FUT2's ROLE IN GUT HEALTH

Ever heard of FUT2?  Most people haven’t.  If you know my work, you know I’m passionate about gut health, and it turns out FUT2 matters for gut health.

FUT2 stands for Fucosyltransferase 2, which is an enzyme that regulates the expression of your blood type antigens on the surfaces of epithelial cells and body fluids.  If you’ve ever donated blood, then you likely know if you are type A, B, AB or O, or maybe you remember studying blood typing in high school biology class. About 80% of people secrete their blood type antigens into their body fluids and others don’t.  If you do, then you fall into the category of a secretor, and if you don’t you are a non-secretor.  If you don’t have a functioning FUT2 genotype then you are a non-secretor.   

 What does all of this have to do with the gut?  There are 2 ways that I’ve found that FUT2 impacts our guts.

Microbiome Impact

When I first heard about secretory status, it was in relationship to blood typing, and some of the health implications associated with being a non-secretor.  I was intrigued, but completely overwhelmed (maybe you’re feeling like that right now).  The only thing I remembered was that non-secretors were more likely to have autoimmune conditions.

I’m going to digress a bit, but here’s how my brain tends to work.  I sometimes wake up at night, maybe because I’m too hot or I have to pee.  After adjusting the blankets or going to the bathroom I’ll be lying in bed, and this is often when I have an ah-ha! moment.  So I’m lying in bed, and my thought train goes something like this:  FUT2 is correlated to autoimmunity - autoimmunity has leaky gut and dysbiosis as a contributing factor – what’s the connection between FUT2 and gut health?  

It turns out that FUT2 genotypes plays a role in microbiome composition with non-secretors having an altered intestinal microbiome compared to secretors(Source). Specifically they have a higher incidence of bacterial species that are associated with IBD (inflammatory bowel disease) and IBS (irritable bowel syndrome)  (Source).  Secretors in contrast, have higher levels of bifidobacteria.  According to Dr D’Adamo non-secretors are also more likely to have Candida infections (Source).

It turns out that having those blood type antigens in your gut mucosa provides a food source to colonizing organisms.  The organisms in your gut get a meal by cleaving off a carbohydrate that’s part of the antigen.  So if you are a non-secretor you got the short end of the stick when it comes to colonizing your gut, and when it comes to health conditions associated with the gut.

Here’s a quote from one research paper that sums things up nicely,

“the FUT2 genotype explains substantial differences in community composition, diversity, and structure, and we identified several bacterial species displaying disease-by-genotype associations. These findings indicate that alterations in resident microbial communities may in part explain the variety of host susceptibilities surrounding nonsecretor status and that FUT2 is an important genetic factor influencing host–microbial diversity.
(Source)

Methylation

When I next started looking into FUT2, I was looking at its role in methylation.  Methylation is a metabolic process that happens in our bodies 1 billion times per second.  Anything that happens that often has to be important.  Methylation is involved in cell regeneration, so if your methylation is impaired your body will have problems in areas where there is high cell regeneration.  As it turns out, your small intestine is one of the areas where there is high cell regeneration, so if you have impaired methylation then you are more likely to suffer from leaky gut (known as intestinal permeability in the medical community).  Due to the methylation problems, your cells can’t regenerate quickly enough to have a strong intestinal barrier.  Imagine a castle wall that is constantly under attack, and there aren’t enough workers to keep rebuilding it.  Your small intestine has a wall made of cells, but these are constantly being sloughed off.  Without good methylation it can’t continually be rebuilt.

One of the vitamins needed for good methylation is B12.  It turns out that the FUT2 enzyme has a role in how well B12 can be absorbed and utilized, so it’s possible that even if you are consuming a lot of B12 in food and supplements, you won’t be able to bring it into your body.  Low B12 levels mean methylation is impaired, which in turn means you are more likely to have leaky gut.

So, why am I even bringing up this gene?  Sometimes I have clients coming to me and wanting to get genetic testing done to see if they have the MTHFR gene.  This is another gene that has an effect on methylation and it has gotten a lot of media attention, so many people know about it.  The reality is that looking at how genes affect your health is complicated, and you can’t just look at MTHFR.  I had looked at a variety of methylation markers for my youngest son, and it wasn’t until I looked at FUT2 that I understood that he had impaired methylation.

If you have been doing everything you can to restore the health of your gut, and you aren’t seeing the results you want, then understanding your FUT2 genotype can provide you with one of the puzzle pieces that fit into your overall health puzzle. 

To find out your secretory status you can get genetic testing done through 23andme.  Once you have your raw data, look up FUT2 rs601338.  If you have the A/A allele, then you are a non-secretor.  To find out about your B12 levels, look up FUT2 rs606662.  The G/G allele indicates low enzyme function and low B12 plasma levels.

NOTE:  as I write this, Canada does not have any laws to protect individuals against insurance companies requesting genetic testing results.  Bill S-201 (the Genetic Non-discrimination Act) is currently before Senate.  Some people are intentionally NOT getting genetic testing done, because they don’t want to risk discrimination, or risk high insurance costs.  The decision is yours, but I want you to be informed.  Hopefully by the time you read this, Bill S-201 will have been passed.