The function of fibre in your body

The use of fibre in your body is probably the most difficult to understand.

Why are there 2 types of fibre that act in different ways? This is what most people find difficult to initially understand, so let’s start with this question.

Dietary fibre consists of complex carbohydrates. These carbohydrates do not supply energy to the body as the human digestive enzymes are unable to break down the sugars in the fibre, as if they are inseparable. Fibre does not have a calorific value and cannot be converted to glucose. In short, you cannot digest fibre, which in fact, makes it so important. Strange, isn’t it?

Just a reminder – you can only glean fibre from plant-based foods, not from animal products. By plant food we include fruit, vegetables, pulses and grains (wholemeal bread and cereals are included in grains). The fibre in these foods does not get broken down and absorbed into the small bowel as other types of food do, it passes through into the large bowel, undigested.

 The difference between the two types

The two types of fibre are called soluble and insoluble. The human body needs both types to keep our digestive system healthy. That’s why it is so important to eat both types of fibre through a varied diet.

Soluble fibre is a type of dietary fibre that is soluble in water. It forms a gel-like substance in the body that slows down the digestive process.

Examples of soluble fibre are:

• Apples, strawberries, citrus fruits, barley, oats, rice, seeds

Insoluble fibre does not attract water and passes through the digestive system to provide the bulk necessary to your stools and for ease of bowel movement. It helps to avoid constipation in most cases.

Examples of insoluble fibre are:

• Green leaves such as cabbage
• roots such as carrots or beets
• whole wheat, bran, beans
• seeds (outer layer) such as bran and whole grains
• plant stems, leaves and skins

These are just a few examples, your doctor or nutritionist can help you with a list of fibre-containing items to help, as the lists above are by no means comprehensive and just a guideline.

There may be some foods that you are sensitive to, particularly if you up your intake of high fibre foods. It would be worthwhile to take a test here if any symptoms arise that you may not have noticed before. If you suddenly increase your fibre intake, your body may well react. The ‘roughage’ (this is what fibre was called a long time ago) may well irritate or upset your intestinal tract and you will certainly see and feel that. Take it slowly if need to increase your fibre, to avoid any blockages in your intestines.

You also need to ensure that your hydration levels are on par with any increase in fibre intake. Dietary fibre is just like a sponge, soaking up with every drop of liquid it can, so a rapid and high dose of fibre is likely to deprive your cells of the necessary water to do their own function.

How dietary fibre helps your gut microbiome

We have mentioned your gut microbiome in many other articles. Just to recap, your microbiome should consist of healthy bacteria to fight off illnesses and more serious diseases. The different types of fibre produce short-chain fatty acids (SCFAs) and other essential items to promote health. Eating a variety of fibre in your foods is very important, and not just eating the same all the time.

Potentially you could say that the most helpful fibre is the soluble (such as pectins and gums and beta-glucans) variety. This fibre is useful in the fermentation process.

The fibre types that are most amenable to fermentation are the soluble ones (gums, pectins, etc.).  These are found in apples, berries, beans, flaxseed, oats, plums and oats, as well as in some fibre supplements, such as those using psyllium and guar gum.

Insoluble fibre (found in such foods as vegetables, the bran of grains, e.g., wheat bran, nuts, and seeds) doesn’t help in fermentation, but it is still important in the colon.

As we never make wild claims regarding any substance ‘curing’ an illness or disease, we still feel the need to mention that insoluble fibre plays an excellent part in keeping the colon healthy.

Other potential health benefits

There is so much research on how fibre reacts in your digestive system, and how it can help certain elements and illnesses in your body.

Research suggests:

• May improve some disorders, like diverticulitis, constipation, and irregularity in bowel movement
• May improve glycaemic levels
• May help you lose weight
• May reduce cholesterol
• May reduce the risks of heart attacks and strokes

Scientists and researchers are particularly keen to continue research in specific cancers such as colon cancer and bowel cancer, but this may be a long time before it is confirmed that fibre intake plays a big part in lowering the cases or preventing it totally.

The one thing for sure is that eating the right level of fibre is going to help your overall health. The mean average of consumption of fibre per day for women up to 50 years old is 30g, which should be increased to around 35g after this age. Men should eat slightly more. Unfortunately, the British Dietetic Association (BDA) report that the average adult consumes only 18g per day. In the US, the average is only 15g per day.