If you read some alternative medicine web sites, you'll here talk of "toxins" and special natural products that can remove them and "cleanse" you through and through. Strangely, I always thought that the job of the liver and kidneys had something to do with that sort of thing. And like me, a real scientist, some people take objection to those magical "cleansers". So it was refreshing to read the article Toxins: the new evil humours, with a nice explanation of how this sort of idea first originated - in a time when the causes of illnesses were simply not understood - a time of "bad airs".
To quote the article, "The preoccupation with “toxins” is a direct lineal descendant of the obsession with evil humours and miasmas as causes of disease." Invisible scary things that threatened people, a bit like ghosts or evil spirits or demons. Something that was disproved when science advanced a bit out of the dark ages. The invention of the microscope helped reveal microbes, and support the germ theory of disease.
To quote again from the article, "The height of inanity is the belief in “detoxifying” diets and colon cleansing. The human body does not produce “toxins.” That’s just a superstition of the “alternative” health community. The waste products produced by the human body are easily metabolized by organs such as the liver, and excreted by organs particularly designed for that purpose such as the kidneys."
Do have a read of this article.
