The microbiome of alcoholics may contribute to pathologies

We have written before about the microbiome’s association with alcoholism, and how it has been implicated in many of the maladies connected with the disease.  Recently, research out of George Mason University, published in PLoS ONE, explored the molecular mechanisms behind this relationship.   The scientists measured the metabolites that were formed by the microbiome of alcoholics and compared it to healthy controls.  They discovered that the metabolites that differed between the two groups have important implications on gut health.

The scientists measured the volatile molecules that were being effused from the feces of 18 healthy controls and 16 alcoholics.  The alcoholics’ feces contained high levels of an organic compound called tetradecane, which is known to cause oxidative stresses.  Increased oxidative stress in the gut, especially in alcoholics, is associated with increased gut permeability (i.e. leaky gut), and alcoholic steatohepatitis (i.e. a type of liver disease).  Moreover, specific fatty acids, which are known to reduce oxidative stress (antioxidants), were more depleted in alcoholics when compared with healthy controls.  In addition, the alcoholic feces consisted of lower abundances of short chained fatty acids (SCFAs), which are nearly always associated with intestinal health (click the SCFA tag below to learn more).  Finally, other molecules which are associated with health, like caryophyllene and camphene, were decreased in the guts of alcoholics.

Overall these results show the possible mechanisms by which the microbiome contributes to alcoholism.  Specifically, it appears that the alcoholic microbiome may create oxidative stress molecules, which contribute to gut toxicity.  In addition, the scientists suggest this work could be used as an alcoholism diagnostic, as the characteristic metabolites between the groups were statistically significant.

Reflecting on the microbiome during National Breast Cancer Awareness Month

As you watched the future Hall of Fame quarterback Eli Manning over the past two weeks, you probably noticed NFL players wearing pink for National Breast Cancer Awareness Month. Before this month comes to a close we want to bring your attention to one of our previous posts about the microbiome and breast cancer.  The study showed that post-menopausal women who had a more diverse gut microbiome had a lower risk of getting breast cancer. You can read more about it here.  

We also want to take this time to encourage natural breast feeding, whenever possible, for all new mothers.  A new review article published in Nature Pediatric Research describes the importance of breast milk in creating a healthy infant microbiome.  Breast milk is a complex food that contains bacteria and also supports the growth of bacteria.  The review highlights that when compared to formula, breast feeding leads to more infant gut colonization of Bifidobacterium, Lactobacillus, and Clostridia, and these bacterial strains are linked to the development of a healthy gut and a healthy immune system.  In addition, breast milk leads to a lower infant gut pH, compared to formula, and infant gut pH affects further species colonization.  Breast milk has evolved to support both us and our microbiomes, and no simple formula can substitute for the real thing.  

Every week there are new studies connecting the microbiome to public health and disease areas that may not seem as obvious as others. We know that the microbiome influences diseases and conditions like obesity, inflammatory bowel disease (IBD), diabetes, and necrotizing enterocolitis (NEC), but we are now learning that the microbiome is also connected to diseases and conditions like breast cancer, alcoholism, autism, and depression. While it is important to keep our excitement about the microbiome in check, the AMI is building new resources for the microbiome field because we believe our impact can be vast.  Advancing the field of research as a whole can influence the development of new treatments and therapies for a wide range of diseases. 

Alcoholism and the microbiome

An article was recently published in PNAS that investigated the relationship between alcohol dependence and the microbiome.  The authors had previously shown that alcohol-dependent people are at higher risk for a 'leaky gut', in which some molecules, such as bacterial metabolites, are passing through the GI tract into the bloodstream.  Leaky guts cause an inflammatory response that leads to further health issues.  In their new study, the authors investigated whether alcohol craving, and depression are associated with the gut microbiome, and suggest the possibility of targeting the microbiome as a therapeutic modality during alcoholism recovery.

The authors studied 60 alcohol dependent subjects who recently stopped drinking and measured their microbiome, leakiness of gut, and mood.  They immediately discovered that the leakiness of the gut was associated with alcohol craving during withdrawal.  The more leaky the gut, the more the subject craved alcohol, whereas patients with less leaky guts had less psychological addictions.

The authors also discovered that leakier guts were associated with microbiome dysbiosis, which included many bacteria associated with inflammatory bowel disease (IBD).  Other studies have shown that similar dysbioses are associated with leaky guts in IBD patients, and in recovering alcoholics the dysbiosis can last long after cessation of drinking.  

This study suggests that potential treatments for recovering alcoholics could include targeting the microbiome to bring it back to a more 'normal' state.  This normal state will decrease the permeability of the gut (make it less leaky), and thus decrease the psychological addiction to alcohol.