VITAMIN D INSUFFICIENCY AFFECTS CALCIUM ABSORPTION EFFECTIVENESS OF PREBIOTICS

Background and objectives: Low Ca intake (CaI) is related to osteoporosis among others pathologies. Passive and active intestinal Ca absorption (Abs) is regulated by vitamin D within limits, which compensate for the lesser CaI. Prebiotics also positively affect Ca Abs by selectively increasing acid lactic bacteria's which releases short-chain fatty acids which improve Ca salts solubility by lowering intestinal pH, and favor colonic epithelial cell proliferation. The aim of the present report was to evaluate the effectiveness of prebiotic to absorb Ca in adult rats feeding a low Ca diet and vitamin D insufficiency. Objectives: The effectiveness of Galacto-oligosaccharides/Fructo-oligosaccharides (GOS/FOS...) mixture to increase CaAbs was evaluated in a model of VD insufficiency (-VD) and established osteopenia. Methods: Female adult Wistar rats were ovariectomized and fed a commercial diet during 15 days postsurgery. Then, rats were divided: 32 fed a diet VD-free (0 IU%) during 45 days to become VD insufficient (-VD) and 16 fed a normal VD diet (100 IU%) (+VD). At day-60, +VD were subdivided in 2 groups and received during 45 days: AIN'93 (control diet)(+VD Ca0.5%); AIN'93 containing 0.3%Ca and 2.5% GOS/FOS® (9:1) (+VD Ca0.3%Prebiotics); -VD were subdivided in 4 groups and received during 45 days: VD free-AIN'93 (-VD Ca0.5%); VD free-AIN'93 containing 0.3%Ca (-VD Ca0.3%); VD free-AIN'93 containing 0.3%Ca and 2.5% prebiotics (-VDCa0.3% Prebiotics) or VD free-AIN'93 containing 0.3%Ca and prebiotics 5% (-VDCa0.3%:Prebioticsx2). Food intake and faeces (F) were collected to determine Ca intake (CaI) and Ca en feces (CaF). Ca Abs% = CaI - CaF/ CaI x 100. Results: Ca Abs % as mean±SD: -VDCa0.5%: 32.71±1.74; -VDCa0.3%: 38.33±2.33; -VD0.3%Prebiotics: 44.71±1.84; -VD0.3%x2Prebiotics: 56.40±1.39; +VD0.3%Prebiotics: 87.45±1.82; +VD0.5%: 67.80±2.21. As expected, VD insufficiency reduced Ca Abs% (-VDCa0.5% and -D0.3% vs. +VDCa0.5%; p