Bone density in premenopausal women: effects of age, dietary intake, physical activity, smoking, and birth-control pills

U.S. Medical Eligibility Criteria for Contraceptive Use, 2024

The 2024 U.S. Medical Eligibility Criteria for Contraceptive Use (U.S. MEC) comprises recommendations for the use of specific contraceptive methods by persons who have certain characteristics or medical conditions. These recommendations for health care providers were updated by CDC after review of the scientific evidence and a meeting with national experts in Atlanta, Georgia, during January 25-27, 2023. The information in this report replaces the 2016 U.S. MEC (CDC. U.S. Medical Eligibility Criteria for Contraceptive Use, 2016. MMWR 2016:65[No. RR-3]:1-103). Notable updates include 1) the addition of recommendations for persons with chronic kidney disease; 2) revisions to the recommendations for persons with certain characteristics or medical conditions (i.e., breastfeeding, postpartum, postabortion, obesity, surgery, deep venous thrombosis or pulmonary embolism with or without anticoagulant therapy, thrombophilia, superficial venous thrombosis, valvular heart disease, peripartum cardiomyopathy, systemic lupus erythematosus, high risk for HIV infection, cirrhosis, liver tumor, sickle cell disease, solid organ transplantation, and drug interactions with antiretrovirals used for prevention or treatment of HIV infection); and 3) inclusion of new contraceptive methods, including new doses or formulations of combined oral contraceptives, contraceptive patches, vaginal rings, progestin-only pills, levonorgestrel intrauterine devices, and vaginal pH modulator. The recommendations in this report are intended to serve as a source of evidence-based clinical practice guidance for health care providers. The goals of these recommendations are to remove unnecessary medical barriers to accessing and using contraception and to support the provision of person-centered contraceptive counseling and services in a noncoercive manner. Health care providers should always consider the individual clinical circumstances of each person seeking contraceptive services. This report is not intended to be a substitute for professional medical advice for individual patients; when needed, patients should seek advice from their health care providers about contraceptive use.

Combined hormonal contraceptive use is not protective against musculoskeletal conditions or injuries: a systematic review with data from 5 million females

OBJECTIVE

Assess the association between combined hormonal contraceptives (CHC) use and musculoskeletal tissue pathophysiology, injuries or conditions.

DESIGN

Systematic review with semiquantitative analyses and certainty of evidence assessment, guided by the Grading of Recommendations Assessment, Development and Evaluation approach.

DATA SOURCES

MEDLINE, EMBASE, CENTRAL, SPORTDiscus, CINAHL searched from inception to April 2022.

ELIGIBILITY

Intervention and cohort studies that assessed the association between new or ongoing use of CHC and an outcome of musculoskeletal tissue pathophysiology, injury or condition in postpubertal premenopausal females.

RESULTS

Across 50 included studies, we assessed the effect of CHC use on 30 unique musculoskeletal outcomes (75% bone related). Serious risk of bias was judged present in 82% of studies, with 52% adequately adjusting for confounding. Meta-analyses were not possible due to poor outcome reporting, and heterogeneity in estimate statistics and comparison conditions. Based on semiquantitative synthesis, there is low certainty evidence that CHC use was associated with elevated future fracture risk (risk ratio 1.02-1.20) and total knee arthroplasty (risk ratio 1.00-1.36). There is very low certainty evidence of unclear relationships between CHC use and a wide range of bone turnover and bone health outcomes. Evidence about the effect of CHC use on musculoskeletal tissues beyond bone, and the influence of CHC use in adolescence versus adulthood, is limited.

CONCLUSION

Given a paucity of high certainty evidence that CHC use is protective against musculoskeletal pathophysiology, injury or conditions, it is premature and inappropriate to advocate, or prescribe CHC for these purposes.

PROSPERO REGISTRATION NUMBER

This review was registered on PROSPERO CRD42021224582 on 8 January 2021.

Effects of "accurate measurement" comprehensive sports activities on balance ability, body composition and bone density of female college students

Background: A sedentary lifestyle with little movement has affected modern youth, and regular exercise has real benefits for people; such studies are mostly for older adults, and more evidence is needed for adolescents. Objective: To compare differences in balance, body composition, and bone mineral density among female college students before and after an exercise intervention to provide precise evidence that exercise promotes college student health. Methods: A whole group of female students in a university was sampled and included in the statistical analysis 50 people, divided into two cohorts, 21 people in the test group and 29 people in the control group; the test group had 4 comprehensive sports activities per week and the control group had 1 comprehensive sports activities per week, and the differences in each index of balance ability, body composition and bone density before and after the intervention were compared after 3 months. Results: After exercise intervention, when maintaining balance, the area of the center of gravity movement trajectory increased by 32.36% in the test group compared with the pre-intervention period and increased by 42.80% compared with the control group, and the differences were all statistically significant (p < 0.01); body mass index (BMI), body fat rate (BFR), visceral fat area (VFA), skeletal muscle content, and Inbody score increased over time more reasonable, and the difference in the effect of time factor (effect) was statistically significant (p < 0.01); bone mineral density (BMD) and BMD Z value increased with time, and the difference in the effect of time factor was statistically significant (p < 0.05). Conclusion: Female college students' body balance ability improved substantially after exercise intervention; at the university level, female college students had a more rational body composition and continued natural increase in BMD, which were not related to exercise intervention.

Exploring the Association Between Emphysema Phenotypes and Low Bone Mineral Density in Smokers with and without COPD

Rationale

Emphysema and osteoporosis are tobacco-related diseases. Many studies have shown that emphysema is a strong and independent predictor of low bone mineral density (BMD) in smokers; however, none of them explored its association with different emphysema subtypes.

Objective

To explore the association between the different emphysema subtypes and the presence of low bone mineral density in a population of active or former smokers with and without chronic obstructive pulmonary disease (COPD).

Methods

One hundred and fifty-three active and former smokers from a pulmonary clinic completed clinical questionnaires, pulmonary function tests, a low-dose chest computed tomography (LDCT) and a dual-energy absorptiometry (DXA) scans. Subjects were classified as having normal BMD or low BMD (osteopenia or osteoporosis). Emphysema was classified visually for its subtype and severity. Logistic regression analysis explored the relationship between the different emphysema subtypes and the presence of low BMD adjusting for other important factors.

Results

Seventy-five percent of the patients had low BMD (78 had osteopenia and 37 had osteoporosis). Emphysema was more frequent (66.1 vs 26.3%, p=<0.001) and severe in those with low BMD. Multivariable analysis adjusting for other significant cofactors (age, sex, FEV₁, and severity of emphysema) showed that BMI (OR=0.91, 95% CI: 0.76–0.92) and centrilobular emphysema (OR=26.19, 95% CI: 1.71 to 399.44) were associated with low BMD.

Conclusion

Low BMD is highly prevalent in current and former smokers. BMI and centrilobular emphysema are strong and independent predictors of its presence, which suggests that they should be considered when evaluating smokers at risk for low BMD.

Rationale and study design of an intervention of increased energy intake in women with exercise-associated menstrual disturbances to improve menstrual function and bone health: The REFUEL study

Purpose

Exercising women who consume inadequate energy relative to expenditure are at risk for downstream health consequences, such as menstrual cycle disturbances and poor bone health. Collectively, these conditions are known as the Female Athlete Triad (Triad). Clinicians often prescribe hormonal contraceptives to address this issue; however, the recommended treatment is reversal of the energy deficit. This paper describes the design of the REFUEL study, a randomized controlled trial (RCT) that explored the effectiveness of a 12-month intervention of increased energy intake on the reversal of an unhealthy energetic status and menstrual dysfunction and subsequent improvements in bone health in exercising women with severe menstrual cycle disturbances.

Methods

Women between the ages of 18–35 years and participating in at least 2 h/week of purposeful exercise were recruited. Those who reported irregular or absent menstrual cycles and were determined to have an exercise-associated menstrual disturbance (EAMD) were randomized into either the treatment group (EAMD + Cal), which was instructed to increase caloric intake throughout the intervention, or a control group (EAMD Control). Women who reported eumenorrhea were eligible for the ovulatory (OV) Control group. Repeated measures of energetic and metabolic status, reproductive status, and skeletal health were obtained.

Discussion

The REFUEL study is the first RCT to explore a non-pharmacological treatment approach among exercising women with the Triad. 118 women were randomized, and 55 women completed the entire study. The findings of this study have the potential to inform and alter clinical practice for exercising young women who present with this condition.

Consensus Statement on the Use of Oral Contraceptive Pills in Polycystic Ovarian Syndrome Women in India

OBJECTIVE

To provide consensus recommendations for health-care providers on the use of oral contraceptive pills (OCPs) in polycystic ovarian syndrome (PCOS) women in India.

PARTICIPANTS

Extensive deliberations, discussions, and brainstorming were done with different fraternities (specialists) being involved. These included endocrinologists, gynecologists, reproductive endocrinologists, dermatologists, public health experts, researchers, and a project manager with a team to develop the guideline.

EVIDENCE

Published literature was retrieved through searches of Medline and The Cochrane Database from January 2003 to December 2017 using appropriate-controlled vocabulary (e.g., oral contraceptive pills, polycystic ovarian syndrome, long term outcomes, infertility). Clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies' publications and data were also reviewed to suggest the recommendations.

PROCESS

The working group for guideline committee included members from the PCOS Society (India), Indian Society for Assisted Reproduction, The Mumbai Obstetric and Gynecological Society, The Endocrine Society of India, Indian Association of Dermatologists, Venereologists and Leprologists, Cosmetic Dermatology Society (India), Academicians from Medical Colleges, National Institute for Research in Reproductive Health, and a Research Associate. The core team included five reproductive endocrinologists, five gynecologists, five dermatologists, three endocrinologists, two public health experts and one research associate.

CONCLUSIONS

This consensus statement provides the guidance/recommendations for Indian practitioners regarding the use of OCP in women with PCOS. PCOS is one of the common endocrinopathies encountered in gynecological/endocrine practice. The spectrum of this disorder may range from prepubertal girls with premature pubarche, young girls with hirsutism, acne and anovulatory cycles, married women with infertility, and elderly women. Although obesity is a common feature for most PCOS patients, 'lean PCOS' also exists. For several years, OCPs have played an important role in the symptom management of PCOS women. This is due to the fact that OCPs decrease the luteinizing hormone, reduce androgen production, and increase sex hormone-binding globulin, which binds androgens. Several new formulations of OCPs have been developed to decrease the side effects. This includes use of less androgenic progestins and lower doses of ethinyl estradiol. These consensus recommendations help the health provider to choose the right type of OCPs, which will alleviate the symptoms with least side effects. It also gives insight into the indications, contraindications, and concerns regarding its short, intermediate and long-term use.

Gender Differences and Socioeconomic Factors Related to Osteoporosis: A Cross-Sectional Analysis of Nationally Representative Data

BACKGROUND

Osteoporosis has been considered a disease that primarily affects women, but recently male osteoporosis is also attracting attention. This study aims to comparatively analyze socioeconomic and other factors that are related to the prevalence of osteoporosis in both men and women.

MATERIALS AND METHODS

This study used data from the Korean Community Health Survey conducted in 2013. To determine factors related to osteoporosis prevalence, researchers applied a binary logistic regression model, first for all research participants, then separately for male and female participants.

RESULTS

Women were more likely than men to have osteoporosis (odds ratio 12.33, 95% confidence interval 11.55-13.17). Factors related to osteoporosis prevalence included age, education level, region, economic activity, alcohol consumption, salt intake, depression, and body mass index in both genders. Low education and income levels were more highly associated with osteoporosis prevalence in women than in men.

CONCLUSIONS

Most of the factors were not gender specific, but some socioeconomic determinants varied by gender. Future studies that will focus on the effects of socioeconomic factors on osteoporosis, as well as gender-related differences in prevention and control of osteoporosis, are needed.

Raman spectral markers of collagen denaturation and hydration in human cortical bone tissue are affected by radiation sterilization and high cycle fatigue damage

BACKGROUND

Thermal denaturation and monotonic mechanical damage alter the organic and water-related compartments of cortical bone. These changes can be detected using Raman spectroscopy. However, less is known regarding Raman sensitivity to detect the effects of cyclic fatigue damage and allograft sterilization doses of gamma radiation.

OBJECTIVE

To determine if Raman spectroscopic biomarkers of collagen denaturation and hydration are sensitive to the effects of (a) high cycle fatigue damage and (b) 25kGy irradiation.

METHODS

Unirradiated and gamma-radiation sterilized human cortical bone specimens previously tested in vitro under high-cycle (> 100,000 cycles) fatigue conditions at 15MPa, 25MPa, 35MPa, 45MPa, and 55MPa cyclic stress levels were studied. Cortical bone Raman spectral profiles from wavenumber ranges of 800-1750cm^-1 and 2700-3800cm^-1 were obtained and compared from: a) non-fatigue vs fatigue fracture sites and b) radiated vs. unirradiated states. Raman biomarker ratios 1670/1640 and 3220/2949, which reflect collagen denaturation and organic matrix (mainly collagen)-bound water, respectively, were assessed. One- and two-way ANOVA analyses were utilized to identify differences between groups along with interaction effects between cyclic fatigue and radiation-induced damage.

RESULTS

Cyclic fatigue damage resulted in increases in collagen denaturation (1670/1640: 1.517 ± 0.043 vs 1.579 ± 0.021, p < 0.001) and organic matrix-bound water (3220/2949: 0.109 ± 0.012 vs 0.131 ± 0.008, p < 0.001). Organic matrix-bound water increased secondary to 25kGy irradiation (3220/2949: 0.105 ± 0.010 vs 0.1161 ± 0.009, p = 0.003). Organic matrix-bound water was correlated positively with collagen denaturation (r = 0.514, p < 0.001).

CONCLUSIONS

Raman spectroscopy can detect the effects of cyclic fatigue damage and 25kGy irradiation via increases in organic matrix (mainly collagen)-bound water. A Raman measure of collagen denaturation was sensitive to cyclic fatigue damage but not 25kGy irradiation. Collagen denaturation was correlated with organic matrix-bound water, suggesting that denaturation of collagen to gelatinous form may expose more binding sites to water by unwinding the triple alpha chains. This research may eventually be useful to help identify allograft quality and more appropriately match donors to recipients.

A Novel Two-Compartment Model for Calculating Bone Volume Fractions and Bone Mineral Densities From Computed Tomography Images

Osteoporosis is a disease characterized by a degradation of bone structures. Various methods have been developed to diagnose osteoporosis by measuring bone mineral density (BMD) of patients. However, BMDs from these methods were not equivalent and were incomparable. In addition, partial volume effect introduces errors in estimating bone volume from computed tomography (CT) images using image segmentation. In this study, a two-compartment model (TCM) was proposed to calculate bone volume fraction (BV/TV) and BMD from CT images. The TCM considers bones to be composed of two sub-materials. Various equivalent BV/TV and BMD can be calculated by applying corresponding sub-material pairs in the TCM. In contrast to image segmentation, the TCM prevented the influence of the partial volume effect by calculating the volume percentage of sub-material in each image voxel. Validations of the TCM were performed using bone-equivalent uniform phantoms, a 3D-printed trabecular-structural phantom, a temporal bone flap, and abdominal CT images. By using the TCM, the calculated BV/TVs of the uniform phantoms were within percent errors of ±2%; the percent errors of the structural volumes with various CT slice thickness were below 9%; the volume of the temporal bone flap was close to that from micro-CT images with a percent error of 4.1%. No significant difference (p >0.01) was found between the areal BMD of lumbar vertebrae calculated using the TCM and measured using dual-energy X-ray absorptiometry. In conclusion, the proposed TCM could be applied to diagnose osteoporosis, while providing a basis for comparing various measurement methods.

Dietary Conjugated Linoleic Acid Does Not Adversely Affect Bone Mass in Obese fa/fa or Lean Zucker Rats

Conjugated linoleic acid (CLA) elevates body ash in healthy animals. The objective of the present study was to determine if single or mixed CLA isomers improve bone mass in an obese and hyperinsulinemic state. Male (n = 120) lean and obese fa/fa Zucker rats (age, 6 weeks) were randomized to 8 weeks on a control diet or to 0.4% (w/w) cis-9, trans-11 CLA (Group 1); 0.4% (w/w) trans-10, cis-12 CLA (Group 2); 0.4% (w/w) cis-9, trans-11 CLA and 0.4% (w/w) trans-10, cis-12 CLA (Group 3); 0.4% (w/w) cis-9, trans-11 CLA, 0.4% (w/w) trans-10, cis-12 CLA, and traces of other CLA isomers (Group 4); and 0.4% (w/w) cis-9, trans-11 CLA, 0.4% (w/w) trans-10, cis-12 CLA, and 0.3% (w/w) other CLA isomers (Group 5). Bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) of the whole body, spine, and femur were measured at baseline (6 weeks) and at 14 weeks of age. Effects of genotype, diet, and genotype × diet interactions were assessed using factorial analysis of variance. At 6 and 14 weeks, whole-body BA and BMC were lower in lean rats compared with fa/fa rats. Similarly, at 14 weeks, fa/fa rats had a higher spine and femur BMD despite a lower femur weight. The fa/fa rats in Groups 4 and 5 had higher adjusted whole-body BMC compared with Group 3, but not with Group 1, Group 2, or the control. In lean rats, Group 3 had a greater adjusted whole-body BMC than Groups 1 and 2, but not Group 4, Group 5, or the control. Thus, commercially available CLA mixtures and single CLA isomers do not affect bone mass in a hyperinsulinemic, obese state.

Dietary Approaches for Bone Health: Lessons from the Framingham Osteoporosis Study

Osteoporosis is characterized by systemic impairment of bone mass, strength, and microarchitecture, resulting in increased risk for fragility fracture, disability, loss of independence, and even death. Adequate nutrition is important in achieving and maintaining optimal bone mass, as well as preventing this debilitating disease. It is widely accepted that adequate calcium and vitamin D intake are necessary for good bone health; however, nutritional benefits to bone go beyond these two nutrients. This review article will provide updated information on all nutrients and foods now understood to alter bone health. Specifically, this paper will focus on related research from the Framingham Osteoporosis Study, an ancillary study of the Framingham Heart Study, with data on more than 5000 adult men and women.

Mammography and osteoporosis screening--clinical risk factors and their association with digital X-ray radiogrammetry bone mineral density

The aim of this study was to study the association between digital X-ray radiogrammetry (DXR) T-score and clinical risk factors for osteoporosis. Women were recruited 2 d per wk at a single mammography screening center between year 2010 and 2012. Included women answered a questionnaire about risk factors for osteoporosis, and a radiograph of the nondominant hand was obtained for DXR analysis. Univariate associations between DXR T-score and risk factors were examined. A generalized linear regression model was fitted to independent variables with univariate associations at p<0.05. The multivariable model was reduced through manual backward elimination, with p>0.1 as the exclusion criterion. Seventy-six percent of the women chose to participate in the study (n=8810). The difference in number of daily mammograms performed on study vs nonstudy days was not significant. All univariate associations between DXR T-score and potential risk factors were highly significant. The multivariable model included height, weight, age, right-handedness, menopause before age 45, alcohol consumption, cortisone treatment, rheumatic disease, and age×smoking status. The coefficient of determination of the model was 0.37. The association between risk factors for osteoporosis and DXR T-score is similar to previously reported associations with dual-energy X-ray absorptiometry.

A descriptive study of knowledge, beliefs and practices regarding osteoporosis among female medical school entrants in Sri Lanka

BACKGROUND

Osteoporosis is a significant problem in rapidly ageing populations in Asian regions. It causes a significant personal and societal impact and increases the burden on health care services.

OBJECTIVES

Aim of this study is to determine the knowledge, beliefs and practices regarding osteoporosis among young females entering medical schools in Sri Lanka.

METHODS

This is a descriptive cross sectional study conducted amongst 186 female medical school entrants of the Faculties of Medicine, Universities of Colombo and Kelaniya from September to December 2010. A self administered questionnaire was used to assess knowledge, beliefs and practices on osteoporosis, including a food frequency chart to assess the calcium intake.

RESULTS

The mean age was 20.7 +/- 2.1 years. Majority of the participants (51.6%, n = 96) had an average score (40-60) on the knowledge test, while 40.8% (n = 76) had a poor score (<40). However, in depth knowledge on risk factors, and protective factors was lacking. Perceived susceptibility for osteoporosis was low with only 13.9% (n = 26) of women agreeing that their chances of getting osteoporosis are high. The mean calcium intake was 528 mg/day and only 18.8% (n = 35) of the participants achieved the Recommended Daily Allowances (RDA) for Calcium. Exercise was grossly inadequate in the majority and only 13.6%( n = 23) engaged in the recommended exercises. Only 3.8% (n =7) of the participants currently engaged in specific behaviours to improve bone health while 10.8% (n = 20) had thought of routinely engaging in such behaviours.

CONCLUSIONS

Although majority of participants had a modest level of knowledge on osteoporosis, there were gaps in their knowledge in relation to risk factors, protective factors and on the insidious nature of osteoporosis. Perceived susceptibility for osteoporosis was low. Practices towards preventing Osteoporosis were inadequate.

The relationship between pulmonary function and bone mineral density in healthy nonsmoking women: the Korean National Health and Nutrition Examination Survey (KNHANES) 2010

The aim of this study was to examine the association between pulmonary function and bone mineral density (BMD) in subjects who had never smoked. Pulmonary function was associated with BMD in premenopausal, but not postmenopausal, women.

INTRODUCTION

It has been reported that low bone mass is common in patients with pulmonary disorders such as chronic obstructive pulmonary disease. However, in healthy nonsmoking women, the relationship between bone mass and pulmonary function has yet to be clarified. The object of this study was to determine whether pulmonary function is related to BMD in healthy nonsmoking women based on menopausal status.

METHODS

This study was a cross-sectional study based on data obtained from the Korean National Health and Nutrition Examination Survey (KNHANES), a nationwide representative survey conducted by the Korean Ministry of Health and Welfare in 2010. This study included 456 subjects who had never smoked and analyzed data concerning pulmonary function and BMD.

RESULTS

Functional vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were correlated with BMD at lumbar spine, femur neck (FN), and total hip in premenopausal women (p = 0.030, p = 0.003, p = 0.019, respectively, for FVC; p = 0.015, p = 0.006, p = 0.059, respectively, for FEV1). However, FVC and FEV1 were only correlated with BMD at FN in postmenopausal women (p = 0.003 for FVC; p = 0.006 for FEV1). Body mass index (BMI), FVC, and FEV1 were significantly related with BMD at FN, even after adjusting for age and other confounding factors (β = 0.334, p < 0.001; β = 0.145, p = 0.017; and β = 0.129, p = 0.037, respectively) in premenopausal women. However, only age and BMI were correlated with BMD at FN (β = -0.268, p = 0.001 and β = 0.384, p > 0.001) in postmenopausal women after adjusting for confounding factors.

CONCLUSIONS

Pulmonary function, including FVC and FEV1 are associated with BMD at FN in healthy nonsmoking premenopausal women but not in postmenopausal women.

Bone mineral density among elderly patients with chronic obstructive pulmonary disease patients in India

BACKGROUND

Osteoporosis is one of the major extra-pulmonary manifestations of chronic obstructive pulmonary disease (COPD), which limits the physical activity. The present study was undertaken to study the bone mineral density (BMD) and osteoporosis in the elderly COPD patients.

MATERIALS AND METHODS

This was a cross-sectional study carried out among elderly COPD patients. After a detailed clinical history spirometry was done to stage the severity of COPD. DEXA scan of the lumbar spine was performed using bone densitometer to determine osteoporosis. Statistical analysis was based on Chi-square test. Risk factors were identified by univariate and multivariate logistic regression analysis.

RESULTS

A total of 70 elderly COPD patients were included. Fourty-six patients (65.7%) had osteoporosis and 13 (18.6%) had osteopenia. Majority of the osteoporosis patients had stage III or stage IV COPD disease (77.2%). As the severity grade of COPD increased, the risk of osteoporosis also increased. Also, with the increasing severity of COPD, BMD decreased. Patients with lower body mass index (BMI) had higher prevalence of osteoporosis (45.7%). Using multivariate regression analysis, stage IV COPD, number of acute exacerbations >3 and steroid cumulative dose >1000 mg were independent risk factors for osteoporosis in elderly COPD patients.

CONCLUSIONS

The prevalence of osteoporosis was 65.7%, and 18.6% had osteopenia. Stage III and IV patients had significantly lower BMI in elderly COPD patients. High clinical suspicion and early diagnosis and treatment are required in the evaluation of osteoporosis in elderly COPD patients.

Adverse effects of smoking on peak bone mass may be attenuated by higher body mass index in young female smokers

Smoking is associated with postmenopausal bone loss and fracture, but the effect of smoking on bone in younger women is unclear. Peak bone mass is an important determinant for fracture risk; therefore, our aim was to evaluate the association between smoking and bone mass in 25-year-old women, specifically the influence of daily cigarette consumption and total exposure, duration, age at starting smoking, and time since smoking cessation on bone density and fracture risk. Smoking and bone mineral density (BMD) data were available for 1,054 women from the PEAK-25 cohort. Analyses comparing current smokers with women who never smoked were performed using number of cigarettes per day, pack-years, smoking duration, age smoking started, and, for former smokers, age at quitting. BMD did not differ between never, former, and current smokers; and the relative fracture risk in smokers was not significant (relative risk [RR] = 1.2, 95 % confidence interval 0.8-1.9). Among current smokers, BMD decreased with a dose response as cigarette consumption increased (femoral neck p = 0.037). BMD was not significantly lower in young women who had smoked for long duration or started smoking early (p = 0.07-0.64); long duration and early start were associated with higher body mass index (BMI; p = 0.038). Lower BMD persisted up to 24 months after smoking cessation (p = 0.027-0.050), becoming comparable to never-smokers after 24 months. Hip BMD was negatively associated with smoking and dose-dependent on cigarette consumption. Smoking duration was not associated with BMD, although young women with a long smoking history had higher BMI, which might attenuate the adverse effects from smoking.

The relationship between body mass index and physical activity levels in relation to bone mineral density in premenopausal and postmenopausal women

We prospectively analyzed 283 women to evaluate the effects of body mass index (BMI) and physical activity levels on bone mineral density (BMD) progression in pre- and postmenopausal women over 2 years. In postmenopausal women, lower BMI was linked with worsening BMD, and moderate activity levels were associated with a lower likelihood of worsening BMD at 2 years.

PURPOSE

The aim of our study is to evaluate the effects of BMI and physical activity levels on BMD progression in pre- and postmenopausal Asian women over 2 years.

METHODS

We prospectively analyzed 283 women from 2006 to 2009. They were divided into two groups (159 pre- and 124 postmenopausal) and analyzed separately to avoid confounding by age and menopausal hormonal status. The mean follow-up period was 771 days. Demographic data was obtained, including medical history, calcium supplementation, BMI, and physical activity levels (IPAQ scale). Bilateral femoral neck BMD was determined at the time of recruitment, 1 year, and after 2 years. Generalized linear modeling was used to evaluate the effects of BMI and physical activity levels on BMD progression over a 2-year period.

RESULTS

Amongst premenopausal women, lower initial femoral neck BMD scores were linked to worsening BMD (p = 0.048). In postmenopausal women, lower BMI was linked with worsening BMD (p = 0.012). Postmenopausal patients with moderate activity levels had a lower likelihood of worsening BMD at 2 years (p = 0.038). High physical activity levels were linked to a lower risk of BMD worsening (p = 0.066).

CONCLUSIONS

Higher BMI scores are protective for osteoporosis in postmenopausal women. Moderate levels of physical activity are beneficial for bone health in postmenopausal women, while low physical activity levels are not helpful. We recommend that, in the secondary prevention of osteoporosis, postmenopausal women should be encouraged to participate regularly in moderate physical activities. A practical approach would be walking 30 min a day for at least 5 days per week.

Association of total protein intake with bone mineral density and bone loss in men and women from the Framingham Offspring Study

OBJECTIVE

To examine (i) the association of percentage of total energy intake from protein (protein intake %) with bone mineral density (BMD, g/cm2) and bone loss at the femoral neck, trochanter and lumbar spine (L2-L4) and (ii) Ca as an effect modifier.

SETTING

The Framingham Offspring Study.

SUBJECTS

Men (n 1280) and women (n 1639) completed an FFQ in 1992-1995 or 1995-1998 and underwent baseline BMD measurement by dual-energy X-ray absorptiometry in 1996-2000. Men (n 495) and women (n 680) had follow-up BMD measured in 2002-2005.

DESIGN

Cohort study using multivariable regression to examine the association of protein intake % with each BMD, adjusting for covariates. Statistical interaction between protein intake % and Ca (total, dietary, supplemental) intake was examined.

RESULTS

The mean age at baseline was 61 (sd 9) years. In the cross-sectional analyses, protein intake % was positively associated with all BMD sites (P range: 0·02-0·04) in women but not in men. Significant interactions were observed with total Ca intake (<800 mg/d v. ≥800 mg/d) in women at all bone sites (P range: 0·002-0·02). Upon stratification, protein intake % was positively associated with all BMD sites (P range: 0·04-0·10) in women with low Ca intakes but not in those with high Ca intakes. In the longitudinal analyses, in men, higher protein intake % was associated with more bone loss at the trochanter (P = 0·01) while no associations were seen in women, regardless of Ca intake.

CONCLUSIONS

This suggests that greater protein intake benefits women especially those with lower Ca intakes. However, protein effects are not significant for short-term changes in bone density. Contrastingly, in men, higher protein intakes lead to greater bone loss at the trochanter. Longer follow-up is required to examine the impact of protein on bone loss.

Dose-related effect of urinary cotinine levels on bone mineral density among Korean females

To evaluate the dose-dependent relationship between smoking and bone mineral density (BMD), the present study used the BMD dataset of the Korean National Health and Nutrition Examination Survey IV (KNHANES IV). The linearity of BMD for urinary cotinine levels was demonstrated with statistical significance in postmenopausal females.

INTRODUCTION

It is well established that smoking is an important lifestyle risk factor for bone health (bone loss, osteoporosis, and fracture). However, several studies demonstrated conflicting evidence for a dose-dependent relationship between smoking and bone health. To evaluate the dose-dependent relationship between smoking and BMD, the present study estimated dose-related effects of smoking (urinary cotinine level) on BMD at various sites (femur neck, total femur, and lumbar spine) in females with controlling menopausal status.

METHODS

The present study used the BMD dataset of the KNHANES IV, which was performed in 2008 and 2009. A total of 4,260 pre- and postmenopausal females were included in the present study. Dose-response relationships between BMD and urinary cotinine levels were estimated using analysis of covariance in pre-menopausal females and postmenopausal females, respectively.

RESULTS

In postmenopausal females, the regression coefficients for BMD with urinary cotinine levels were -0.006, -0.006, and -0.008 (g/cm2 per ng/ml) at femur neck, total femur, and lumbar spine, respectively (p value<0.05). Thus, the linearity of BMD for urinary cotinine levels was demonstrated with statistical significance in postmenopausal females.

CONCLUSION

Our findings suggested a significant dose-related effect of urinary cotinine level with BMD at femur neck, total femur, and lumbar spine among postmenopausal females.

Physical activity during life course and bone mass: a systematic review of methods and findings from cohort studies with young adults

Background

The purpose of this paper was to review the literature of the cohort studies which evaluated the association between physical activity during the life course and bone mineral content or density in young adults.

Methods

Prospective cohort studies with bone mineral density or content measured in the whole body, lumbar spine and femoral neck by dual energy x-ray absorptiometry as outcome and physical activity as exposure were searched. Two independent reviewers selected studies retrieved from electronic databases (Medline, Lilacs, Web of Science and Scielo) and reviewed references of all selected full text articles. Downs & Black criterion was used in the quality assessment of these studies.

Results

Nineteen manuscripts met inclusion criteria. Lumbar spine was the skeletal site most studied (n = 15). Different questionnaires were used for physical activity evaluation. Peak strain score was also used to evaluate physical activity in 5 manuscripts. Lack of statistical power calculation was the main problem found in the quality assessment. Positive associations between physical activity and bone mass were found more in males than in females; in weight bearing anatomical sites (lumbar spine and femoral neck) than in total body and when physical activity measurements were done from adolescence to adulthood – than when evaluated in only one period. Physical activity during growth period was associated with greater bone mass in males. It was not possible to conduct pooled analyses due to the heterogeneity of the studies, considering mainly the different instruments used for physical activity measurements.

Conclusions

Physical activity seems to be important for bone mass in all periods of life, but especially the growth period should be taking into account due to its important direct effect on bone mass and its influence in physical activity practice in later life. Low participation in peak strain activities may also explain the lower number of associations found in females.

Bone mineral density and body composition of adult premenopausal women with three levels of physical activity

Weight-bearing and resistance physical activities are recommended for osteoporosis prevention, but it is unclear whether an intensity level above current recommendations has a positive effect on adult premenopausal women. Body composition and bone mineral density (BMD) by DXA were compared in three groups of women as follows: Sedentary, Maintenance exercise, and federated Sport Team (n = 16 for each group). Physical activity was estimated from the International Physical Activity Questionnaire (IPAQ). The groups did not differ in age, height, weight, or body mass index. Bone mineral content and non-fat soft tissue mass were higher and fat mass was lower in the Sport Team group than in the other groups. The same was true for BMD of total skeleton, lumbar spine, femoral neck, and total hip. A test for linear trend of body composition and BMD showed significant results when including all three groups. Simple and multiple regression analyses showed significant associations between physical activity level (or alternatively, years of participation in programmed physical activity) and bone mass measures at all sites except for the middle third of radius. It is concluded that a level of physical activity higher than that usually recommended benefits bone health in adult premenopausal women.

Smoking is associated with impaired bone mass development in young adult men: a 5-year longitudinal study

It has previously been shown that smoking is associated with reduced bone mass and increased fracture risk, but no longitudinal studies have been published investigating altered smoking behavior at the time of bone mass acquisition. The aim of this study was to investigate the development of bone density and geometry according to alterations in smoking behavior in a 5-year, longitudinal, population-based study of 833 young men, age 18 to 20 years (baseline). Furthermore, we aimed to examine the cross-sectional, associations between current smoking and parameters of trabecular microarchitecture of the radius and tibia, using high-resolution peripheral quantitative computed tomography (HR-pQCT), in young men aged 23 to 25 years (5-year follow-up). Men who had started to smoke since baseline had considerably smaller increases in areal bone mineral density (aBMD) at the total body (mean ± SD, 0.020 ± 0.047 mg/cm(2) versus 0.043 ± 0.040 mg/cm(2) , p < 0.01) and lumbar spine (0.027 ± 0.062 mg/cm(2) versus 0.052 ± 0.065 mg/cm(2) , p = 0.04), and substantially greater decreases in aBMD at the total hip (-0.055 ± 0.058 mg/cm(2) versus -0.021 ± 0.062 mg/cm(2) , p < 0.01) and femoral neck (-0.077 ± 0.059 mg/cm(2) versus -0.042 ± 0.070 mg/cm(2) , p < 0.01) than men who were nonsmokers at both the baseline and follow-up visits. At the tibia, subjects who had started to smoke had a smaller increment of the cortical cross-sectional area (CSA) than nonsmokers (8.1 ± 4.3 mm(2) versus 11.5 ± 8.9 mm(2) , p = 0.03), and a larger decrement of trabecular volumetric BMD (vBMD) than nonsmokers (-13.9 ± 20.5 mg/mm(3) versus -4.1 ± 13.9 mg/mm(3) , p < 0.001). In the cross-sectional analysis at follow-up (23-25 years of age), smokers had significantly lower trabecular vBMD at the tibia (7.0%, p < 0.01) due to reduced trabecular thickness (8.9%, p < 0.001), as assessed using HR-pQCT, than nonsmokers. In conclusion, this study is the first to report that men who start to smoke in young adulthood have poorer development of their aBMD at clinically important sites such as the spine and hip than nonsmokers, possibly due to augmented loss of trabecular density and impaired growth of cortical cross-sectional area.

The smoking patterns of women in their forties: their relationship to later osteoporosis

Osteoporosis is prevalent among women 50 years of age and older and accounts for numerous fractures and the related deaths of many sufferers. In this study, 22.4% of the women reported having osteoporosis. Smoking contributes substantially to osteoporotic fractures. This study assessed how different trajectories of women's smoking, covering the ages 40 to 48 years, relate to osteoporosis at age 65. Trajectory analysis of tobacco use data reveals smoking patterns which may have differing relationships to osteoporosis. Logistic regression analyses revealed the varying relationships of different smoking patterns to osteoporosis. As hypothesized, the chronic/heavy smokers were significantly more likely than the non-smokers to report having osteoporosis. Quitters and moderate smokers did not differ significantly from non-smokers on the osteoporosis measure. Chronic/heavy smokers should not be the only focus of public health efforts to reduce smoking and the associated risks of osteoporosis. The findings also highlight the efficacy of women smokers quitting in their 40s in order to reduce their likelihood of contracting osteoporosis.

Bone mass, depressive, and anxiety symptoms in adolescent girls: variation by smoking and alcohol use

PURPOSE

The purpose of the study was to examine (a) the association between depressive and anxiety symptoms with bone health, (b) the association of smoking or alcohol use with bone health, and, in turn (c) whether the association between depressive and anxiety symptoms with bone health varied by smoking or alcohol use individually or by combined use. Bone health included total body bone mineral content (TB BMC) and bone mineral density (BMD) of the lumbar spine, total hip, and femoral neck. Previously published data have not examined these issues in adolescence, a period when more than 50% of bone mass is accrued.

METHODS

An observational study enrolled 262 healthy adolescent girls by age cohort (11, 13, 15, and 17 years). Participants completed questionnaires and interviews on substance use, depressive symptoms, and anxiety. BMC and BMD were measured by dual-energy X-ray absorptiometry.

RESULTS

Higher depressive symptoms were associated with lower TB BMC and BMD (total hip, femoral neck). Those with the lowest level of smoking had higher BMD of the hip and femoral neck, whereas no main effect differences were noted by alcohol use. Regular users of both cigarettes and alcohol demonstrated a stronger negative association between depressive symptoms and TB BMC as compared with nonusers/experimental users and regular alcohol users. Findings were parallel for anxiety symptoms.

CONCLUSION

Depressive and anxiety symptoms may negatively influence bone health in adolescent girls. Consideration of multiple substances, rather than cigarettes or alcohol separately, may be particularly informative with respect to the association of depression with bone health.

Long-term effect of exercise on bone mineral density and body composition in post-menopausal ex-elite athletes: a retrospective study

OBJECTIVES

The aim of this retrospective study was to determine the long-term effect of exercise on bone mineral density (BMD), bone mineral content (BMC) and body composition (BC) in post-menopausal women who were elite athletes during their youth compared with sedentary controls.

SUBJECTS/METHODS

It is a retrospective study and carried out in an outpatient clinic. A total of 48 post-menopausal women (54-73 years of age) were enrolled. Ex-elite athletes with long-term (>20 years) histories of significant training and performance were divided into two groups: weight-bearing sports (runners, n=12) and non-weight-bearing sports (swimmers, n=12). The athletes were age matched with sedentary controls (n=24). BMD, BMC and BC were measured using dual-energy X-ray absorptiometry. Healthcare and sport activity histories were evaluated using a questionnaire.

RESULTS

No significant differences were found with regard to body weight, height, body mass index and hours of activity between the two groups of athletes. There were no significant differences in activity levels between athletes and controls at the time of this study. BMD and BMC were not significantly different between athletes; they were significantly higher in athletes than in controls (P<0.001). Although the ex-athletes did not significantly differ in BC, left and right lean arm mass and arm BMD were significantly higher in swimmers than in runners (P<0.0001).

CONCLUSIONS

The high level of physical activity observed in female athletes is associated with improved muscle mass, BMD and BMC, and physical activity during youth seems to have a beneficial effect on bone mass and helps to prevent bone loss due to aging.

Update on hormonal contraception and bone density

Combination hormonal contraception and progestin-only contraception (including depot medroxyprogesterone acetate [DMPA]) are effective and convenient forms of reversible contraception that millions of women use worldwide. In recent years, observations of reduced bone mineral density in current users of these methods have led to concerns that this hormone-induced bone loss might translate into long-term increased fracture risk. Special focus has been placed on adolescent users who have not yet attained their peak bone mass as well as perimenopausal users. In 2004, the FDA added a black box warning to DMPA package labeling warning of the risk of significant bone loss and cautioning against long-term use (> 2 years). This article reviews evidence on the use of hormonal contraception and its effect on bone density in adolescent, premenopausal, and perimenopausal populations. Recommendations from reproductive healthcare organizations are reviewed and clinical recommendations are provided.

Nicotinic modulation of gene expression in osteoblast cells, MG-63

Exposure to nicotine causes a broad range of biological and molecular effects on osteoblasts which are known to play a crucial role in bone metabolism and fracture healing. Most effects of nicotine on the osteoblasts are long-term adaptations at the genomic level. To identify the nicotine-regulated genes, the Agilent technologies whole human genome gene expression microarray was performed on RNA samples from osteoblast-like cells, MG-63, exposed to 100 μM nicotine. Repeat and cross-controlled microarray analyses revealed 842 genes whose expression was consistently altered at P<0.05 level following nicotine treatment. Gene ontology analysis suggested effects of nicotine on various biological and cellular processes which were associated with survival, proliferation, differentiation and apoptosis processes within the cell. Quantitative real-time reverse transcriptase PCR analysis confirmed altered expression in 7 out of 9 genes tested. The identified genes tested in the current study support our previous report that nicotine regulates the expression of genes that promote osteoblast proliferation and/or anti-apoptosis processes. Furthermore, using nicotinic acetylcholine receptor antagonists blocked the majority of the nicotine effects, indicating that these changes are dependent on nAChR activation. These results established a novel and consistent nicotinic activation of nAChR in osteoblast cells which has a broad role affecting cellular physiology through modulation of gene expression.

Protective effect of high protein and calcium intake on the risk of hip fracture in the Framingham offspring cohort

The effect of protein on bone is controversial, and calcium intake may modify protein's effect on bone. We evaluated associations of energy-adjusted tertiles of protein intake (ie, total, animal, plant, animal/plant ratio) with incident hip fracture and whether total calcium intake modified these associations in the Framingham Offspring Study. A total of 1752 men and 1972 women completed a baseline food frequency questionnaire (1991-1995 or 1995-1998) and were followed for hip fracture until 2005. Hazard ratios (HRs) were estimated using Cox proportional hazards regression adjusting for confounders. Baseline mean age was 55 years (SD 9.9 years, range 26 to 86 years). Forty-four hip fractures occurred over 12 years of follow-up. Owing to significant interaction between protein (total, animal, animal/plant ratio) and calcium intake (p interaction range = .03 to .04), stratified results are presented. Among those with calcium intakes less than 800 mg/day, the highest tertile (T3) of animal protein intake had 2.8 times the risk of hip fracture [HR = 2.84, 95% confidence interval (CI) 1.20-6.74, p = .02] versus the lowest tertile (T1, p trend = .02). In the 800 mg/day or more group, T3 of animal protein had an 85% reduced hip fracture risk (HR = 0.15, 95% CI 0.02-0.92, p = .04) versus T1 (p trend = .04). Total protein intake and the animal/plant ratio were not significantly associated with hip fracture (p range = .12 to .65). Our results from middle-aged men and women show that higher animal protein intake coupled with calcium intake of 800 mg/day or more may protect against hip fracture, whereas the effect appears reversed for those with lower calcium intake. Calcium intake modifies the association of protein intake and the risk of hip fracture in this cohort and may explain the lack of concordance seen in previous studies.

Risk factors associated with self-reported training-related injury before arrival at the US army ordnance school

OBJECTIVE

This study examined risk factors for self-reported injury incurred before arrival at Ordnance School for advanced individual training (AIT).

STUDY DESIGN

During AIT in-processing, soldiers (n=27,289 men and 3856 women) completed a questionnaire that collected demographic and lifestyle information, and asked if the soldier currently had an injury that would affect their AIT performance.

METHODS

Potential risk factors for self-reported injury were explored using logistic regression.

RESULTS

For men, self-reported injury was associated with older age [odds ratio (OR) >or=30 years/17-19 years=1.9], race (OR Black/Caucasian=1.2), basic combat training (BCT) site (OR Fort Benning/Fort Jackson=1.7; OR Fort Leonard Wood/Fort Jackson=1.6, OR Fort Knox/Fort Jackson=1.3), smoking on 20 or more days in the 30 days prior to BCT (OR smoker/non-smoker=1.2) and current illness (OR ill/not ill=6.2). For women, increased self-reported injury was associated with older age (OR>or=30 years/17-19 years=2.0), BCT site (OR Fort Leonard Wood/Fort Jackson=1.5) and current illness (OR ill/not ill=5.8).

CONCLUSIONS

Certain demographic characteristics and lifestyle behaviours may be identified as injury risk factors on arrival at Ordnance AIT.

Smoking among premenopausal women is associated with increased risk of low bone status: the JPOS Study

The impact of smoking on peak bone density has not been conclusively established. We examined how smoking exposure influences bone mineral density (BMD) or the risk of low bone status in premenopausal women. We conducted a baseline survey with a representative sample of Japanese women in 1996. The effect of current and former smokers (ever-smoker) was investigated with 789 premenopausal women aged 20-40 years. The multiple regression with stepwise method was used to identify significant determinants for BMD or the risk of low bone status (T-score < -1) with age, height, weight, calcium intake, coffee consumption, exercise habits, level of daily activity, parity >or= 1, and smoking as explanatory variables. The smoking effect was determined after adjusting for age, height, weight, and significant variables in the multiple regression with stepwise method. Ever-smoker was significantly associated with decreased lumbar BMD adjusted for age, height, and weight. The odds ratio of an ever-smoker for low bone status at the lumbar spine was 2.03 (95% CI 1.12, 5.82) adjusted for age, height, weight, and parity. The odds ratio for low bone status at the lumbar spine was 1.59 (95% CI 0.65, 3.91) and 2.55 (95% CI 1.12, 5.82) in those with less than 3 pack-years of tobacco use and in those with 3 or more pack-years of tobacco use, respectively. These values were adjusted for age, height, weight, and parity using a never-smoker as a reference. Cumulative smoking exposure may be associated with increased risk of low bone status among premenopausal women.

Socioeconomic status and bone mineral density in a population-based sample of men

Overall, socioeconomic status (SES) is inversely associated with poorer health outcomes. However, current literature provides conflicting data of the relationship between SES and bone mineral density (BMD) in men. In an age-stratified population-based randomly selected cross-sectional study of men (n=1467) we assessed the association between SES and lifestyle exposures in relation to BMD. SES was determined by matching the residential address for each subject with Australian Bureau of Statistics 2006 census data for the study region. BMD was measured at the spine and femoral neck by dual energy X-ray absorptiometry. Lifestyle variables were collected by self-report. Regression models were age-stratified into younger and older groups and adjusted for age, weight, dietary calcium, physical activity, and medications known to affect bone. Subjects with spinal abnormalities were excluded from analyses of BMD at the spine. In younger men, BMD was highest at the spine in the mid quintiles of SES, where differences were observed compared to quintile 1 (1-7%, p<0.05). In older men, the pattern of BMD across SES quintiles was reversed, and subjects from mid quintiles had the lowest BMD, with differences observed compared to quintile 5 (1-7%, p<0.05). Differences in BMD at the spine across SES quintiles represent a potential 1.5-fold increase in fracture risk for those with the lowest BMD. There were no differences in BMD at the femoral neck. Further research is warranted which examines the mechanisms that may underpin differences in BMD across SES quintiles and to address the current paucity of data in this field of enquiry.

Changes in bone mineral density of adolescent mothers during the 12-month postpartum period

Objective

Bone mineral density (BMD) loss has been described in adult women in the 12-month postpartum period. However, little is known about the precise BMD pattern in adolescent mothers. The present study aimed to evaluate BMD in Argentinean adolescent mothers followed up during the 12-month postpartum period.

Design

Analytical, prospective clinical trial. BMD and body composition were determined by dual-energy X-ray absorptiometry; bone mineral content (BMC) and BMD were measured in the lumbar spine (L2–L4), femoral neck (FN), femur trochanter (TR), total hip (TH) and total body. Changes in BMD and BMC were analysed using ANOVA for pairwise comparisons. Other comparisons were performed with the paired-sample t test and Wilcoxon test; Pearson’s correlation coefficient was used to analyse the relationship among continuous variables.

Setting

La Plata, Argentina.

Subjects

Adolescent mothers (n 35; 17 years old or less) were recruited within 15 d after delivery. Studies and follow-up were performed at 15 d and 3, 6 and 12 months postpartum.

Results

BMD and BMC losses at 3 and 6 months and recovery at 12 months fitted a quadratic curve (ANOVA) at the three sites studied (FN, TH, TR), in total-body BMD (P = 0·000) and BMC (P = 0·038). At hip sites, BMD loss occurred at 3 months (FN, P = 0·000; TR, P = 0·000; TH, P = 0·000) and 6 months (FN, P = 0·000; TR, P = 0·000; TH, P = 0·000) compared with basal values. Percentage BMD loss immediately after delivery up to 6 months was about 5 %.

Conclusions

Adolescents showed significant BMD and BMC losses at 6 months postpartum, with an almost total recovery at 12 months in all sites studied.

Soy isoflavone supplementation and bone mineral density in menopausal women: a 2-y multicenter clinical trial

BACKGROUND

Isoflavones are naturally occurring plant estrogens that are abundant in soy. Although purported to protect against bone loss, the efficacy of soy isoflavone supplementation in the prevention of osteoporosis in postmenopausal women remains controversial.

OBJECTIVE

Our aim was to test the effect of soy isoflavone supplementation on bone health.

DESIGN

A multicenter, randomized, double-blind, placebo-controlled 24-mo trial was conducted to assess the effects of daily supplementation with 80 or 120 mg of soy hypocotyl aglycone isoflavones plus calcium and vitamin D on bone changes in 403 postmenopausal women. Study subjects were tested annually and changes in whole-body and regional bone mineral density (BMD), bone mineral content (BMC), and T scores were assessed. Changes in serum biochemical markers of bone metabolism were also assessed.

RESULTS

After study site, soy intake, and pretreatment values were controlled for, subjects receiving a daily supplement with 120 mg soy isoflavones had a statistically significant smaller reduction in whole-body BMD than did the placebo group both at 1 y (P < 0.03) and at 2 y (P < 0.05) of treatment. Smaller decreases in whole-body BMD T score were observed among this group of women at 1 y (P < 0.03) but not at 2 y of treatment. When compared with the placebo, soy isoflavone supplementation had no effect on changes in regional BMD, BMC, T scores, or biochemical markers of bone metabolism.

CONCLUSION

Daily supplementation with 120 mg soy hypocotyl isoflavones reduces whole-body bone loss but does not slow bone loss at common fracture sites in healthy postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00665860.

Associations of genetic lactase non-persistence and sex with bone loss in young adulthood

Some studies have reported that after attainment of peak bone mass (PBM), slow bone loss may occur in both men and women; however, findings are inconsistent. Genetic factors play a significant role in bone loss, but the available evidence is conflicting. Genetic lactase non-persistence (lactase C/C(-13910) genotype) is suggested to increase risk for inadequate calcium intake predisposing to poorer bone health. We investigated whether this genotype is associated with PBM and bone loss in young Finnish adults. Subjects belong to the Cardiovascular Risk in Young Finns Study that is an ongoing multi-centre follow-up of atherosclerosis risk factors. From the original cohort, randomly selected subjects aged 20-29 participated in baseline bone mineral density (BMD) measurements (n=358), and in follow-up measurements 12 years later (n=157). Bone mineral content (BMC) and BMD at lumbar spine (LS) and femoral neck (FN) were measured at baseline and follow-up with dual energy X-ray absorptiometry (DXA). Lactase C/T(-13910) polymorphism was determined by PCR and allele-specific fluorogenic probes. Information on lifestyle was elicited with questionnaires. During the follow-up, bone loss at both bone sites was greater in males (LS BMD: -1.1%, FN BMD: -5.2%) than in females (LS BMD: +2.1%, FN BMD: -0.7%) (both bone sites p=0.001). Younger age predicted greater loss of FN BMC and BMD in females (p=0.013 and p=0.001, respectively). Increased calcium intake predicted FN BMD gain in both sexes (in females B=0.007 g/cm(2)/mg, p=0.002; in males B=0.006, p=0.045), and increased physical activity LS BMD gain in females (B=0.091 g/cm(2)/physical activity point, p=0.023). PBM did not differ between the lactase genotypes, but males with the CC(-13910) genotype seemed to be prone to greater bone loss during the follow-up (LS BMD: C/C vs. T/T p=0.081). In conclusion, bone loss in young adulthood was more common in males than in females and seemed to occur mainly at the femoral neck. Young males with the lactase CC(-13910) genotype may be more susceptible to bone loss; however, calcium intake predicts changes in bone mass more than the lactase genotype.

Nicotine modulates bone metabolism-associated gene expression in osteoblast cells

Smoking has a broad range of physiological effects, such as being a risk factor in osteoporosis, bone fracture incidence, and increased nonunion rates. Recent studies showed that nicotine has effects at the cellular level in human osteoblast cells. To identify possible mechanisms underlying nicotine-induced changes in osteogenic metabolism, we defined changes in proliferation and osteocalcin, type I collagen, and alkaline phosphatase gene expression after treating human osteosarcoma cells (MG63), with various concentration of nicotine. Nicotine affects cell proliferation in a biphasic manner, including toxic and antiproliferative effects at high levels of nicotine and stimulatory effects at low levels. Moreover, low levels of nicotine upregulated osteocalcin, type I collagen, and alkaline phosphatase gene expression. The increased cell proliferation and gene upregulation induced by nicotine were inhibited by addition of the nicotinic receptor antagonist D: -tubocurarine. High nicotine concentrations downregulated the investigated genes. Our results demonstrate, for the first time, that the addition of nicotine concentrations analogous to those acquired by a light to moderate smoker yields increased osteoblast proliferation and bone metabolism, whereas the addition of nicotine concentrations analogous to heavy smokers leads to the opposite effect. The inhibition of these effects by D: -tubocurarine suggests that nicotine acts via the nicotinic acetylcholine receptor (nAChR).

Quantitative ultrasound in relation to risk factors for low bone mineral density in South African pre-menopausal women

SUMMARY: The study describes the association between risk factors and quantitative ultrasound bone measures in black and mixed-race pre-menopausal South African women. Despite some differences between the two study groups, the findings generally lend support to the use of ultrasound for epidemiological studies of bone mass in resource-limited settings. INTRODUCTION: Quantitative ultrasound at the calcaneus is a convenient and inexpensive method of estimating bone strength well suited to community-based research in countries with limited resources. This study determines, in a large sample of pre-menopausal South African women, whether characteristics associated with quantitative ultrasound measures are similar to those shown to be associated with bone mineral density as measured by dual X-ray absorptiometry. METHODS: This cross-sectional study included 3,493 women (1,598 black and 1,895 mixed race), aged 18-44 living in Cape Town. Study nurses administered structured interviews on reproductive history, lifestyle factors, and measured height and weight. Calcaneus quantitative ultrasound measurements were obtained using the Sahara device. Adjusted means of ultrasound measures according to categories of risk factors were obtained using multivariable regression analysis. RESULTS: Associations between quantitative ultrasound measures and age, body mass index, age at menarche, parity, and primary school physical activity were similar to those known for bone mineral density as measured by dual X-ray absorptiometry. There were no clear associations between quantitative ultrasound measures and educational level, alcohol use, cigarette smoking, and current calcium intake. CONCLUSION: The data give qualified support to the use of quantitative ultrasound as an epidemiological tool in large studies of bone strength in pre-menopausal women.

[The relationship between lifetime sports activity measured with MET and peak strain score and bone measurement in college-aged women]

PURPOSE

The aim of this study was to compare the relation between differently measured sports activities (metabolic equivalent [MET] and peak strain score) and distal radius bone mineral density in college-aged women.

METHODS

Lifetime sports activity was scored in two different ways: 1) a sports activity score by multiplying the intensity (METs) and duration and 2) a sports activity score by adding up physical strain scores based on the ground reaction force of each sports activities. Bone mineral density was measured using dual energy x-ray densitometry (DTX-200) in the distal radius site.

RESULTS

In stepwise multiple regression analysis, body weight and sports activities during the college period were significant positive predictors for distal radius bone mineral density. The explained variance of sports activity measured with a peak strain score (8.8%) for distal radius bone mineral density was higher than one measured with the MET score (3.3%).

CONCLUSION

It can be concluded that sports activity scores based on MET and peak strain scores during college are very important for determining the bone mineral density in the distal radius site in women under 30.

Multigenerational exposure to ethinyl estradiol affects bone geometry, but not bone mineral density in rats

Estrogenic compounds are known to prevent bone loss in ovariectomized adult rats; however, their effects on bone in developing and reproductively-intact rats are less well-understood. In a large multigenerational experiment 0, 2, 10, or 50 ppb ethinyl estradiol (EE) in the diet was fed to intact male and female rats from conception until either weaning, postnatal day 140, or continuously for 2 years. Vertebrae (lumbar and caudal) and femurs were collected from subsets of these animals at necropsy at 48 days, 70 days, 140 days, or 2 years of age and subjected to dual-energy X-ray absorptiometry (DXA) scanning to measure bone mineral density (BMD), bone mineral content (BMC), and bone area. In addition, the length, cross-sectional area, marrow area, and cortical bone area of the femurs were measured directly in all animals at PND 140 and 2 years. Continuous dietary intake of 50 ppb EE decreased body weight by 8-27%. BMD adjusted for body weight was not affected by EE, with the exception of an increase in the caudal vertebrae in males treated with 50 ppb EE. In female rats, continuous treatment with 50 ppb EE decreased length and cross-sectional area of the femur. The length of the femur was decreased in the first two generations following institution of a phytoestrogen-free diet at the initiation of the study in all animals, including controls, but returned to the original length by the third or fourth generation. The cross-sectional area of the femur also varied by generation. In conclusion, a high dose of EE throughout the lifespan resulted in decreased bone size in females, which could reduce the force required to break the bone. Furthermore, dietary changes may have epigenetic effects which persist for multiple generations.

Investigating heavy-metal hyperaccumulation using Thlaspi caerulescens as a model system

BACKGROUND

Metal-hyperaccumulating plant species are plants that are endemic to metalliferous soils and are able to tolerate and accumulate metals in their above-ground tissues to very high concentrations. One such hyperaccumulator, Thlaspi caerulescens, has been widely studied for its remarkable properties to tolerate toxic levels of zinc (Zn), cadmium (Cd) and sometimes nickel (Ni) in the soil, and accumulate these metals to very high levels in the shoot. The increased awareness regarding metal-hyperaccumulating plants by the plant biology community has helped spur interest in the possible use of plants to remove heavy metals from contaminated soils, a process known as phytoremediation. Hence, there has been a focus on understanding the mechanisms that metal-hyperaccumulator plant species such as Thlaspi caerulescens employ to absorb, detoxify and store metals in order to use this information to develop plants better suited for the phytoremediation of metal-contaminated soils.

SCOPE

In this review, an overview of the findings from recent research aimed at better understanding the physiological mechanisms of Thlaspi caerulescens heavy-metal hyperaccumulation as well as the underlying molecular and genetic determinants for this trait will be discussed. Progress has been made in understanding some of the fundamental Zn and Cd transport physiology in T. caerulescens. Furthermore, some interesting metal-related genes have been identified and characterized in this plant species, and regulation of the expression of some of these genes may be important for hyperaccumulation.

CONCLUSIONS

Thlaspi caerulescens is a fascinating and useful model system not only for studying metal hyperaccumulation, but also for better understanding micronutrient homeostasis and nutrition. Considerable future research is still needed to elucidate the molecular, genetic and physiological bases for the extreme metal tolerance and hyperaccumulation exhibited by plant species such as T. caerulescens.