwave radiation? No. Is it indirectly, as a result of food being in contact with very hot water? No, although, if yes, then watch out for your pot of tea. Or any food stuff that has been heated, really, by any cooking method, as most everything we eat contains water.

As an aside, here is an example of the kind of nonsense out there about microwave ovens.

“The problem with microwave cooking starts in the molecule of the food/liquid. The molecule of the food/liquid is vibrated from the inside out by the action of the microwave… The electromagnetic radiation causes some of the electrons to be dislodged from the food molecule, which converts the stable food molecule to an unstable molecule. This is called a free radical… When you consume this massive pile of free radicals, it will rob your cells of electrons. It does this so that the unstable molecule can be stable, which then causes your cells to become unstable.”

Scary stuff! Molecules of food are “vibrated from the inside out.” Food cooked in a microwave becomes “a massive pile of free radicals.” Your cells become “robbed of electrons.” Well, don’t worry. It’s all wrong.

Free radicals are atoms, molecules, or ions, with unpaired electrons on an otherwise open shell configuration. They are highly reactive, and thus likely to take part in chemical reactions, which can lead to cell damage. The trouble is, production of free radicals takes a significant amount of energy, and a microwave oven doesn’t provide enough. Don’t believe me? Heating a mug of water in a microwave will not result in a mug of superoxide, singlet oxygen and 2H. Heating a mug of water in a microwave results in a mug of hot water. That is why millions upon millions of people can use microwave ovens every single day. Microwave ovens are safe, produce chemically uninteresting food, and are culinarily quite dull.

Claim 2. “The mechanism by which a microwave oven cooks food ‘would not destroy as many bad chemicals as ordinary cooking'”

Actually, Professor Plant’s point number two  is almost an acknowledgement of safety of microwave ovens. The thing is, free radicals, being highly reactive, would do a lot destruction to ‘bad chemicals’. That is one reason why our own bodies produce free radicals. Our phagocytes churn out superoxide to kill invading pathogens, and that does the job very well. So microwave cooking doesn’t destroy as many ‘bad chemicals’? If microwaving were producing sufficient free radicals to be a concern to human health, then microwaving would be producing enough free radicals to destroy these bad chemicals. But, of course, microwaving doesn’t produce free radicals. It just heats water molecules. I won’t say more about point number two, because Professor Plant had indicated that it was her own supposition, and acknowledged that she could not find any data.

I think it is worth reiterating that what microwaves do is really very simple. They agitate water molecules, creating friction and heat, and that in turn heats the food. In fact, because the process of microwave cooking is chemically simple and fast, there is an additional and pertinent nutritional benefit with microwave food: it can be more nutritious than food cooked by other methods. Here’s why.

For one, the shorter preparation time required for microwave cooking may result in a tendency toward better preservation of micronutrients.

For another, in a 2009 study published in the Journal of Food Science, the antioxidant potential of 20 vegetables was assessed after variously boiling, microwaving, pressure cooking, griddling, frying, and baking. Antioxidant potential was found to be best preserved after griddling, microwaving and baking. The greatest losses of antioxidant potential took place in food that was pressure cooked and boiled. This is not the first time the antioxidant preservation by microwaving was observed. All of that is relevant if one accepts the premise that antioxidant potential in food is a worthy nutritional goal, and a lot of people, including Professor Plant, do.


There’s a lot of merit to the overall message Professor Plant sets forth in her books. The effect of diet on certain cancers is attracting more and more research interest. The problem is, some of the details in the books, like the statements on microwave ovens, border on the superstitious. People with cancer deserve the facts, not vague and unsupported notions about free radicals and microwave ovens. It may not be a big deal to live without a microwave, but encouraging people to give up their microwave oven because doing so will help with curing or preventing cancer, as my friend had done, based on such little evidence; that strikes me as being altogether unhelpful.