why do we need fibre and water
What is dietary fibre? The word fibre maybe makes us think of string! However, dietary fibre is not string or even stringy, but a group of carbohydrate compounds with rather special physiological actions. P It includes:
non-starch polysaccharide Resistant starch starch which has been altered by cooking. Both of whose structures are not digested by the enzymes in our intestines. Resistant oligosaccharides -another form of indigestible carbohydrate, such as lactose. Did you know? Lactose from cow s milk is partly undigested, so it functions as dietary fibre for babies. Insoluble fibre binds water and increases stool bulk. It increases the contraction and relaxation (peristalsis) which moves materials through your intestine. An example is cellulose in cereal foods. Soluble fibre forms a viscous gel in the presence of water, which has particular value for smoothing out the absorption of nutrients after meals. P Once in the large intestine, soluble fibre is almost entirely fermented by bacteria. Examples are pectin and guar gum, from fruits and beans respectively. All types of dietary fibre are fermented, by the natural and healthful bacteria which live in our large intestines.
P Without them we would soon become ill. P From dietary fibre the bacteria release small molecules called volatile fatty acids which are important as energy sources for our large bowel, and may reduce cancer risks. P Eating more dietary fibre increases the bulk of our stools, mainly by increasing the number of healthy bacteria. Everyone needs the right amount of fibre in their diet we tell you how much you need and how to get it. What is it? is the indigestible part of plants that passes relatively unchanged through the stomach and intestines. It is mostly made up of, which consist of different types of sugars. There are two types of : soluble and insoluble. Both types are present, in varying degrees, in all plant foods. Soluble fibre can t be digested, but it absorbs water to become a gelatinous substance that passes through the body. Good sources of soluble fibre include fruits, oat bran, barley, beans, lentils, peas, soy milk and soy products. Insoluble fibre is mostly unchanged as it passes through the body and adds bulk to faeces.
Good sources include wheat, corn and rice bran, nuts, seeds and wholegrain foods. Resistant starch is not traditionally thought of as fibre, but it acts in a similar way. It is found in many unprocessed cereals and grains, firm bananas, potatoes and lentils. The Heart Foundation recommends adults consume about 30 grams of fibre a day. Experts suggest children should eat 10 grams of fibre a day, plus an additional gram for every year of their age. Fibre is important in aiding digestion. Soluble fibre soaks up water, which helps to plump out the faeces, and allows it to pass through the gut more easily. It slows down the rate of digestion, and this is then counteracted by insoluble fibre, which speeds up the time that food takes to pass through the gut. A lack of fibre, particularly insoluble fibre, can lead to gastrointestinal problems such as constipation, irritable bowel syndrome, colitis, colon cancer and haemorrhoids. It is thought that soluble fibre helps protect against heart disease by lowering blood cholesterol.
Cereal fibre seems to offer more protection against coronary heart disease than the fibre from fruit and vegetables. People who are overweight have been shown to lose significant amounts of body fat by increasing the amount of fibre, especially soluble fibre, in their diets. A high-fibre diet also slows glucose absorption from the small intestine into the blood, reducing the possibility of a surge of insulin. Fibre is therefore recommended for people with diabetes and a high-fibre diet can help to prevent development of the condition. Resistant starch is also important for bowel health. Bacteria in the large bowel ferment and change the resistant starch into short-chain fatty acids, which are important for bowel health. A sudden switch from a low- to high-fibre diet can create abdominal pain and increased flatulence. Increase your fibre intake gradually and add it from food rather than supplements. Very high-fibre diets may decrease absorption of minerals such as iron, zinc and calcium, so stick to the recommended intake.
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