Dietary/supplement intake and bone mineral density.
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Biomedical subjects
Publications and source records attributed to E R Brooks.
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The lateral (LAT) spine scan has been suggested as a more sensitive measure than posterior-anterior (PA) scanning for assessing age-related bone loss in normal-weight postmenopausal women. The measurement error of PA and LAT bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) has also been shown to rise with incremental increases in fat and from large variance in fat thickness, respectively. The purpose of this cross-sectional study was to determine specific affects of obesity on paired PA and LAT lumbar (L2-L4) BMD and Z score (BMD of patient versus age-matched reference data-base) correlation in 30 obese postmenopausal women (mean BMI +/- SD = 33.3 +/- 4.06). The mean PA and LAT BMD +/- SD were 0.946 +/- 0.123 and 0.749 +/- 0.134, respectively. The mean PA and LAT Z scores were -0.17 +/- 1.15 and 0.80 +/- 1.7. The correlation between PA and LAT BMD was significantly lower (r = 0.55; P < 0.05) than previously reported, and PA and LAT Z score correlation was (r = 0.57; P = 0.0016). After adjusting for body mass index (BMI), percent body fat, fat mass, and truncal fat by DXA, waist:hip ratio (WHR) and visceral and subcutaneous abdominal fat by computerized axial tomography (CT), PA and LAT Z score correlation increased to r = 0.62; P = 0.0065. In our subjects, the mean LAT Z score was 4.6 times higher than the mean AP Z, contrary to previous observations in normal-weight postmenopausal women. Our findings may be due to increased soft tissue composition and fat inhomogeneity in the LAT scanning field resulting in increased X-ray attenuation in obesity.
This investigation evaluated bone density in 36 premenopausal women (mean +/- SD age = 29.5 +/- 8.4 years) an average of 11.4 years after diagnosis for anorexia nervosa. Twenty-nine women were aged 20-45 years, and seven were aged 16-19 years. Body composition, age of menarche, length of amenorrhea, estrogen exposure, and lumbar spine and proximal femur bone density were determined. Average appendicular bone density for those > or = 20 years was found to meet World Health Organization T score criteria for osteopenia: total femur T = -1.22 and femoral neck T = -1.33. The average total lumbar Z score for all 36 participants was -0.95, which was 90% of the mean for their age, and the mean Z scores for adolescent subjects were within 91% of the mean for their age (Z = -0.84). Years of estrogen exposure were correlated with lumbar mineral content (r = 0.50, p = 0.002). A modest but significant inverse relationship was observed between length of amenorrhea and femoral and lumbar bone density. The total proximal femur and trochanteric bone densities were best predicted, using stepwise regression, by the number of years after diagnosis and years of amenorrhea, respectively (R2 = 0.23, p = 0.02 and R2 = 0.21, p = 0.04). Lumbar density was best predicted by years of amenorrhea and current percent of ideal body weight (%IBW)(R2 = 0.25, p = 0.02). Length of amenorrhea, estrogen exposure, and %IBW independently contribute to axial and appendicular bone density. Because of risk for compromised bone density, women with a history of anorexia nervosa should be followed longitudinally to maximize premenopausal bone replacement.
Contradictory reports on the protective effect of fish consumption on cardiovascular disease (CVD) risk could be due to variations in the intake of n-3 and n-6 polyunsaturated fatty acids (PUFAs). Metabolic competition between n-3 and n-6 PUFAs suggests that n-6 PUFAs in vegetable oils could attenuate the efficacy of n-3 PUFAs in fish oil to favorably alter endpoints relevant to CVD risk. We determined the effects of varying dietary amounts of fish oil on lipid and thrombotic endpoints relevant to risk factors for CVD and whether these effects were attenuated by vegetable oils. Two randomized, double-blind, placebo-controlled, parallel studies were conducted in human subjects fed varying amounts of n-3 and n-6 PUFAs; n-3 PUFA intake was varied by using fish or placebo oil capsules, and n-6 PUFA intake was modified by incorporating varying amounts of safflower oil into the diet. Endpoints included changes in membrane fatty acid composition, blood lipids, and thrombotic profile. The results indicated that absolute amounts of fish oil, and not the relative amounts of fish and vegetable oil (ratios of n-3 to n-6 PUFAs), determined the magnitude of the reduction of arachidonic acid and increase in eicosapentaenoic acid in phospholipids of plasma and platelets. The suppression of plasma triacylglycerols by fish oil was not affected by varying amounts of dietary n-6 PUFAs. Fibrinogen concentrations decreased with 15 g but not with 9 g fish oil/d fed at the same ratio of n-3 to n-6 PUFAs. The efficacy of fish oil in favorably modifying certain risk factors for CVD was not attenuated by vegetable oil.
The hypotheses that dieting and/or overeating are associated with adiposity, eating disturbances, and lowered energy expenditure were tested in this study. A sample of 44 premenopausal women scoring high and low on measures of dietary restraint and disinhibition of dietary control, as measured by the Three Factor Eating Questionnaire, was studied. A 2 x 2 factorial design was employed (High/Low restraint x High/Low Disinhibition). Dependent variables were: body composition, dietary intake, activity, resting metabolic rate, and thermic effect of food. Unrestrained overeaters (Low Restraint/High Disinhibition group) were very obese. High Dietary Restraint was associated with intent to diet and controlled eating. High scores on the Disinhibition Scale were associated with episodic overeating. Groups did not differ in resting metabolic rate (controlled for fat-free mass). Lower thermic effect of food was found to be associated with the obesity found in High Disinhibition subjects. Thus, Dietary Restraint was not associated with significant adverse effects upon physical or psychological health. High Disinhibition, however, was associated with adiposity and significant disturbances of eating.
The relationship of disinhibition and dietary restraint with body mass was studied in a sample of 293 women. Results suggested that higher body mass was associated with an interaction of disinhibition and dietary restraint. The association of disinhibition with higher body mass was moderated by increased dietary restraint. Symptoms of an eating disorder were more strongly associated with disinhibition than with dietary restraint. These results suggest that dieting may moderate the increased body mass associated with overeating. Psychological and eating problems associated with dietary restraint were found to be of less significance than those associated with disinhibition.
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