In this article Dr Geoff discusses how fibre in our diet effects our health, as well as our general mood. He also looks into the short term and long term issues of having a low fibre diet:
Fibre slows down the digestive process and so high fibre meals make us feel full for longer. This is said to lower our risk of obesity and adult onset diabetes if we regularly eat such meals. Soluble fibre has a small lowering effect on blood cholesterol and of course high fibre diets usually contain less saturated fat and cholesterol which also helps keep our cholesterol level down.
High fibre diets speed up the passage of waste products through the large bowel and make the stools bulkier and softer (due to higher water and bacterial content). This in turn reduces constipation and eases some other bowel problems like piles. Beware, however, that dehydration is a major cause of constipation, especially in the elderly, and taking bran without extra water will make the constipation worse. Increased fluid intake often alleviates constipation in older people and may also make them more alert and less confused.
Although fibre cannot be digested by humans, much of it can be fermented by the bacteria that live in the large bowel. This fermentation process produces gas and a substance called butyric acid. The gas produced is the reason why some foods rich in soluble fibre like beans have a reputation for increasing flatulence and a sudden large increase in fibre intake may also increase flatulence for a while. The butyric acid produced by this fermentation process seems to have a number of good effects on the cells lining the bowel and this may help to explain the lowered rates of bowel cancer seen in people who eat fibre-rich diets.
Experimental studies show that butyric acid reduces the risk of mutated bowel cells rapidly developing into cancerous tumours and also reduces conversion of substances derived from bile being converted into toxic substances that may convert healthy cells into potentially cancerous cells.Making sure that you eat your five portions of fruit and vegetables each day will boost your fibre intake. Eating at least some of your cereals in whole grain form will also help but even more refined cereals do contain some fibre so wholemeal bread is better than white bread but white bread does still have useful amounts of fibre.
If you or your children don’t like whole meal bread or brown then maybe try a whole grain breakfast cereal. Some of the starch in foods like rice, potatoes and white bread becomes indigestible during cooling and so acts like dietary fibre; most of the starch in unripe bananas and uncooked starchy foods may be indigestible. Sprinkling extra bran onto your existing diet or eating foods with added fibre may have some benefits but is not a substitute for eating a diet that is naturally rich in fibre. If you do use concentrated bran, make sure you drink plenty.
Dr Geoff’s last post on Dietary Fibre will be posted tomorrow! Don’t forget to keeping on the look out for next week’s topic!