Palm-oil derived vitamin E as prophylaxis against osteoporosis in chronic glucocorticoid excess: An in vivo study

Palm oil from the fruit of the palm tree, Elais guineensis is rich in vitamin E, a strong antioxidant. Palm vitamin E (PVE) is composed of 80% tocotrienols (γ, α, δ-isomers), and 20% α-tocopherol. Our earlier studies showed that oxidative stress induced by ferric ions in a male rat model resulted in reduced bone density. This was prevented by supplemention with oral PVE extract. Osteoporosis is a known side effect of longterm treatment with systemic glucocorticoids. In this study we determined the effects of PVE on cellular bone histomorphometry and biomechanical strength in a rat model of glucocorticoid-induced bone loss. 3 month old male Sprague-Dawley rats were divided into groups of 10: (i) Adrenalectomised (Adrx) + 120 µg/kg/day intramuscular (IM) dexamethasone (Dexa) + oral PVE 60 mg/kg/day. (ii) Adrx + Dexa + vehicle oral palm olein 0.1 ml/kg/day. (iii) Sham operated + vehicle palm olein 0.05 ml/kg/day IM + 0.1 ml/kg/day orally. The PVE was a gift from Sime Darby Ltd. and its composition was similar to Gold Tri-E™. The treatments were given for two months. The left femora were analyzed for cellular bone histomorphometry and the right femora were tested for biomechanical strength (3-point bending test). The results showed that longterm glucocorticoid treatment significantly decreased Osteoblast Surface (Ob.S) [Sham 39.71+1.88, Adrx+Dexa 15.33+2.77, p = 0.011], while Osteoid Surface/Bone Surface (OS/BS) significantly increased compared to Sham [Sham 3.64+0.55, Adrx+Dexa 10.54+ 1.52, p = 0.01]. Supplementation with PVE maintained the Ob.S (Adrx+Dexa+PVE 40.31+7.6, p = 0.907) and the OS/BS (Adrx+Dexa+VE 6.9+0.72, p = 0.121) comparable to Sham. Biomechanical strength (Load to fracture) were reduced in the glucocorticoid group compared to Sham [Sham 133.13+5.94, Adrx+Dexa 108.18+4.15, p = 0.016]. Supplementation with PVE maintained bone strength comparable to Sham [118.45+0.071' p = 0.718]. Thus PVE may be developed as a prophylactic anti-osteoporotic agent.