Long-term supplementation of dietary omega-6/omega-3 ratios alters bone marrow fatty acid and biomarkers of bone metabolism in growing rabbits

The long-term effects of different dietary lipid sources with varying ratios of omega-6/omega-3 (omega 6/omega 3) polyunsaturated fatty acids (PUFAs) on the bone marrow fatty acid profile, ex vivo prostaglandin E-2 (PGE(2)) release in bone, and plasma biomarkers of bone metabolism were evaluated in rabbits. Weanling male and female New Zealand white rabbits were randomly assigned to five groups and fed ad libitum on diets containing 70 g/kg of added oil for 100 days as follow: soy bean oil (SBO control), sesame oil (SO), fish oil (FO), DHA algae oil (DHA), and DHA and ARA algae oils (DHA/ARA). The dietary lipid treatments were formulated to provide the following ratios of omega 6/omega 3 fatty acids: 8.7 (SBO), 21.8 (SO), 0.4 (FO), 0.6 (DHA), and 0.7 (DHA/ARA). The bone marrow fatty acid profile of rabbits was significantly influenced by and reflected the dietary lipid treatments. Rabbits fed the FO diet had the highest omega 3 PUFA concentration, and those fed the SBO diet were highest in omega 6 PUFA. Ex vivo PGE(2) level declined progressively as the omega 6/omega 3 dietary ratio declined. Plasma alkaline phosphatase (ALP) activity was significantly higher in male and female rabbits fed the DHA/ARA diet compared with those fed the control, SO, FO, or DHA diets. These results demonstrated that the dietary omega 6/omega 3 ratio modulates bone PGE(2) production and plasma ALP activity in growing rabbits. In addition, the significant elevation in ALP activity in the DHA/ARA fed group proved that algae oils may be promising dietary sources for promoting bone formation during the growing stage. (c) 2012 Elsevier Ltd. All rights reserved.