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Can eating and body attitudes affect physiological health outcomes in premenopausal women? Prospective 2-year changes in bone, and relationships with ovulation, cortisol and blood pressure.

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Title: Can eating and body attitudes affect physiological health outcomes in premenopausal women? Prospective 2-year changes in bone, and relationships with ovulation, cortisol and blood pressure.
Author: Bedford, Jennifer Lynn
Degree Doctor of Philosophy - PhD
Program Human Nutrition
Copyright Date: 2010
Publicly Available in cIRcle 2010-03-29
Abstract: Cognitive dietary restraint (CDR) is the perception that one is limiting food intake in an effort to achieve/maintain a perceived ideal body weight. Cross-sectional studies suggest CDR is associated with an increased frequency of subclinical ovulatory disturbances (%SOD; anovulation and luteal phase <10 days long) and lower bone mass, possibly mediated by cortisol, a stress hormone. This research was conducted to prospectively examine relationships among CDR, %SOD, 24-hour urinary free cortisol (UFC) and 2-year areal bone mineral density change (ΔaBMD) in non-obese, regularly-menstruating women, aged 19-35. To monitor %SOD, least-squares quantitative basal temperature (LS-QBT) analysis was used. LS-QBT was first further validated against urinary pregnanediol glucuronide (PdG), an indirect indicator of ovulation (n=40, Chapter 2). Relative to PdG, LS-QBT showed excellent detection of ovulatory cycles (97%) but poor detection of anovulatory cycles (25%). Estimated day of luteal onset was correlated between methods (r=0.8, P<0.001). Chapter 3 presents prospective findings (n=123). Women with higher CDR had higher %SOD (56% versus 34%, P<0.001) and higher UFC (28.0 µg/day versus 24.0 µg/day, P=0.021). ΔaBMD did not differ by CDR level. Women with higher %SOD had less positive lumbar spine (L1-4; 0.7% versus 1.9%, P=0.034) and hip (-0.6% versus 0.9%, P=0.001) ΔaBMD, and higher CDR scores (8.7 versus 7.1, P=0.04). UFC was not associated with %SOD or ΔaBMD. Whether eating/body attitudes (EBA) were associated with 12-hour daytime ambulatory blood pressure (ABP) was explored as a secondary objective (n=120, Chapter 4). Women with negative EBA had higher diastolic ABP and mean arterial pressure, independently of weight loss effort. Finally, at baseline (n=137, Chapter 5), UFC was inversely associated with total body bone mineral content (BMC; r= -0.30, P<0.001) and aBMD (r= -0.27, P=0.003); L1-4 aBMD (r= -0.19, P=0.035) and BMC (r= -0.18, P=0.049); and hip BMC (r= -0.23, P=0.011), after adjustment for potential confounders. In summary, findings suggest CDR and other negative EBA may be associated with adverse health outcomes including higher ABP and %SOD. Furthermore, more frequent SOD, which are not apparent to women, were associated with less positive ΔaBMD. However, cortisol may not be the only or most important mediator of these relationships.
URI: http://hdl.handle.net/2429/22824
Scholarly Level: Graduate

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