"This research is the first published work to demonstrate that supplemental vitamin E supports bone growth," says food scientist and nutritionist Bruce Watkins, associate professor at Purdue. Watkins is presenting additional findings on his research with vitamin E at the American Oil Chemists' Society annual meeting May 1 in Indianapolis.
Both Watkins and his collaborator, bone biologist Mark Seifert, associate professor at the Indiana University School of Medicine, stress that the results don't necessarily apply to humans. "Because bone growth is a little different in birds than in people, we need to be careful not to directly extrapolate research findings from any animal model to humans," Seifert says. Researchers commonly use chicks, mice and rats when they study bone growth and development.
Watkins and Seifert found that when chicks were given extra vitamin E, the rate of bone formation in the spongy ends of leg bones was greater than that in chicks not given the supplement. The results, published last summer in Calcified Tissue International, indicate that vitamin E increases the rate of bone formation and may slow natural bone breakdown.
In both cases, Watkins says, vitamin E most likely exerts its influence as an antioxidant by protecting cells from the damaging effects of free radicals, molecules that chemically break down fats, proteins and DNA in the body. Apparently, vitamin E protects bone-forming cells from free radicals and helps those cells produce new bone.
Of the several different antioxidant vitamins in the human diet, experts who look at ways to reduce stress in our bodies concentrate on vitamin E, vitamin C and beta-carotene. Vitamin E is the most potent of the three, which is one reason Watkins chose to study it.
"The whole reason we started looking at vitamin E in bone growth was that we noticed that there was much more polyunsaturated fat in bone than in cartilage," Watkins says. Free radicals break down polyunsaturated fatty acids into reactive molecules that, along with the free radicals, could impair bone growth, he says. Watkins decided to look at vitamin E as a way to stop the free radical damage and improve bone growth.
According to subsequent findings published by Watkins and co-workers this year in the Proceedings of the Society for Experimental Biology and Medicine, vitamin E specifically reverses the damaging effects of the reactive molecules that can form from polyunsaturated fatty acids.
Watkins says he and Seifert plan future experiments to measure the strength of bones in rats grown with and without supplemental vitamin E. These experiments will help the researchers understand vitamin E's role in supporting bone growth in the young and will help predict how human bone reacts to the vitamin.
Watkins says he believes that their findings support the general recommendation that children and adults need to eat balanced diets for the best bone growth and health. Vitamin E may help bones adapt to changes in weight and activity in adults and the elderly, he says.
"We suspect that dietary vitamin E has a specific role in maintaining normal bone formation and in reducing oxidative stress," Watkins says. He says that vitamin E also might benefit bone healing.
"Our research may have implications in reducing risk for osteoporosis if vitamin E reduces bone breakdown and enhances bone formation," Watkins says. "Also, vitamin E has been used with some success in reducing the severity of inflammatory arthritis in the elderly."
Good sources of vitamin E are fruits, nuts and vegetables, according to Watkins. Corn and soybean oils also contain some of the vitamin. However, cooking and exposure to moisture and air can reduce the amounts of the vitamin in vegetable oils.
Sources: Bruce Watkins (765) 494-5802; Internet email@example.com
Mark Seifert (317) 274-3353; Internet seifert@anatomy.IUPUI.edu
Writer: Rebecca J. Goetz (765) 494-0461; Internet firstname.lastname@example.org
NOTE TO JOURNALISTS: Copies of the article in Calcified Tissue International are available from Rebecca J. Goetz, (765) 494-0461. A color photo of Bruce Watkins examining a chicken bone is available from Purdue News Service, (765) 494-2096. Ask for the photo called "Vitamin E/Watkins." or download here
Vitamin E Stimulates Trabecular Bone Formation and Alters Epiphyseal Cartilage Morphometry
H. Xu and B.A. Watkins, Department of Food Science, Lipid Chemistry and Metabolism Laboratory, Purdue University; and M.F. Seifert, Department of Anatomy, Indiana University School of Medicine.
The effects of dietary vitamin E (VIT E) and lipids on tissue lipid peroxidation and fatty acid composition, epiphyseal growth plate cartilage development, and trabecular bone formation were evaluated in chicks. A 2x2 factorial design was followed using two levels (30 and 90 IU/kg of diet) of dl-alpha-tocopherol acetate and two different dietary lipids. The basal semipurified diet contained one of the following lipid treatments: anhydrous butter oil (40 g/kg) + soybean oil (60 g/kg), [BSO], or soybean oil (100 g/kg), [SBO]. After 14 days of feeding, the level of alpha-tocopherol in plasma was higher and thiobarbituric acid reactive substances (TBARS) were less in plasma and liver of chicks supplemented with 90 IU of VIT E compared with those given 30 IU of VIT E. Body weights and tibiotarsal bone lengths were not affected by the dietary treatments. Saturated fatty acids (14:0, 15:0, 16:0, 17:0, and 18:0) were increased in tibiotarsal bone of chicks fed the BSO diet. In contrast, total polyunsaturated fatty acids and the ratio of unsaturated fatty acids/saturated fatty acids were higher in plasma of chicks fed SBO compared with the values from chicks fed the BSO diet. In contrast, total polyunsaturated fatty acids and the ratio of unsaturated fatty acids/saturated fatty acids were higher in plasma of chicks fed SBO compared with the values from chicks fed BSO. The thickness of the entire growth plate cartilage and the lower hypertrophic chondrocyte zone was significantly greater in chicks fed 90 IU/kg of VIT E. Kinetic parameters on bone histomorphometry indicated that mineral apposition rate was higher in chicks fed 90 IU/kg of VIT E. The interaction effect between the VIT E and BSO treatments led to the highest trabecular bone formation rate among the groups. These data suggest that VIT E protects against cellular lipid peroxidation in cartilage to sustain normal bone growth and modeling.
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