The effect of dietary fibre isolates on gastric secretion, acidity and emptying

Abstract

1. In six volunteers, the effect of intragastric administration of different water-soluble chemical isolates of dietary fibre on gastric secretion, acidity and emptying was studied.2. At 30 min after administration of the test meals, the stomach contents were completely aspirated and the volume, pH, phenol red concentration, totai titratable acidity and different electrolytes were measured.3. Compared with the control meal, the pH and unionized (combined) hydrogen concentrations were significantly higher (P < 0.05) following most of the fibre-containing meals, while the total titratable acid concentration was not significantly different. None of the fibre-containing meals appreciably altered the volume or type of gastric secretion but had a low-grade variable effect on gastric emptying. 4. It is concluded that most dietary fibre isolates, although having a definite and notable buffering effect on the acid in the stomach, have a minimal effect on gastric secretion and a variable and small effect on gastric emptying.There have been several reports of studies investigating the effects of dietary fibre on different aspects of gastric function (Royal College of Physicians of London, 1980). One of the well-documented observations is the effect of fibre on gastric emptying, but most of the evidence on which it is based is indirect. The few direct studies to date are conflicting and difficult to interpret (McCance et al. 1953;Grimes & Goddard, 1977;Carryer et al. 1982;Holt et al. 1979). Although the reason for the apparent difference in findings is partly due to differences in methodology, of much more importance may be the heterogeneity of the fibre type used and the unavoidable variation in the levels of the different chemical components. Another aspect of gastric function which has attracted attention recently is the effect of fibre on acid secretion. In vitro studies show that fibre, because of its ion-binding properties, binds different acids (McConnell et al. 1974; Jalan et al. 1977). There is also some suggestion from human studies that dietary fibre may have some acid-buffering effect (Lennard-Jones et al. 1968;Jalan et al. 1979). This is further supported by epidemiological observations and by two clinical trials which show that the frequency of duodenal ulcer recurrence was much reduced while on a diet with a high-fibre content (Malhotra, 1978;Rydning et al. 1982). As in gastric emptying, the evidence for the possible action on gastric acidity is mainly indirect and there is a need for standardization of the fibre source. There is also lack of identification of the chemical(s) responsible for this action from the heterogenous mixture that constitutes the entity recognized as dietary fibre.It is desirable to investigate the effect of fibre as eaten, but the chemical complexity of the substance makes interpretation of the results very difficult. Moreover, using fibre in its natural form may introduce other nutrient variables which may have an effect on gastric function. Alternatively, studies using defined chemi...

A matrix effect in pectin‐rich fruits hampers digestion of allergen by pepsin in vivo and in vitro

“…An influence of increased viscosity in a sample or pH changes in gastric acid resulting from the presence of polysaccharides on gastric digestion was observed by other researchers in animals [26–30]. We obtained partial protection when pectin was added to the purified kiwi TLP in vitro .…”

“…We applied the same standardized assay to study the susceptibility of the proteins tested in our study to the pepsin digestion in the presence of fruit matrix, pectin and viscosity phenomena due to a high sugar content with the same purpose. An influence of increased viscosity in a sample or pH changes in gastric acid resulting from the presence of polysaccharides on gastric digestion was observed by other researchers in animals [26][27][28][29][30]. We obtained partial protection when pectin was added to the purified kiwi TLP in vitro.…”

Chemical Composition of Garden Cress (Lepidium sativum) Seeds and Its Fractions and use of Bran as a Functional Ingredient

“…The viscosity of the formulation in the present study is higher than that of the proprietary formulation at slurry concentration ranging from 1-5%. Its consistency is not affected by variations in acidity or alkalinity of the aqueous suspension exhibiting buffering action (Table 6), which indicated its beneficial effect in controlling acidity and similar complications of the digestive tract [33]. The formulation or the bran can be mixed with other traditional foods such as chapathi or bread to enhance the dietary fibre content.…”

Gastric emptying of a solid meal is accelerated by the removal of dietary fibre naturally present in food.

“…This has been clearly shown for liquid meals. In fact, it has been repeatedly shown that pectin and guar gum delay the gastric emptying of glucose solutions, reducing the glycaemic response, [8][9][10][11][12][13] and that this delay is mediated, at least in short term experiments, by the increase in viscosity of gastric contents.14 15 The relation between postprandial glycaemia and gastric emptying is more complex when liquid starch is ingested, as other factors, such as the susceptibility to ao-amylase,16 play a part. The effect of fibre on solid meals is even more controversial.…”