01 October 2007
The Link Between Smoking and IBD
Inflammatory bowel disease is actually two different but similar diseases, Crohn's disease and ulcerative colitis. As said in the previous blog Crohn's disease generally tends to involve the entire bowel wall, whereas ulcerative colitis affects only the lining of the bowel. Even though it is still unknown what causes this uncomfortable disease, researchers have found that a number of factors such as environment, diet, and genetics can lead to this two diseases. While reading the article Inflammatory bowel disease: cause and immunobiology, I was surprised in discovering an interesting fact linking smoking and inflammatory bowel disease. It turns out that studies have shown that people who smoke are more likely to develop Crohn's disease than non-smokers. Smoker's tend to have a more aggressive form of Crohn's disease. However, when associated with ulcerative colitis it was shown that those who smoked were less likely to develop ulcerative colitis and tend to have a less severe course than those who do not smoke. Trials have shown that nicotine is of some benefit in ulcerative colitis due to increased mucus production and decreased cytokines. The article Smoking and inflammatory bowel disease. A case control study on gut.bmj.com goes into great detail about the results and statistics that they found when comparing smokers and non-smokers to UC and CD. They took non-smokers, ex-smokers and smokers and found that with heavy smokers, the risk of acquiring UC was lower than the non-smokers. Little is known on how smoking effects the location and the course of this disease. Although these studies have shown that smokers are less likely to have ulcerative colitis, smoking can lead to many other deadly diseases and is not advised as a therapeutic method for those who develop UC.
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12 comments:
Interesting information on the link, even potential positive contribution, that smoking may play in ulcerative colitis. This article just struck me that in a world where we really want to classify things as black and white - things are usually shades of gray. Certainly, I would not recommend taking up smoking either, but interesting how sometimes harmful, in other ways, substances can participate potentially positively to something. I wonder if this is being investigated further to clearly establish this link or not?
I never thought that smoking could have a link with IBD. You always hear about lung and mouth cancer so it is interesting to see that smoking affects less obvious parts of our bodies as well. I wonder why smokers get a more severe case of CD but seem to be more resistent to UC.
One of the biggest problems with case-control studies are confounding factors. So, there may be a 3rd factor that is related to both smoking and reduced risk of UC that is not being assessed in these case-control studies. I am hesitant to believe this relationship, although it appears that a few studies have found such an assocation. I actually found a recent article of a cohort study of young children. It found that smoking at an earlier age was associated with an increased risk of the incidence of UC. This type of study design is much more preferable when assessing risk.
Reference: Mahid SS et al. Active and passive smoking in childhood is related to the development of inflammatory bowel disease. Inflamm Bowel Dis 2007;13(4): 431-8.
Another study I found showed that smokers who had quit smoking still had a higher probability of developing IBD. If nicotine is the cause of the problem, causing a decrease in smooth muscle contraction and gut motility, then smokers who have quit should not have a higher probability of developing IBD. Also, it sounds as though through the Human Genome Project and SNJP haplotype mapping, specific cures for each one of many varied genetic or acquired aberation that cause IBD will be available in the near future!
After reading some articles on Pub Med about Nicotine and CD, I too am skeptical of the beneficial connection. Pub Med articles stated that similar studies were done with nicotine chewing gum and the same results were not found. The mechanism is not yet known as to how this helps. Only clinical trial case studies have shown nicotine smoking beneficial. Nicotine patches are currently being tested and the results are being waited for. Considering, the more harmful side affects of smoking, I would rather be stuck on a can than stuck in a box 6 feet under.
Oh Nathan, I guess we can sit side by side on our cans then! It is very interesting to think that nicotine could help reduce some symptoms of UC all the while destroying other parts of the body. But...would it not be a more feasible idea that if nicotine was at all helpful with UC, that there would be certain dose restrictions? Also, could there be a something else in cigarettes that is paired with the nicotine that is actually the helpful ingredient??
there are many complications involved with cigarettes that go well beyond nicotene
JennaL7630...that is an excellent point about case control studies. You're right...there could be either moderating (contributing) or mediating variable at play here.
These comments about nicotine actually having a potential benefit for patients with UC are interesting. It made me think about the new drug, Rimonobant, which appears to be a promising new therapy to treat obesity. Guess how it works? It is a cannaboid receptor blocker. Yes...that's cannaboid, as in marijuana! I guess the lesson is that some questionable agents might be beneficial...somehow. TLH
While the cause of IBD and Crohn's disease is largely unknown, it is thought to be determined by both genetic and environmental factors. Would it be plausible then to think non-smokers that develop IBD are genetically pre-dispositioned to the disease, while smokers with Crohn's disease have both the genetic pre-dispostion as well as an environmental factor? In this way, smoking does not protect against IBD, but rather NOT smoking prevents the development of Crohn's in people that are pre-disposed develop IBD in the first place.
Second-hand smoke can be equally dangerous for people with Crohn's disease as well.
I think that there might be something else that is in cigarettes that is paired with the nicotine but all the articles that I have looked at just focus on the nicotine part.
I also believe that the bottom line is smoking and second hand smoke is bad for all. I would not recommend smoking as a treatment due to the fact that smoking causes so many other complications.
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