Tocotrienols are needed for normal bone calcification in growing female rats

Abstract

In this study the effects of vitamin E deficiency and supplementation on bone calcification were determined using 4-month-old female Sprague-Dawley rats. The rats weighed between 180 and 200 g. The study was divided in three parts. In experiment 1 the rats were given normal rat chow (RC, control group), a vitamin E deficient (VED) diet or a 50% vitamin E deficient (50%VED) diet. In experiment 2 the rats were given VED supplemented with 30 mg/kg palm vitamin E (PVE30), 60 mg/kg palm vitamin E (PVE60) or 30 mg/kg pure α-tocopherol (ATF). In experiment 3 the rats were fed RC and given the same supplements as in experiment 2. The treatment lasted 8 months. Vitamin E derived from palm oil contained a mixture of ATF and tocotrienols. Rats on the VED and 50%VED diets had lower bone calcium content in the left femur compared to the RC group (91.6 ± 13.3 mg and 118.3 ± 26.0 mg cf. 165.7 ± 15.2 mg; P < 0.05) and L5 vertebra (28.3 ± 4.0 mg and 39.5 ± 6.2 mg compared with 51.4 ± 5.8 mg; P < 0.05). Supplementing the VED group with PVE60 improved bone calcification in the left femur (133.6 ± 5.0 mg compared with 91.6 ± 13.3 mg; P < 0.05) and L5 vertebra (41.3 ± 3.3 mg compared with 28.3 ± 4.0 mg; P < 0.05) while supplementation with PVE30 improved bone calcium content in the L5 vertebra (35.6 ± 3.1 mg compared with 28.3 ± 4.0 mg; P < 0.05). However, supplementation with ATF did not change the lumbar and femoral bone calcium content compared to the VED group. Supplementing the RC group with PVE30, PVE60 or ATF did not cause any significant changes in bone calcium content. In conclusion, vitamin E deficiency impaired bone calcification. Supplementation with the higher dose of palm vitamin E improved bone calcium content, but supplementation with pure ATF alone did not. This effect may be attributed to the tocotrienol content of palm vitamin E. Therefore, tocotrienols play an important role in bone calcification.