The Microbial Effects of Smoking: More Evidence

My original post on the microbial effects of smoking led to a line of inquiry that is still ongoing, and which I plan to return to shortly. But since that original post, I’ve come across quite a few pieces of data and supporting evidence for the broader smoking/microbial link, and I think it’s worth recording them.

Baby Colic

An NPR article last week reported that probotics — specifically Lactobacillus reuteri — have been found to greatly reduce the symptoms of colic in babies (a condition that results in excessive and uncontrollable crying in infants). It’s a condition that affects 8 to 15 percent of babies, and can take a major toll on families. Not only does the probiotic reduce the symptoms, but if given during the first few weeks of life, it can actually prevent colic.

I found this pretty intriguing, but I don’t know much about colic. So I read up on it. Guess what’s been shown to be strongly associated with colic? Smoking during pregnancy. According to a Danish epidemiological study in 2005, mothers who smoked 15 or more cigarettes a day were twice as likely to have babies with colic. Furthermore, studies have found that a) smoking leads to an increase of a hormone (motilin) secreted in the digestive tract; and b) baby colic is associated with an increase in this hormone, thus pointing to a mechanistic link.

According to that study, half of all women smokers continue to smoke during their pregnancies — 12% of all women who give birth.

Inflammatory Bowel Diseases

Crohn’s Disease and Ulcerative Colitis are the twin inflammatory bowel diseases — the first affects the small intestine, the second affects the large intestine. If any kind of disease has a strong microbial connection, it is inflammatory bowel disease. As I mentioned in this post, even animals with IBD present with the dysbiosis pattern found in humans.

What does this have to do with smoking? It’s well known in research circles and those afflicted with IBD that a strange paradox exists between smoking and these diseases. In Crohn’s sufferers, smoking exacerbates the disease. In Ulcerative Colitis sufferers, smoking ameliorates the disease.

The fact that smoking has such a profound effect on the course of two diseases with such a strong microbial connection — negative or positive — is further corroboration of the smoking/microbial link.

Cigarettes, Live Bacteria, Nicotine

Since the original post, I’ve gotten a few questions about how cigarettes may be inducing this effect, and what role nicotine plays in all of this. As I mentioned in that post, cigarette tobacco has been shown to contain gram-negative bacteria, and can introduce endotoxins directly into smokers. What I didn’t quite make clear is that cigarettes introduce live bacteria — and known human pathogens — into smokers:

The research team found 15 different classes of bacteria and a number of potentially pathogenic organisms. The most notorious organisms present were Acinetobacter, Bacillus, Burkholderia, Clostridium, Klebsiella, Pseudomonas aeruginosa, and Serratia. These bacteria were found in more than 90 percent of all cigarette samples tested. Also found in the samples were the pathogens Campylobacter, Enterococcus, Proteus, and Staphylococcus.

Apparently, it is the fermentation of tobacco leaves that creates extremely dense concentrations of bacteria. The bacteria, dead or alive, and the endotoxins they produce can lead to disease:

Even dead bacteria produce endotoxins that can activate cells that cause inflammation. He says there is some concern that the chemicals and bacteria might work together to speed up the malignancy of cancer cells.

This information would indicate that nicotine is not involved with the microbial effect. But more importantly, we also have evidence that nicotine is not involved in the broader smoking/heart disease correlation. Many like to explain smoking’s heart disease correlation by blaming nicotine’s inducement of abnormal heart rate (arrhythmia) and high blood pressure, which can lead to ischemia (insufficient blood flow to the heart). However:

— Heisenbug


13 thoughts on “The Microbial Effects of Smoking: More Evidence

  1. OK! I’ll stop smoking! It’s going to be hard, I have a 4 pack a day habit. I wonder why the health agencies responsible to get people to stop smoking never used any of this logic….too new I guess. Ever see those really long Indian peace pipes. I wonder if they cut down on the problems. I’ve read for a long time that nicotine and some other compounds in tobacco are anti-inflammatory. Have you looked into chewing tobacco? Wonder how this conveys to that and snuff, too. Tim Date: Thu, 30 Jan 2014 15:42:03 +0000 To:

    • Tim, you smoke?! If we get you to quit, it will be the greatest accomplishment of this blog. 🙂 Good point on chewing tobacco, I’ll have to look into that. I wonder how lighting up versus chewing affects things.

    • Really? Four packs!?! Get that book finished and make a new resolution. 🙂

      Four packs, huh? I just checked and, wow, AK ain’t a cheap state for smokes. Taxes are $2/pack and 10th highest in the union. Are you rollin’ your own? I knew a guy in college addicted to rolling them. Had the coolest little pull-lever machine for making them. It almost hooked me and I didn’t even smoke. 🙂

  2. My 2 year old niece had terrible colic as an infant, and neither parent was a smoker. Luckily their doctor put her on a probiotic – probably the Lactobacillus reuteri you mention – and it worked great. They were told later that if they had panicked and taken her to the ER (which some new parents would of course do with an infant that cried all night and was in such obvious distress) she would have been subjected to lots of tests and drugs when the answer was very simple.

    • Interesting. In the specific case of colic, I think the microbial/GI link is probably more important than the smoking link. Smoking is probably just one way to get there. Thank goodness your niece had good care.

  3. I have no doubt smoking is not good for your microbiome. Beware of associative studies they can be very misleading. I have three children who all had colic as babies and I am not a smoker. ( Also definition of colic is fairly vague.) I did at that stage eat too many grains and sugar and probably not enough good fat. The components of my own gut flora may not have been ideal at that point in time, but it had nothing to do with smoking. As a microbiologist however I am sure an “optimized” gut flora holds some of the keys to good health.

    • Hi DT. As I mentioned in another comment, I do think that the gut connection is probably more important than the smoking one. Smoking may be just one way to get there. Or there could be other factors entirely. And I agree, colic does seem to be a pretty loosely defined thing.

  4. Hi. I was chewing 2mg nicotine gum for 3 or 4 years, like 12 gums a day. Around the start of this times my longstanding IBS problem worsened and I became diagnosed with SIBO, which is now thought by a lot of gastroenterologists to cause IBS. If you doubt the link, all you have to do is look at my stool before antibiotics (loose, diarrhea, floats, etc) and after (normal as can be). Plus, my IBS disappears after treatment. Anyways, I kicked the nicotine and I feel a lot better. I don’t think it’s so much smoking but more the nicotine’s effect in our bloodstream. It takes a toll somehow and it’s too bad there’s not much research here. I kept going to the docs and they said chew away, it has no effect other than what you’d typically expect from too much nicotine at times (nausea, diarrhea).

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