膳食纤维对大鼠钙平衡及骨生物力学性能的影响

目的：研究不同结构的膳食纤维对钙平衡及生物力学性能的影响。方法：以大鼠作为动物模型分组饲养，分别饲喂含有50 g/kg麦麸、纤维素、木聚糖、果胶、菊粉、魔芋胶及其混合物的饲料。利用原子吸收光谱法检测饲料、粪便、尿样、股骨中钙含量；利用电解质分析仪测定血清中的总钙、游离钙、结合钙浓度；用三点弯曲法检测股骨的最大载荷。比较摄入不同膳食纤维大鼠钙吸收、血钙水平、尿钙流失、钙保留率、骨钙含量、骨的生物力学性能等参数的差异。结果：在钙吸收率方面，麦麸、纤维素组高于木聚糖、果胶、菊粉、魔芋组，其中木聚糖和魔芋组与麦麸组具有极显著差异（P<0.01）；在尿钙日排出量方面，木聚糖和纤维素组低于其余各组；在钙保留率方面，果胶组最低，处于负钙平衡；在血清钙水平方面，麦麸组血清游离钙浓度和其余实验组没有显著性差异（P>0.05），但麦麸组结合钙和总钙浓度均高于其他各组；在骨钙含量和骨生物力学性能方面，果胶组明显低于其他各组，木聚糖组的骨最大载荷高于其他各组。结论：麦麸和纤维素等低发酵型膳食纤维的肠道钙吸收率高于木聚糖、果胶、菊粉、魔芋等高发酵型膳食纤维；木聚糖有助于提高大鼠骨生物力学性能；不同膳...

Effects of Dietary Fibers on Calcium Balance and Bone Biomechanics in Rats

Objective: To study the effects of dietary fibers with different structures on calcium balance and biomechanical properties. Methods: Rats were fed a basal diet supplemented with 50 g/kg wheat bran, cellulose, xylan, pectin, inulin, konjac gum or their mixture. The contents of calcium in diets, feces, urine and femur were detected by atomic absorption spectrometry (AAS). The levels of total calcium, free calcium and bound calcium in serum were measured by an electrolyte analyzer. The maximum load of femur was measured by a three-point bending method. The effects of different dietary fibers on calcium absorption, blood calcium level, urinary calcium loss, calcium retention, bone calcium content and bone biomechanical properties were compared. Results: The calcium absorption rates in the wheat bran and cellulose supplementation groups were higher than those in the xylan, pectin, inulin and konjac supplementation groups, and the difference between the xylan and konjac supplementation groups and the wheat bran supplementation group was significant (P < 0.01). The level of urinary calcium in the xylan and cellulose supplementation groups were lower than that in the other groups. The pectin supplementation group had the lowest calcium retention rate and showed a negative calcium balance. There was no difference in serum free calcium level between the wheat bran supplementation group and the other groups (P > 0.05), but the concentrations of bound calcium and total calcium in the wheat bran supplementation group were higher than those in the other groups. The bone calcium content and bone biomechanical properties in the pectin supplementation group were significantly lower than those in the other groups, and the maximum load of femur was the highest in the xylan supplementation group. Conclusion: The intestinal calcium absorption of low fermentable dietary fibers such as wheat bran and cellulose is higher than that of high fermentable dietary fibers such as xylan, pectin, inulin and konjac. Xylan can improve the biomechanical properties of rat bones. Different dietary fibers have different effects on calcium absorption, bone calcium content and calcium balance in rats.