How to support our gut microbiome with optimal dietary fibre?

POSTED BY sian | Aug, 24, 2019 |

The fuss over fibre

Box.1. Fibre-Rich Foods:
Nuts and seeds
Whole-grain breads, wholegrain cereals & pastas,  oats, barley and rye
Most fruits such as berries, oranges, melon
Peas, beans and pulses
Vegetables such as carrots, sweetcorn, broccoli & potatoes with their skins left on.

We’ve all heard by now that fibre is good for a healthy gut, but do we really understand the ins and outs of this?

Fibre is a plant-based carbohydrate (check out Box.1 for food sources of fibre). There are different types of fibre such as soluble and insoluble fibre. They each provide different benefits as they both work differently in our body. For instance, soluble fibre can dissolve in liquid whereas insoluble fibre cannot. For this reason, soluble fibre can work well in creating a feeling of fullness (aiding in weight loss) and slowing down fat absorption. Whereas insoluble fibre does not dissolve easily in liquid and can therefore be advantageous in adding bulk to stool as it speeds through the digestive process to exit our bodies.

Check out the British Dietetic Association Fibre poster for further information:

Fibre is different to other carbohydrates as it is not digested in the small intestine. Instead, it travels through our 30 foot (ish) digestive tract until it reaches the colon where our gut microbiota breaks it down.

The gut microbiota (also known as gut flora) is the name for the complex and dynamic microbe community living in our intestine.

There are trillions of microorganisms living there, consisting of different species and of different genes. Taking genetic and environmental factors into account, every one of us have our own individual and specific set of microorganisms. So in other words, our gut is the cosy home to a unique set of bugs.

Just like any community, the gut microbiota is no different in that it’s strengthened when there is diversity. A lower bacterial diversity is seen as a marker of dysbiosis (microbial imbalance) which has been linked to autoimmune diseases and obesity. The more ‘’good’’ bacteria, the better!

There is emerging research on the different effects that the gut microbiota has on our bodies. From meddling in with our mood swings to influencing a healthy gut. I’ll explain what I mean below.

The Gut-Brain Axis

It’s no surprise that every one of us have experienced feeling a certain type of way after eating something. Does feeling sluggish after a greasy take-out ring a bell? Or perhaps feeling angry, or ‘’hangry’’ when hungry. This is caused by an interaction between two systems in our body: the enteric nervous system (ENS) and the central nervous system (CNS). It is this idea which the gut-brain axis is based upon.

A quick biology lesson: The ENS is responsible for the gastrointestinal (GI) tract and is sometimes known as the ‘’little brain’’. This is because it is in charge of important things like motility, secretion and blood flow. On the other hand, the CNS is responsible for the brain and spinal cord, which is in charge of the coordination and communication side of things.

The ENS and the bacteria in our gut microbiome work in harmony together to carry out body functions, such as aiding digestion and producing neurotransmitters. Research suggests that a strain of bacteria called Lactobacillus brevis can produce one of the most abundant neurotransmitters called gamma-aminobutyric acid (GABA). Even the well-known serotonin (responsible for behaviour and body temperature) is regulated by our gut microbiome.

The bacteria in our gut may be more powerful than we think. It is therefore important that we care for our body in its totality, this includes our gut health and the bacteria residing within it.


Feasting on Fibre – Short Chain Fatty Acids (SCFAs)

Our gut microbiome also breaks down the fibre we eat and produces an important by-product called short-chain fatty acids (SCFAs). SCFAs are molecules which are produced by the colon when they ferment fibre. It’s these magnificent molecules which have been found to benefit human health.

As much as we need food, the bacterial community in our bodies need fibre to produce SCFAs. The deal is that the more fibre we eat, the more SCFAs the bacteria in our gut produces.

There are different SCFAs, including acetate, butyrate, and propionate. Scientists have found that these SCFAs work wonders for our body.

  1. Influence on gut health

SCFAs affect our GI tract as they can be absorbed and used as fuel in the colon. So in the very place they are created, they are utilised too. They also play a role in maintaining the protective mucus layer in our colon which in turn strengthens the gut barrier. As if that wasn’t enough, it has also been found that they can improve the transit of material through the large intestine. Impressive?

  1. Role in supporting the immune system

Research shows that SCFAs (butyrate in particular) have anti-inflammatory effects. They begin the peaceful process in differentiation of T helper cells (when a cell develops into a specialised cell). Remember, T helper cells are the most important cells during an immune response.



Changes to the gut microbiota can occur within days of changing diet; remarkable differences were found after African Americans and rural Africans switched diets for only two weeks – see reference below:

Could it be this simple? A combination of dietary and lifestyle factors tailored to each individual is needed to maintain a healthy gut. The current recommendation for fibre is 30g  per day for adults. On average, we are consuming around 18-20g, so there is room for improvement. Below are some ideas to kick-start your gut health journey from the comfort of your own home:

  1. As mentioned earlier a diverse gut microbiota is generally considered more healthy. This calls for a diverse diet! A diet inclusive of all the food groups is the goal.
  2. Go whole(grain)heartedly on your breakfast choice. A bowl of oats or bran flakes with chopped berries and/or nuts or seeds is a great start to the day.
  3. Mediterranean Style. As you may have heard before, the Mediterranean diet is full of goodness with a variety of fibre sources –just what we need. The keyword here is variety as the different species of our gut bacteria need all types of fibre to thrive on. You can check out our blog which talks more about the Mediterranean diet: Eat, live and love Mediterranean.
  4. Switch to wholegrain. Opting for wholegrain bread, pasta and brown rice. If you are finding this tricky why not ease yourself into it with going for a version that is a combination of white and wholemeal bread or flour?
  5. Include plenty of vegetables with meals – either as a side dish/salad or added to sauces, stews or curries – this is a good way of getting children to eat more veg.
  6. For snacks, try fresh fruit, vegetable sticks, rye crackers, oatcakes and unsalted nuts or seeds


At BeGoodToYourGut, we appreciate that change can be hard. We recognise that one size does not fit all.  For this reason, we pride ourselves in adopting a holistic approach for each individual. So if you find that you would like more information, please contact Sian or Andrew via the Contact page.



Role of the gut microbiota in nutrition and health’ BMJ 2018; 361


Authors: Ana M Valdes, associate professor,Jens Walter, CAIP chair for nutrition, microbes, and gastrointestinal health

Eran Segal, professor, Tim D Spector, professor


 hyperlink (Published 13 June 2018)

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