The effect of aging on bone mineral metabolism and bone mass in Native American women

The Problem of Vitamin D Scarcity: Cultural and Genetic Solutions by Indigenous Arctic and Tropical Peoples

Vitamin D metabolism differs among human populations because our species has adapted to different natural and cultural environments. Two environments are particularly difficult for the production of vitamin D by the skin: the Arctic, where the skin receives little solar UVB over the year; and the Tropics, where the skin is highly melanized and blocks UVB. In both cases, natural selection has favored the survival of those individuals who use vitamin D more efficiently or have some kind of workaround that ensures sufficient uptake of calcium and other essential minerals from food passing through the intestines. Vitamin D scarcity has either cultural or genetic solutions. Cultural solutions include consumption of meat in a raw or boiled state and extended breastfeeding of children. Genetic solutions include higher uptake of calcium from the intestines, higher rate of conversion of vitamin D to its most active form, stronger binding of vitamin D to carrier proteins in the bloodstream, and greater use of alternative metabolic pathways for calcium uptake. Because their bodies use vitamin D more sparingly, indigenous Arctic and Tropical peoples can be misdiagnosed with vitamin D deficiency and wrongly prescribed dietary supplements that may push their vitamin D level over the threshold of toxicity.

Relationship of American Indian blood quantum with osteoporosis risk: a cross-sectional study of American Indian women in Oklahoma

Information regarding the prevalence and risk of osteoporosis among American Indian (AI) women is limited. This study showed that with increasing AI blood quantum, the prevalence of osteoporosis at the hip based on BMD T-scores decreased and this appeared to be independent of other risk factors.

INTRODUCTION

This study was designed to investigate the effects of AI blood quantum (BQ) on osteoporosis prevalence and risk in a cohort of AI women in Oklahoma.

METHODS

Women (n = 301), aged 50 years and older, were recruited to participate in the Oklahoma American Indian Women's Osteoporosis Study. Baseline bone density, fracture history, bone biochemical markers, and potential risk factors were assessed. Participants were stratified by AI BQ into BQ1 ≤ 25%, BQ2 = 25-49%, BQ3 = 50-74%, and BQ4 = 75-100%. The effects of BQ on the prevalence and risk of osteoporosis were evaluated.

RESULTS

Based on T-scores, one in approximately eight women in the study was osteoporotic at one or more sites. The prevalence of osteoporosis decreased (p < 0.05) with increasing BQ, especially at the hip, trochanteric, and intertrochanter regions. No differences in bone-specific alkaline phosphatase and C-telopeptide were observed across BQ that could account for the differences in bone density. 25-OH vitamin D decreased with increasing BQ, but mean for each BQ1-4 was > 40 ng/mL. Fracture history did not differ across BQ, and though 52% of the population consumed less than the RDA for calcium, no effect of BQ was observed.

CONCLUSIONS

In this cohort of women who identified as AI, greater Indian BQ was associated with a decrease in the prevalence of osteoporosis.

The effect of vernal solar UV radiation on serum 25-hydroxyvitamin D concentration depends on the baseline level: observations from a high latitude in Finland

Humans obtain vitamin D from conversion of 7-dehydrocholesterol in the skin by ultraviolet B (UVB) radiation or from dietary sources. As the radiation level is insufficient in winter, vitamin D deficiency is common at higher latitudes. We assessed whether vernal solar UVB radiation at latitudes 61°N and 67°N in Finland has an impact on serum 25-hydroxyvitamin D [S-25(OH)D] concentrations. Twenty-seven healthy volunteers participated in outdoor activities in snow-covered terrain for 4–10 days in March or April, with their face and hands sun-exposed. The personal UVB doses and S-25(OH)D levels were monitored. A mean UVB dose of 11.8 standard erythema doses (SED) was received during an average of 12.3 outdoor hours. The mean S-25(OH)D concentration in subjects with a baseline concentration below 90.0 nmol/L (n=13) increased significantly, by 6.0 nmol/L from an initial mean of 62.4 nmol/L (p<0.001), whereas in those with a basal concentration above 90.0 nmol/L (n=12) it decreased significantly, by 6.7 nmol/L from a mean of 116.9 nmol/L (p<0.01). To conclude, only 7% of total body surface area was exposed to vernal sunlight and this was capable of increasing S-25(OH)D levels in subjects with a baseline level below 90 nmol/L but not in those with higher levels.

Bone Mineral Density in Navajo Men and Women and Comparison to Non-Hispanic Whites from NHANES (2005-2008)

PURPOSE

To describe bone mineral density (BMD) at the hip and spine and prevalence of low bone mass and osteoporosis in Navajo men and women across age, gender, and body mass index (BMI) compared with non-Hispanic (NH) Whites from NHANES (2005-2008).

METHODS

Cross-sectional dual energy x-ray absorptiometry measurements at the hip and spine in 1,097 participants from the Education and Research Towards Health study.

RESULTS

Bone mineral density was lower among younger Navajo than NH-Whites at lower BMI, and in overweight, younger men at lumbar spine and total hip. Spine BMD was lower in Navajo women, across BMI. Prevalence of low bone mass and osteoporosis in Navajo was higher than NH-Whites, particularly among women.

CONCLUSIONS

Further research is needed to understand if lower BMD among younger Navajo signals a risk for future fracture, and fracture risk relative to BMD, given the challenges in health care access and fracture morbidity among minorities.

Vitamin D status of northern indigenous people of Russia leading traditional and "modernized" way of life

Background

Vitamin D status in groups of northern indigenous people of Russia leading close to traditional (seminomadic reindeer herding), post-traditional (in settlements) or “modernized” (in towns) way of life was analysed.

Design

The survey study groups consisted of 178 Nenets and Komi aged 18–60 living in the Arctic (66–67°N). Urban Komi, Udmurts and Komi-Permiaks (n=150) living in a non-Arctic area (57–61°N) formed a control group. The concentration of serum 25-hydroxyvitamin D (25OHD), as a transport form of vitamin D, was assessed by enzyme immunoassay analysis.

Results

The group average 25OHD levels in both rural and urban Arctic residents are within the range of values seen in the non-Arctic urban subjects adjusted for season: 39.7–47.7 nmol/l. Abandoning traditional lifestyle associates with lower vitamin D levels in indigenous Arctic people. Mean±standard deviation 25OHD values among Nenets were lower in those living in the administrative centre (a big settlement) with a population of 1,460 (32.2±12.90 nmol/l) than in the residents of small settlements (39.6±14.08 nmol/l), and in reindeer herders (42.4±13.45 nmol/l; p<0.05 in both cases). Komi townspeople had lower 25OHD concentrations (47.7±12.00 nmol/l) than Komi reindeer herders (68.7±25.20; p<0.01).

Conclusions

The transition from seminomadic to post-traditional and “modernized” way of life has led to a decrease in the consumption of traditional foods among the indigenous people of the Russian Arctic. Our data support the notion that the traditional northern diet promotes healthy vitamin D levels, while adherence to the “western” type of diet correlates with a lower 25OHD concentration.

Efficacy of optimization of vitamin D in preventing osteoporosis and osteoporotic fractures: A systematic review

Increased intake or supplementation of vitamin D is often recommended for normal bone health; however, its preventive effect on osteoporosis has not been fully evaluated. The aim of this review is to gather evidence of the efficacy of the optimization of vitamin D nutrition in preventing osteoporosis and osteoporotic fractures. PubMed was used for searching the relevant literature using the MeSH terms "Bone Density (limited to "human", "female", and "English" literature)" or "Fractures (limited to "human", "age ≥45 years", and "English" literature)", and "Vitamin D". The searches yielded 19 randomized controlled trials (RCTs), nine cohort studies, 19 case-control studies, 19 cross-sectional studies, and one meta-analysis. We attempted to answer three questions: 1) does increased vitamin D intake prevent bone loss in peri- and postmenopausal women?, 2) does increased vitamin D intake prevent osteoporotic fractures in the elderly?, and 3) does increased vitamin D in take positively affect peak bone mass attainment in young women? The answer to questions 1 and 2 is that a vitamin D intake of 10-17.5 μg/day (400-700 IU/day) or more is effective in preventing bone loss in late postmenopausal women and an intake of 17.5-20 μg/day (700-800 IU/day) or more together with a calcium supplement reduces the risk of osteoporotic fractures. For question 3, some lines of evidence support the negative effect of low vitamin D nutrition on the attainment of peak bone mass in young women. Further studies are needed to clarify the effect of vitamin D in this age group.

Higher body mass, older age and higher monounsaturated fatty acids intake reflect better quantitative ultrasound parameters in Inuit preschoolers

OBJECTIVES

Investigate the effects of selected factors associated with quantitative ultrasound parameters among Inuit preschoolers living in Arctic communities (56° 32'-72° 40'N).

MATERIALS AND METHODS

Children were selected randomly in summer and early fall (n=296). Dietary intake was assessed through the administration of a 24-h dietary recall (24-h recall) and a food frequency questionnaire (FFQ). Anthropometry was measured using standardized procedures. Plasma 25-hydroxy vitamin D (25(OH)D) and parathyroid hormone (PTH) were measured using a chemiluminescent assay (Liaison, Diasorin). Quantitative ultrasound parameters were measured using Sahara Sonometer, (Hologic Inc.).

RESULTS

Children divided by speed of sound (SoS) and broadband ultrasound attenuation (BUA) quartiles were not different for age (years), sex (M/F), calcium (mg/d) and vitamin D intake (µg/d) and plasma 25(OH)D concentration (nmol/L). However, children in the highest BUA and SoS quartile had higher body mass index (BMI) compared to those in quartile 1. Using multivariate linear regression, higher BMI, older age and monounsaturated fatty acids (MUFA) intake were predictors of BUA while only BMI was a predictor of SoS.

CONCLUSIONS

Further investigation assessing intakes of traditional foods (TF) and nutrients affecting bone parameters along with assessment of vitamin D status of Inuit children across seasons is required.

Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences

Bone mineral density (BMD) has been reported to be both higher and lower in Indigenous women from different populations. Body composition data have been reported for Indigenous Australians, but there are few published BMD data in this population. We assessed BMD in 161 Indigenous Australians, identified as Aboriginal (n=70), Torres Strait Islander (n=68) or both (n=23). BMD measurements were made on Norland-XR46 (n=107) and Hologic (n=90) dual-energy X-ray absorptiometry (DXA) machines. Norland BMD and body composition measurements in these individuals, and also in 36 Caucasian Australians, were converted to equivalent Hologic BMD (BMD(H)) and body composition measurements for comparison. Femoral neck (FN) and lumbar spine Z-scores were high in Indigenous participants (mean FN Z-score: Indigenous men +0.98, p<0.0001 vs. mean zero; Indigenous women +0.82, p<0.0001 vs. mean zero). FN BMD(H) was higher in Aboriginal and/or Torres Strait Islander than Caucasian participants, after adjusting for age, gender, diabetes and height and remained higher in men after addition of lean mass to the model. We conclude that FN BMD is higher in Aboriginal and/or Torres Strait Islander Australians than Caucasian Australian reference ranges and these differences still remained significant in men after adjustment for lean mass. It remains to be seen whether these BMD differences translate to differences in fracture rates.

Vitamin D deficiency among northern Native Peoples: a real or apparent problem?

Vitamin D deficiency seems to be common among northern Native peoples, notably Inuit and Amerindians. It has usually been attributed to: (1) higher latitudes that prevent vitamin D synthesis most of the year; (2) darker skin that blocks solar UVB; and (3) fewer dietary sources of vitamin D. Although vitamin D levels are clearly lower among northern Natives, it is less clear that these lower levels indicate a deficiency. The above factors predate European contact, yet pre-Columbian skeletons show few signs of rickets-the most visible sign of vitamin D deficiency. Furthermore, because northern Natives have long inhabited high latitudes, natural selection should have progressively reduced their vitamin D requirements. There is in fact evidence that the Inuit have compensated for decreased production of vitamin D through increased conversion to its most active form and through receptors that bind more effectively. Thus, when diagnosing vitamin D deficiency in these populations, we should not use norms that were originally developed for European-descended populations who produce this vitamin more easily and have adapted accordingly.

Bone mineral density and its relationship with body mass index in postmenopausal women with type 2 diabetes mellitus in mainland China

Bone mineral density (BMD) and its association with body mass index (BMI) are uncertain in postmenopausal women with type 2 diabetes mellitus (T2DM) in mainland China. This study was performed to assess this association including 1,042 postmenopausal women with T2DM and 919 non-diabetic control subjects. Bone mineral density of the posteroanterior spine and of the left hip was measured by use of dual-energy X-ray absorptiometry. Diabetic participants were divided into three groups according to BMI, i.e. low BMI (DML < 18.5 kg/m(2)), intermediate BMI (DMM 18.5-24.9 kg/m(2)), and high BMI (DMH >or= 25 kg/m(2)). The BMD values of diabetic subjects between groups exhibited a significant gradient difference, with DML < DMM < DMH. On the fitting curves, where BMD in various skeletal regions varied with age, BMDs of DML were approximately 15% lower than those of DMM, and those of DMM were approximately 10% lower than those of DMH. For prevalence and risks of osteoporosis a gradient difference was observed among diabetic groups, DML > DMM approximately control > DMH. The osteoporosis risk was higher for the hip than for the lumbar spine, especially in DML. This study indicated that postmenopausal women with T2DM had higher BMD and lower osteoporosis risk in the lumbar spine, and that lower BMI was an indicator of osteoporosis in mainland China.

The bare bones of race

In this paper I examine claims of racial difference in bone density and find that the use and definitions of race in medicine lack a theoretical foundation. My central argument is that the social produces the biological in a system of constant feedback between body and social experience. By providing a different angle of vision on claimed racial differences I hope to move the conversation away from an ultimately futile discussion of nature versus nurture, where time is held constant and place seen as irrelevant, and begin to build a new paradigm for examining the contributions of geographic ancestry, individual lifecycle experience, race, and gender to varied patterns of health and disease.

Parathyroid hormone is predictive of low bone mass in Canadian aboriginal and white women

Canadian Aboriginal women have lower age- and weight-corrected bone mineral density (BMD) and lower vitamin D status than White women. This study was undertaken to describe the differences in biomarkers of bone metabolism and vitamin D in Aboriginal and non-Aboriginal women and to establish which biomarkers were predictive of BMD. In total, 41 rural Aboriginal, 212 urban Aboriginal and 182 urban White women were studied for BMD of the distal radius, calcaneus, lumbar spine, femoral neck, total hip and whole body using dual-energy X-ray absorptiometry. Serum biomarkers measured included calcium, phosphate, alkaline phosphatase (ALP), C-telopeptide of type 1 collagen (CTX), osteocalcin (OC), osteoprotegerin (OPG), parathyroid hormone (PTH) and 25(OH)D. Data were analyzed for differences among the three groups stratified by age (25 to 39, 40 to 59 and 60 to 75 y) using factorial ANOVA. Predictors of BMD including ethnicity, age and body weight were identified using step-wise regression. Unadjusted BMD of all sites declined with age regardless of ethnic grouping. Prediction models for 5 of 6 BMD sites included PTH accounting for age and body weight. Other predictors of BMD included OC for the radius and calcaneus; OPG for spine and total hip; and ALP for whole body and calcaneus. Serum 25(OH)D was not included in any model of BMD. After accounting for all variables in the regression equation, an average Aboriginal woman of 46 y and 79 kg was predicted to have 6% lower calcaneus BMD and 3% lower radius BMD compared to a White woman of the same age and weight. In conclusion, PTH is a better predictor of BMD than 25(OH)D in this population of Aboriginal and White women.

Timing of peak bone mass: discrepancies between CT and DXA

CONTEXT

The time of life in which peak bone mass in the axial skeleton is attained has been the subject of considerable controversy, with estimates ranging from the time of sexual and skeletal maturity to the fifth decade of life.

OBJECTIVE

The objective was to examine whether dual energy x-ray absorptiometry (DXA) and computed tomography (CT) values for bone mass and bone density (BD) in the axial skeleton increase after sexual and skeletal maturity.

DESIGN/PARTICIPANTS

Measurements of vertebral bone mineral density and bone mineral content (BMC) by DXA and vertebral BD and BMC by CT were obtained in 50 sexually and skeletally mature white females at baseline and 3 yr later. CT BMC values were calculated through analysis of vertebral volume in relation to density (BMC = vertebral volume x BD).

RESULTS

Although neither CT BD nor BMC measures changed with time, DXA bone mineral density and BMC values were significantly higher at follow-up (P < 0.0001). Despite strong correlations between DXA and CT bone measures, DXA yielded greater changes in bone values in 47 of 50 subjects.

CONCLUSIONS

Bone acquisition in the lumbar spine as measured by CT reaches its peak by sexual and skeletal maturity. In contrast, bone values by DXA continue to increase after puberty and cessation of longitudinal growth. Increases in DXA measures are likely a reflection of inhomogeneous changes in soft tissues around the spine or of disproportionate increases in the posterior elements of the vertebrae rather than of changes within the vertebral body.

Canadian Aboriginal women have a higher prevalence of vitamin D deficiency than non-Aboriginal women despite similar dietary vitamin D intakes

Canadian Aboriginal women have high rates of bone fractures, which is possibly due to low dietary intake of minerals or vitamin D. This study was undertaken to estimate dietary intake of calcium and vitamin D by designing a culturally appropriate dietary survey instrument and to determine whether disparities exist between Aboriginal and white women. After validation of a FFQ, 183 urban-dwelling and 26 rural-dwelling Aboriginal women and 146 urban white women completed the validated FFQ and had serum 25-hydroxyvitamin D [25(OH)D] measured. Urban Aboriginal women had lower (P=0.0004) intakes of total dietary calcium than urban white women; there was no difference in rural Aboriginal women. Only a minority of all women met the adequate intake (AI) for calcium intake. Ethnicity did not affect total vitamin D intake; however, rural Aboriginal women consumed all of their dietary vitamin D from food sources, which was more (P<0.03) than both urban Aboriginal and white women. Rural and urban Aboriginal women had lower (P<0.0004) serum 25(OH)D than urban white women. We found that 32% of rural Aboriginal, 30.4% of urban Aboriginal, and 18.6% of urban white women were vitamin D deficient, with serum 25(OH)D concentrations<37.5 nmol/L. The high prevalence of vitamin D deficiency among Aboriginal women, combined with lower dietary intake of calcium, especially in older women, likely contributes to the higher incidence of fracture in this population.

Bone density and bone area in Canadian Aboriginal women: the First Nations Bone Health Study

INTRODUCTION

Canadian Aboriginal women are at increased risk of fracture compared with the general population.

HYPOTHESIS

There is disproportionately reduced bone density in Aboriginal women as compared to white females of similar age.

METHODS

A random age-stratified (25-39, 40-59 and 60-75) sample of Aboriginal women (n=258) and white women (n=181) was recruited. All subjects had calcaneus and distal forearm bone density measurements, and urban participants (n=397 [90.4%]) also had measurements of the lumbar spine, hip and total body.

RESULTS

Unadjusted measurements were similar in the two groups apart from the distal forearm which showed a significantly lower mean Z-score in the Aboriginal women (p=0.03). Aboriginal women were heavier than white women (81.0+/-18.0 kg vs. 76.0+/-18.0 kg, p=0.02). Weight was directly associated with BMD at all measurement sites (p<0.00001) and potentially confounded the assessment of ethnicity on bone mass measurements. Weight-adjusted ANCOVA models demonstrated significantly lower bone density in Aboriginal than white women for the calcaneus, distal forearm, and total body (all p<0.05), but not at the other sites. ANCOVA models (adjusted for age, height and weight) were used to explore differences in bone area and bone mineral content (BMC). There was a significant effect of ethnicity on bone area with Aboriginal women having larger adjusted mean values than white women (lumbar spine p=0.038, total hip p=0.0004, total body p=0.020). In contrast, there was no detectable effect of ethnicity on BMC (all p>0.2).

CONCLUSIONS

We identified significant site-specific differences in age-and weight-adjusted bone density for Aboriginal and white women. Larger bone area, rather than a reduction in BMC, appeared to be primarily responsible. Further work is needed to define how these differences in bone density and geometry affect indices of bone strength.

Smokeless tobacco use accelerates age-related loss of bone mineral density among older women in a multi-ethnic rural community

Cigarette smoking is a recognized risk factor for low bone mineral density (BMD) and osteoporosis. Despite the prevalence of smokeless tobacco (ST) use by women in some areas of the United States, minority groups in the United Kingdom, and populations in South Asia and Africa, no data exist to evaluate its effect on bone health. The objective of the study is to identify risk factors for low BMD among older women in a multi-ethnic population, with particular attention to smoking and ST use. Data were collected in Robeson County, North Carolina. ST use from childhood is common among women in this community. Two hundred-forty women aged 60 years and older (approximately equal numbers of African Americans, Native Americans and whites) were recruited at a variety of community events to obtain a cross-section of the demographic composition of the county. The main outcome was BMD measured in the heel using a portable dual energy x-ray absorptiometry. Twenty-nine percent of women were current or former smokers, and 26% current or former ST users. Increased BMD was predicted by greater body mass index, estrogen use in the past year, and African American and Native American ethnicity. There was a significant interaction between ST use and age, and between smoking and nutritional supplement use. BMD declined with age; the decline with age was greater for women who were current or former ST users than for those who never used ST. Women who formerly smoked and did not use supplements had a decreased BMD. ST should be considered as an additional risk factor for osteoporosis in populations where its use is prevalent.

Serum concentrations of MMP-1, MMP-2, and TIMP-1 in Chinese women: Age-related changes, and the relationships with bone biochemical markers, bone mineral density

BACKGROUND

Osteoblast-derived matrix metalloproteinse-1 (MMP-1), MMP-2 and tissue inhibitor of metalloproteinase-1 (TIMP-1) play a role in bone metabolism by degrading bone matrix.

METHODS

We measured MMP-1, MMMP-2, TIMP-1 and associated results with age and bone metabolism in 591 Chinese women aged 20-80 y.

RESULTS

Serum MMP-1, MMP-2, and TIMP-1 concentrations exhibited positive correlation with age. Serum concentrations of MMP-1 were higher in 40-69 y old women. The concentrations of MMP-2 were significantly increased in the 50-69 y olds. Serum TIMP-1 concentrations were significantly lower in women aged 30-59 y, and then these were followed by an increase at >60 y olds. We found a significant negative weaker correlation between MMP-2 and BMD. But multiple linear stepwise regression analysis showed that MMP-2 was not a determinant factor for BMD. There were significant positive correlations between MMP-2 and bone alkaline phosphatase (BAP), osteocalcin (OC), and cross-linked N-telopeptides of type I collagen (NTX).

CONCLUSIONS

The serum concentrations of MMP-1, MMP-2, and TIMP-1 exhibit age-related changes, and circulating MMP-2 and bone turnover are related.

Ethnic Variation in Risk for Osteoporosis among Women: A Review of Biological and Behavioral Factors

Most studies of risk factors for osteoporosis and nontraumatic fracture involve white women, although more research is being geared toward bone health among various ethnic groups. The purpose of this review is to provide an overview of health disparity in osteoporosis, including assessment of bone mineral density (BMD), bone health screening, lifestyle risk factors, and treatment involving white, black, Hispanic, Asian, and Native American women. This review summarizes evidence that white, Asian, Hispanic, and Native American women are more at risk for osteoporosis than black women. These conclusions are supported by the disparity in BMD between white and black women, although the reason for this biological difference is not well characterized. Additional research is needed to determine if there is a significant difference in BMD among Hispanic, Asian, and Native American women independent of body weight and size. Similarly, there is also disparity in fracture rates, with the causes presumed to be multifactorial. Calcium intake is lower than recommended in all females at all ages; however, it is much lower in black and Native American women and highest in white and Hispanic women. Black women also have a lower vitamin D status than white women, with mean vitamin D status of Hispanic American women lying between that of black and white women. Similarly, although white women are more active than black and Hispanic women at all ages, data are lacking about physical activity habits of women of other ethnic backgrounds and how this impacts bone health. Finally, screening protocols for women of various ethnicities and effectiveness of treatments are not well established and remain a priority in women's health.

Relationship of circulating MMP-2, MMP-1, and TIMP-1 levels with bone biochemical markers and bone mineral density in postmenopausal Chinese women

INTRODUCTION

Osteoblast-derived matrix metalloproteinase (MMP)-2, MMP-1 and tissue inhibitor of metalloproteinase (TIMP)-1 have been shown to play a role in bone metabolism by degrading the bone matrix.

METHODS

The present study was performed to investigate the relationships between serum MMP-2, MMP-1, or TIMP-1 levels and bone mineral density (BMD), as well as bone biochemical markers, in 297 Chinese postmenopausal women aged 42-80 years.

RESULTS

We found a significant negative weak correlation between MMP-2 and BMD at various skeletal regions. After adjustment for age and BMI, the correlation with BMD at the femoral neck and total hip disappeared. Multiple linear stepwise regression analysis showed that MMP-2 was not a determinant factor for BMD. The significant positive correlations between MMP-2 and bone cross-linked N-telopeptides of type I collagen (NTX), alkaline phosphatase (BAP), and osteocalcin (OC) and were found, and remained significant after adjustment for age and BMI. Moreover, serum MMP-2 concentrations were significantly higher in postmenopausal women with osteoporosis than in age-matched normal controls. There were no significant correlations between MMP-1, TIMP-1 and BMD. There were no significant relationships between MMP-1 and BAP, OC, and NTX. The associations between TIMP-1 and BAP and OC were not specific and constant.

CONCLUSIONS

In conclusion, our results suggest that circulating MMP-2 and markers of bone turnover are correlated, and serum MMP-2 levels may rise with increase in bone turnover.

Bone mineral density of American Indian and Alaska Native women compared with non-Hispanic white women: results from the Women's Health Initiative Study

OBJECTIVE

To compare bone mineral density (BMD) of American Indian/Alaska Native (AI/AN) women with that of non-Hispanic white women.

DESIGN

This cross-sectional study compared mean BMD between AI/AN women and a random sample of non-Hispanic white women matched on geographic region in the Women's Health Initiative Study, a prospective study of postmenopausal women. We analyzed baseline BMD measurements for the total hip, spine, and whole body from 139 AI/AN women and 1,431 non-Hispanic white women.

RESULTS

Unadjusted mean spine and whole body BMDs were not significantly different between the two races. Controlling for age, education, and hormone therapy use, adjusted mean BMD was similar by race among women who were underweight, normal, or obese. We found a significant interaction of race by body mass index on spine (P = 0.003) and whole body (P = 0.0003) BMD; thus, analyses were stratified by body mass index. Overweight AI/AN women had slightly lower adjusted mean whole body and spine BMD than overweight non-Hispanic white women (whole body: 0.97 vs 1.03 g/cm, P = 0.02; spine: 0.96 versus 1.03 g/cm, P = 0.001). Among extremely obese (body mass index: > or =40.0 kg/m) women, adjusted mean total hip BMD was higher in the AI/AN women (1.07 vs 0.97 g/cm, respectively, P = 0.03).

CONCLUSIONS

Overall, AI/AN and non-Hispanic white women had similar BMDs. This study suggests that extremely obese AI/AN women may have higher BMD at certain skeletal sites compared with extremely obese non-Hispanic white women. However, these results need to be confirmed by additional research.

Demographic risk factors for fracture in First Nations people

BACKGROUND

Recently, First Nations people were shown to be at high fracture risk compared with the general population. However, factors contributing to this risk have not been examined. This analysis focusses on geographic area of residence, income level, and diabetes mellitus as possible explanatory variables since they have been implicated in the fracture rates observed in other populations.

METHODS

A retrospective, population-based matched cohort study of fracture rates was performed using the Manitoba administrative health data (1987-1999). The First Nations cohort included all Registered First Nations adults (20 years or older) as indicated in either federal and/or provincial files (n = 32,692). Controls (up to three for each First Nations subject) were matched by year of birth, sex and geographic area of residence. After exclusion of unmatched subjects, analysis was based upon 31,557 First Nations subjects and 79,720 controls.

RESULTS

Overall and site-specific fracture rates were significantly higher in the First Nations cohort. Income quintile, geographic area of residence, and diabetes were fracture determinants but the excess fracture risk of First Nations ethnicity persisted even after adjustment for these factors.

CONCLUSION

First Nations people are at high risk for fracture but the causal factors contributing to this are unclear. Further research is needed to evaluate the importance of other potential explanatory variables.

Osteoporosis and fracture risk in women of different ethnic groups

Osteoporosis and 1-year fracture risk were studied in 197,848 postmenopausal American women from five ethnic groups. Weight explained differences in BMD, except among blacks, who had the highest BMD. One SD decrease in BMD predicted a 50% increased fracture risk in each group. Despite similar relative risks, absolute fracture rates differed.

INTRODUCTION

Most information about osteoporosis comes from studies of white women. This study describes the frequency of osteoporosis and the association between BMD and fracture in women from five ethnic groups.

MATERIALS AND METHODS

This study was made up of a cohort of 197,848 community-dwelling postmenopausal women (7784 blacks, 1912 Asians, 6973 Hispanics, and 1708 Native Americans) from the United States, without known osteoporosis or a recent BMD test. Heel, forearm, or finger BMD was measured, and risk factor information was obtained; 82% were followed for 1 year for new fractures. BMD and fracture rates were compared, adjusting for differences in covariates.

RESULTS

By age 80, more than one-fifth of women in each ethnic group had peripheral BMD T scores <-2.5. Black women had the highest BMD; Asian women had the lowest. Only the BMD differences for blacks were not explained by differences in weight. After 1 year, 2414 new fractures of the spine, hip, forearm, wrist, or rib were reported. BMD at each site predicted fractures equally well within each ethnic group. After adjusting for BMD, weight, and other covariates, white and Hispanic women had the highest risk for fracture (relative risk [RR] 1.0 [referent group] and 0.95, 95% CI, 0.76, 1.20, respectively), followed by Native Americans (RR, 0.87; 95% CI, 0.57, 1.32), blacks (RR, 0.52; 95% CI, 0.38, 0.70), and Asian Americans (RR, 0.32; 95% CI, 0.15, 0.66). In age- and weight-adjusted models, each SD decrease in peripheral BMD predicted a 1.54 times increased risk of fracture in each ethnic group (95% CI, 1.48-1.61). Excluding wrist fractures, the most common fracture, did not materially change associations.

CONCLUSIONS

Ethnic differences in BMD are strongly influenced by body weight; fracture risk is strongly influenced by BMD in each group. Ethnic differences in absolute fracture risk remain, which may warrant ethnic-specific clinical recommendations.

Fracture risk among First Nations people: a retrospective matched cohort study

BACKGROUND

Canadian First Nations people have unique cultural, socioeconomic and health-related factors that may affect fracture rates. We sought to determine the overall and site-specific fracture rates of First Nations people compared with non-First Nations people.

METHODS

We studied fracture rates among First Nations people aged 20 years and older (n = 32 692) using the Manitoba administrative health database (1987-1999). We used federal and provincial sources to identify ethnicity, and we randomly matched each First Nations person with 3 people of the same sex and year of birth who did not meet this definition of First Nations ethnicity (n = 98 076). We used a provincial database of hospital separations and physician billing claims to calculate standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for each fracture type based on a 5-year age strata.

RESULTS

First Nations people had significantly higher rates of any fracture (age- and sex-adjusted SIR 2.23, 95% CI 2.18-2.29). Hip fractures (SIR 1.88, 95% CI 1.61-2.14), wrist fractures (SIR 3.01, 95% CI 2.63-3.42) and spine fractures (SIR 1.93, 95% CI 1.79-2.20) occurred predominantly in older people and women. In contrast, craniofacial fractures (SIR 5.07, 95% CI 4.74-5.42) were predominant in men and younger adults.

INTERPRETATION

First Nations people are a previously unidentified group at high risk for fracture.

Impact of long-term inhaled corticosteroid therapy on bone mineral density: results of a meta-analysis

BACKGROUND

The impact of long-term inhaled corticosteroid (ICS) therapy on bone mineral density (BMD) is poorly understood.

OBJECTIVE

To evaluate the impact of long-term ICS use on BMD.

METHODS

Random-effects meta-analysis. Published and unpublished literature were identified by searches of MEDLINE and EMBASE databases and consultation with experts. Studies reporting BMD among adult asthma and chronic obstructive pulmonary disease (COPD) patients using ICS and non-ICS controls were identified. Studies selected for review included at least 1 year of follow-up. Two independent reviewers evaluated studies; data from those meeting specified inclusion criteria were abstracted for inclusion in the meta-analysis.

RESULTS

Fourteen (5.3%) of 266 reviewed studies met specified inclusion criteria. Sufficient data were available to perform meta-analysis on 3 measures for ICS-using patients (lumbar, femoral neck, and major trochanter BMD) and 1 measure (lumbar BMD) for non-ICS-using controls. Using current National Asthma Education and Prevention Program definitions, the majority of studies (12 of 14) included patients receiving moderate to high doses of ICSs. Among ICS users, annual changes from baseline in lumbar, femoral neck, and major trochanter BMD (-0.23%, -0.17%, and +1.46%, respectively) were not statistically significant. Mean changes in lumbar BMD were also not significantly different from controls (-0.02%). Further, annual changes in lumbar BMD were not statistically significant for subgroups of patients with asthma or COPD.

CONCLUSIONS

Long-term use of ICSs in patients with asthma or COPD was not associated with significant changes in BMD.

The epidemiology of osteoporosis and fractures in geriatric medicine

Several conclusions can be drawn from this article, the most important of which are as follows: 1. Low bone mass is widely prevalent among older men and women and is associated with important fracture consequences. 2. The prevalence of osteoporosis and fracture is projected to increase over the next several decades. 3. Although Caucasian women are at greatest risk, substantial numbers of men and women of non-Caucasian heritage are also affected. 4. The population burden of disease consequences, including mortality, morbidity, and social and personal cost, is anticipated to increase as well. 5. In the group at greatest risk (Caucasian women), osteoporosis and fracture have well-established risk factors, many of which are modifiable. 6. Relevance of these risk factors for groups other than Caucasian women appears likely but requires further investigation. 7. Personal and societal costs associated with osteoporosis are enormous; as such, identification of persons at risk and prevention and treatment of this disease should be public health priorities.

Aboriginal women and menopause

OBJECTIVE

To determine the characteristics of menopause in Aboriginal women, in particular Canadian Aboriginal women.

METHODS

An extensive review of articles extracted from both medical and non-medical databases was undertaken. The search strategy combined the key word "menopause" with any of the following terms: Aboriginals, Native Americans, Natives, Indians, Métis, Inuit, Eskimo, and Indigenous people.

RESULTS

A total of 29 records were found, 13 of which had results relevant to the objective of the study. These articles suggest that menopause may have a positive effect on the lives of Aboriginal women with respect to increasing their freedom within the community. Aboriginal women appear to experience fewer vasomotor symptoms than other North American women.

CONCLUSION

More research needs to be done to determine the effect menopause has on Canadian Aboriginal women and their coexisting diseases such as cardiovascular disease, hypertension, and diabetes mellitus. This work will allow health care providers to make more informed decisions on managing Aboriginal women's transition through menopause in areas such as hormone replacement therapy.

Efficacy and safety of vitamin D3 intake exceeding the lowest observed adverse effect level

BACKGROUND

The Food and Nutrition Board of the National Academy of Sciences states that 95 microg vitamin D/d is the lowest observed adverse effect level (LOAEL).

OBJECTIVE

Our objective was to assess the efficacy and safety of prolonged vitamin D3 intakes of 25 and 100 microg (1000 and 4000 IU)/d. Efficacy was based on the lowest serum 25-hydroxyvitamin D [25(OH)D] concentration achieved by subjects taking vitamin D3; potential toxicity was monitored by measuring serum calcium concentrations and by calculating urinary calcium-creatinine ratios.

DESIGN

Healthy men and women (n = 61) aged 41 +/- 9 y (mean +/- SD) were randomly assigned to receive either 25 or 100 microg vitamin D3/d for 2-5 mo, starting between January and February. Serum 25(OH)D was measured by radioimmunoassay.

RESULTS

Baseline serum 25(OH)D was 40.7 +/- 15.4 nmol/L (mean +/- SD). From 3 mo on, serum 25(OH)D plateaued at 68.7 +/- 16.9 nmol/L in the 25-microg/d group and at 96.4 +/- 14.6 nmol/L in the 100-microg/d group. Summertime serum 25(OH)D concentrations in 25 comparable subjects not taking vitamin D3 were 46.7 +/- 17.8 nmol/L. The minimum and maximum plateau serum 25(OH)D concentrations in subjects taking 25 and 100 microg vitamin D3/d were 40 and 100 nmol/L and 69 and 125 nmol/L, respectively. Serum calcium and urinary calcium excretion did not change significantly at either dosage during the study.

CONCLUSIONS

The 100-microg/d dosage of vitamin D3 effectively increased 25(OH)D to high-normal concentrations in practically all adults and serum 25(OH)D remained within the physiologic range; therefore, we consider 100 microg vitamin D3/d to be a safe intake.