Repeat After Me: The Dose Makes the Poison

Today I came across this on the web:

why is everyone quitting gluten now?

There are a number of very valid reasons for the growing number of people having to pass on the pizza.

The short form: gluten is a poison (see below). We tolerate it, and tolerate it, like cigarettes in the lungs. And then. One day. It’s too much. Things tip over and BANG we have lung cancer. Or gluten intolerance. Or celiac’s disease.

But more detail…and they’re facts, mind.

Toxicology is a complex subject which I know little about, but I do know the first rule of it: the dose makes the poison.

Everything is toxic at some level: water, oxygen, peaches, brazil nuts. Everything.

The question is always how much, over what time period (and possibly in what pattern).  It makes no sense to talk about something as a poison apart from dose.

This seems to be one of the primary public misunderstandings of science. The idea is if a little of something is good for you, then a lot must be really good (see the harmful nonsense around antioxidants), and if a lot of something is bad for you, then even a little must be harming you in ways you don’t realize (see wheat, yeast, sugar, vinegar, and just about everything else).

I don’t doubt, by the way, that there are many people with horrible reactions to gluten. I know at least one person who has celiac’s disease. It’s horrible.

But in those cases, that’s due to personal factors, individual physiology. There’s really no reason that celiac’s disease is telling us something fundamental about our bodies any more than a latex allergy tells us some dark secret about latex.

I’m allergic to dogs, for example. Been hit so bad with it that I’ve ended up in the ER, and even after a mild attack I am messed up for quite a bit. So is every dog owner really just in denial about the slow death their dog is causing them?

My daughter is deathly allergic to peanuts. We found this out when she was two — she had a peanut butter cookie and in about 20 minutes looked like the Elephant Man. Her eyes swelled shut, her breathing got labored, and only Benadryl saved her. We now have an epi-pen around at all times.

So are peanuts a secret killer? (Someone should let India know!)

Once we get past edge cases, it’s all about dose. Star fruit contains a neurotoxin. Too much Vitamin A will kill you, and even a Vitamin E pill a day may radically increase your chance of prostate cancer. Fish contains mercury, and of course overdosing on water is not uncommon.

All these things are pretty good for you (or even necessary) in moderation. None of these facts tell us anything except that the cases at the edges are seldom some secret key to the center.

Does it matter? I think I agree with Ben Goldacre on this one — it matters, but not in the way you might think. Avoiding wheat is unlikely to kill you, but the magical reasoning invoked to explain why you are avoiding it may kill someone else. “Gluten is a toxin” is a gateway drug into anti-vax nonsense and global warming skepticism. And the flood of diet nonsense in popular magazines and on daytime TV support a notion that science is as simple as making a few logical connections and calling it a day.

If you don’t want to eat wheat, or if you are a person who really *is* harmed by wheat consumption, then please don’t eat wheat. But leave science alone, we need it for other things.


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