Appendicitis
Appendicitis is inflammation of the appendix, the small blind-ended tube at the beginning of the large bowel. Although the underlying causes of appendicitis are not clearly understood, there is evidence that regular intake of fibre may prevent the development of the disease.
Hiatus hernia, varicose veins and piles
Many doctors believe that abdominal straining due to constipation encourages the development of conditions such as hiatus hernia (where the top of the stomach is pushed upwards, out of the abdomen and into the thoracic cavity), varicose veins and haemorrhoids (piles). It is often necessary to have surgical treatment for these conditions. Treating constipation with high fibre diets and, as a result, avoiding straining, may prevent these problems and may even reduce the need for more drastic treatment in some cases.
Coronary heart disease (CHD)
Coronary heart disease is the most common cause of death in affluent Western countries (see page 151). A large number of factors influence the development of the disease, of which raised blood cholesterol levels, high blood pressure and hypercoagulability (the tendency of the blood to clot too easily) are probably the most important.
Researchers believe that high-fibre, low fat diets protect against CHD by lowering blood cholesterol and probably also by decreasing blood pressure and the clotting ability of blood. It is especially the water soluble or gel-forming dietary fibres - found in oats, legumes and some fruit and vegetables - which help to lower cholesterol levels. While it should be borne in mind that diet is but one of the many factors which influence the development of CHD, it is also one of the controllable ones.
Diabetes mellitus
There are two forms of diabetes mellitus, a disease characterised by the excretion of glucose (sugar) in the urine (see What is diabetes? on page 175). Both forms are today treated with a high carbohydrate, high fibre, low fat diet. Fibre in the diet normalizes the body's response to dietary carbohydrate (glucose tolerance). A regular high intake of dietary fibre also improves insulin function by increasing the sensitivity of muscle and fat cells to the hormone.
Gallstones
The body manufactures these crystalline substances when the amount of cholesterol in the bile is so high that the bile salts cannot keep it in solution. The stones may block bile ducts between the liver and gall bladder or between the gall bladder and small intestine, resulting in severe pain and even jaundice. As in the case of other diseases of affluence, a number of factors may contribute to the development of gallstones. It has however been shown that high fibre intakes stimulate the production of those bile salts which keep cholesterol in solution, thus decreasing the risk of gallstone formation. Populations who follow high fibre diets have a significantly lower risk of the disease than those on the average refined Western diet.
To what degree is fibre involved?
Although research has proved that dietary fibre has a positive effect on body functions in general, the degree to which it is involved in the risk and development of the above diseases is still unclear. Studies are hampered by the fact that a variety of causes play some role and also because high-fibre diets differ in more than one respect from low-fibre ones. For example, they usually have a lower fat content - especially saturated fatty acids from food of animal origin - and are higher in vitamins and minerals. These factors could add to the beneficial effects seen in people who eat a high-fibre diet.
What is diabetes?
Diabetes is a disorder in which the pancreas cannot produce enough insulin, a hormone which prevents blood sugar levels from rising too high, or in which the insulin that has been produced does not function properly. It does this by helping body cells to take up glucose - either to metabolise to energy or to store as glycogen or fat.
If an individual manufactures too little insulin, there are two possible forms of treatment: The young, more severely affected diabetic can only survive if given daily injections of insulin for the rest of his or her life. However, if diabetes develops at a later age, treatment with pills is usually effective. These pills are not insulin; they are essentially compounds which give the pancreas the necessary stimulus to produce more insulin to cope with the carbohydrate (sugars and starches) which the individual eats. Because sugar causes a dramatic rise in blood sugar levels, diabetics should obviously avoid it in their diets; indeed, they should avoid all unnecessary food in general if they are overweight, as not only is the insulin requirement related to food intake, but excess weight has an aggravating effect on the condition. Obese diabetics who develop the disease in later life can often be treated by diet alone.
A low fat, high fibre intake - which 'dilutes' the contents of the digestive tract - slows down the passage of glucose into the blood stream and hence the elevation of the blood sugar is less dramatic.