Effect of vitamin e isoforms differs on bone in c57bl/6j mice fed a high fat diet
In humans and animals, high fat diet (HFD) is associated with low bone density. High fat intake increases production of reactive oxygen species causing increased osteoclast activity and bone loss. Previous studies with Vitamin E, a free radical scavenger, have demonstrated its positive effect on bone. However, no studies have compared the effectiveness across different vitamin E isoforms. In this study, C57BL/6 mice were used as a model of HFD-induced bone loss. Animals were randomized to low fat diet (LFD), HFD, HFD supplemented with alpha tocopherol (HFD-AT), HFD supplemented with gamma tocopherol (HFD-GT), or HFD supplemented with both alpha and gamma tocopherols (HFD-AGT). After 12-weeks, mice were euthanized and bone specimens were collected for analysis. HFD resulted in low fibular bone density and high tibial bone fat content (p<.05) in comparison to LFD. HFD-GT, but not HFD-AT, reduced the negative impact of HFD on BMD. However, HFD-AGT had the lowest BMD, BMC, and percent fat content in tibias. Additionally, HFD-GT noted higher concentrations of alkaline phosphatase (ALP) and n-terminal propeptide of type I procollagen (PINP) compared to LFD, implying an increase in bone growth and formation rate. The effect of increasing HFD-GT treatment on tartrate-resistant acid phosphatase (TRACP) was also significant in comparison to HFD, implicating the impact of bone resorption in combination with bone formation. This data demonstrates that different isoforms of vitamin E, have differing protective effects on bone quality, with GT being the most protective.