Cummings, Cesar Libanati, Daniel D. Bikle, Irene S.
This study tested whether racial differences in bone density can be explained by differences in bone metabolism and lifestyle. A cohort of black and white men and women, ages 25—36 yr, was studied at the Kaiser Permanente Medical Care Program in Northern California, a prepaid health plan. Body composition fat, lean, and bone mineral density was measured using a Hologic dual-energy x-ray densitometer.
Muscle strength, blood and urine chemistry values related to calcium metabolism, bone turnover, growth White female for black muscular guy, and level of sex and adrenal hormones were also measured.
Medical history, physical activity, and lifestyle were assessed. Statistical analyses using t - and chi-square tests and multiple regression were done to determine whether racial difference in bone density remained after adjustment for covariates. Adjusted bone density at various skeletal sites was 4.
We concluded that racial differences in bone mineral density are not accounted for by clinical or biochemical variables White female for black muscular guy in early adulthood.
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The greater bone density among black persons may be caused by their higher obesity rate 7greater frame size 7and greater muscle mass 8. However, HWite and coworkers 3 found that premenopausal black women had statistically significantly greater spinal and radial bone density than white women, even after adjusting for height, weight, and body mass index. Many have hypothesized that genetically determined differences in skeletal metabolism account for racial differences in bone density; this hypothesis is supported by musculad that show racial differences in calciotropic hormones 910 and bone turnover markers Compared with white persons, black persons have lower urinary calcium excretion, higher 1,dihydroxyvitamin D 1, 25D level, and lower hydroxyvitamin D 25D and osteocalcin level 9.
Moreover, bone biopsies in black persons have shown lower bone turnover Peak bone density can be influenced by White female for black muscular guy factors such as dietary calcium intake 13 Shady dale GA bi horny wives, physical activity 13smoking, 14 and White female for black muscular guy intake 14 Menstrual and reproductive factors, including age of menarche 16pregnancy early in life 15breast-feeding 17and oral contraceptive use 13have also been found by some to influence peak bone density.
Gonadal steroids may account for gender differences 18 and for racial differences in bone density. Regardless of cause, it is generally agreed that lower estrogen level results in lower peak bone mass.
Positive associations between bone density and serum estrogen 19 and androgen 20 level have been reported in young women. A positive association between androgen level and bone density exists in young men also Black persons may differ from white persons in sex hormone level.
Two studies have demonstrated statistically significantly higher serum testosterone level in young adult black men 22 and women Our study tested whether racial differences in bone density could be explained by differences in bone metabolism and lifestyle Accordingly, we White female for black muscular guy most of the clinical and White female for black muscular guy variables believed to be related to skeletal health in young adult black and white men and women.
Eight hundred fifty volunteer subjects took part in this study, all age 25—36 yr and all simultaneously participants in the Cardiovascular Risk Development in Want to get hot horny girl no strings Adults CARDIA study, a study initiated by the National Heart, Lung, and Blood Institute NHLBI in to determine risk factors for coronary heart disease among black and white men and women Sweet housewives seeking hot sex Traralgon-Morwell Victoria to identify lifestyle characteristics associated with these risk factors After exclusions for certain laboratory abnormalities and pregnancy-related criteria, subjects were used in the analysis: Because of financial constraints, blood and urine chemistry studies, planned for only the first in each sex-race subject group, were obtained for of the study subjects the core group: We excluded women who were currently breast-feeding or who, within the previous year, had been pregnant or had less than 10 spontaneous menstrual cycles.
We also excluded women from the core group if White female for black muscular guy reported current usage of oral contraceptive agents. Dual energy x-ray absorptiometry DXA of total body, hip, and lumbar spine was done by using a Hologic densitometer Hologic, Inc, Waltham, MA in the array scanning mode.
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In vivo precision for bone mineral density BMDfoor on repeated scans of 20 volunteers done 1—6 weeks apart and expressed as a coefficient of variation, was. Femape software calculates the estimated volume for L-3 vertebra from the product of the projected area of the lateral scan and the vertebral width.
The latter is the quotient of the projected area of the PA scan divided by the vertebral height. L-3 volumetric density White female for black muscular guy the L-3 blak mineral content divided by L-3 estimated volume Lean body mass, fat mass, and ratio of trunk to leg fat White female for black muscular guy also measured using DXA in the Sweet women seeking nsa Aurora Illinois total body array scanning mode.
In vivo precision for fat mass based on repeated scans in 18 volunteers was 5. Average isokinetic muscle strength of the quadriceps and hamstring muscles was measured with a Cybex II dynamometer Lumex, Ronkonkoma, NY.
The best of five repetitions was used for both flexion and extension.
The following markers of bone Adult want casual sex OK Porter 74454 mineral metabolism were obtained from blood drawn when the subject was fasting: The following growth factors were measured by immunoassay: Sex and adrenal hormone immunoassays were done at Endocrine Sciences Laboratory, Calabasas Hills, California; these included assays for testosterone total, free, and bioavailablesex-hormone-binding globulin, estradiol, and dehydroepiandrosterone sulfate.
Fmeale was measured in women only, and this measurement was obtained between day 3 and day 11 of the menstrual cycle. The estradiol index was White female for black muscular guy by dividing the estradiol by the sex-hormone-binding globulin. Urine collected during 24 h was obtained for calcium, creatinine, and free total pyridinoline measurement. Usual diet was assessed by a diet history interview in which food models Who wants ome White female for black muscular guy cups and spoons were used to estimate portion size forr Daily nutrient intake, including intake of calcium and vitamin D, was estimated by translating the precoded CARDIA diet history from the database.
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Calcium and vitamin D intake estimates included supplemental sources. Physical activity was assessed by an interviewer-administered questionnaire, which asked about level of participation during the last year in 13 specific activities or groups of activities that have similar intensity. Because type and intensity of different activities were documented separately, we were able to separately analyze the effect of heavy-weight-bearing activity.
We computed physical activity scores based on the sum of time spent in each activity weighted by an estimate of kilocalories expended for White female for black muscular guy activity The test-retest correlation of the total score was. Medical histories and histories of tobacco use and alcohol use were obtained by a self-administered and interview-administered questionnaire.
The purpose of these analyses was to determine how White female for black muscular guy racial differences in bone density would remain after adjustment for covariates. Sex meets in ravenswood west virginia analysis was done separately for men and women in 3 phases.
These variables were assigned to 1 of 10 categories: Regression analyses were first done within each of the 10 categories. Variables that were significant within a category were then tested simultaneously in a regression model that included variables from all categories. Because variables in the fat category were highly correlated, we separated them into 2 groups, those that measured overall fat total fat by DXA, weight, BMI, and sum of skinfolds and those that measured fat distribution ratio of trunk: BMI, as a measure of overall fat, and waist: The difference in adjusted means by race in muscupar final model is a measure of remaining racial differences in BMD.
As a measure of relative magnitude of difference in bone density, we calculated percentage difference musculaf each skeletal site; this was defined as Need some one for Pateley Bridge mean for black persons minus mean for white persons divided by mean femaoe white Wuite.
Demographic, anthropometric, and lifestyle characteristics of the core group are shown in Table 1. Differences were noted in a White female for black muscular guy of these variables; statistically significant racial differences in the full cohort for clinical and laboratory variables are summarized in Table White female for black muscular guy.
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Among men, physical activity scores were higher among black participants; among women, white participants had higher scores. White female for black muscular guy and vitamin D intake were higher Whige white women than in black women, but no statistically muscullar differences were seen among men. Black participants were heavier than white participants, had higher caloric intake, and reported more hours of sun exposure per week. The proportion of current smokers among black participants was about twice as high, while the amount of caffeine consumption was about half.
Black women were more likely to have earlier menarche, to have more children, and to give birth before age 21 yr. In contrast, breast feeding was more common among white women than black women. Both black men and black women had lower 25D as well as higher 1,25D levels and markedly lower urinary calcium excretion. We plan to report the details of calciotropic hormone analyses elsewhere Bikle D.
Inconsistent racial differences were observed in markers of bone turnover and growth factors. Summary significance for clinical and biochemical variables that differed between races when tested in musxular entire cohort. Mean hip and spine size, determined by DXA, was smaller in black than in white women; among men, there were no statistically significant racial differences in these sites.
Lean body mass was greater in black persons than in white persons; differences observed were 6. Black women had blaci mean body fat and other mean fat indexes than white women, but black men White female for black muscular guy leaner than white men.
Measures of fat distribution showed higher ratio of muscupar to lower extremity fat in men compared with women; however, white men showed greater abdominal fat than black men, whereas black women showed greater abdominal fat than femxle women.
Black men and women tended Anybody know single moms wanting sex Velva have higher mean total, free, and bioavailable testosterone levels but lower dehydroepiandrosterone sulfate levels than their white counterparts. Among women, White female for black muscular guy statistically significant racial differences were found in mean estradiol or estradiol index Table 4.
Bone density at all skeletal sites was statistically significantly greater in black persons than in white persons Table 5 ; the racial ffemale were about 1. In the relatively narrow age range of our subjects, no consistent age-related change in BMD was found for BMD measurements data not shown.
Anthropometric variables appeared in all White female for black muscular guy final models; most frequently included for men was lean mass, and for women, body mass index. At least one lifestyle variable appeared in most of the final models, with caloric intake most consistent.
Biochemical tests did not show a consistent pattern of inclusion in these models. After these adjustments, similar racial differences in total body BMD in both genders remained, but larger racial differences were found between spine and hip densities in men than in women. Difference in various BMD measurements between black and white subjects, adjusted and unadjusted.Local Swingers In Collinwood Tennessee
By using DXA area measurements, we White female for black muscular guy that young, adult, black men and women have substantially greater BMD than white persons 2 — 6 ; this finding is true at all skeletal sites, and we have extended these observations to volumetric estimates of spinal BMD.
Despite an extensive search for clinical and biochemical explanations, we were unable to account for most of the racial differences in BMD. Although the greater area bone density White female for black muscular guy after measurement with DXA could Adult looking real sex KS Rice 66901 caused by larger bone size and therefore may not represent a true increase in volumetric density, our measurement of area and volume of both spine and hip show that black persons do not have larger vertebrae or upper femurs than white persons.
Further, the magnitude of the BMD differences in spinal volumetric density are similar to those for spinal area White female for black muscular guy. Muxcular large, population-based study had sufficient power to detect racial differences in clinical and biochemical variables on the order of 0.
Clinical and biochemical assessment was extensive and enabled us to study a comprehensive list of variables that others have considered relevant to bone mass. After Housewives looking sex tonight Bridgeport Stamford adjustments for these variables, about half gor racial differences in BMD still remained. This finding suggests that other factors than those controlling muscle mass and body size must act specifically on the skeleton.
We conclude that racial differences in BMD are established early guh childhood 33 and are not explained by clinical and biochemical variables measured in young adulthood. Studies of adolescents might find differences in metabolic or lifestyle factors that account for a larger share of the racial differences in bone mass than those that we observed.
However, most of the difference would be expected to remain evident 10—20 yr later. Thus, the appearance of such a large racial difference in young adults cannot be attributed to persistent differences in metabolic or lifestyle factors and supports the view that bone density differences result from influences operating during childhood and adolescence.