What is dietary fibre?
Your grandma probably called it roughage. And although she didn't know the scientific basis of fibre, she did know that it was important to include some of it in your diet every day. Well, dietary fibre is not a single food or substance. It is the non-digestible complex of carbohydrates that are found only in plant foods. Fibre itself contribute little to your calorific intake because the body cannot easily absorb it. That's why high fibre foods are low calorie foods.
Fibre can be classified into two categories according to physical characteristics and effects on the body. Fibre is either soluble or insoluble in water. Examples of soluble fibres are gum arabic and pectin found in apples, oranges, pears, peaches and grapes. Soluble fibre absorbs toxins in the large intestine and neutralises them. Insoluble fibre helps to maintain normal blood pressure levels and promotes a growth of beneficial bacteria in the large intestine. I'll talk more about that in a moment. Insoluble fibre also acts like tiny scrub brushes that sweep out faecal residue from the large intestine. With this sweeping action, insoluble fibre aids digestion, elimination and promotes overall bowel regularity. Good examples of insoluble fibres are cellulose and lignin found in fruits, vegetables, dried beans, wheat bran, peas and corn.
There are several reasons why dietary fibre doesn't get the attention it deserves from the medical establishment. First recognition of its role in human physiology is relatively recent. Only in the late 1960s did research on fibre begin in earnest. Second there is still some disagreement on just what dietary fibre really is. Even the word fibre itself is not quite accurate reminding us as it does of long fibrules primarily of cellulose. Its true that the major portion of dietary fibre in foods is derived from plant cell walls, but there are many other substances in plant foods that are considered to be dietary fibre including polysaccharides and gums. While dietary fibre is not considered to be an essential nutrient by many medical authorities, that position may say as much about how far behind the times conventional medical is as it does about the value of fibre in the diet. After all one of the most important reasons why traditional diets such as the Asian diet and the Mediterranean diet were and still are so healthy is because they are high in fibre content.
With a better idea of what dietary fibre is, the next question is: what are the health benefits of consuming adequate amounts of it every day? As on-going clinical studies are showing, the physiological effects of a high fibre diet are many and they are very complex. The first and most obvious thing that fibre does is to increase the bulk of the gastro-intestinal waste forming larger, softer stools that move more quickly through the colon. Its easy to see how this would help to prevent constipation. Many studies indicate that it has a significant effect on moderating glucose levels in the blood. A third major health benefit is that fibre prevents reabsorption from the gut of toxins such as the enzymes in bile acid. The bulk of a high fibre meal causes you to feel satisfied when you eat a moderate-sized meal which helps you to avoid overeating. Also important in weight management is the point that fibre provides almost no calories. Finally, fibre from different sources includes a wide range of micro-nutrients helping you to achieve optimal micro-nutrition.
Fibre's benefits over the long-term are even more impressive and very significant for preventing degenerative disease largely as a result of its cleansing and detoxifying activity. A high fibre diet can significantly reduce the risk of several major degenerative diseases including diabetes, hypertension, heart disease and certain cancers. Both adequate amounts of total fibre consumed daily in a recommended ratio of soluble to insoluble fibre are important for promoting gastro-intestinal health. The human GI tract is subjected to enormous and continual stimulation and challenge by foreign antigens from food and ingested microbes. This system of organs must integrate the many complex interactions between your diet, external pathogens, and local immunological processes. There are lymphoid tissues, components of the immune system, all through the gut including the piers patches and lymph nodes in the intestines. There is increasing evidence that fibre especially the types of fibre called prebiotics can help to modulate immune system function.
With more and more studies showing the healthy benefits of a high fibre diet, more nutrition authorities are agreeing that we should include at least a minimal amount of fibre in our daily diet. The US Surgeon General and many professional organisations are recommending a diet containing 20 - 35 grams of fibre per day. I consider this amount to be less than optimal but then the average American diet barely includes half this amount with only about 11 grams per day.
You know, in my travels to underdeveloped parts of the world visiting primitive villages for the Childrens Hunger Fund, I've seen that generally the higher the fibre content in the diet the less need for hospitals, as long as the diets contain sufficient essential nutrients. In these cultures where people consume large amounts of unprocessed starch staples, there a few examples of degenerative diseases like osteoarthritis, heart disease, diabetes and cancer. So rather than using guidelines like the RDA of 20 to 35 grams per day, you should simply include as much fibre as you can in your diet from a wide variety of sources and from both plant foods and fibre supplements.
There are still many nutrition authorities who say that consuming healthy amounts of both types of fibre is fairly easy if you are eating the recommended amounts of fruits and vegetables. However eating large enough portions of fruits and vegetables every day to achieve an optimal amount of fibre can be quite difficult especially in today's fast-paced society. That's why you need to consider a fibre supplement. The American Dietetic Association emphasises obtaining your fibre from a wide variety of sources not just a few fruits and vegetables. If you supplement with fibre, you should always look for a product that includes fibre from many different sources. You should also be sure that your fibre supplement provides the correct ratio of soluble to insoluble fibre. An ideal ratio is one unit of insoluble fibre to every two units of soluble fibre.
An effective formulation of dietary supplement also includes types of fibre called prebiotics. Basically they are food for the bacteria in your intestines. You know billions and billions of bacteria are living inside you. The human gastro-intestinal tract is inhabited by several species of beneficial bacteria and you couldn't stay healthy without them. In all the human body is home to more than 200 species of bacteria, but the normal flora of the intestine represents the largest populations. An estimated 10 14 bacteria, that's 1 followed by 14 zeros, are normally in the gastro-intestinal tract. That's as many or more individual organisms than cells in your whole body.
Prebiotics such as the fruit dough, oligosaccharides or FOS, and inulin pass undigested from the stomach into the lower intestine. Once in the lower intestine they nurture the growth of beneficial bacteria both by altering the pH of the environment and by providing food for them. Prebiotics have also been shown to improve the absorption of calcium and they help to balance lipid and cholesterol metabolism as well as aid in immune function of the gastro-intestinal tract.
A modern diet high in meats laced with antibiotics, alcohol and toxic substances in processed foods combined with the stress of contemporary society upsets the normal flora of the gastro-intestinal tract. Prebiotic fibre supplements can help to maintain a healthy environment for beneficial bacteria. As you can see, fibre is valuable for your health more for its function than its content and that's why it plays important roles in so many health conditions.
Since the sources of fibre are natural plant foods, determining your daily intake is not as straight-forward as reading the calorie content from labels on food packages. But if you make a list of each item that you eat for breakfast, lunch, dinner and snacks then refer to a table of fibre content of foods, you can get a rough idea of how much you need to add to get the recommended amounts. The American Dietetic Association, Hopkins Technology and the American Council of Science and Health, all have websites that provide tables listing the dietary fibre content of common foods. If your diet has been severely deficient in fibre or if you are finding it difficult to consume as much fibre-rich food as you would like, you may not want to add a large dose of fibre to your daily routine suddenly. Instead increase your intake gradually to avoid discomfort. In any case, make sure you drink plenty of water along with your fibre supplement. For efficient functioning of the gastro-intestinal system and elimination of toxins as well as an enhanced immune function, you need to include fibre in your diet every day.
Your grandmother knew that and now you do too ...
Source: Transcript of Dr Myron Wentz, LifeMasters Audio October 2006
