The effect of inulin-type fructans on bone mineral content (Ca, Mg, P, and Zn) was investigated not only in rats fed a standard diet76,109,111,133,135 or a diet supplemented with phytic acid112 but also in ovariectomized female rats.120,121 136 Results are somehow contradictory.
In their early study to investigate the effect of oligofructose (5% w/w in diet for 31 d) on mineral absorption, Ohta et al. have reported no effect on femur dry weight but a small significant increase in ash (+2.8%, p < 0.001), Ca (+7.8% p < 0.001), and Mg (+5% p < 0.05) contents.109 In a study aimed primarily at investigating if coprophagy significantly influenced Ca and Mg absorption in rats, the same research group has shown that oligofructose (5% w/w in diet for 10 d) significantly increased Ca (+20% p < 0.001) but not Mg content in the femur.111 These data were not confirmed in a later publication that reported no effect of oligofructose (5% w/w in diet) on Ca and Mg concentrations in the femur after direct infusion of these minerals into the stomach.76 However, after feeding oligofructose (5% w/w in diet) for a longer period (8 weeks), Takahara et al. have reported a significant increase in the concentration not only of Ca but also of Mg and P in three regions of the rat femur bone surface, i.e., distal metaphysis, the middle of diaphysis, and neck.133 Moreover, Ca concentration in bone correlated with absorbed Ca (r = 0.72; p < 0.001). Similarly, and after ash analysis, Richardson et al. concluded that feeding (for 12 weeks) male Fisher 344 rats a diet containing either oligofructose or inulin significantly increased Ca concentration in the femur (+14 and +8%, respectively).136 Using whole body dual x-ray absorptiometry, Roberfroid et al. have also reported that dietary inulin (5 and 10% w/w in diet) increased bone mineral content (p = 0.02) in rats fed diets with low (0.2%), recommended (0.5%) or high (1%) Ca content.135 The effect was similar at 5 or 10% (w/w) inulin in the diet and it was significant at all time points between 9 and 22 weeks.
Adding phytic acid (7% w/w) to the diet had no effect on Ca or Mg content but reduced Zn content (D25%) of rat tibia after 3 weeks. Feeding inulin (10% w/w) increased Mg femur concentration (+13%) both in rats fed the standard and the phytate-containing diet. It restored the Zn concentration back to the control value. But it had no significant effect on Ca content.113
Ovariectomy (OVX) in the adult or aged rat is an accepted method to simulate human postmenopausal state.119 In adult ovariectomized female rats, oligofructose effectively prevented loss of bone mineral content. The preventive effect in the femur was more prominent after 8 weeks than after 16 weeks while in the lumbar vertebra it occurred persistently over 16 weeks but with less magnitude. The addition of 5% oligofructose prevented bone loss significantly in the femur and lumbar vertebra in the presence of high dietary calcium (1%) but not at 0.5%. At 0.5% calcium 10% oligofructose were needed to significantly increase bone mineralization, and this was only observed in the femur.120 In the same experimental model, Zafar et al. reported that feeding (3 weeks) the inulin mixture oligofructose-enriched inulin Synergy 1 (5% w/w in diet) signifcantly increased femoral Ca content (+7%; p < 0.05).120
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A time for giving and receiving, getting closer with the ones we love and marking the end of another year and all the eating also. We eat because the food is yummy and plentiful but we don't usually count calories at this time of year. This book will help you do just this.