There's something about this guy's story that doesn't seem quite believable. On the one hand, he claims to have suffered, for years, from acute intestinal trouble. On the other, he claims to have been clinically obese. These two things don't usually go together. The people I've know who've had IBS for any length of time have been thin - partly because they aren't digesting their food properly, and partly because when your innards are on fire most of the time, you don't feel like eating much. They also were fairly frail. John Nicholson's health problems don't seem to have stopped him running a business and taking extended holidays in America (another curious inconsistency - what self-employed person goes on holiday for more than a long weekend?) And I can't help but feel if his bowels had been in that sort of distress for such a long time,how it was he didn't end up in hospital with a large section of his bowel removed, the usual sad fate of long-term sufferers from colitis or severe IBS. The reason why they take out bowel sections like that is because permanent inflammation of the bowel can lead to cancer, so I think his doctors would have probably taken his complaints rather more seriously than they seem to have done (also, which I find odd, none of the doctors at any time asked him for a stool sample - they almost always ask for one when someone has gut problems)
I know a bit about bowel problems, because my husband gets them from time to time. And the complete reverse of John Nicholson's - he finds that it's too much meat an fatty food that sets him off. Much though he likes steak and Stilton, he has to ration himself in that department carefully.
I told someone about this book just after I read it. He said: 'Sounds like one of those "misery memoirs" to me. You know, where they claim to have been locked in a cupboard throughout their childhood, and only brought out for beatings? Then someone says "Hang on,how could that be? I went to school with him."'
As a postscript, I note that in the 'sciencey' bit, he namechecks the Weston A. Price Foundation (and gets it wrong, missing out the 'A'), and its chief executive, Sally Fallon - the carnivore's Gillian Mckeith. Never mention Sally Fallon if you want your nutritional theories taken seriously. She's the woman who says that unpasteurised cow's milk is better for babies than breast milk, and also advocates feeding them raw liver.