Whole Body Vibration as a Treatment to Counter Bone Detriment and Obesity Caused by Poor Nutritional Intake
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Consumption of diets high in fat content or carbohydrate content is known to cause obesity and diabetes. In fact the causes and effects of diabetes and obesity are inter-related and are known to have associations with the onset of osteoporosis. Despite the availability of pharmacological treatments, an effective cure for osteoporosis has not yet been developed highlighting the need to ensure optimal, maximum bone growth during the growing years of the skeleton. It is therefore important to identify factors which can be detrimental or beneficial to healthy bone deposition or increase rate of bone resorption. It is known that nutrition plays a major role in bone development. The first part of this project was aimed at documenting the hypothesized detrimental effects of a high-fat diet and high-fructose diet consumption on the morphology, density, mass and architecture of load-bearing bones in mice over a short (6 week) and long (15 week) study period. We also proposed that changes in bone tissue will be accompanied by and will be related to increases in bodily fat content and disturbances in glycemic balance. Results showed that the high-fructose diet consumption led to significant decreases in bone quantity and density with deterioration of trabecular micro-architecture over a 6 week period. The fructose diet also caused severe decreases in insulin and hyperglycemia accompanied with loss of body mass. Both the increased levels of glucose and decreased weight bearing were found to have negative implications on bone volume and density. The high-fat diet was detrimental to bone quantity, density and structure over a longer (15 week) period and attrition of bone tissue was accompanied by large increases in bodily fat content. Exercise is recommended as being the most effective non-pharmacological therapy to increase bone formation, decrease adipogenesis and prevent obesity related complications such as diabetes. But compliance to regular exercise is low and strenuous or regular exercise regimens are not suited to some populations of individuals such as the elderly. Recently it has been proposed that high frequency low magnitude mechanical signals which mimic the low level forces generated by muscular contractions during daily activity can elicit an anabolic bone response and decrease adipogenesis. However, the response of the skeleton to WBV treatment has varied with skeletal site, species of animal, sex, genetic background and age which are all factors that may modulate the sensitivity of the skeleton to mechanical signals. We proposed that composition of daily nutritional intake is another such factor which can alter the body's response to WBV. The second part of this project aimed at testing the efficacy of whole body vibration therapy in increasing bone formation in animals suffering from the catabolic skeletal effects of daily high-fat and high-fructose consumption over 6 weeks or 15 weeks. We found that response of load-bearing bones to WBV varied from being catabolic to no-response to anabolic depending on diet-type and duration of treatment. In this research, the efficacy of WBV in eliciting an anabolic response from bone tissue was not strongly supported except in the high-fat diet group which saw an anti-resorptive effect. Application of WBV for 6 weeks was able to attenuate the severe glucose-insulin imbalances caused by high-fructose diet consumption. Finally, WBV did not have any effects on the fat deposition in any diet group. The results presented in this thesis emphasize the damaging effects of high-fat and high-fructose diets on load-bearing bones, metabolic health and body composition. Further, the data suggests the potential of WBV as a tool to ameliorate not only the bone loss caused by poor nutrition and also to regulate metabolic balance. Finally, our findings indicate that the sensitivity of the skeleton to WBV can be different in populations that have different dietary lifestyles, thus emphasizing the necessity of taking diet into account as an important factor that will affect efficacy while developing WBV as a treatment for osteoporosis and obesity.