Exploring the connection between the microbiome and disease development
Part II – The microbiome and disease development
Last week we spoke about what makes up our microbiome, gut health and probiotics (if you missed it, click here to read it!). This week we will discuss 3 hot areas where the microbiome and disease development are being studied. As I mentioned in our last post, I am FASCINATED by the microbiome. I could dedicate a blog just to it! If you are interested in learning more about it, the human microbiome website from the University of Utah is an amazing resource.
Before talking about the role of the microbiome in particular disease processes, I want to talk about a term called microbial dysbiosis. This is at the root of many of the problems we have with the gut microbiome.
As we mentioned last week, we have friendly bacteria and not so friendly bacteria in our microbiome. The good guys keep the bad ones in check and balance. Microbial dysbiosis results from disruption of this balance.
With this, the usually abundant microorganisms become underrepresented. This leads to inflammation and, therefore, the link between the microbiome and disease development. Through a process called 16S rRNA sequencing (basically genetic mapping of the microorganisms) we know which bacteria are prevalent during health and illness. Although the microbiota varies between individuals, studies show at least half of the general population shares almost 40% of the microbial genes present in each individual. This led to the theory that there is a core microbiome in humans.
Ok, now that we know about microbial dysbiosis, let’s talk about some conditions and their relationship with the gut microbiome.
The microbiome, obesity and diabetes:
This one is a hot topic just because of the increased incidence of diabetes and obesity we are seeing world-wide. Scientists and clinicians have been hard at work studying the microbiome and any impact on the development of diabetes and obesity.
Data from rats has shown some really interesting information. Genetically diabetic prone rats have a higher incidence of developing diabetes if they have a less diverse microbiome. Furthermore, the transfer of a single species of bacteria from diabetes-resistant animals has been shown to protect their diabetes-prone counterparts.
Whaaaatttt? I don’t know if I’m the only nerd getting excited about this! Mind-blowing, IMHO!
Specific bacterial species also seem to play a role in the development of obesity as well. For example, several studies showed that administration of probiotics with Bifidobacterium species could decrease body weight gain and adipose (fat) tissue in high-fat diet obese rats.
When they looked at humans, various studies report greater microbial diversity among healthy people compared with those that had type 1 diabetes. Another human study, noticed that the composition of our gut-flora changes in obesity.
Obese individuals’ microbiome is more efficient at gathering energy from the diet. They took some stool (and therefore gut microbiome) from lean men and transplanted it into obese males with diabetes. I know this sounds gross, but actually fecal transplant is all the rage for several medical issues. Regardless, the results are really cool. They noticed that the recipients had an increase in microbial diversity AND with this, improved insulin sensitivity (meaning their insulin works better)!
Another interesting fact: Metformin, which is a drug used for glucose control in type II diabetics, seems to modify the gut microbiome and may have some antibiotic properties.
It appears there is a definitive link between obesity, diabetes and the microbiome. So, here we have our first area showing the microbiome and disease development link.
The microbiome and the brain
Let’s move on and explore the connection between the brain and microbiome.
We discussed in our last post the embryological connection between the development of our enteric nervous system and our central nervous system. We inherently know our bowel is very much in tune with our emotions. If we are anxious or nervous, our gastrointestinal tract will often times respond with stomach discomfort or diarrhea. Scientists refer to this connection as the gut-brain axis.
It seems the depth of this connection is greater than we ever imagined. We are now beginning to understand the role of the microbiome in our mood and even in the development of neuropsychiatric disorders. From a neurologic standpoint, there is also a connection between the microbiome and disease development. Studies suggests that the microbiome may play a role in the development of disorders such as Alzheimer’s, Parkinson’s, autism and depression.
If we look at animal studies, scientists took germ-free mice and compared them with their normal germ-flora counterparts and noticed some interesting features. The germ-free mice have impaired social behavior, exaggerated stress response and increased anxiety. In addition, these guys had some structural and functional changes in certain areas of their brains.
Even more interesting, when they did fecal transplantation from the normal-flora mice to the germ-free mice, they noticed that their behavioral symptoms improved. Furthermore, different probiotic preparations administered to rats and mice showed reduction in behaviors consistent with anxiety and depression! I mean, WOW!
Our brain communicates with our body and with other parts of the nervous system via chemical messengers called neurotransmitters. It turns out we aren’t the only ones who produce neurotransmitters, our ever-more amazing microbiome does as well! It is also bacteria specific.
For example, one of our neurotransmitters called gamma-aminobutyric acid (GABA) is an important inhibitory neurotransmitter that reduces feelings of anxiety and fear. Studies show that Lactobacillus and Bifidobacterium species in our gut microbiome produce this neurotransmitter. Other species produce key neurotransmitters as well, such as serotonin (we usually find low levels of serotonin with depression) and dopamine (important for movement and key in the development of Parkinson’s disease).
Although we need more research in terms of the effects of these neurotransmitters produced by our microbiome, it is easy to make the connection between behavior, illness and microbial disbyosis. A second area where we can see that link between the microbiome and disease developmnet.
Brain findings summary
Let me close this section be pointing out some of the links between neurologic/psychiatric conditions and our microbiome:
Autism: abundance in Bacteroidetes species in the gut microbiome is linked to severe autism.
Depression: lower numbers of Bifidobacterium and Lactobacillus have been found in patients with depression. A probiotic combination with two particular strains of the above-mentioned species has been shown to increase a person’s resilience to stress.
Parkinson’s disease: Parkinson’s patients have reduced numbers of Prevotellaceae species. Also, the higher the levels of Enterobacteriaceae species in the gut, the more instability and difficulty walking seen in patients.
Alzheimer’s disease: amyloid plaques are seen in the brains of patients with this condition and mice models suggest that the gut microbiome is involved in the accumulation of plaques.
The microbiome and cancer
For our last topic, I would like to discuss the role of the gut microbiome and the development of cancer. A third area studying the link between the microbiome and disease development. This has been studied for several years, particularly when it comes to colon cancer.
Microbiome Consortium Update
There was actually a cancer microbiome consortium held in London last September and a lot of interesting information was shared. Among the highlights, they discussed the role of the gut microbiome in colon cancer and urologic cancer. They also discussed the role of the respiratory system microbiome in the development of lung cancer.
In addition, there was much discussion on the metabolic byproducts that bacteria produce during metabolism. Some of them, such as the short chain fatty acid called butyrate, has anti-inflammatory and anti-cancer properties. While others, such as hydrogen sulphide, are pro-inflammatory and toxic. Interestingly, low fiber intake (as is typical in our western diet), leads to decrease production of butyrate. High animal protein and fat intake results in the increased production of toxic nitrogenous waste and sulphur metabolites.
Finally, they talked about future therapies involving our microbiome to treat different types of cancer.
Studies looking specifically at colon cancer show that there seems to be an abundance of particular types of bacteria (for example, Fusobacterium nucleatum, Bacteroides fragilis, Escherichia coli) in patients with the disease. However, others species, like Faecalibacterium prausnitziivseem, seem to be protective against colon cancer. This has brought up the potential of using our gut microbiome in colon cancer screening!
As mentioned previously, it is not just the gut microbiome that may have a role in cancer development. Just like our respiratory microbiome, the vaginal/cervical microbiome has been implicated in the development of cervical cancer.
Certainly, much work remains in this area to further evaluate the role of the microbiome in cancerogenesis (“cancer birth”). We already know that the development of cancer is multifactorial. Genes, lifestyle and environment all contribute to its development. It will be exciting to see what novel therapies and prevention ideas result from further understanding of the microbiome.
Putting it all together
This was so much information! Now we know about some of the links between the microbiome and disease development. What do you do with all of it? How does this help in your daily life?
Well, here is the usual no brainer: eat a diet rich in probiotics (discussed in our previous post) and fiber, while minimizing animal fat and protein. Also, consider taking a daily probiotic. As you saw, different species have different health effects, but Lactobacillus and Bifidobacterium are two of the most studied species. So, consider taking a probiotic that has these strains.
These are simple steps we can take to optimize our gut microbiome and easy enough to incorporate into our busy lives. Although there are no guarantees that this will help prevent microbiome and disease development issues, based on the research it may be worth a try.
There are TONS of probiotic supplement brands out there. Make sure capsules are pH resistant, otherwise your stomach acid may destroy the bacteria before they can get to your bowel and you lose benefit. Also, many need to be refrigerated to keep the cultures alive, so make sure you look at that. I have used several brands, but I always keep coming back to this one. Feel free to comment below if you have a favorite brand!
What’s in the pipeline?
There is a lot more information out there that I didn’t even get to cover in terms of prebiotics, initial colonization with our microbiome, the effect of fasting on our microbiome and the effects of antibiotics on our gut flora! There is much more than just the role of the microbiome and disease development. I may come back and discuss these further along the year.
Speaking of plans for the year, I am super excited about the posts planned for this year! We will discuss acupuncture, hormones, yoga and functional exercises to name a few! So keep checking back, or better yet subscribe below AND get a free gift, our e-booklet “The easiest thing you can do for better health.”
Have a healthy, amazing week!