Palm vitamin E is comparable to α-tocopherol in maintaining bone mineral density in ovariectomised female rats

Summary:

Vitamin E has been shown to affect bone metabolism. In this study we determined the effects of palm vitamin E and α-tocopherol on bone metabolism. Sprague-Dawley female rats fed with normal rat chow were divided into 4 groups and supplemented with either palm vitamin E 30 mg/kg rat weight, palm vitamin E 60 mg/kg rat weight or α-tocopherol 30 mg/kg rat weight. One group was not supplemented. Half of these rats were ovariectomised before supplementation was given for 10 months. As expected, bone mineral density of the ovariectomised rats fed on normal rat chow diet was lower compared to the intact rats. However, these changes were not seen in the supplemented group of rats. Both intact and ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight had a lower bone calcium content in both femoral and vertebral bones whilst rats fed palm vitamin E 60 mg/kg rat weight or α-tocopherol 30 mg/kg rat weight were able to maintain bone calcium content. Alkaline phosphatase activity was elevated in ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight and α-tocopherol 30 mg/kg rat weight compared to the intact rats. Alpha-tocopherol also reduced the activity of tartrate-resistant acid phosphatase post-ovariectomy. These findings indicate that both palm vitamin E and α-tocopherol maintained bone mineral density in ovariectomised rats but caused conflicting effects on bone calcium content. Further study is needed in order to determine the mechanisms involved.

Key words:

Vitamin E - bone mineral density - ovariectomy - rats

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1 Ovx = ovariectomised; L3-L5 = 3^rd lumbar to 5^th lumbar vertebrae; L4 = 4^th lumbar vertebra; RC = normal rat chow; PVE30 = palm vitamin E 30 mg/kg rat weight; PVE60 = palm vitamin E 60 mg/kg rat weight; ATF = α-tocopherol 30 mg/kg rat weigh; * indicate significant difference between the intact and ovariectomised group of rats (p < 0.05)

2 Ovx = ovariectomised; L3-L5 = 3^rd lumbar to 5^th lumbar vertebrae; L4 = 4^th lumbar vertebra; RC = normal rat chow; PVE30 = palm vitamin E 30 mg/kg rat weight; PVE60 = palm vitamin E 60 mg/kg rat weight; ATF = α-tocopherol 30 mg/kg rat weight; Groups which share the common alphabet indicate significant difference (p < 0.05)

3 Ovx = ovariectomised; L3-L5 = 3^rd lumbar to 5^th lumbar vertebrae; L4 = 4^th lumbar vertebra; RC = normal rat chow; PVE30 = palm vitamin E 30 mg/kg rat weight; PVE60 = palm vitamin E 60 mg/kg rat weight; ATF = α-tocopherol 30 mg/kg rat weight; Groups which share the common alphabet indicate significant difference (p < 0.05). **,* indicate significant difference between the intact and ovariectomised group of rats (p < 0.01 and p < 0.05 respectively) ALP = alkaline phosphatase; TRAP = tartrate-resistant acid phosphatase