Differences in mineral homeostasis, volumetric bone mass and femoral neck axis length in black and white South African women

In South Africa, appendicular and lumbar spine bone mineral density (BMD) have been found to be similar in black and white women. However, femoral BMD has been found to be higher in black than in white women. Two different techniques were used to recalculate BMD to eliminate the possible confounding influence of ethnic differences in height on areal BMD measurements. Volumetric bone mineral apparent density (BMAD) values were calculated and bone mineral content (BMC) was corrected for body and bone size. This report analyses differences in BMD (corrected for height and weight), BMAD, BMC (corrected for body and bone size), femoral neck axis length (FNAL), mineral homeostasis and bone turnover (BT) in a group of 20 to 49-year-old premenopausal (105 whites and 74 blacks) and 45 to 64-year-old postmenopausal (50 whites and 65 blacks) female South African nurses. The corrected BMD and BMC findings were congruous, showing that both pre- and postmenopausal blacks and whites have similar distal radius and lumbar spine bone mass but that whites have lower femoral neck bone mass than blacks. In contrast, BMAD findings suggest that pre- and postmenopausal whites have lower bone mass at the lumbar spine and femoral neck than blacks but similar bone mass at the distal radius to blacks. There is a greater rate of decline in BMD in postmenopausal whites than in blacks. BMD at the femoral neck was 12.1% lower in premenopausal whites and 16.5% lower in postmenopausal whites than in blacks. There was a positive association between femoral neck BMD and weight in premenopausal blacks (R ²=0.5,p=0.0001) but not in whites. Blacks had shorter FNAL than whites in both the pre- and postmenopausal groups. Blacks had lower serum 25-hydroxyvitamin D (25-(OH)D) and higher 1,25-dihydroxyvitamin D (1,25-(OH)₂D) levels than whites. There were no ethnic differences in biochemical markers of bone formation (serum alkaline phosphatase and osteocalcin) or bone resorption (urine hydroxyproline and pyridinoline), or in dietary calcium intake in either the pre- or postmenopausal groups. In the postmenopausal group, whites had higher ionized serum calcium (p=0.003), similar serum albumin, lower serum parathyroid hormone (p=0.003) and higher urinary calcium excretion (p=0.0001) than blacks. These results suggest that the higher peak femoral neck BMD in South African blacks than in whites might be determined by greater weight-bearing in blacks and that the significantly lower femoral neck BMD in postmenopausal whites than in blacks is determined by lower peak femoral neck BMD and a faster postmenopausal decline in BMD in whites. The higher incidence of femoral neck fractures in South African whites than in blacks is probably determined by the lower femoral neck BMD and longer FNAL in whites. The greater rate of decline in BMD in postmenopausal whites than in blacks is associated with an increase in urinary calcium excretion in whites. Measurement of biochemical markers of BT has not contributed to the understanding of ethnic differences in BMD and skeletal metabolism in our subjects.     

Detrimental effect of oral contraceptives on parameters of bone mass and geometry in a cohort of 248 young women

The aim of this cross-sectional analysis was to examine the skeletal effects of low-dose monophasic oral contraceptive (OC) use in a cohort of 248 young Caucasian women aged 18-24 years. Areal bone mineral density (BMD) of the femoral neck and lumbar spine was evaluated by dual-energy X-ray absorptiometry. Volumetric BMD, bone mineral content (BMC), and bone geometry were assessed in the tibia by peripheral quantitative computed tomography (pQCT). The women were allocated into ever or never OC users, and also into 5 different OC groups according to duration and time of initiation of OC use. Women with >2 years of OC use and OC initiation within 3 years after menarche were characterized by 10% lower femoral neck areal BMD (P<0.001), 5% lower spine areal BMD (not significant, P=0.101), 7% lower distal tibial total BMC (P<0.05), and 6% lower total BMC at the tibial shaft (P<0.05) relative to never users. In addition, women who had ever used OCs had lower bone mass at the femoral neck and tibial shaft, despite similar age, height, weight, BMI, hours of exercise, and calcium intake compared with never users. At the tibial shaft, OC users showed reduced total cross-sectional area, and increased cortical BMD. In conclusion, our data suggest that OC use is associated with a detrimental effect on bone mass in young women, and provide further insight into the pathophysiological mechanisms involved.     

Vitamin C supplement use and bone mineral density in postmenopausal women.

Vitamin C is known to stimulate procollagen, enhance collagen synthesis, and stimulate alkaline phosphatase activity, a marker for osteoblast formation. Studies of dietary vitamin C intake and the relation with bone mineral density (BMD) have been conflicting, probably because of the well-known limitations of dietary nutrient assessment questionnaires. The purpose of this study was to evaluate the independent relation of daily vitamin C supplement use with BMD in a population-based sample of postmenopausal women. Subjects were 994 women from a community-based cohort of whom 277 women were regular vitamin C supplement users. Vitamin C supplement use was validated. Daily vitamin C supplement intake ranged from 100 to 5,000 mg; the mean daily dose was 745 mg. Average duration of use was 12.4 years; 85% had taken vitamin C supplements for more than 3 years. BMD levels were measured at the ultradistal and midshaft radii, hip, and lumbar spine. After adjusting for age, body mass index (BMI), and total calcium intake, vitamin C users had BMD levels approximately 3% higher at the midshaft radius, femoral neck, and total hip (p < 0.05). In a fully adjusted model, significant differences remained at the femoral neck (p < 0.02) and marginal significance was observed at the total hip (p < 0.06). Women taking both estrogen and vitamin C had significantly higher BMD levels at all sites. Among current estrogen users, those also taking vitamin C had higher BMD levels at all sites, with marginal significance achieved at the ultradistal radius (p < 0.07), femoral neck (p < 0.07), and total hip (p < 0.09). Women who took vitamin C plus calcium and estrogen had the highest BMD at the femoral neck (p = 0.001), total hip (p = 0.05), ultradistal radius (p = 0.02), and lumbar spine. Vitamin C supplement use appears to have a beneficial effect on levels of BMD, especially among postmenopausal women using concurrent estrogen therapy and calcium supplements.     

Peak spine and femoral neck bone mass in young women

Achievement of higher peak bone mass early in life may play a critical role against postmenopausal bone loss. Bone mineral density (BMD) of the spine, femoral neck, greater trochanter, Ward's triangle, and spine bone mineral content (BMC) and bone surface area (BSA) were assessed by dual energy x-ray absorptiometry in 300 healthy females (age 6-32 years). Bone measurements were described by using nonlinear models with age, weight, height, or dietary calcium intake as the explanatory variables. At the spine, femoral neck, greater trochanter, and Ward's triangle, the highest BMD level was observed at 23.0 +/- 1.4, 18.5 +/- 1.6, 14.2 +/- 2.0, and 15.8 +/- 2.1 years, respectively. The age of attaining peak spine BMC and BSA cannot be estimated, as significant increases in these two measures were observed through this age group. Age, weight, and height were all significant predictors of all these bone measurements. Weight was a stronger predictor than age for all sites. Dietary calcium intake was not a significant predictor for any of these bone measurements. We conclude that age of attaining peak bone mass at the hip is younger than at the spine, and BMC and BSA at the spine continue to increase through the early thirties in females.     

Epidemiology of osteoporosis in Okinawa

International comparisons of fracture incidence of the femoral neck, bone mineral density of the axial and appendicular bones, calcium intake and daily activities in aged populations are extremely important for identifying preventive measures to be taken against senile osteoporosis. We surveyed the femoral neck fracture rate for four years from 1986 to 1989 in Okinawa Prefecture, and investigated bone mineral density of the lumbar spine and proximal femur by dual photon absortiometry or dual energy quantitative computed tomography in both normal subjects and osteoporotics with spinal compression fractures or hip fractures. Information on past and current daily activities and calcium intakes were collected through interviews or questionnaires on some of these control or osteoporotic subjects. The incidence of hip fracture in Okinawa was relatively higher than that in other prefectures of Japan, but apparently lower than that in Caucasian populations. In normal subjects, the slope of the overall regression line for bone mass vs age in women was 2.2 times steeper than that in men at the lumbar spine, but it was almost identical at the proximal femur in both sexes. Middle aged women lost BMD at both skeltal sites almost 2 times faster than that of overall women. BMD values of the osteoporotics with fractures were significantly lower than those of control subjects before 70 years. The high calcium intake group (more than 600mg/day) showed significantly higher BMD values at both skeltal sites comapred to the low calcium group (less than 600mg/day). Past daily activity level was significantly correlated with BMD values of each skeltal site, but current daily activity level correlated only with BMD for the lumbar spine.     

Long-Term Vegetarian Diet and Bone Mineral Density in Postmenopausal Taiwanese Women

This study examined bone density among postmenopausal Buddhist nuns and female religious followers of Buddhism in southern Taiwan and related the measurements to subject characteristics including age, body mass, physical activity, nutrient intake, and vegetarian practice. A total of 258 postmenopausal Taiwanese vegetarian women participated in the study. Lumbar spine and femoral neck bone mineral density (BMD) were measured using dual-photon absorptimetry. BMD measurements were analyzed first as quantitative outcomes in multiple regression analyses and next as indicators of osteopenia status in logistic regression analyses. Among the independent variables examined, age inversely and body mass index positively correlated with both the spine and femoral neck BMD measurements. They were also significant predictors of the osteopenia status. Energy intake from protein was a significant correlate of lumbar spine BMD only. Other nutrients, including calcium and energy intake from nonprotein sources, did not correlate significantly with the two bone density parameters. Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold (adjusted odds ratio = 2.48, 95% confidence interval = 1.03–5.96) and of being classified as having osteopenia of the femoral neck (3.94, 1.21–12.82). Identification of effective nutrition supplements may be necessary to improve BMD levels and to reduce the risk of osteoporosis among long-term female vegetarians. Received: 10 May 1996 / Accepted: 9 August 1996     

绝经后妇女骨质疏松性椎体骨折与腰椎骨密度的关系

目的探讨绝经后妇女骨质疏松性椎体骨折与腰椎骨密度的关系。方法选择骨质疏松性椎体骨折的绝经后妇女23例为骨折组,无椎体骨折的25例绝经后骨质疏松妇女为对照组。两组的年龄、绝经年限、身高、体重、体重指数差异无显著性,均行胸腰椎正侧位X线摄片。用双能X线吸收仪（DXA）测量的腰椎（L2-4）前后位骨密度（BMD）、骨矿含量（BMC）和T值。结果骨折组BMD、BMC和T值均低于对照组（P〈0.01）。结论腰椎BMD降低与绝经后妇女的骨质疏松性椎体骨折相关。绝经后骨质疏松妇女应重视BMD变化,预防椎体骨折的发生。     

Weight-training effects on bone mineral density in early postmenopausal women.

We tested the hypothesis that weight training would be an effective modality in maintaining or increasing bone mineral density (BMD) at the lumbar spine, femoral neck, and bone mineral content (BMC) at the distal wrist in early postmenopausal women. A total of 17 women completed a 9 month weight-training program, and 9 women served as a control group. Resistance training occurred three times per week using exercises designed to increase muscular strength. Mean change in lumbar BMD in the weight-trained group (1.6 +/- 1.2%, mean +/- SEM) was significantly different from the change in the control group (-3.6 +/- 1.5%, p less than 0.01) over the 9 month period. No significant weight-training effect was detected at the femoral neck or distal wrist site. We conclude that weight training may be a useful exercise modality for maintaining lumbar BMD in early postmenopausal women.     

Bone mineral content at three sites in normal perimenopausal women

Bone mineral content (BMC) in 217 healthy white women between the ages of 40 and 55 years was measured using single- and dual-photon absorptiometry. The sites measured included the distal radius, midradius, proximal femur, and lumbar spine. The relationship between BMC and age was constant over the age range studied when the confounding effect of menopause was controlled. Women with low body mass indices (BMIs) had significantly lower BMC than women with average or greater than average BMIs. More active women had higher BMC than less active women at both appendicular and axial sites. A trend suggesting that women with higher calcium intake may have higher BMC was statistically significant only at the midradial site. A trend of postmenopausal women having lower BMC than pre- or perimenopausal women was also statistically significant only at the midradial site. Only modest correlations were found between the various sites. These correlations are too weak to allow accurate clinical predictions of BMC at axial sites from the BMC at an appendicular site in individual patients.     

Decreased bone mineral density at the distal radius, but not at the lumbar spine or the femoral neck, in Japanese type 2 diabetic patients

The purpose of this study is to assess the association between type 2 diabetes and bone mineral density. This study included 145 Japanese patients (64 men and 81 women) with type 2 diabetes and 95 non-diabetic control subjects (41 men and 54 women) of similar age. We measured bone mineral density (BMD) at the sites with different cortical/cancellous bone ratio (lumbar spine, femoral neck, and distal radius) using dual-energy X-ray absorptiometry. BMD and Z score at the distal radius were significantly lower in type 2 diabetic patients than those in control subjects, and in type 2 diabetic patients, the Z score at the distal radius was lower than that at their own lumbar spine and femoral neck. In type 2 diabetic patients, negative correlation between BMD and the mean HbA1c during the previous 2 years was found significantly at the distal radius in both genders and at the femoral neck in women. These results indicate the selective cortical bone loss in type 2 diabetes and suggest the importance of also determining BMD at the radius and keeping good metabolic control to prevent bone loss in type 2 diabetic patients.     

Bone density of the radius,spine, and hip in relation to percent of ideal body weight in postmenopausal women

Summary Bone mineral content (BMC) and bone mineral density (BMD) of the spine (L2–L4) and hip (at femoral neck, Ward's triangle, and greater trochanter sites) were determined by dual-photon absorptiometry (DPA), and of the radius by single-photon absorptiometry (SPA) in healthy postmenopausal women aged 40–70 years. The relationships of BMC and BMD to years since menopause were examined separately in 97 women who were above 115% of ideal body weight (IBW) and in 128 women below. The heavier women had significantly greater mean BMC and BMD at each site than did the normal-weight women. In the normal-weight women, there was a significant negative correlation between BMD and years since menopause at each measurement site except the greater trochanter. In the obese women, BMD decreased with increasing years since menopause at the radius site only and BMC declined with increasing years after menopause at the hip (femoral neck and Ward's triangle region) as well as the radius. Thus, body size is a significant determinant of BMD in this population. The pattern of loss of BMD from Ward's triangle and femoral neck regions of hip are similar to that of the spine. The BMC and BMD findings in the hip suggest that remodeling occurs at this weight-bearing site which has a favorable effect on bone strength.     

Associations of vitamin C, calcium and protein with bone mass in postmenopausal Mexican American women

We investigated the associations of vitamin C, calcium and protein intakes with bone mass at the femoral neck and lumbar spine in postmenopausal Mexican American women. Bone mass was measured by dual-energy X-ray absorptiometry (DXA) and expressed as areal (BMD, g/cm²) and volumetric (bone mineral apparent density or BMAD, g/cm³) bone mineral density. Diet was assessed using a modified version of the National Cancer Institute Food Questionnaire, which was administered by trained bilingual interviewers familiar with Mexican dietary practices. Data gathered from 125 subjects were analyzed using multiple linear regression analysis with age, body mass index (BMI), acculturation, years of estrogen use, physical activity, total energy intake, and the nutrient of interest as independent variables. Neither calcium nor calcium/protein ratio was associated with bone mineral density. There was evidence of a positive association between dietary vitamin C intake and femoral neck BMD (β=0.0002 g/cm² per mg/day, SE=0.0001,p=0.07) and BMAD (β=0.0001 g/cm³ per mg/day, SE=0.00006,p<0.05), but vitamin C was not associated with lumbar spine bone mass. Further investigation of the role of vitamin C in skeletal health is warranted.     

Bone Changes in Pre- and Postmenopausal Women with Thyroid Cancer on Levothyroxine Therapy: Evolution of Axial and Appendicular Bone Mass

The effects of suppressive doses of levothyroxine (LT₄) on bone mass are controversial. Our aim was to evaluate the effects on axial and appendicular bone mineral density (BMD) and bone metabolism of long-term LT₄ suppressive therapy in women by means of cross-sectional and longitudinal studies, and also to assess the potential influence of menopausal status and LT₄ dose. Seventy-six women (aged 47 + 13 years, 37 pre- and 39 postmenopausal) on suppressive therapy (67 + 34 months duration, mean LT₄ dose 168 + 41 mg/day) from our Thyroid Cancer Unit without previous hyperthyroidism or concomitant hypoparathyroidism were studied. Serum TSH, T₃ free T₄, calcium, phosphorus, alkaline phosphatase, BGP, iPTH and urinary calcium (uCA) were measured. BMD was measured by dual-energy X-ray absorptiometry (DXA) at lumbar spine, femoral neck, Ward's triangle, ultradistal and distal third radius and expressed as a Z-score. In a subset of 27 women aged 46 + 15 years (14 pre- and 13 postmenopausal) a second densitometry scan was performed 27 + 5 months later. Patients on suppressive therapy showed a small reduction in BMD at the distal third radius (Z-score: 70.77 + 0.98; 95% confidence interval: 71.11, 70.44) without differences between pre- and postmenopausal women. Significant relations with the regimen of suppressive therapy and bone turnover markers were detected except at the lumbar spine. In the longitudinal study a significant although mild reduction in femoral neck BMD was found that correlated with prior T₃ and iPTH. In conclusion, our data show a small detrimental effect of cautious LT₄ suppressive therapy on bone mass assessed by DXA; it remains to be established whether this increases the prevalence of fractures. Received: 30 June 1997 / Accepted: 7 November 1997     

Dietary protein intake and bone mass in women

Population-based strategies to combat osteoporosis are urgently needed. The role of nutrition in such strategies has been particularly contentious. We examined the relationship among six key nutrients that are thought to affect bone metabolism and bone mineral density in the axial and appendicular skeleton using data from a population-based study in the northern United States. Data on the dietary intake of calcium, phosphorus, vitamin D, protein, fat, and total energy were obtained from a 7-day dietary record. Bone density measurements were made by dual photon absorptiometry in the lumbar spine and proximal femur, and by single photon absorptiometry in the distal and midradius. Among the 72 premenopausal women studied, there was a statistically significant positive association between protein intake and bone mineral in the distal radius and proximal femur, which was not altered by adjustment for age, weight, and physical activity. Among 218 postmenoprusal women, no such relationship was found between protein intake and bone mineral, and the only significant findings in this group were negative associations between fat consumption and bone density in the lumbar spine and radius. Our results suggest that dietary protein intake may be a determinant of the peak bone mass attained by premenopausal white women. The relevance of this finding for the design of population strategies to maximize skeletal growth requires further investigation.     

12周社区运动干预对绝经后骨质疏松症女性骨密度的影响研究

目的探讨四种运动方式对绝经后骨质疏松症女性骨密度(bone mineral density, BMD)的干预效果,并比较不同运动方式对股骨颈和腰椎L_(2～4)骨密度干预效果的差异。方法采用负重、自重、跳跃和健步走四种训练方式对社区51名绝经后骨质疏松症女性进行为期12周的训练;采用GE双能X线骨密度仪测量股骨颈和腰椎L_(2～4)骨密度;组内比较用配对样本t检验(正态分布)和Mann-Whitney检验(非正态分布),组间比较采用单因素ANOVA检验或秩和检验干预前后BMD的差值,P0.05为差异有统计学意义。结果与干预前相比,整体上运动组股骨颈和腰椎L_(2～4) BMD在干预后的变化均表现出增长趋势,而对照组的BMD则呈减少趋势;运动组股骨颈BMD相对基线的增长率表现为负重组健步组自重组跳跃组(1.91%1.34%0.72%0.24%),腰椎L_(2～4)BMD增长率则表现为健步组跳跃组负重组自重组(29.07%11.17%4.22%0.01%)。结论运动可有效缓解绝经后骨质疏松症女性骨量丢失,不同方式的运动对不同部位骨骼的作用效果也不一样,负重训练对股骨颈BMD的改善效果最好,而健步走则对腰椎BMD的作用效果最优。具有冲击性的健步走和跳跃训练对腰椎BMD的改善要好于非冲击性的负重和自重训练,负重训练对股骨颈和腰椎BMD作用均要好于自重训练。     

Differential effects of hormone replacement therapy on bone mineral density and axial transmission ultrasound measurements in cortical bone

The menopause has a large effect on bone density, and hormone replacement therapy (HRT) has been shown to be an effective treatment for preventing postmenopausal bone loss. The aim of this study was to compare the effects of HRT use on speed of sound (SOS) measurements at the radius, tibia, phalanx, and metatarsal with bone mineral density (BMD) measurements of the lumbar spine and proximal femur. The study population consisted of 278 healthy premenopausal women, 194 healthy postmenopausal women, and 126 healthy postmenopausal women currently receiving HRT for one or more years. SOS measurements were taken at the radius, tibia, phalanx, and metatarsal using the Sunlight Omnisense, and BMD measurements at the lumbar spine and proximal femur using Hologic QDR-4500 densitometers. Z-scores were calculated using the postmenopausal control group. Z-score differences between the postmenopausal controls and HRT group, for the entire group and with the HRT group subdivided into three groups based on duration of HRT usage, were calculated. Significant postmenopausal bone loss was found for all SOS and BMD measurements. A positive effect of HRT usage was found for all SOS measurement sites and lumbar spine BMD, although only the radius and tibia SOS and lumbar spine BMD reached statistical significance. The Z-score differences between the two groups were 0.44, 0.37, 0.15, and 0.26 for the radius, tibia, phalanx, and metatarsal SOS respectively, and 0.28, 0.00, and -0.03 for the lumbar spine, femoral neck, and total hip BMD respectively. A clear effect of the duration of HRT use was seen for the radius measurements, the differences being less marked elsewhere. In conclusion, these results demonstrate a positive effect of HRT on SOS measurements at the radius and tibia and BMD measurements of the lumbar spine.     

围绝经期妇女血清铁蛋白水平和股骨颈骨强度相关性研究

目的探索围绝经期妇女血清铁蛋白与股骨颈强度综合指数之间的关系。方法选择2014年7月至2017年12月在我院就诊的116例围绝经期妇女纳入本研究。使用双能X射线吸收扫描仪测量髋部骨几何结构性质,包括髋轴长度(HAL)和股骨颈宽度(FNW),并将其与BMD,体重和身高结合以产生股骨颈的综合指数(CSI)、弯曲(BSI)和冲击强度指数(ISI)三种不同的失效模式下的强度。结果在对年龄、体质量指数(BMI)、生活方式因素、血清25-羟基维生素D、钙和磷摄入量、糖尿病和更年期状态进行校正后,多元回归分析显示血清铁蛋白与腰椎和股骨颈,以及股骨颈皮质厚度密切相关。重要的是,在所有的调整模型中,血清铁蛋白与三种股骨颈综合指数(如CSI、BSI和ISI)显示负相关(P0.05)。结论本研究表明高血清铁蛋白反映的全身铁储存增加可能与骨强度相对于负荷的减少有关。     

Negative correlation between bone mineral density and TSH receptor antibodies in male patients with untreated Graves’ disease

Introduction Although it has been established that hyperthyroidism leads to reduced bone mineral density (BMD), with accelerated bone turnover promoting bone resorption in female patients, there is a dearth of data for male patients with hyperthyroidism. This study evaluated BMD and bone metabolism in male patients with Graves’ disease. Methods The study included 56 Japanese male patients with newly diagnosed Graves’ disease and 34 normal Japanese male control subjects of similar age and body mass index. We used dual energy x-ray absorptiometry to measure BMD at sites with different cortical/cancellous bone ratios (lumbar spine, femoral neck, and distal radius). Results At the lumbar spine and the distal radius, BMD and T-scores were significantly lower for patients than for controls. At the femoral neck, on the other hand, the same values were relatively, but not significantly, lower in patients than in controls. However, Z-scores at all three sites were significantly lower for patients than for controls. The Z -score at the distal radius of patients was significantly lower than that at their lumbar spine and femoral neck. In addition, Z-score at the distal radius correlated negatively with age, free thyroxine, thyroid stimulating hormone receptor antibodies, thyroid stimulating antibody, and urinary N-terminal telopeptide of type I collagen normalized by creatinine. Conclusions These results indicate a high prevalence of cortical bone loss in male patients with Graves’ disease, especially elderly patients. We conclude that BMD measurement is crucial in all Graves’ disease patients regardless of their gender and that the radial BMD as well as BMD at the lumbar spine and femoral neck should be monitored to effectively prevent bone loss and subsequent fracture.     

Association between caffeine intake and bone mass among young women: potential effect modification by depot medroxyprogesterone acetate use

Summary This study assessed associations between habitual caffeine intake and bone mass among young women. Analyses of the entire study population revealed no significant associations, while analyses restricted to women using depot medroxyprogesterone acetate (DMPA) showed modest inverse associations between caffeine intake and bone mineral content (BMC). Introduction Some previous investigations among postmenopausal women suggest an inverse relationship between caffeine intake and bone mass, yet studies of this association among young women are few. Methods The association between habitual caffeine intake and bone mass was evaluated prospectively in a population-based cohort of 625 females, aged 14 to 40 years, adjusting for relevant biological and lifestyle factors. Caffeinated beverage intake was self-reported, and bone mineral content (BMC) and bone mineral density (BMD) were measured at baseline and every 6 months throughout a 24-month follow-up period using dual-energy x-ray absorptiometry. Results Cross-sectional analyses revealed no significant differences in mean BMC or BMD at baseline. Mean percentage and absolute changes in BMC and BMD were not associated with caffeine use. Repeated measures analyses similarly showed no significant association between caffeine intake at baseline and mean BMC or BMD measured during follow-up. However, among women using depot medroxyprogesterone acetate (DMPA), modest inverse associations between caffeine and BMC (but not BMD) were detected. Conclusions Our data suggest that heavy habitual consumption of caffeinated beverages does not adversely impact bone mass among young women in general. Greater caffeine intake may be associated with lower BMC among DMPA users. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Jumping improves hip and lumbar spine bone mass in prepubescent children: a randomized controlled trial.

Physical activity during childhood is advocated as one strategy for enhancing peak bone mass (bone mineral content [BMC]) as a means to reduce osteoporosis-related fractures. Thus, we investigated the effects of high-intensity jumping on hip and lumbar spine bone mass in children. Eighty-nine prepubescent children between the ages of 5.9 and 9.8 years were randomized into a jumping (n = 25 boys and n = 20 girls) or control group (n = 26 boys and n = 18 girls). Both groups participated in the 7-month exercise intervention during the school day three times per week. The jumping group performed 100, two-footed jumps off 61-cm boxes each session, while the control group performed nonimpact stretching exercises. BMC (g), bone area (BA; cm2), and bone mineral density (BMD; g/cm2) of the left proximal femoral neck and lumbar spine (L1-L4) were assessed by dual-energy X-ray absorptiometry (DXA; Hologic QDR/4500-A). Peak ground reaction forces were calculated across 100, two-footed jumps from a 61-cm box. In addition, anthropometric characteristics (height, weight, and body fat), physical activity, and dietary calcium intake were assessed. At baseline there were no differences between groups for anthropometric characteristics, dietary calcium intake, or bone variables. After 7 months, jumpers and controls had similar increases in height, weight, and body fat. Using repeated measures analysis of covariance (ANCOVA; covariates, initial age and bone values, and changes in height and weight) for BMC, the primary outcome variable, jumpers had significantly greater 7-month changes at the femoral neck and lumbar spine than controls (4.5% and 3.1%, respectively). In repeated measures ANCOVA of secondary outcomes (BMD and BA), BMD at the lumbar spine was significantly greater in jumpers than in controls (2.0%) and approached statistical significance at the femoral neck (1.4%; p = 0.085). For BA, jumpers had significantly greater increases at the femoral neck area than controls (2.9%) but were not different at the spine. Our data indicate that jumping at ground reaction forces of eight times body weight is a safe, effective, and simple method of improving bone mass at the hip and spine in children. This program could be easily incorporated into physical education classes.