Couple of points... If you are going to buy veggies like spinach, lettuce, etc., don't buy the bagged, pre-washed variety. Their handling increases the risk of bacteria by approx. 700%. (what, you thought those veggies were handled by surgeons wearing sterile everything, right?). Buy it from as close to the field as possible... farmers markets, etc., THEN wash it like it came from a plague area.
I love spinach... oh, the days of greek salads are long gone. It is high in iron, and fibre... but it is extremely hard on the digestive tracts if they're inflamed.
So, for many of us, spinach (even surgically sterile) is a no no. However, not all veggies are the same... iceberg lettuce has very little nutritional value to offer, but the fibre in it is easier to digest than spinach, or even romaine lettuce. Why? I don't know... think there are some folks on here with sufficient know how of nutrition to fill in that missing bit of info. And bear in mind that it isn't just fibre that can be hard on our systems... fat is off my list, and so are foods that are high in residue... not exactly sure why or what the difference is, but I was put on a hi protein, low fat, fibre, and residue diet (and lactose free too)..
I've seen links to low residue diets, but these days it seems they are adding fibre to just about EVERYTHING. And, if you are lactose sensitive/intolerant like me, then watch out. It is added to everything from margarine to vitamins... and it virtually everywhere in dairy (higher in skim milk than 3.5% ..why? I dunno), and it is non existent in some cheeses... but common in most soft, semi soft or processed cheeses... Why? Again, I dunno... part of the natural aging process or because it is common in mozzarella, or added to cheese products or slices.
Anyway, I've strayed... But, a final thought... if e-coli were the principal culprit behind crohns, "I" would expect it to be more common in 3rd world countries than in westernized countries, but just the opposite is the case. E-coli knows no boundaries, but it is far more prevalent there than it is in North America, etc yet it is here where crohns is the highest in incidence. It doesn't add up to me.