Fibre is a heterogeneous group of non-digestible carbohydrates that show beneficial health effects. Broadly fibre is divided into soluble and insoluble fibre types, but in reality these groups do not accurately describe the wide variety of dietary fibres frequently ingested by humans. Evidence suggests that dietary fibre is beneficial to the health. The traditional view is that fibre provides roughage to the diet and this decreases transit time through the gut, preventing the putrefaction of other foods within the gut. However, as more is learned about fibre, novel functions have been elucidated. Fibre is now known to provide a considerable contribution to daily energy needs, and may also be a requirement for correct immune function, through the supply of gut bacteria with an energy source. Fibre may also provide beneficial glycaemic effects by delaying the digestion of starch and the absorption of glucose. Fibre may be considered a conditionally essential nutrient, as it appears to be a requirement of health if starch is consumed.
While many studies have been performed on individual fibre components, and much useful information has been obtained in this way, it is nutritionally more useful to look at the diet at a whole. In this respect, high fibre diets have been shown to be healthy because they are usually of high quality and contain other foods that are beneficial to the health. At the same time, high fibre diets are often low in disease causing nutrients such as sugar and refined starch. In a recent study, the consumption of high fibre diets was shown to be inversely associated with the risk of periodontal disease, amongst a group of over 6000 individuals living in the United States of America. In particular, periodontal disease was associated with a low intake of whole grain cereals (but not fruit and vegetables). This sort of study is useful because although it does not prove that dietary fibre is beneficial at protecting from periodontal disease (associations are not cause and effect), it does show that eating a high fibre diet provides a health benefit.
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