The cause of Crohn's disease – If there is such a thing or what causes Crohn's disease?

I'd be lying if I tell you that I, or anybody else, knows the actual cause of Crohn's disease. But we do know a lot. And what we know translates into important worthwhile dietary and nutritional advice. 

Perhaps the best way of explaining the basics is by using a series of experiments begun by Dr. Balfour Sartor and continued by Dr. Sandy Kim. They took a mouse with an immune defect and gave it a bacteria. That mouse developed a condition similar to Crohn's disease. If they took one of those genetically bred mice and never gave it the bacteria, it was fine and so was the normal, healthy mice who were exposed to the same bacteria. They even were able to vary the bacterial strain and that caused the disease to develop on different areas in the mice with the immune defect. 

What they showed was that that someone who has a particular immune problem (caused by their genetic makeup) is susceptible to developing Crohn's disease when they exposed to certain bacterial strains.  What we now know is that other environmental factors and even some medicines as simple as ibuprofen seem to be able to trigger Crohn's in those with particular immune defects–and it isn't a single gene in humans that make you susceptible but the combination of a number of genetic defects that can contribute to someone's susceptibility. In fact, over 140 genes seem to have some impact on someone developing either Crohn's disease or ulcerative colitis. 

The other question that is important: why is Crohn's increasing?

Certainly, our human genes haven't changed over the past thirty years, but the number of people getting Crohn's, and ulcerative colitis has and so have the other diseases where the immune system is involved. In fact, the number of people getting Crohn's has doubled. One of the reasons is known as the Hygiene Hypothesis. It's based on the fact that those from underdeveloped countries aren't prone to these problems the way people in developed countries are–until their families move to countries like ours. The reason: those who don't get infections with parasites tend to have weaker immune systems which can then allow certain types of diseases like Crohn's develop.

There's No Such Thing As Crohn's Disease or ulcerative colitis

Actually, there is. In 1932, when Burrill Crohn and his colleagues described the condition named after him, they were trying to show there was a disease that typically occurred at the junction of the small and large intestine that was different from appendicitis in the same region and the much more common problem of tuberculosis in those days that was causing a similar illness. But what's happened is that a lot of similar but slightly different patterns have all gotten lumped together into being called Crohn's disease. Are they all the same? We're trying to tease that answer out, by separating the categories. The same is true in ulcerative colitis. Some have their entire large intestine (the colon) affected; others just have the very end of their intestine involved. 

Unfortunately, younger children with either Crohn's or ulcerative colitis have more severe disease than adults and even older children who develop Inflammatory Bowel Disease (IBD). 

And all of that leads me to say there are Crohn's diseases, so that patients and parents don't label all the same way and think they should be treat the same. And the same is true for all the types of ulcerative colitis that the medical community treats according to the disease location and its severity.