Effect of oligofructose or dietary calcium on repeated calcium and phosphorus balances, bone mineralization and trabecular structure in ovariectomized rats

Abstract

We investigated the effects of dietary oligofructose and Ca on bone structure in ovariectomized rats, using microradiography and histomorphometry. Ninety-six animals were allocated to seven experimental groups: G1, sham-operated; G2-G7, ovariectomized. Semi-purified diets containing 5 g Ca/kg (recommended content) without oligofructose (G1, G2) or with 25, 50 or 100 g oligofructose/kg (G3, G4, G5) or 10 g Ca/kg (high content) without oligofructose (G6) or with 50 g oligofructose/kg (G7) were fed for 16 weeks. At the recommended level of Ca, high oligofructose (G5) increased femur mineral levels in ovariectomized rats, while medium oligofructose did so at high Ca. Increasing Ca in the absence of oligofructose did not increase femur mineral content. Trabecular bone area (%) analysed in the tibia was 10·3 (SEM 1·2) (G1), 7·7 (SEM 0·6) (G2), 9·3 (SEM 0·7) (G3), 9·4 (SEM 1·0) (G4), 9·5 (SEM 0·7) (G5), 10·2 (SEM 0·8) (G6), and 12·6 (SEM 0·8) (G7). At the recommended level of Ca, 25 g oligofructose/kg prevented loss of trabecular area due to increased trabecular thickness, while 50 or 100 g oligofructose/kg increased trabecular perimeter. At high Ca, oligofructose prevented loss of bone area due to increased trabecular number but similar thickness (G7 v. G6). When Ca was raised in the presence of oligofructose (G7), trabecular area and cortical thickness were highest, while loss of trabecular connectivity was lowest of all groups. At the same time, lumbar vertebra Ca was higher; 44·0 (SEM 0·8) (G7) compared with 41·6 (SEM 0·8) (G2), 41·4 (SEM 0·7) (G4), and 40·5 (SEM 1·0) mg (G6). We conclude that ovariectomy-induced loss of bone structure in the tibia was prevented but with different trabecular architecture, depending on whether dietary Ca was increased, oligofructose was incorporated, or both. Oligofructose was most effective when dietary Ca was high.Oligofructose: Calcium and phosphorus balance: Osteoporosis: Trabecular structure:Bone qualityCertain groups of carbohydrates are not digested by gastrointestinal enzymes but are fermented by the microbial flora in the large intestine (Roberfroid et al. 1998). Non-digestible oligosaccharides (NDO), including inulin, oligofructose and fructo-oligosaccharides, and galacto-oligosaccharides, as well as lactulose, maltitol and resistant starch, were studied for their gastrointestinal effects. Several effects of NDO on the colonic milieu, composition of the microflora, production of microbial metabolites (Gibson et al. 1995) and mineral metabolism have been described (for reviews, see ScholzAhrens et al. 2001ScholzAhrens et al. , 2002. A potential for benefits to the host's health was postulated. In this regard, consensus was achieved that there is promising evidence for positive effects on mineral metabolism and thus a potential for prevention of osteoporosis (van Loo et al. 1999). Most of the scientific evidence for the effects of NDO is based on the results of experiments with rats, where these carbohydrates increase the availability of Ca (Delzenne et al.

Differential Expression of Vascular Endothelial Growth Factor in Glucocorticoid-related Osteonecrosis of the Femoral Head

“…A crosstalk between osteoblasts and adjacent endothelial cells in view of altering the vascularity of the bone-forming site is also possible. The expression of VEGF can be enhanced by several growth factors, such as PGE2, FGF-2, TGF-b1, IGF-1, and BMP-4, -2, and -6 [25]. Basic fibroblast growth factor stimulates VEGF release through p42/p43 mitogenactivated protein (MAP) kinase in osteoblasts and negatively regulates it by p38 MAP kinase [28].…”

Effect of oligofructose-enriched inulin on bone metabolism in girls with low calcium intakes

“…Indeed, the efficiency of measuring bone metabolism biomarkers has been demonstrated (van Coeverden et al, 2002). Studies in diverse animal models have shown the beneficial effect of inulin and oligofructose in the colonic epithelium, stimulating proliferation in the crypts, increasing the concentration of polyamines, changing the profile of mucins and modulating endocrine as well as immune functions (Roberfroid, 2005;Budiño et al, 2005), and on calcium absorption and bone mass (Roberfroid, 2002;Scholz-Ahrens et al, 2002;Cashman, 2003;Kruger et al, 2003;Lobo et al, 2006). This was also observed in adolescents (Griffin et al, 2002), showing a significant increase in calcium absorption with oligofructose-enriched inulin supplementation (8 g/d of Synergy1).…”

Prebiotics: An update

“…Although the small intestine is the principal site of calcium absorption in humans, significant amounts may be absorbed throughout the length of the gut, consequently maximising of colonic effects is desirable. Numerous animal studies have indicated that prebiotics increase calcium, zinc and magnesium absorption from the colon (Delzenne et al, 1995;Younes et al, 2001;Coudray et al, 2003;Raschka & Daniel, 2005a), resulting in increased bone density and bone trabecular structure (Ohta et al, 2002;Scholz-Ahrens et al, 2002;Raschka & Daniel, 2005b). Raschke and Daniel (2005b) reported increased absorption, retention and femur content of calcium, zinc and magnesium in a rat model only when the basic diet of the control group contained no intrinsic fructans and when the mineral demand was particularly high, as during growth.…”

“…(reviewed recently by Scholz-Ahrens et al, 2007). The intake of prebiotics acidifies the intestinal contents, which aids the solubilisation of minerals .…”

“…Bacterial fermentation products, predominantly lactate and butyrate, enlarge the absorption surface by promoting proliferation of enterocytes (reviewed by Scholz-Ahrens et al, 2001). Other mechanisms that have been proposed include an increased capacity of the calcium transporters (calbindin) in the colon (Ohta et al, 1998), suppression of bone resorption rate relative to bone formation rate (Zafar et al, 2004), release of bone-modulating factors such as phytoestrogens (Ohta et al, 2002) and improvement in gut health and gut-associated immune defence (Scholz-Ahrens et al, 2007). Raschka and Daniel (2005a) studied the effects of fermentation of inulin-type fructans on transepithelial calcium transport in the large intestine of rats.…”