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There is no microbial overlap between Crohn's disease and UC.


Well-known member
It is a shame Crohn's Disease and UC still share an "IBD" umbrella.

They are completely different diseases that share nothing in common.

Crohn's disease shares immunological overlap with chronic granulomatous disease and very little with UC, pathological overlap with acute gastroenteritis and clinical overlap with intestinal TB.

There is no microbial overlap between Crohn's an UC.




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Well-known member
San Diego
UC and Crohn's are lumped together not only for their similarity in symptoms but also because they respond to many (but not all) of the same medications.

These two diseases do have have some differences, but their similarities are so many and so strong that docs often have trouble telling them apart and settling on a firm diagnosis. Here on this forum it's common to see members post that they first came down with UC that later "turned into Crohn's." It very likely didn't "turn into" Crohn's so much as it was Crohn's all along. But the doctor couldn't tell for sure and first diagnosed UC and later switched it Crohn's when the picture became clearer.
Finding the next therapeutics will be difficult if the researchers are still stuck on why one treatment works for Crohn's but not UC or why one factor or lifestyle worsens one but not the other.
I also wish that more distinction was made by researchers in terms of location of disease, when looking at treatment effectiveness.

For example, with regard to the features listed as distinct to Crohn's above, I've heard that EEN is less effective for isolated colonic Crohn's - has anyone else heard that?


Well-known member
For example, with regard to the features listed as distinct to Crohn's above, I've heard that EEN is less effective for isolated colonic Crohn's - has anyone else heard that?
EN is only slightly less effective in Crohn's disease involving the colon than ileal, we've known this for decades. But the differences are small. The higher up the GI tract you go, the more effective EN seems to be. EN is also effective in treating SIBO.

People with ileal disease also remain in remission slightly longer after EN treatment than those with colonic disease. But the differences are always very small.

EN still has much higher remission rates, even in colonic disease, than any other treatment.



It prefer looking at older studies. It is hard to take many current studies at face value anymore. Some GI now call IBD "a spectrum" and argue that there are some patients where they can't figure out if they have UC or Crohn's. If you can't figure it out, find a different profession, because it obfuscates treatment for patients. These GI try everything they have in their medicine cabinet until something works, that's not how treatment is supposed to work, treatment needs to be personalized because a large and increasing number of treatments that work for UC do not work for Crohn's disease at all.

This also impacts studies, there have been many clinical trials for crohn's disease that had to be stopped lately, because researchers want specific candidates that meet certain criteria regarding disease location and clinical presence of the disease and the process of diagonsis is not rigorous enough. If you start calling IBD "a spectrum" these researches can't find the right patients. The pathology and medical treatment falls apart, the link between research and medicine becomes clouded and you get contradicting studies.

There was this recent study called "We can't find patients", where researchers lament the fact they can't find the right patients for crohn's disease trials anymore because many patients with colonic disease might not have crohn's disease because of diagnostic failures.

Every anti-inflammatory that doesn't target main cytokine involved in the inflammatory process like TNF and IL23 has failed in crohn's disease. JAK, α4β7, etc, they have all failed to reach high enough remission rates, but they work for UC. UC has a whole laundry list of anti-inflammatories and biologics that work, crohn's disease has very few.

We have clearly reached a plateau on biologics for crohn's disease, where for decades no biologics has improved upon the remission rates of TNF-a blockers, which have existed for decades. Remission rates on biologics are still extremely low and relapse and loss of effectiveness is incredibly common. The only exception has been EN, which has incredibly high remission rates of 88%+.
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You've hit upon another question of mine. Correct me if I'm wrong, but it seems as if this study defined remission in terms of symptoms, not in terms of mucosal healing. What I've been told (again, please correct me if I'm wrong, and I would love to see studies on this) is that diet can improve symptoms, but it doesn't lead to actual mucosal healing, especially in the colon. I would love evidence that this isn't the case.


Well-known member
EN leads to endoscopic healing in both the ileum and colon. Most studies on diet like SCD, low-FODMAP, etc, are not rigorous enough. They often don't take into account severity of disease or age of onset (Montreal Classification) which makes it hard to translate the research to other patients. In most cases of crohn's disease, age of onset is puberty. Kids where age of onset falls below puberty have very different disease, they have genetic differences and because peyer's patches are not involved yet, it's hard to compare them with people where age of onset happened at puberty.

That's another reason why newer studies regarding EN and diets can be quite difficult to trust. Kids where age of onset happens prior to puberty is a new phenomenon. When someone develops crohn's diseae prior to puberty, it means peyer's patches and antigen uptake by M cells is unlikely, and everything from EN to anti-inflammatories will react differently.
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Can you please point me to a study that shows that EN leads to endoscopic healing the colon for onset in very early adulthood? I'm not questioning you, it would just be helpful.


Well-known member

If you mean in kids that develop crohn's disease prior to puberty, I rarely read those studies. I have pretty classical ileal crohn's disease diagnosed at puberty, and that's where my interest is. Young kids developing crohn's disease is a new phenomenon I know very little about, it's possibly a different type of disease because they haven't gone through peyer's patches development yet.