Your gut is connected to your brain, and here's an example why
There's a lot of talk about MTHFR and COMT gene these days, but another gene that is getting alot of attention is the FUT2 gene. This is another gene that proves the connection between your gut and your brain health, as the different phenotypes for this gene will determine the type of gut microbiota that you will have. As many of us are starting to be aware of the importance of our gut health, more and more studies are trying to demonstrate how it impacts our health longevity.
Let me start off first by letting you know that there is no "good" or "bad" phenotype, much like there are no "good" or "bad" exercises, having a certain type of gene only allows you to understand whether your life style choices suits your body (the same way as certain type of exercises may or may not suit your life style choices). The reason these genes, including MTHFT, COMT, and FUT2, are getting more attention than any other genes (even though they are all important), is because of the array of affects it has on our bodily system. FUT2 gene is just ONE example of how the gut can affect our health.
To understand what FUT2 gene does, I'll need to talk about blood type first. So we all know that the general population are designated with ABO blood group, which really doesn't mean much other than in the world of blood transfusion, and some sort of self identity. In a more sophisticated way of looking at blood types, it basically tells us the type of antigens (antibody generators) we have in our system. Antigen is a very confusing way of describing the type of sugars and protein that are present in our cells. All ABO blood group requires an H antigen, you can think of this H antigen as the pre-requisite of having ANY blood type, this H antigen is made up of fucose and galactose (which are different types of sugars). For people with type O blood, they possess the H antigen, which is the precursor form of A and B antigen, but do not possess A or B antigens. As you can imagine, type A and type B will then possess antigen A or antigen B, respectively. Those who do not possess the H antigen, will not have any designated blood type and are called Bombay blood type, which means they cannot receive blood from any of the ABO blood type groups, and can only receive blood from other Bombay blood type.
The most important thing to take away from blood groups, is that they are basically made up of different antigen aka, different types of sugar, and our genes is what determines what kind of sugar we will possess in our red blood cells (FUT1 gene). So what does FUT2 gene do? Much like our red blood cells, many other parts of our body also "express" our blood type, meaning that our unique ability of our cells to bind to different types of sugar is also present in many other parts of the cells in our body. Next to our blood, our digestive system (especially the small intestine), our thyroid gland, adrenal gland, reproductive system (especially the ovaries), kidneys, pancreas and lungs shows expression of these antigens in order from highest to lowest. FUT2 gene is what determines the presence of H antigen (again, the same type of sugar seen that make up the H antigen in blood groups) in the cells that lines the small intestine and bodily fluids. Depending on whether they have the presence of H antigen in the cells of small intestine and bodily fluids, they will be called either "secretors" or "non-secretors". If they have an active FUT2 gene, they will be able to make the enzyme necessary to produce H antigen and hence will be present in the cells of the small intestine and bodily fluids, hence, "secretors" (because...they secret cells that possess H antigen). If they have a relatively low activity or no activity in FUT2 gene, they will NOT be able to demonstrate H antigen in the cell present in small intestine and bodily fluid, hence, "non-secretors". Let me explain FUT2 genes relevance in 2 different ways:
1. People with an active FUT2
2. People with an inactive FUT2
People with an active FUT2:
These are the people who are called secretors, they have H antigen in the cells lining the small intestine and bodily fluids. If you recall what I typed above, H antigen is a complex of sugar made up of fucose and galactose. Now fucose, also happens to be a very important sugar/food source for a particular type of bacteria in our gut called bifidobacteria. These are the "good bacteria" in our gut that will readily "bind" or feed on these fucose, and because food makes everyone happy, including our bacteria, they are readily able to fend off other bugs by occupying all the space in our gut, so these foreign pathogens will simply get excreted out. As most of us know, a healthy gut is important for our immune system, and this is one of the reasons. Having an active FUT2 gives these individuals a better ability to create a stable symbiotic microbiota that can readily defend against other bacteria that can compromise our health.
Now, other than maintaining a good gut health because of the presence of these bifidobacteria, what's cool about these bacteria is their ability to produce important AA such as tyrosine, tryptophan, and phenolalanine, which are precursors of important neurotransmitters that we all know of - serotonin, and catecholamine (dopamine, norepinephrine, epinephrine). These neurotransmitters has a direct connection to your sense of well being. Most of you may know catecholamines in the context of the "fight or fight" response, it is the endogenous "drug" that allows us to feel excited and focused; and dopamine is directly involved in our sense of happiness and fulfillment. The synthesis of these amino acids (tyrosine) is also crucial for the uptake by other neighbouring bacteria in the gut to use as a substrate to synthesize other important neuroprotective antioxidants such as IPA. Antioxidants are important in eliminating toxins (reactive oxygen species), in this case, in the brain, hence the presence of good bacteria can directly relate to how well your brain is capable of maintaining a toxin free environment, and hence provide more cognitive clarity. Having high levels of serotonin and catecholamine of course has its pros and cons, but typically under a healthy life style, this sets up extreme success for mental well being, high pain tolerance, cognitive focus, etc. Now I'm a huge believer of evolutionary trade offs, and genetic phenotype also follows this rule. It just so happens that bacteria like H. Pylori, and Norovirus loves fucose. So these individuals may be more susceptible to these type of infections.
People with an inactive FUT2:
As you can imagine, people with an inactive FUT2 gene will be presented with opposite conditions as mentioned above. Because these individuals do not readily produce fucose, they are more susceptible to losing these good bacteria in our gut. Individuals with this variant should then put more diligence in maintaining a good healthy microbiota in their gut by maybe supplementing themselves with probiotics, but also avoid food that are susceptible to bacteria (such as raw food..) and food that can further resist our intestinal cells ability to synthesize these amino acids such as GMO food (they have active chemicals in them that can block the ability of our good bacteria to synthesize tyrosine, tryptophan and phenolalanine). These individuals are also more susceptible to having lower levels of lysine which are crucial in the synthesis of carnitine (which is important in fat utilization and hence is a way to indicate your mitochondiral efficiency). Just like people with active FUT2 having a trade off, individuals with an inactive FUT2 shows a better ability to absorb vitamin B12 in our gut (for reasons thats beyond what I understand), which directly impacts our ability to recycle homocysteine (many see this as a toxin to the body, I see it more as a POSSIBLE biomarker for issues to happen..) back into an important amino acid called methionine (which is crucial in facilitating all other processes in our body including activating certain proteins, synthesis of enzymes etc.).
So how do these information help me as a movement specialist? For those of you who have taken my course, I stress on 3 core values:
1. Understanding physiological health of a client
2. Understanding the participation risk that the client is par-taking
3. Trying your best to understand their decision modifiers (their social values, personal values, and their mental health)
Understanding a person's genetic make up allows me to touch on #1 and #3 in more details. For example, it is absolutely critical for someone with osetoarthritis in the knee to lose weight, if they have an inactive FUT2, it indicates that their ability to synthesize lysine is compromised and hence the ability to synthesize carnitine and hence, their metabolic health. Before even providing any sort of exercise regimine, its more important to provide nutritional advice to hopefully change their microbiota in the gut, and up their carnitine levels (preferably in the form of alpha-L-carnitine) so that when training in zone 1 (between 50% - 60% of maximum heart rate) their mitochondria can effectively burn fat. Another example is if someone had just gone through an ACL injury and cannot perform the necessary activities to keep up what he/she sane, there is more reason for me to provide nutritional advice to hopefully shift their microbiota into a more stabilized environment, so they have the ability to synthesize tyrosine, trytophan and phenolalanine from their bacterium and help with their confidence, pain tolerance, and mental wellbeing.
If you are like me who are obsessed with trying to optimize your health and movement capacity, understanding your genetic make up is crucial in making the necessary changes to facilitate that goal.
As usual, this is just my 2cent. This is absolutely NOT a means to provide you with a medical diagnosis, but only a means to provide better advice on exercise regimine and nutritional intake.