Roles for dietary fibre in the upper GI tract: The importance of viscosity

Abstract

Dietary fibre has long been recognized as healthy because of its prebiotic quality and a number of dietary fibres, especially beta glucan have been shown to lower levels of circulating LDL cholesterol. However, although EFSA allow health claims to be made for this, there is no fundamental understanding of the detailed mechanism involved. More recently dietary fibre has been shown to have a range of functionality in the upper GI tract. The presence of fibre can alter gastric emptying thus affecting fullness and satiety. These alterations are a result of differences in viscosity, nutrient release and nutrient sensing in the duodenum. The current proposed mechanisms for the cholesterol lowering effects involve disruption of the normal recycling of bile possibly by sequestering bile salts and fatty acids or by significantly decreasing the rate of absorption as a result of entanglement with intestinal mucus.The use of quantitative confocal microscopy methods such as fluorescence recovery after photobleaching (FRAP) and multiple particle tracking has provided evidence that dietary fibre can combine with intestinal mucus and produce a layer that significantly delays the transport of lipid digestion products. We have also used similar methods in conjunction with more conventional rheology to show that DNA from the gut epithelium can contribute significantly to the barrier properties of the intestinal mucus layer.The delay in the transport of nutrients to the gut epithelium has implications for the control of gastric emptying and through secretion of GI hormones such as CCK and thus for the satiating ability of foods. It may also have implications for the reabsorption of bile.

Core/Shell Gel Beads with Embedded Halloysite Nanotubes for Controlled Drug Release

“…Alginate fluorescent labelling was carried out following the literature [59]. Sodium alginate (10 mg cm −3 ) was solubilized in sodium bicarbonate (50 mM) and 1.0 M NaOH was used to adjust the pH to 9.…”

Nutritional and antioxidant potential of a desert underutilized legume – tepary bean (Phaseolus acutifolius). Optimization of germination bioprocess

“…Ot is well known that dietary fiber is part of a healthy diet. Studies have shown that the dietary fiber influences the gut physiology and protects against different diseases such as haemorrhoids or cardiovascular disease, atherosclerosis, dyslipidemia, hypertension, and some types of cancer (Kendall et al, 2010;Brownlee, 2011;Mackie et al, 2015;Zhu et al, 2015). Table 2 shows the EAA content of unprocessed and germinated tepary bean flours (UTBF, DGTBF).…”

Implications of static in vitro digestion of starch in the presence of dietary fiber

“…Consumption of a diet with sufficient dietary fiber is recognized as a means of reducing the risk of cardiovascular diseases and diabetes [3,69] . The mechanisms by which these beneficial effects are associated with dietary consumption include increase in viscosity caused by the presence of the fiber (particularly soluble fibers) [4,26,69,70] in the GIT and the ability of the fiber to bind to endogenous enzymes and inhibit their activity [7] . The authors of these studies have associated an increase in viscosity in the presence of fibers in the diet with a reduced rate of gastric emptying, glucose release and absorption.…”

“…For insoluble fibers such cellulose, it is known that the fiber component physically binds to the enzyme and reduces its availability to degrade starch [7] . In the case of soluble gel forming fibers, such as gums, viscosity is key to the glucose release rate and absorption [26,69] . The relevance of static digestion models in nutrition and food science continues to promote the development and growth static simulated digestion (Table 3).…”