Dietary fibre and health: an overview

Abstract

Summary Many studies have found that people on diets high in fibre have reduced risks of certain diseases such as cancers, coronary heart disease, obesity and possibly diabetes. Fibre is a collective term for a group of compounds, which differ in their chemical structure and physical properties and elicit a variety of physiological effects. Some health benefits linked to fibre consumption are well established (e.g. promoting a regular bowel habit) and others are becoming more firmly established. The effects of the various non‐digestible components are not always fully interchangeable, although there is considerable overlap, but they share an ability to pass undigested into the large bowel. This makes it important that fibre intake comes from a range of sources to ensure maximum health benefits. There are disagreements as to which plant‐derived compounds constitute ‘fibre’ and which analytical methodologies should be used to determine the fibre content of foods. This lack of a universal definition for these carbohydrates that resist digestion in the small intestine has led to complications in establishing and communicating consistent recommendations for the type and amounts of fibre components in the diet, as well as issues related to food labelling and health claims. Furthermore, current analytical methods may typically underestimate the fibre content of foods, using the definition advised by the European Food Safety Authority. Chemical nomenclature is necessary for a coherent and enforceable approach to the measurement of fibre (and related to this, product labelling), but reconciling chemical definitions for fibre with definitions that reflect physiological effects remains a major challenge. Progress in the application of the emerging evidence regarding dietary fibre and health is constrained by a need to resolve the definition and methodology issues. Most consumers are likely to be unaware of the more recent developments and the overlapping properties of different types of carbohydrate that resist digestion in the small intestine, and the particular sources of these carbohydrates. Long overdue is the translation of the growing knowledge about the physiological properties of carbohydrates, particularly non‐digestible carbohydrates, into clear and unambiguous public health messages. Many terms in common use stem from chemistry rather than physiology, and this makes derivation of health messages more difficult. Meanwhile in the UK, where the main sources of fibre are cereals and cereal products, followed by vegetables and potatoes, adults are not meeting the recommended 18 g of fibre per day (defined in the UK as non‐starch polysaccharide measured by the Englyst method). The recommended amount for the UK, established in 1991, is lower than elsewhere in the world and corresponds to about 24 g according to the method used by the Association of Official Analytical Chemists (the AOAC method). Reference values in other parts of the world are typically between 25 and 35 g (AOAC fibre). A diet rich in whole grains, pul...

Dietary fibre in Europe: current state of knowledge on definitions, sources, recommendations, intakes and relationships to health

“…With a strong relationship with unhealthy lifestyles, including tobacco smoking, low levels of physical activity and poor diets, the WHO has estimated that over three-quarters of CVD deaths may be preventable by appropriate lifestyle change (42) . One such change may be adherence to a dietary pattern encompassing a range of high-fibre foods which may make an impact on reducing CVD risk through reduction in recognised CVD risk factors such as raised blood cholesterol, hypertension, systemic inflammation, impaired glucose tolerance and elevated body fat (43) . A recently published systematic review and meta-analysis of seventeen cohort studies that provided risk estimates for incident fatal events of CVD in relation to intakes of total fibre and fibre sources confirmed the association between low dietary fibre consumption and increased risk of CVD (44) .…”

In vitro physicochemical, phytochemical and functional properties of fiber rich fractions derived from by-products of six fruits

“…This could be due to the fermentation and production of short chain fatty acids in the large intestine by the gut micro flora residing there. A healthy adult person is usually recommended to consume between 25 and 30 g of fiber daily (Buttriss and Stokes 2008). Fruits and vegetables are naturally rich in dietary fiber.…”

Dietary Fibre: Wheat Genes for Enhanced Human Health

“…There is also a signifi cant shortfall in the intake of DF in many countries. For example, in the UK the daily intake of DF is only about 13 g per day (Buttress and Stokes 2008 ) compared with a recommended daily intake of 25-40 g a day in most other countries. Most of the DF consumed is non-starch polysaccharides, with resistant starch contributing about 20-25 % of the total in European diets (Cummings 1983 ).…”

“…Most of the DF consumed is non-starch polysaccharides, with resistant starch contributing about 20-25 % of the total in European diets (Cummings 1983 ). There is strong evidence that DF in wholegrain provides protection against the risk of a number of chronic diseases, including type 2 diabetes, obesity and cardiovascular disease, with both soluble and insoluble forms contributing to the benefi cial effects (Slavin 2004 ;Topping 2007 ;Wood 2007 ;Lunn and Buttriss 2007 ;Buttress and Stokes 2008 ;Anderson et al 2009 ;Fardet 2010 ). DF is not digested in the upper gastrointestinal (GI) tract and many of the benefi cial effects result from fermentation in the colon.…”