As we eat ever more processed food, fruit and vegetables are keys to health, writes Sylvia Thompson.
Fibre is back in the news, with US and European studies highlighting yet again that a diet rich in fruit, vegetables and wholegrain cereals will reduce your risk of colon cancer, Ireland's second most common cause of cancer death.
Fibre is the part of plants we neither digest nor absorb, so, paradoxically, it has no nutritional value itself. Yet it helps to clean our digestive systems and is believed to be crucial for normal gastrointestinal functioning.
"The greater emphasis placed on fibre nowadays is not because it is suddenly deemed more valuable but because, with the increased consumption of processed foods, we are getting much less of it," says Maria Costello, a nutritionist.
"Twenty-five to 30 per cent of our diet should be made up of fruit, vegetables and grains, which would give us plenty of fibre," says Costello. She warns, however, that if you plan to increase your fibre intake radically, you should do it gradually, over six to 12 weeks.
There are two types of fibre: soluble and insoluble. Many foods, such as fruit and vegetables, are good sources of both types. You get most fibre from them if you eat them raw and unpeeled - and if you eat organic and seasonally grown crops rather than forced crops.
Insoluble fibre is found in wheat bran and wholewheat flour, as well as in many cereals, fruits and vegetables. It is this type of fibre that is believed to reduce the risk of colon cancer, as it prevents constipation and other gastrointestinal conditions. Large quantities of insoluble fibre, from wheat sources particularly, are, however, inappropriate for children and can cause diarrhoea and inadequate absorption of nutrients.
Foods high in soluble fibre include oatmeal, oat bran, barley, legumes (dried beans, peas and lentils) and fruit and vegetables, especially apples, figs and carrots. Pectin, a soluble fibre found in apples and carrots, is particularly important, as it absorbs heavy metals, helps our bodies to eliminate waste products and prevents the reabsorption of toxins in the bowel.
Finally, anything that contains fibre requires chewing. This stimulates the flow of saliva, which protects our teeth and encourages healthy digestion.