Calcium–inulin wheat bread: prebiotic effect and bone mineralisation in growing rats

Abstract

The nutritional performance of wheat bread prepared with calcium carbonate and inulin was studied in growing rats fed with three diets (BD: diet containing bread with calcium and inulin, SD: diet with synergy1® and CD: diet control-AIN 93G-) up to 60 days. Animals fed with BD consumed less diet and presented a caecal pH (5.5) lower than that of the CD group (7.0) with the highest amount of anaerobic micro-organisms (1.68 × 1010 cfu g−1) at 23 days. Microbiota profiles (DGGE) indicated that BD groups presented 66% of similarity and greater variability than the CD group, suggesting changes due to the prebiotic effect of inulin. In the BD group, calcium apparent absorption (AAC a: 83%), bone mineral content (18 g kg−1), proximal tibia density (242 mg cm−2) and bone volume (BV: 41%) were higher than in the CD group. The decrease in pH due to fermentation in the large intestine increased calcium bioavailability. Although all variables studied on animals fed with diets containing the prebiotic were improved with respect to a control without inulin, in the case of bread diet, many of them were similar to those of the positive control. Consequently, the prebiotic effect was not altered during the baking process. Results suggest that wheat bread, a highly consumed product throughout the world, is an adequate vehicle for including calcium and inulin in healthy food.