In school biology classes you probably learned that your appendix is vestigial – i.e., a structure that has remained through evolution but has no function.  Now we know different, and this weekend, I’ve been grateful I have mine. 

Microbiota safe-house

I just returned home from visiting family in the UK and came back with either food poisoning or a stomach bug.  Not necessary to go into all the details, only to say that I was thoroughly cleaned out.

I take good care of my microbiota (micro-organisms in my gut) and have a good healthy microbiota with excellent diversity. While others believe “you are what you eat” I believe in the importance of “you are who you host.” Our microbiota affects so much of our body, so I nourish it carefully. 

So as I’m going through this “purging,” I was concerned for my micro-organisms.  But thankfully, I still have my appendix.

You see that early thinking that the appendix doesn’t have a function, turns out to be wrong.  The appendix appears, in fact, to be a safe-house for our gut microbiota.   Beneficial bacteria that are stored in your appendix can ride out a bout of sickness and diarrhea that completely evacuates the intestines.  These good bacteria can then repopulate the gut again before the bad guys get in and take over. So I’m keeping my fingers crossed that my appendix was doing its job. 

Let’s back up a bit and see how this happens. 

What is the appendix?

The appendix is said to be vermiform, i.e., worm-like!  It is a 5-10cm long and 0.5-1cm wide pouch located near the junction between the small and large intestine. But it has a relatively narrow opening so feces traveling from the small to large intestine tend to bypass the appendix, as you can imagine when you look at the figure in the header image.  The flow just keeps on going, avoiding the little ‘worm.’ Thus it is part of the system, but also somewhat separated.  Perfect for a safe-house!

Microbiota as a biofilm

The appendix is comprised of lymphoid tissue which has immune function. These immune cells seem to support the formation of biofilms in the gut. Biofilms are collections of gut microorganisms bound with mucin and secretory IgA (a type of antibody). As this forms a type of film (think ‘slime’), it is more resistant to destruction than isolated organisms so enhances survival.

Biofilms are found lots of different places – like dental plaque or the slime you see on ponds.  Yes, slime is a good thing!

So think of this layer of good slime throughout our guts, including the appendix.  It isn’t static; rather it continues to shed and regenerate. Thus the biofilms that are found in the appendix can shed into the large intestine to repopulate the large bowel with commensal organisms in the event that it becomes infected or flushed out as a defensive response. 

Do only humans have an appendix?

Very few species have appendices. Those known to include rabbits, and the two marsupials opossums, and wombats. A curious grouping, don’t you think? 

Is the appendix only useful after an infection?

While, in my situation, my microbiota was purged due to sickness and diarrhea, the appendix may also be involved in restoring your microbiota after antibiotic use too. Similarly, after surgery of the colon or a colonoscopy, shedding of that appendix biofilms becomes important to restoring your gut microbiota.

What if I’ve had my appendix removed?

If you have had your appendix removed it may mean you need to work harder to replenish your microbiota after stomach bugs, antibiotics, etc., as you have lost this safety backup. 

The first step is to ingest foods that provide fiber in the form of prebiotics –  i.e., that nourish our microbiota. This can be from plants and grains.  Good examples include garlic, onions, leeks, asparagus, oats, and bananas.  

Add to that some fermented foods like yogurt, preferably the unsweetened kind.  Or kefir or kombucha or pickled vegetables. Make sure they contain “live” bacteria.

Supplementation with prebiotics (e.g., inulin, or fructo-or galacto-oligosaccharides) and probiotics can also help.

While this approach is particularly important if you have had your appendix removed it should also be something we consider even if we still have our appendix, just to keep things functioning well. 

What am I doing?

Me and my happy appendix?  We are eating plant-based, easy to digest foods in small amounts as I still feel a little nauseous.  This includes stewed apple and pears, my AHA breakfast with sheep yogurt, flax, and good quality protein sources.  Adding to that, I have a pre- and probiotic. Hopefully, all those little bugs will be happy and thriving again soon. 

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