Interaction between fructooligosaccharides (FOS) and dietary lipids: Effects on mineral absorption and balance, bone mass and biomechanical properties in rats

Abstract

Fructooligosaccharides (FOS) stimulate the mineral absorption in the large intestine, which increases bone mineral retention. Changes in lipid composition have been related to changes on fluidity of enterocytes brush border membranes. Our hypothesis was that dietary lipid composition might influence the effects of FOS on the intestinal absorption of Ca, Mg, Fe and Cu, and some bone characteristics. Male rats (n=24) were fed a 15% lipid diet (soy oil or a 1:0.3 mix of fish and soy oils) or diets containing the same lipid sources supplemented with 10% FOS (Raftilose® Synergy 1) for 15 days. Feces and urine were collected for the evaluation of mineral absorption and balance. At sacrifice, the cecum contents and walls were weighed and the pH was determined in situ. Femurs were collected for Ca analyses (AAS) and bone strength evaluation (3-point bending assay). FOS consumption resulted in an increase (p<0.05) in cecal wall and contents, as well as a decrease in the luminal pH. These effects probably contributed to the higher intestinal mineral absorption (p<0.05) which, except for Mg, was increased by the fish oil (p<0.001). A higher Ca balance and bone retention (p<0.05) was observed in the FOS + fish-oil group with a significant increase in the peak and yield load bone strength variables. The results confirm the positive influence of FOS on mineral absorption and bone parameters which were potentialized by the fish oil.