Effects of two fermentable carbohydrates (inulin and resistant starch) and their combination on calcium and magnesium balance in rats

Abstract

Resistant starch and inulin are complex carbohydrates that are fermented by the microflora and known to increase colonic absorption of minerals in animals. The fermentation of these substrates in the large bowel to short-chain fatty acids is the main reason for this increase in mineral absorption. The purpose of the present study was to examine the potential synergistic effect of a combination of these two fermentable carbohydrates. For this purpose, thirty-two adult male Wistar rats weighing 200 g were used in the present study. The rats were distributed into four groups, and fed for 21 d a fibre-free basal purified diet or diet containing 100 g inulin, or 150 g resistant starch (raw potato starch)/kg diet or a blend of 50 g inulin and 75 g resistant starch/kg diet. After an adaptation period of 14 d, the rats were then transferred to metabolic cages and dietary intake, faeces and urine were monitored for 5 d. The animals were then anaesthetized and caecal Ca and Mg absorption were measured. Finally, the rats were killed and blood, caecum and tissues were sampled. Ca and Mg levels were assessed in diets, faeces, urine, caecum and plasma by atomic absorption spectrometry. Our results confirmed that inulin and resistant starch ingestion led to considerable caecal fermentation in the three experimental groups compared with the control group diet. Moreover, both carbohydrates significantly increased the intestinal absorption and balance of Ca and Mg, without altering the plasma level of these two minerals. Interestingly, the combination of the studied carbohydrates increased significantly ðP , 0 : 05Þ the caecal soluble Ca and Mg concentrations, the apparent intestinal absorption and balance of Ca, and non-significantly the plasma Mg level. In conclusion, a combination of different carbohydrates showed synergistic effects on intestinal Ca absorption and balance in rats. Further studies with other types of carbohydrate combinations should be carried out to extend these findings.

Effects of inulin supplementation on selected faecal characteristics and health of neonatal Saanen kids sucking milk from their dams

“…In the current study, faecal pH was lower for EG in comparison to CG on day 14 and 28 (Table 2). Inulin is a highly fermentable substrate (Propst et al, 2003) and SCFA produced in response to inulin fermentation in the colon may decrease faecal pH (Younes et al, 2001). Hesta et al (2001) observed that faecal pH was decreased in adult cats when 6% or 9% OF was added to the diet, but there was no significant decrease in faecal pH when 3% or 6% inulin was added to the diet.…”

Breadmaking performance and technological characteristic of gluten-free bread with inulin supplemented with calcium salts

“…Besides luminal pH reduction, their effect was accompanied by modifications in the architecture of the rat's intestinal mucosa that arise as a consequence of the increase in cellularity and the number of crypts, mechanisms that could contribute to an increase in the absorptive surface for mineral uptake [32]. Younes et al [33] analysing intestine fermentation of inulin and resistant starch in rats reported increased absorption and balance of Ca and Mg, without altering the plasma level of these two minerals. Inulin-type fructans added to the diet increased the retention of calcium in the whole body [34] and affects positively bones mineralisation [35,36].…”

Dietary fibre in infancy and childhood

“…In adults it has been well established that a high-fibre diet has very little impact on mineral balance, but there have been almost no studies in children. However, several animal studies have demonstrated that an increased intake of fermentable material increases the amount of Ca absorbed in the large intestine (Lopez et al 1998;Scholz-Ahrens et al 2001;Younes et al 2001). This increase may be due to the release of trapped Ca from the fermented material and the low colonic pH.…”