Warning! If you have bought the Guardian today, and are intending to read it over a leisurely lunch, do not read the magazine. Or, if you do, make sure you skip pages 30 to 37. Here's a - um - sample:

When photographer Anthony Cullen heard the clank of glass on porcelain, he didn't need to examine the contents of the toilet bowl between his legs. He instinctively knew he had just passed the marble he had swallowed as a five-year-old; the small coloured sphere - "I think it was a bluey" - had lodged in his colon for 22 years. His nonchalance was understandable. Having flushed 400 pints of coffee and vinegar solution around his large intestine through 10 enemas, and taken 100 herbal laxatives, he had become hardened to extraordinary sights. He had already excreted yards of long stringy mucus "with a strange yellow glaze", several hard black pellets and numerous pieces of undigested rump steak. Like an iceberg breaking away from a glacier, the marble was simply the latest object to drop off the furred up wall of his colon.

If you have a strong stomach, you can read the rest of the article on colon-cleansing here, but it can't compare with the horror of a full-page, full-colour, photo of a woman proudly showing off a colander full of the debris collected from her own colon - a yellow, slimy jellied mass.