The F Word

No – not an article on swearing, but an introduction into the importance of dietary fibre!

So what is fibre? Fibre is indigestible plant material e.g. cellulose and is sometimes described as a non-starch polysaccharide. This basically means it is a calorie free carbohydrate. Humans lack the necessary digestive enzymes or specially designed stomachs to break down fibre so it passes through our digestive tracts pretty much unchanged. Ironically, it is this “passing through unchanged” which gives fibre its healthful properties.

Fibre comes in two varieties – soluble and insoluble. Both varieties are very important to our health and it’s important we consume plenty of both. However, so you can dazzle your friends with your dietary knowledge. I’d like to explain the difference between the two types…

Healthy on the out side, healthy on the inside? A very large percentage of the population suffers from constipation. Constipation is commonly caused by dehydration and low levels of fibre in the diet. Whilst this might seem like a fairly benign condition, it is actually a very major health concern which, if left untreated, can lead to a condition called Diverticular Disease. Diverticular Disease is caused by a build of pressure in the large intestine due to straining to push faecal matter out of the body. Pockets or bulges called Diverticuli develop in the large intestine which encourages a build up of bacteria. We have a large amount of “good” bacteria in our intestines and this intestinal flora and fauna is vital to our health. It is constantly being renewed and has many functions including the production of vitamins Biotin, Riboflavin and vitamin K. However, the bacterium in the diverticuli is old, “bad” bacteria and its presence causes inflammation of the colon and may result in sections of the colon having to be surgically removed. Diverticular disease used to be the reserve of the older generation but due to the severe lack of fibre in the modern diet, it is becoming increasingly common in younger people too.

Intestinal sponges.
Soluble fibre is natures’ G.I. (Gastrointestinal) tract sponge. Once eaten, soluble fibre passes though your intestines and colon forming a gel which soaks up numerous odds and ends and transports them into the outside world. Soluble fibre has the ability to soak up excess bile acid (caused by excess saturated fat in the diet), lowers “bad” cholesterol, helps regulate blood glucose levels by delaying gastric emptying (keeps food in your stomach longer) and reduces the absorption of a small amount of dietary fat.

Sources of soluble fibre include beans, oats, barley and the soft part of fruit and vegetables e.g. the flesh of apples, broccoli and prunes. By eating plenty of fruit and vegetables, it’s fairly easy to ensure your diet contains adequate soluble fibre.

Number twos and toothpaste tubes.
If soluble fibre is a sponge, then insoluble fibre is natures’ scrubbing brush. Insoluble fibre does not dissolve in water and is sometimes referred to as “roughage” which describes its structure very well. When we eat insoluble fibre, it passes though the G.I. tract giving our intestines a good cleaning. Insoluble fibre also “bulks up” our faecal matter making it easier to push through our bodies and results in less straining which will dramatically reduce the likelihood of developing Diverticular Disease. Just imagine for a moment what it’s like trying to get the very last bit of toothpaste out of a nearly-empty tube….you squeeze it as hard as you can and still you might only get a small amount of paste out of the tube. Compare this to a full tube where we only need to use a small amount of pressure to push the toothpaste out...the empty tube is an analogy for a diet low in insoluble fibre and the full tube represents a diet high in soluble fibre. So, if you are straining and turning blue when having a poo, (!!!) you may well be deficient in vital insoluble fibre.

Insoluble fibre is found in the “woody” part of plants i.e. the husks of grains and the skins of fruit and vegetables. By seeking out whole grain foods as apposed to the more refined “white” versions, it’s pretty easy to get sufficient insoluble fibre.

And there’s more!
Dietary fibre has a number of additional benefits. Fibre can be very useful in weight management and dieting. Remember fibre has NO calories. High fibre foods are naturally low in calories but are still satisfying to eat. Fibre makes as feel full up sooner and stay that way longer. Because of its bulk, fibre will cause greater distension (stretching) of the stomach. The hunger centre of the brain – the hypothalamus – receives messages from stretch receptors in the stomach when it’s full. The sooner this message reaches the brain, the sooner we will feel full and the sooner we will stop eating. Also, the presence of fibre makes food stay in our stomachs for longer which contributes to a feeling of fullness. And if that wasn’t enough, fibrous foods generally take longer to eat and require more chewing which also adds to an overall feeling of fullness.

Fibre also causes something called “Gastric Inhibition”. Gastric Inhibition is just a technical term to describe the slowing down of food leaving the stomach and entering the intestines where nutrient absorption occurs. By slowing Gastric Emptying (the time it takes for food to leave the stomach and enter the intestines) we are able to control blood glucose levels. By releasing glucose into the blood in a slow and controlled manner, we ensure a nice steady supply of energy to the brain which will help avoid very high or very low levels of blood glucose. Low levels of blood glucose are often associated with fatigue, hunger, sweet cravings and poor levels of concentration whilst persistently high levels of blood glucose have been attributed as the cause of obesity and diabetes.

Make haste slowly.
Now, before you go rushing out to buy as much fibre as you can lay your hands on a word of warning. The average Westerner consumes around 10 grams of fibre a day, compared to the recommended amount of 18 – 20 grams. To make the jump from 10 to 20 grams in a short period would be the nutritional equivalent of a non-exerciser waking up one morning and running a marathon! Needless to say, the resulting muscle soreness would pretty much cripple our budding runner. Likewise, with our diet, if we are to avoid intestinal discomfort, bloating, flatulence and possible permanent residence on the toilet (!!!) it is vital to increase our fibre intake gradually. Start by switching to whole grains, then maybe eating your fruit and vegetables with their skin on to finally adding extra fibre to your diet in the form of seeds and grain husks. Do this gradually to avoid the dietary equivalent of very sore muscles!

Summary.
So fibre comes in two types – soluble and insoluble and they are both vital to intestinal health. Soluble fibre soaks stuff up and insoluble fibre makes waste elimination easier and less of an effort thus protecting the colon. Both types of fibre help control blood glucose levels and are calorie free so can aid in weight management. High fibre foods promote a feeling of long-lasting fullness and generally they take longer to eat. The easiest way to get adequate fibre in your diet is to eat plenty of whole foods such as fruit and vegetables with their skin still on and whole grains which have not been milled excessively.

Patrick Dale
http://www.solar-fitness.com/