Prebiotics Vs Probiotics - The Importance of Fibre for Healthy Gut Bacteria

With the ever increasing focus on probiotic supplementation in today’s society, I wanted to discuss what is it that helps us maintain healthy gut flora naturally. Supplementation can sometimes feel like the easy way out, but it is not always the best solution. So how do we keep the good bacteria in and the bad ones out? The answer is Fibre. Fibre is a natural prebiotic that good bacteria feed on, which means that it helps us create and keep the beneficial bacteria in the gut.

Let’s go into a little more detail, The total surface area of our gut is about 3,000 square feet, counting all the little folds, larger than a tennis court. Yet, only a single layer of cells separates our inner core from the outer chaos. The primary fuel that keeps this critical cell layer alive is a short chain fatty acid called butyrate, which our good bacteria make from the fibre we eat. We feed the good bacteria in our gut, and they feed us right back. They take the prebiotics we eat, like fibre, and in return provide the vital fuel source that feeds the cells that line our colon, a prototypical example of the symbiosis between us and our gut flora.

Butyrate is a critical component of maintaining a healthy gut as it suppresses the inflammatory reaction and tells our body's defence system to stand down. So, butyrate may behave as a microbial signal to inform our defence system that the relative levels of good bacteria are within the desired range.

So, we evolved to have butyrate allow our defence system to know the type of bacteria in the gut. So, should our good bacteria ever get wiped out and bad bacteria take over, our defence system would be able to sense this and go on a rampage and destroy the invaders, and continue rampaging until there were only good bacteria creating butyrate to put the defence system back to sleep.

Here’s why this all matters. What if we don’t eat enough fibre? If we don’t eat enough fibre, then we can’t make enough butyrate. We could have lots of good bacteria, but if we don’t feed them fibre, they can’t make butyrate. Sensing such low levels of butyrate, our body thinks our gut must be filled with bad bacteria and reacts accordingly. Our body can mistake low fibre intake for having a population of bad bacteria in our gut. Our body doesn’t know about processed food; it evolved over millions of years getting massive fibre intake. Even during the Palaeolithic period, 100 grams of fibre a day. So, on fibre-deficient Western diets, when our body detects low butyrate levels in the gut, it doesn’t think low fibre. As far as our body’s concerned, there’s no such thing as low fibre. It thinks: bad bacteria. For millions of years, low butyrate has meant bad bacteria; so, that’s the signal for our body to go on the inflammatory offensive.

So, that’s one reason why fibre can be so anti-inflammatory, one of the reasons fibre intake is critical for optimal health. Not fibre supplements, but whole plant foods. Fibre supplementation with something like Metamucil may not replicate the results seen with a diet naturally high in fibre.

This is one of the major reasons there are so many people having IBS and IBD (such as Ulcerative Colitis & Crohns Disease) type issues in modern society. The absence of fibre in our diet has meant that the body can create a significant inflammatory response.

We are currently trying to solve this problem by taking probiotics, but these are just a band-aid solution to the real issue of not getting enough prebiotics from the fibre we eat.


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