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30 August 2012

The Dangerous Truth Behind Cooked Food

Cross-posted from the Winnipeg Skeptics blog.

Brevity is not one of my strengths. For this reason, what often begins as a minor correction or a response to a question in the comments section often becomes its own blog post (the character limits imposed by various blogging platforms also plays a role).

This is a follow-up to a post from several months ago, in which I discuss the shortcomings of an article from the hilarious The Not-So-Dangerous Truth Behind Microwaves. Here, I respond to some criticism that I received.

This blog is no more an authority than the ones you mocked.


Seriously, that's great! I'm just some beardy dude who likes science and occasionally has the opportunity to do science, but my specialty is in artificial intelligence (although recently I've been helping out with research in robotics and psychology). I make no claim to either authority (something that's pretty much worthless in matters of science) or expertise (something that's a little more relevant) in this (or any) subject. I'm trying to instill in people an appreciation for science and critical thinking generally. If you think that I want people to consider me an authority on matters scientific in any domain, either I'm not getting a properly skeptical message across (certainly debatable) or you're not paying attention.

Firstly, lets define "harmful": carcinogens are harmful...

Granted. well as, destroying phytonutrients that the body needs to sustain itself and strengthen defenses.

I do not grant that the reduction of phytochemicals in food is harmful. Stipulating that the compounds in question are healthful, it does not stand to reason that reducing the phytochemical content of a given food is harmful unless it is also established that the subject has a deficiency.

To illustrate by example: I would not consider a carton of pasteurized orange juice to be "harmful" (although its high sugar content may be problemmatic for some), despite the fact that the pasteurization process destroys much of the vitamin C content in the juice (and not all manufacterers add supplemental vitamin C to their juices)—unless, of course, the person consuming the product were deficient in vitamin C and counting on the orange juice in this regard.

Returning to the point about carcinogenicity, I'll remind the commenter that many common methods of cooking are implicated as cancer-causing, to some degree or other, including pan-frying, grilling, or barbecuing meat (source), smoking meats, roasting coffee beans, or even cooking with vegetable oils (source), or simply heating carbohydrate-rich food by means other than boiling (source).

This is complicated by the fact that several foods contain both compounds found to be carcinogenic and anticarcinogenic compounds.

What's worse, these phenomena are much better established both epidemeologically and from a basic science standpoint than the carcinogenicity of some microwaved foods. So why the outcry over microwaves? If I had to hazard a guess, I'd say it's because they're scary and new and complicated, and people tend to distrust things that they don't understand. Luckily, I'm under no obligation to hazard such a guess, so I won't.

Name the evidence that would be good enough to convince you there is "proof"?

The word "proof" is in scare quotes, as though to imply I'm asking for proof. I'm not. Science doesn't deal in "proofs": it deals in evidence, and no level of evidence constitutes "proof" in any sense but the colloquial.

But here's what I think would qualify as good evidence that microwaved foods are harmfully carcinogenic (for example): Replicable (and replicated), peer-reviewed studies establishing from a basic science standpoint that carcinogenic compounds are formed in foods heated or cooked in microwave ovens (and that these compounds are not formed in foods heated by other conventional methods), followed by epidemiological studies showing both statistically and clinically significant correlations between microwave use and cancer incidence.

That's a lot to ask for, of course, but I'd be happy to give my provisional assent to the proposition if it looks like a consensus is forming in the literature. It would also help if the IARC recognised microwaved foodstuffs as even potentially carcinogenic (Group 2B); but, as it stands, microwaved foods don't even make the list of things that the IARC can't rule out.

Is it possible that some foods are less nutritious when microwaved? Of course! I'd say that it's likely! But the same could be said for boiling, for frying, or for just about any other method of cooking, depending on the food.

Is it possible that some foods are carcinogenic when microwaved? Again, of course! But let's look at the specifics, and let's not forget (while we make sweeping generalizations), that the same is also already well established for many popular methods of cooking.

Do these admissions run contrary to my previous article on the safety of microwaves? Hardly. Even if it were (somehow) conclusively "proven" that microwaved food was harmful, that would not make the article I was critiquing "true" in any meaningful sense!

As I've said several times now, my problem with the original article had nothing to do with its conclusions and everything to do with the fact that it put ideology first and evidence second. It was horrendously sourced, made sweeping generalizations, got the basic science wrong, and cited as sources sites that were (to put it very mildly) disreputable and dishonest.


  1. I feel honored you devoted a blog post to my question – thank you.

    First, to clarify, I’m not on a crusade against microwaves. I completely agree that cooking food in any matter reduces nutritional value. The article I cited previously, specifically ranked cooking procedures in order of micronutrient destruction, and microwaves came out as the worst offender.

    It is a hard choice, what is better: an ideological, awkwardly cited article on some truth – or an eloquently written article, which ignores vital conclusions and instead focuses on critiquing another's poor explanations and hyperbole. Personally, I’d rather read a completely obfuscated truth than a pretty lie. I respectfully suggest aiming your skepticism talents/passion on seeking Answers, not pontificating about how others are doing such a fecal job at the very same thing.

    I appreciate the vitamin C in OJ example. I would go one step further, and question if the supplemented Vitamin C that gets added after pasteurization yields an equivalent product to the unadulterated fresh squeezed OJ. There are hundreds of phytonutrients that we know of, and an unknown amount yet to be discovered. All of these, coming together into a micro dance that we call nutrition. It reminds me of Isaac Newtown, “To myself I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me.”

    I do believe your skepticism comes across, however, I also believe it falls far short of that which is needed to wake people up to the utter disaster humanity is facing. I feel we are quibbling over bread crumbs on railroad tracks as a train is hurtling down at us. I am going to take a shot in the dark here, but I assume you would not have favorable words for Dr. Gerson’s methods of curing cancer. The reason I bring it up, is because it is a case where research was sabotaged, misrepresented, and ridiculed by the majority of the health science industry/academia without proper consideration. I’m not making that claim here about microwaves, but just as an example of where the scientific peer-review process breaks down in the face of enormous financial interests. Furthermore, it is a typical case where certain scientific methods/procedures break down – such as a implementing a double blind study.

    To be fair, it was definitely more of a ‘gotcha’ question than a scare tactic.

    1. A "pretty lie"?

      You comment provides nothing of substance.

      I spend an enormous amount of time campaigning for good science on issues that really matter, and you don't get to dictate my priorities or what I happen to fancy writing about in my (very rare, and correspondingly precious) personal free time. Free time that I'm not going to waste further on you.