Smoking Seriously Harms You – And Your Microbiome

Studies on smoking and the impact on the microbiome are rare, but pretty explicit. To put it in a nutshell: guess what, smoking is not good for you. You can read the various impacts of smoking on the warnings printed on the cigarette boxes: smoking kills. Smoking causes lung cancer. Smoking damages your gums and teeth. And so on. Interestingly, most of these consequences are caused by the influence of smoking on your microbiome. So, let’s have a closer look.

Let’s start off with a meta-study by Ziv Savin et al., a group of Israeli scientists from Tel Aviv and Tel-Hashomer. A meta-study is a summary of previously released studies under defined criteria, in that particular case all studies on smoking and the gut microbiome between 2000 and 2016. Smoking increases proteobacteria and Bacteroidetes phyla, along with Clostridium and Prevotella. At the same time, a reduction of Actinobacteria, Fimicutes, Bifidobacteria and Lactococcus, was observed. Smokers show an increased amount in anaerobic bacteria, possibly due to the immunosuppressive properties of tobacco.

Double risk for smokers with gut issues

All in all, the diversity of a smoker’s microbiome is reduced in comparison to former or non-smokers. The consequence is a weaker immune system and therefore a higher vulnerability to diseases. Oxidative stress and an imbalance in the acid-base-relationship were also examined. The composition of a smoker’s microbiome resembles the one of patients suffering from obesity and inflammatory bowel diseases such as the Crohn’s Disease. As one of the main reasons, scientists identify the reduction of the anti-inflammatory response caused by reduced amounts of Lactobacillus. This should be taken as a warning to all patients with the above-named diseases. Smoking additionally harms the impaired gut (even if probably no-one ever thought that smoking is good for anything). The good news is: if you give up smoking, your microbiome will re-gain in diversity and the shifts in components of the microbiome is normalising. It is never to late to give up smoking, also and even more so for diseased smokers.

Smoking and the oral microbiome

The further ISME journal articles (Wu et al. 2016 and Ganesan et al. 2017) shed some light on the oral microbiome and how it is altered with smokers. Wu et al. name similar shifts in the oral microbiome to the findings of the previously mentioned Savin et al. study. However, the shifts occur in partially contrary directions. Smokers show an increased amount of Actinobacteria, as well as a reduction in Prevotella (just the other way around in the gut microbiome). An additional reduction in beta- and gamma-proteobacteria is observed. On the contrary, Bifidobacterium as well as Streptococcus are significantly increased in comparison to non-smokers. The authors see cases of head and neck cancer and also of pancreatic cancer as the clear consequence of this de-regulation. But, again, also these scientists plead for the consoling solution that giving up smoking can restore the microbiome to the level of non-smokers and that even the number of cigarettes per day shows an impact in the concentrations of the examined components of the microbiome.

Two risks, multiplied danger

An accordingly disastrous impact of smoking is proven by Ganesan et al. Smoking alters the subgingival microbiome in a way that is promoting periodontitis. The elevated blood sugar level (hyperglycemia) that smokers apparently show, is similar to that of diabetics. And here, the article points out a fact that was also mentioned above with smokers and gut issues: Patients suffering from hyperglycemia or related diseases or even predisposition, should not fall back on the convenient conclusion that it does not make any difference anyway if they do or don’t smoke. Not only do the risk factors add up, they mutually multiply. Giving up smoking is always a reasonable change for the better.