The epidemiology and pathogenesis of osteoporosis

Gut microbiota and microbial metabolites for osteoporosis

Osteoporosis is an age-related bone metabolic disease. As an essential endocrine organ, the skeletal system is intricately connected with extraosseous organs. The crosstalk between bones and other organs supports this view. In recent years, the link between the gut microecology and bone metabolism has become an important research topic, both in preclinical studies and in clinical trials. Many studies have shown that skeletal changes are accompanied by changes in the composition and structure of the gut microbiota (GM). At the same time, natural or artificial interventions targeting the GM can subsequently affect bone metabolism. Moreover, microbiome-related metabolites may have important effects on bone metabolism. We aim to review the relationships among the GM, microbial metabolites, and bone metabolism and to summarize the potential mechanisms involved and the theory of the gut‒bone axis. We also describe existing bottlenecks in laboratory studies, as well as existing challenges in clinical settings, and propose possible future research directions.

Correlation of bone mineral density using the dual energy x-ray absorptiometry and the magnetic resonance imaging of the lumbar spine in Indian patients

BACKGROUND

Dual-energy x-ray absorptiometry (DEXA) scan is extensively used to diagnose osteoporosis. But surprisingly, osteoporosis remains an underdiagnosed condition with many fragility fracture patients who have failed to undergo DEXA or received concomitant treatment for osteoporosis. Magnetic resonance imaging (MRI) of the lumbar spine is a routine radiological investigation bring done for low back pain. MRI can detect changes in the bone marrow signal intensity on the standard T1-weighted images. This correlation can be explored to measure osteoporosis in elderly and post-menopausal patients. The present study aims to find any correlation of bone mineral density using the DEXA and MRI of the lumbar spine in Indian patients.

METHODS

Five regions of interest (ROI) of size 130-180 mm2 were placed in the vertebral body in the mid-sagittal section and parasagittal sections on either side (four in L1-L4 and one outside body) of elderly patients who underwent MRI for back pain. They also underwent a DEXA scan for osteoporosis. Signal to Noise Ratio (SNR) was calculated by dividing the mean signal intensity obtained for each vertebra by the standard deviation of the noise. Similarly, SNR was measured for 24 controls. An MRI-based "M score" was calculated by getting the difference in SNR patients to SNR controls and then dividing it by the control's standard deviation (SD). Correlation between the T score on DEXA and M scores on MRI was found out.

RESULTS

With the M score greater than or equal to 2.82, the sensitivity was 87.5%, and the specificity was 76.5%. M scores negatively correlated with the T score. With the increase in the T score, the M score decreased. The Spearman correlation coefficient for the spine T score was -0.651, with a p-value of <0.001, and the hip T score was -0.428, with a p-value of 0.013.

CONCLUSION

Our study indicates that MRI investigations are helpful in Osteoporosis assessments. Even though MRI may not replace DEXA, it can give insight into elderly patients who get an MRI routinely for back pain. It may also have a prognostic value.

Dietary acid load is associated with primary osteoporosis in postmenopausal women aged 50-65 years: A cross-sectional study

This study aimed to investigate the association between dietary acid load (DAL) and primary osteoporosis. This was a cross-sectional study. Among 850 randomly selected postmenopausal women aged 50-65 years, 232 women consisted of 124 women with normal bone mineral density (BMD) and 108 with primary osteoporosis were selected after examining the eligibility criteria. Demographic characteristics, anthropometric indices, and physical activity were collected through questionnaires. Osteoporosis was diagnosed using the dual-energy X-ray absorptiometry method. DAL was assessed by a valid and reliable semiquantitative food frequency questionnaire during the last year. Independent t-test, Mann-Whitney, Chi-square, and adjusted binary logistic regression were used for data analysis through SPSS/24. There were significant differences between the two groups in terms of age, body mass index (BMI), number of deliveries, and years after menopause (p < .05). The mean (standard deviation (SD)) potential renal acid load (PRAL) and net endogenous acid production (NEAP) were higher in postmenopausal women with osteoporosis than those with normal BMD (PRAL: -13.1 ± 11.1 mEq/day vs. -10.8 ± 12.7 mEq/day; NEAP: 29.5 ± 8.5 mEq/day vs. 31.2 ± 9.2 mEq/day). The mean consumption of potassium, magnesium, and calcium in the osteoporosis group was significantly lower than in the other group (p < .05). There were significant associations between osteoporosis with PRAL (odds ratio (OR) = 1.030; 95% confidence interval (CI): 1.001 to 1.060, p = .027) and NEAP scores (OR = 1.041; 95% CI: 1.003 to 1.081, p = .037). The odds of osteoporosis increased by 3% following one unit increase in PRAL score. Similarly, it increased by 4% with increasing NEAP score up to one unit. Therefore, dietary patterns that produce high DAL can have a detrimental effect on bone health.

Screening for Underlying Osteoporosis in Fragility Fracture Patients: The Patients Perspective

Background:

Early detection and treatment of osteoporosis are essential in preventing fractures and fracture-related morbidity and mortality. Fractures beget fractures and it is relevant and well-documented beneficial to target osteoporosis screening in patients already suffering a fracture. The associated increased number of patients being confronted with a potential diagnosis of osteoporosis makes it worth considering how this affects patients.

Objective:

The aim of this study was to explore fracture patients’ experiences when confronted with the option of being screened for osteoporosis as the underlying reason of their fracture.

Methods:

In a phenomenological hermeneutic framework, semi-structured interviews were performed in 15 fragiligty fracture patients being offered screening for osteoporosis. Analysis inspired by Ricoeur consisting of naive reading, structural analysis, and critical analysis and discussion was applied.

Results:

Fracture patients were condemned to make a choice when confronted with the possibility of the early detection of osteoporosis. Many questions regarding prevention of new fractures and prospects in the case of a positive test result were raised. The major themes were related to the consequences of knowing what might be hidden in the bones, and the responsibility to prevent illness.

Conclusion:

The confrontation with the potential risk of osteoporosis provokes fear and worry in patients about lived daily life and anxiety about being treated as a sick person, but in return, it motivates patients to adopt a bone-healthy lifestyle. In general, patients prefer to be given knowledge of their bone health status over not knowing, and being able to seek further information on the condition facing them.

OFELIA: Prevalence of Osteoporosis in Fragility Fracture Patients

Worldwide, a care gap has been recognized between presenting with a fracture and prevention of the next fracture. Fracture Liaison Service is the most cost-effective method to close this gap, but its implementation is sparse in the Nordic countries. To assess the need for a fracture prevention program, the primary aim of this study was to estimate the prevalence of osteoporosis in patients treated for fragility fractures at Aarhus University Hospital, Denmark. Secondary aims were to identify clinical risk factors associated with osteoporosis and the up-take of anti-osteoporosis treatment. The study was conducted as a cross-sectional study and patients aged 18+ years were consecutively identified over a 12 months period. Of 1164 identified patients, 832 were included and 794 (70% women, 66% aged ≥ 50 years) patients completed the study. Bone mineral density was measured by DXA and information about clinical risk factors were obtained. The overall prevalence of osteoporosis in this cohort was 14.9%, increasing to 20.3% in patients ≥ 50 years (22.9% in women, 9.6% in men). In addition to age above 50 years, female sex, low BMI, and early menopause were significantly associated with osteoporosis. At 3-years follow-up in patients diagnosed with osteoporosis, 95% of patients who initiated anti-osteoporosis treatment after their fracture were still adherent to treatment. Given that osteoporosis was demonstrated in one in five fragility fracture patients above 50 years, OFELIA stresses the need for implementation of a program aiming at securing appropriate investigation and treatment of osteoporosis in patients presenting a fragility fracture.

Parent/Child training to increase preteens' calcium, physical activity, and bone density: a controlled trial

PURPOSE

To test effects of parent/child training designed to increase calcium intake, bone-loading physical activity (PA), and bone density.

DESIGN

Two-group randomized controlled trial.

SETTING

Family-based intervention delivered at research center.

SUBJECTS

117 healthy children aged 10-13 years (58.1% female, 42.7% Hispanic, 40.2% White). Ninety-seven percent of participants had at least one parent graduate from high school and 37.2 % had at least one parent graduate from a 4-year university.

INTERVENTION

Children and parents were randomly assigned to diet and exercise (experimental) or injury prevention (control) interventions. Children were taught in eight weekly classes how to engage in bone-loading PA and eat calcium-rich foods or avoid injuries. Parents were taught behavior management techniques to modify children's behaviors.

MEASURES

Measures at baseline and at 3, 9, and 12 months included 24-hour diet and PA recalls, and bone mineral density (BMD) by dual-energy x-ray absorptiometry.

ANALYSIS

Analysis of variance and generalized estimating equations (GEE) assessed group by time differences. Comparisons were conducted separately for boys and girls.

RESULTS

For boys, cross-sectional differences between experimental and control groups were achieved for 3- and 9-month calcium intake (1352 vs. 1052 mg/day, 1298 vs. 970 mg/day, p < .05). For girls, marginal cross-sectional differences were achieved for high-impact PA at 12 months (p < .10). For calcium intake, a significant group by time interaction was observed from pretest to posttest for the full sample (p = .008) and for girls (p = .006) but not for boys. No significant group by time differences in calcium were observed across the follow-up period. No group by time differences were observed for high-impact PA. Among boys, longitudinal group by time differences reached significance for total hip BMD (p = .045) and femoral neck BMD (p = .033), even after adjusting for skeletal growth. Similar differential increases were observed among boys for bone mineral content (BMC) at the hip (p = .068) and total body (p = .054) regions. No significant group by time interaction effects were observed for girls at any bone site for BMD. For BMC, control girls showed a significant increase (p = .03) in spine BMC compared to intervention girls.

CONCLUSION

This study demonstrated that parent/preteen training can increase calcium intake and attenuate the decline in high-impact PA. Results suggest that more powerful interventions are needed to increase activity levels and maximize bone mineral accrual during preadolescent years.

Hip fractures cluster in space: an epidemiological analysis in Portugal

Using Portuguese hospital registers (2000-2002) we calculated age-standardized incidence rates of hip fractures. Spatial clusters of high incidence rates were found, with annual averages (per 100,000 inhabitants) varying from 154.4 to 572.2 and 77.3 to 231.5 for women and men, respectively. Geographic inequalities in the occurrence of hip fractures were also found.

INTRODUCTION

The aim of this study was to identify spatial patterns in the incidence of hip fracture in Portugal during the period 2000 to 2002.

METHODS

From the National Hospital Discharge Register, admissions of patients (50 years of age or more) with low-energy hip fracture were selected. Age-standardized incidence rates in relation to the municipality of the patients' place of residence were calculated. Empirical Bayes estimators were used to smooth the local risk and spatial statistics methods were used to identify spatial clusters.

RESULTS

Of 25,634 hip fractures in individuals aged 50 years or more caused by low or moderate impact, 19,759 occurred in women (age, mean+/-SD, 80.6+/-8.6 years) and 5,875 in men (age 77.7+/-10.0 years). Incidence rates increased exponentially with age, being higher in women nation-wide (female to male ratio from 1.5 to 5.1). Significant geographic differences were found: the incidence rates (95% CI) varied from 154.4 (153.6-155.3) to 572.2 (569.5-575.0) in women and 77.3 (76.64-78.05) to 231.5 (229.9-233.0) in men per 100,000 inhabitants. Spatial autocorrelation values (Moran index) were 0.56 and 0.45 for women and men, respectively.

CONCLUSION

Spatial clusters (p<0.0001) of high incidences were identified. Geographic differences in incidence rates were about threefold. Some regions had incidence rates as high as some north European countries. The geographic inequalities could be due to environmental or socioeconomic factors, but further investigation needs to be done to confirm this hypothesis.

Intraskeletal variability in bone mass

For methodological or other reasons, a variety of skeletal elements are analyzed and subsequently used as a basis for describing general bone loss and mass. However, bone loss and mass may not be uniform within and among skeletal elements of the same individual because of biomechanical factors. We test the hypothesis that a homogeneity in bone mass exists among skeletal elements of the same individual. Measures indicative of bone mass were calculated from the midshafts of six skeletal elements from the same individuals (N = 41). The extent of intraskeletal variability in bone mass (relative cortical area) was then examined for the entire sample, according to age, sex, and pathological status. The results of the analysis showed that all measures reflect a heterogeneity in bone mass (P </= 0.001). Specifically, differences were observed between the bones of the upper limb and those of the lower limb. Both sexes showed intraskeletal variability in bone mass, but the difference between the sexes is not significant (P = 0.509). When the sample is subdivided according to age, all groups show intraskeletal variability in bone mass, but the difference did not differ significantly among the groups (P = 0.217). However, significant differences in intraskeletal variability are observed between individuals below and above the age of 50. Pathological individuals show intraskeletal variability in bone mass, but the difference between the pathological and non-pathological groups is not significant (P = 0.095). These results indicate that the bone mass of any particular skeletal element is intricately tethered to its specific mechanical loading environment.

Dried plum reverses bone loss in an osteopenic rat model of osteoporosis

OBJECTIVE

We previously reported the efficacy of dried plum (Prunus domestica L.) in preventing ovariectomy-induced bone loss in a rat model of osteoporosis and improving bone biomarkers in postmenopausal women. The present study evaluated whether dried plum was able to restore bone mass in osteopenic ovariectomized rats.

DESIGN

Ninety-day-old Sprague-Dawley rats were either sham-operated (Sham; one group) or ovariectomized (Ovx; five groups) and were fed a standard diet for 40 days to establish bone loss and subsequently experimental treatments were initiated. Sham, Ovx control, and Ovx + 17beta-estradiol (E2; 10 microg/kg body weight per day) animals continued to receive the standard diet, whereas the remaining three Ovx groups received the following dietary treatments: Ovx + 5% dried plum (low dose), Ovx + 15% dried plum (medium dose), and Ovx + 25% dried plum (high dose). After 60 days, blood and bone specimens were collected for analyses.

RESULTS

Dried plum, as low as 5%, was effective in restoring femoral and tibial bone density. Dried plum increased lumbar bone density as well, with HD achieving a statistical significance. The increase in femoral bone density of dried plum-fed rats resulted in improved bone quality as indicated by 6.9% and 6.0% improvement in overall yield and ultimate force, respectively. Varying doses of dried plum were also able to significantly improve trabecular microarchitectural properties in comparison with ovariectomized controls.

CONCLUSIONS

The improvement in biomechanical properties of long bones due to dried plum, in part, may be due to the favorable microstructural changes as evident by enhanced tibial bone volume and connectivity. Loss of bone volume accompanied by loss of trabecular connectivity is generally believed to be an irreversible process, but our observations suggest that dried plum improves trabecular microstructure of tibia after losses have already occurred.

Effects of resistance training and protein supplementation on bone turnover in young adult women

BACKGROUND

The strength of aging bone depends on the balance between the resorption and formation phases of the remodeling process. The purpose of this study was to examine the interaction of two factors with the potential to exert opposing influences on bone turnover, resistance exercise training and high dietary protein intake. It was hypothesized that resistance training by young, healthy, untrained women with protein intakes near recommended levels (0.8 g.kg(-1).d(-1)) would promote bone formation and/or inhibit bone resorption, and that subsequent supplementation to provide 2.4 g protein.kg(-1).d(-1) would reverse these effects.

METHODS

Bone formation was assessed with serum bone-specific alkaline phosphatase (BAP) and osteocalcin (OC), and bone resorption with urinary calcium and deoxypyridinoline (DPD). Biochemical, strength, anthropometric, dietary, and physical activity data were obtained from 24 healthy, untrained, eumenorrheic women (18-29 y) at baseline, after eight weeks of resistance training (3 d.wk(-1), approximately 1 hr.d(-1); 3 sets, 6-10 repetitions, 13 exercises, 75-85% maximum voluntary contraction), and after 12 weeks of resistance training and 10 days of protein/placebo supplementation. Subjects were randomized (double-blind) to either a high protein (HP) or training control (TC) group and, during the final 10 days, consumed either enough purified whey protein to bring daily protein intake to 2.4 g.kg(-1).d(-1), or an equivalent dose of isoenergetic, carbohydrate placebo.

RESULTS

Strength, lean tissue mass, and DPD increased significantly in both groups over time, while percent body fat and BAP decreased (repeated measures ANOVA, p < or = 0.05, Bonferroni correction). No significant changes were observed for serum OC or urinary calcium, and no significant group (TC, HP) x time (baseline, week 8, week 12) interactions emerged for any of the biochemical measures.

CONCLUSION

(1) Twelve weeks of high-intensity resistance training did not appear to enhance bone formation or inhibit bone resorption in young adult women, as assessed by biochemical markers of bone metabolism. (2) Subsequent maintenance of a high protein intake for 10 days in these regularly-training, calcium-replete women also showed no effects on bone metabolism.

Contralateral differences in quantitative ultrasound of the heel: the importance of side in clinical practice

Quantitative ultrasound (QUS) of the heel is becoming increasingly popular for the assessment of skeletal status, although there appears to be a general lack of agreement regarding which side to measure. The purpose of the present study was to evaluate possible side differences (right versus left) in heel QUS within the general population, including children (10-15 years old, n=406), adults (26-33 years old, n=339), and elderly subjects (60-75 years old, n=455) of both genders (818 females and 382 males), and to examine the impact of these differences on prevalence estimates of osteoporosis and individual fracture risk assessment. All participants had both their heels measured twice with the Sahara device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) through the os calcis; a composite parameter, that is, quantitative ultrasound index (QUI) and an estimate of heel BMD (eBMD) were also derived. Significant side differences were detected for BUA and SOS (P<0.05), but not for QUI or eBMD. Contralateral differences were rather small in absolute terms, but were in the order of 12.6% for BUA, 0.72% for SOS, 7.9% for QUI, and 9.9% for eBMD, when expressed as percentage of the mean values for the two heels. Bilateral differences appeared to vary across age and gender. Significant correlations between QUS indices of the right and left heel were observed (r=0.75-0.85; P<0.001), which seemed to be stronger among the elderly and among male individuals. Prevalence rates of osteopenia and osteoporosis were not significantly different when estimated from eBMD T-scores for the one or the other foot (chi(2)=1.781, df=2, P=0.410). However, cross-classification analysis revealed that only 84% of the subjects classified into each risk category by the two calcanei were actually the same persons. In conclusion, results from the present study strongly suggest that QUS measurements of opposite heels may not be equivalent with respect to the evaluation of bone status and classification of individual fracture risk assessment, although the degree of discrepancy appears to be related to the primary outcome of interest.

A genome-screen of a large twin cohort reveals linkage for quantitative ultrasound of the calcaneus to 2q33-37 and 4q12-21

A genome-wide screen was performed on a large cohort of dizygous twin pairs to identify regions of the genome that contain QTL for QUS of bone. Suggestive linkage of QUS parameters to 2q33-37 and 4q12-21 highlighted these regions as potentially important for studies of genes that regulate bone.

INTRODUCTION

The genetics of osteoporotic fracture is only partly explained by bone mineral density (BMD). Quantitative ultrasound (QUS) of the calcaneus can also be used for independent clinical assessment of osteoporotic fracture risk. Two specific indices are derived from this assessment: broadband ultrasound attenuation (BUA) and velocity of sound (VOS). Both parameters provide information on fracture risk; however, BUA has been studied more extensively and may be favored because it is thought to have a stronger predictive value for osteoporotic fracture and incorporates aspects of trabecular structure and bone quality as well as BMD. Studies of QUS in twins have shown that both derived parameters are under substantial genetic control, independent of BMD.

MATERIALS AND METHODS

To identify regions of the genome that contain quantitative trait loci (QTL) for QUS of bone, we performed a genome-wide screen on a large cohort of dizygous twin pairs. Unselected female dizygous twins from 1067 pedigrees from the St Thomas' UK Adult Twin Registry were genome scanned (737 highly polymorphic microsatellite markers). Multipoint linkage analyses provided maximum evidence of linkage for BUA (LOD 2.1-5.1) to 2q33-37. Linkage for VOS (LOD 2.2-3.4) was maximal at 4q12-21. Potential evidence of linkage in the cohort indicated five other possible locations of QTL (LOD > 2.0) relevant to bone density or structure on chromosomes 1, 2, 13, 14, and X.

RESULTS AND CONCLUSIONS

This study has identified eight genomic locations with linkage of LOD > 2.0. This data should be of value in assisting researchers to localize genes that regulate bone mass and microstructure. These results should complement genome screens of BMD and bone structure and serve to enable further targeted positional candidate and positional cloning studies to advance our understanding of genetic control of bone quality and risk of fracture.

Epidemiology of hip and wrist fractures in Cameroon, Africa

Osteoporosis and fragility fractures are believed to be uncommon in Africa. To reevaluate this notion, we documented all patients aged 35 years and older admitted to the two main urban hospitals in Cameroon following a diagnosis of fracture during 2 years. Among 513 patients sustaining fractures (192 women, 321 men), 13.5% of all fractures in women occurred at the hip (n=26), 4.7% at the forearm (n=9), and 81.8% (n=157) at other sites (mainly tibia and femoral shaft). In men, the corresponding figures were 9% (n=29), 1.9% (n=6), and 89.1% (n=286). Of the hip and wrist fractures occurring in women, 80.0% were low energy trauma fractures due to falls, 8.6% were high-energy trauma fractures (road accidents), and 11.4% were undefined. In men, the corresponding figures were 42.9%, 34.3%, and 22.9%. Using the 1997 estimates of the population, the annual incidence rates of low-energy trauma fractures (per 100,000 persons over 35 years and above) were 4.1 in women, 2.2 in men for hip fractures, 1.2 in women, and 0.2 in men for wrist fractures. The pattern of most of the hip and wrist fractures in women is consistent with underlying bone fragility. The low incidence of fragility fractures is confirmed and is likely to be, in part, the result of reduced longevity as only 1.1% of women and 0.7% of men survive beyond 65 years of age.

Differential influence of physical activity on lumbar spine and femoral neck bone mineral density in the elderly population

This study investigates the relationship between lifetime physical activity and bone mineral density (BMD) at various sites in 129 healthy men and women aged 72.1 +/- 6.5 years. BMD was measured by dual energy x-ray absorptiometry, and physical activity was assessed by using the QUANTAP system (Quantification de l'Activité Physique), a standardized and structured computer-assisted interview tool designed to assess lifetime physical activity. Linear regression models controlling for age, gender, height, body mass, lean mass, and smoking habits were performed. Higher levels of sporting activity during youth were associated with greater lumbar spine BMD ( p < .001). Similarly, femoral neck BMD was greatest in subjects who reported regularly taking part in sports over the previous 20 years ( p <. 05) and during their whole lifetime ( p < 0.05). Sporting activity at the time of bone mass development increases subsequent lumbar spine BMD, and more recent sporting activity contributes to the preservation of femoral neck BMD. These results suggest that physical activity has a differential influence on BMD at different sites and at different ages, possibly related to the processes of bone construction and bone aging taking place at the time.

Epidemiology and pathogenesis of osteoporosis

Osteoporosis is likely to become the most common disorder of our aging population. An understanding of factors that affect the incidence of osteoporosis is critical if we are to successfully minimize the impact of this disorder on morbidity, mortality, and the cost of health care. This article will provide an overview of the frequency, distribution, and consequences of the various types of osteoporotic fractures in different populations. We will discuss the major risk factors, emphasizing those that are reversible. Fracture risk not only involves abnormalities of bone mass and architecture, but also factors that affect the incidence of falls. The racial, ethnic, and geographic differences in fracture incidence are associated with parallel differences in bone mineral density (BMD), but the differences are often relatively small, suggesting that other architectural or metabolic differences in the skeleton make an important contribution. On the other hand, when combined with low BMD, multiple risk factors and comorbid conditions increase the risk of fracture as well as morbidity and mortality from fracture. Osteoporosis can result pathogenetically from inadequate peak bone mass, excessive bone resorption, or impaired bone formation. These can be affected by genetics, nutrition, lifestyle, systemic hormones, and local factors. The relative importance of these mechanisms is not fully understood and may differ among patients. Nevertheless, our current understanding of epidemiology and pathogenesis can help clinicians to develop the optimal approach to diagnosis and management.

Bone histology of prehistoric inhabitants of the Canary Islands: comparison between El Hierro and Gran Canaria

The trabecular bone mass (TBM) of the proximal epiphyses of right tibiae belonging to 273 prehispanic inhabitants of Gran Canaria (60. 81% males and 35.53% females) were assessed by histomorphometrical analysis of undecalcified samples and compared with that of 41 samples from El Hierro (52.63% males and 47.37% females). Among the prehispanic population of Gran Canaria 19.05% showed TBM values below 13.5% and 30.40% below 15%, although individual variability was high (range 6.71-35.4%). In sharp contrast with these results, only one case (2.44%) from El Hierro showed a TBM value below 15%, whereas mean TBM (23.50;+/- 5.60%) was significantly higher than that of the population of Gran Canaria (17.88 +/- 5.20%). The high prevalence of osteoporosis on Gran Canaria may reflect protein-calorie malnutrition. Prehistorically Gran Canaria exhibited a relatively high population density (30-40/km(2)) and a strong reliance on agriculture, in contrast with a lower population density (4/km(2)) on the island El Hierro, where the population consumed mainly marine products.