We have all heard the message for years that we need to up our intake of dietary fibre, but why? What is so special about it that means we need to get more of it in. Well, there is one benefit that I am sure we are all familiar with that I wont particularly labour on - it increases digestive transit and keeps us regular and everything flowing smoothly. This is though, in my opinion, probably the least exciting benefit we get from it. There are three areas where dietary fibre can really benefit us that go far beyond just keeping things moving.
One of the major benefits of dietary fibre is it really does help to curb our appetite and keep us full. It takes on water almost immediately. Many times its ow weight in fact and It can begin to swell. Whilst most of this happens lower down in the digestive tract, it begins to happen in the upper digestive tract too. This enlarges the stomach contents. The stomach does have stretch receptors within its walls that detect ‘how full’ we are. The receptors basically send nerve signals to the brain that the stomach is expanding and our appetite begins to diminish. So - we eat less!!! This can really help to curb excess food consumption. How many times when you have eaten dead refined white carbohydrates like white bread or pastries, have you felt hungry again a little while later. There is also emerging evidence that high fibre diets positively impact upon satiety hormones, the hormones that actually influence appetite.
One extremely positive impact that dietary fibre can have is that it can positively impact cardiovascular health. There are two distinct fibre types that both coexist in high fibre foods - soluble fibre and insoluble fibre. The insoluble variety literally goes straight through us relatively intact. The soluble on the other hand partially dissolves, takes on many times its own weight in water, and forms a gel like substance in the gut. This substance traps cholesterol in the digestive tract and prevents it from being absorbed. This isn't cholesterol from food, this is cholesterol that has been made in the liver, and then used to form bile for fat digestion. Once it has played its role in digestion, this cholesterol gets absorbed from the digestive tract into systemic circulation. By trapping it here, soluble fibre gradually pulls down serum cholesterol. Remember though, total cholesterol number is only one tiny part of the picture, we need far more information to make a decision.
The final exciting thing that dietary fibre can do for us, is help to grow and establish our gut flora, the bacterial colony that lives in the gut. This is due to the presence of prebiotic substances. These are very large high molecular weight carbohydrates in high fibre foods that do not get broken down in the upper part of the digestive tract, ie the small intestine, like the more simple carbohydrates do. These large complex sugars actually require our gut bacteria to break them down in a fermentation process called saccharolytic fermentation. When this takes place, several beneficial events occur. Our gut flora start to increase in number so the population and colony gets stronger. As well as an increase in bacteria number, during the fermentation process, the bacteria release by products that are formed, such as butyric acid. These byproducts are incredibly useful as they stimuate many repair mechanisms within gut tissue. So consuming these types of prebiotic substances we increase gut bacterial number and create a healthier local environment for them to flourish.