Is caffeine consumption a risk factor for osteoporosis?

The effect of coffee consumption on three main bone disorders: a Mendelian randomization trial

INTRODUCTION

Despite a large number of observational studies examining the effect of coffee consumption(CC) on bone disorders(BDs), particularly, osteoarthritis(OA), osteoportic fracture(OF), and rheumatoid arthritis(RA), the conclusions are highly controversial. Thus, it is essential to examine the causal association between CC and BDs.

MATERIALS AND METHODS

Mendelian randomization (MR) analysis was performed to assess the causal influence of CC on OF, RA, and OA. The main endpoint was the odds ratio (OR) of the inverse variance weighted (IVW) approach. In addition, the weighted median (WM), MR-Egger regressions, MR-pleiotropy residual sum and outlier (MR-PRESSO) and multivariable MR (MVMR) were included in sensitivity analyses. Furthermore, the function of causal SNPs was evaluated by gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and protein-protein interaction networks.

RESULTS

Primary MR analysis based on the IVW method suggested that changes in CC alter risk of OF (OR = 1.383, 95%CI 1.079-1.853, P = 0.039), RA(OR: 1.623, 95%CI 1.042-2.527, P = 0.032) and HOA (hip osteoarthritis, OR = 1.536, 95% CI 1.044-2.259, P = 0.021). However, these causal relationships were not robust in sensitivity analyses. In contrast, there is a positive causal relationship between increased CC and the risk of KOA (knee osteoarthritis, OR: 2.094, 95%CI: 1.592-2.754, P = 1.41 × 10-7), as evidenced by the IVW using random effect. A similar effect size was observed across all MR sensitivity analyses, with no evidence of horizontal pleiotropy.

CONCLUSION

Based on our MR analysis, increased CC was causally linked to an increase in the risk of KOA. Genetic predictions suggested that CC reduction may have benefits for bone health.

Causal association of genetically determined caffeine intake from tea or coffee with bone health: a two-sample Mendelian randomization study

BACKGROUND

Relationship of caffeine intake and consumption of caffeinated beverages, such as tea and coffee, with bone health remains controversial. This study aimed to evaluate whether genetically determined caffeine intake from tea or coffee has causal effects on overall total body bone mineral density (TB-BMD) and fracture. We also assessed the association with TB-BMD in five age strata.

METHODS

Using two-sample Mendelian randomization approach, summary statistics were retrieved from genome-wide association studies (GWAS)/GWAS meta-analyses of caffeine intake from tea (n = 395 866)/coffee (n = 373 522), TB-BMD (n = 66 628), and fracture (n = 426 795). Inverse variance weighted method was adopted as the main univariable analysis. Multivariable analysis was conducted to evaluate whether the causal effect is independent.

RESULTS

In univariable analysis, genetically determined caffeine intake from tea had positive association with overall TB-BMD (per SD increase in genetically determined caffeine intake, beta of TB-BMD [in SD]: 0.166; 95% confidence interval (CI): 0.006-0.326) and inverse association with fracture (OR = 0.79; 95% CI: 0.654-0.954). Genetically determined caffeine intake from coffee was also positively associated with overall TB-BMD (beta = 0.231; 95% CI: 0.093-0.369). The association remained significant after adjustment for smoking in multivariable analysis. Genetically determined caffeine intake from tea or coffee was both positively associated with TB-BMD in the age strata of 45-60 years, but we lacked evidence of association in other strata.

CONCLUSIONS

Genetically, caffeine intake from tea or coffee may be beneficial to bone health. Due to the ascertainment method of caffeine intake from tea, our study also implied genetically higher tea consumption may improve TB-BMD and lower fracture risk.

Demystifying the Risk Factors and Preventive Measures for Osteoporosis

Background

Osteoporosis is a major health problem, globally. It is characterized by structural bone weakness leading to an increased risk of fragility fractures. These fractures commonly affect the spine, hip and wrist bones. Consequently, Osteoporosis related proximal femur and vertebral fractures represent a substantial, growing social and economic burden on healthcare systems worldwide. Indentification of the risk factors, clinical risk assessment, utilization of risk assessment tools and appropriate management that play a crucial role in reducing the burden of Osteoporosis by tackling modifiable risk factors.

Methods

This chapter explores various risk factors that are associated with Osteoporosis and provides an overview of various clinical and diagnostic risk assessment tools with a particular emphasis on evidence-based strategies for their prevention.

Conclusion

The role of emerging technologies such as Artificial Intelligence (AI) and perspectives such as newer diagnostic modalities, monitoring and surveillance approaches in prevention of risk factors in the pathogenesis of Osteoporosis is highlighted.

Coffee consumption and caffeine intake in relation to risk of fractures: a systematic review and dose-response meta-analysis of observational studies

BACKGROUND

Conflicting reports are available about the association of coffee or caffeine intake and risk of fracture. We performed the current updated systematic review and dose-response meta-analysis of coffee consumption and caffeine intake and risk of fracture to quantify this association.

MATERIALS AND METHODS

PubMed/Medline, ISI Web of Science, and Scopus, Cochrane database were searched up to July 2021. Random-effects model or fixed-effects model was used to pool the study-specific effect sizes (ESs) and 95% confidence intervals (CIs). Dose-response relationship was examined using linear and non-linear dose-response analyses. The certainty of evidence was assessed using NutriGrade tool.

RESULTS

Out of 22 eligible studies included in the meta-analysis, 15 had cohort and 7 had case-control design. We found no significant association between coffee consumption and risk of fracture, either based on pooling cohort (RR: 0.99; 95% CI: 0.88, 1.12; I2 = 71.4%, Pheterogeneity < 0.01) or case-control studies (OR: 1.13; 95% CI: 0.87, 1.46; I2 = 49.0%, Pheterogeneity=0.08). In the subgroup analysis of cohort studies, we observed that higher coffee intake was inversely associated with risk of fracture in men (RR: 0.85; 95% CI: 0.76 to 0.94). In addition, a positive association was seen between coffee consumption and risk of fracture in studies with less than 12 years of follow-up (RR: 1.14; 95% CI: 1.02 to 1.27). With regard to caffeine intake, a statistically significant positive association was seen with risk of fracture (RR: 1.15; 95% CI, 1.08 to 1.23; I2=26.6%, n = 8). In the dose-response analysis, we found that each additional 100 mg caffeine intake was marginally associated with 2% greater risk of fracture (RR: 1.02; 95% CI: 1 to 1.05; I2= 70.3%, n = 6).

CONCLUSION

High coffee consumption was protectively associated with risk of fracture in men, while caffeine intake was positive associated with risk.

Recent advances in the utilization of tea active ingredients to regulate sleep through neuroendocrine pathway, immune system and intestinal microbiota

Sleep disorders have received widespread attention nowadays, which have been promoted by the accelerated pace of life, unhealthy diets and lack of exercise in modern society. The chemical medications to improve sleep has shown serious side effects and risks with high costs. Therefore, it is urgent to develop efficient nutraceuticals from natural sources to ensure sleep quality as a sustainable strategy. As the second most consumed beverage worldwide, the health-promoting effects of tea have long been widely recognized. However, the modulatory effect of teas on sleep disorders has received much less attention. Tea contains various natural sleep-modulating active ingredients such as L-theanine (LTA), caffeine, tea polyphenols (TPP), tea pigments, tea polysaccharides (TPS) and γ-aminobutyric acid (GABA). This review focuses on the potential influence and main regulating mechanisms of different tea active ingredients on sleep, including being absorbed by the small intestine and then cross the blood-brain barrier to act on neurons in the brain as neurotransmitters, manipulating the immune system and further affect sleep-wake cycle by regulating the levels of cytokines, and controlling the gut microbes to maintain the homeostasis of circadian rhythm. Current research progress and limitations are summarized and several future development directions are also proposed. This review hopes to provide new insights into the future elucidation of the sleep-regulating mechanisms of different teas and their natural active ingredients and the development of tea-based functional foods for alleviating sleep disorders. HighlightsNatural sleep-modulating active ingredients in tea have been summarized.Influences of drinking tea or tea active ingredients on sleep are reviewed.Three main regulating mechanisms of tea active ingredients on sleep are explained.The associations among nervous system, immune system and intestinal microbiota are investigated.The potential of developing delivery carriers for tea active ingredients is proposed.

Role of Herbal Teas in Regulating Cellular Homeostasis and Autophagy and Their Implications in Regulating Overall Health

Tea is one of the most popular and widely consumed beverages worldwide, and possesses numerous potential health benefits. Herbal teas are well-known to contain an abundance of polyphenol antioxidants and other ingredients, thereby implicating protection and treatment against various ailments, and maintaining overall health in humans, although their mechanisms of action have not yet been fully identified. Autophagy is a conserved mechanism present in organisms that maintains basal cellular homeostasis and is essential in mediating the pathogenesis of several diseases, including cancer, type II diabetes, obesity, and Alzheimer’s disease. The increasing prevalence of these diseases, which could be attributed to the imbalance in the level of autophagy, presents a considerable challenge in the healthcare industry. Natural medicine stands as an effective, safe, and economical alternative in balancing autophagy and maintaining homeostasis. Tea is a part of the diet for many people, and it could mediate autophagy as well. Here, we aim to provide an updated overview of popular herbal teas’ health-promoting and disease healing properties and in-depth information on their relation to autophagy and its related signaling molecules. The present review sheds more light on the significance of herbal teas in regulating autophagy, thereby improving overall health.

Knowledge and Beliefs on Osteoporosis among African Postmenopausal Women in a Kenyan Semi-Rural County of Kiambu

BACKGROUND

Assessing people's knowledge and beliefs about osteoporosis is fundamental to the formulation of preventive strategies for this condition. To our knowledge, no randomized community survey has been conducted using Facts on Osteoporosis Quiz (FOOQ) and Osteoporosis Health Belief Scale (OHBS) exclusively in the postmenopausal women in Kenya. This study aimed to assess postmenopausal women&apos;s knowledge and beliefs concerning osteoporosis in semirural Kiambu County, Kenya.

METHODS

A cross-sectional study involving face-to-face interviews with 254 African postmenopausal women was conducted between October 2017 and February 2018. The questionnaire explored the socio-demographic characteristics; FOOQ was used to evaluate the knowledge these women had about osteoporosis, while OHBS was used to assess their beliefs.

RESULTS

The mean age of the participants was 64.6±10.7 years. About 26.4% (67/254) of the participants had no formal education, while 3.1% (8/254) were in formal employment. About 54.3% (138/254) of the women were married, and 51.2% (130/254) were in the lowest and lower wealth quintile. FOOQ had a mean score of 8.6 (standard deviation±1.8; range, 0-17). OHBS revealed a low level of perceived susceptibility to osteoporosis. Perceived benefits of exercising and calcium intake as well as perceived seriousness of osteoporosis as a disease were at moderate levels. The level of health motivation was also moderate.

CONCLUSIONS

The women in this study demonstrated limited knowledge about osteoporosis. The low susceptibility score makes the prevention and treatment of osteoporosis in this population challenging. We recommend public health education for all postmenopausal women in this setting.

Prolonged caffeine intake decreases alveolar bone damage induced by binge-like ethanol consumption in adolescent female rats

Ethanol consumption has been reported to negatively impact on periodontal disease. In particular, oral cavity disorders occur upon ethanol exposure during adolescence, a life period associated with particular patterns of short and intense ('binge-like') ethanol consumption that is most deleterious to oral health. The hazardous central effects of ethanol have been linked to the overfunction of adenosine receptors, which are antagonized by caffeine, a bioactive substance present in numerous natural nutrients, which can also modify bone metabolism. The aim of this study was to investigate the effects of caffeine on alveolar bone damage induced by an ethanol binge drinking paradigm during adolescence. Female Wistar rats (35 days old; n = 30) were allocated to six groups: control (vehicle), ethanol (3 g/kg/day; 3 days On-4 days Off challenge), caffeine (10 mg/kg/day), caffeine plus ethanol, SCH58261 (0.1 mg/kg/day, an antagonist of A_2A receptors), and SCH58261 plus ethanol. Bone micromorphology and vertical bone loss were analyzed by computed microtomography. Our data showed that ethanol binge drinking reduced alveolar bone quality, with repercussion on alveolar bone size. This ethanol-induced alveolar bone deterioration was abrogated upon treatment with caffeine, but not with SCH58261. This shows that caffeine prevented the periodontal disorder caused by ethanol binge drinking during adolescence, an effect that was not mediated by adenosine A_2A receptor blockade.

Is Impregnation of Xenograft with Caffeine Effective on Bone Healing Rate in Mandibular Defects? A Pilot Histological Animal Study

Introduction and Aim

The aim of this study was to evaluate the effect of two concentrations of caffeine (1.5% and 3%) powder added to Bio-Oss xenograft on bone healing rate of iatrogenic mandibular defects in dogs.

Materials and Method

The researchers implemented a pilot study on ten male adult mongrel dogs. Two 4-mm circular critical-sized defects were trephined on each side of the mandibular body (a total of 4 defects for each dog). One of the defects remained empty as a control group. The other three defects in each case were randomly filled with 1.5% or 3% caffeinated Bio-Oss or pure Bio-Oss. The mandible specimens were sent for histological and histomorphometric assessments, 4 months postoperatively. Our predictor variable was the type of bone substitute. The study outcomes were new bone formation, angiogenesis, and fibrosis. The p value was set at 0.05 using SPSS 16.

Results

The histological assessment showed that the administration of 1.5% caffeinated Bio-Oss to mandibular defects caused more angiogenesis and more new bone formation as well as less fibrosis compared to the other groups (p < 0.05).

Conclusion

This study suggested that the application of 1.5% caffeinated Bio-Oss in bone defects of dogs resulted in the higher new bone formation. However, further clinical trials are needed to support its relevancy.

Coffee consumption and plasma biomarkers of metabolic and inflammatory pathways in US health professionals

BACKGROUND

Coffee consumption has been linked to lower risk of various health outcomes. However, the biological pathways mediating the associations remain poorly understood.

OBJECTIVES

The aim of this study was to assess the association between coffee consumption and concentrations of plasma biomarkers in key metabolic and inflammatory pathways underlying common chronic diseases.

METHODS

We investigated the associations of total, caffeinated, and decaffeinated coffee consumption with 14 plasma biomarkers, including C-peptide, insulin-like growth factor 1 (IGF-1), IGF binding protein (IGFBP) 1, IGFBP-3, estrone, total and free estradiol, total and free testosterone, sex hormone-binding globulin (SHBG), total adiponectin, high-molecular-weight (HMW) adiponectin, leptin, C-reactive protein (CRP), interleukin 6 (IL-6), and soluble tumor necrosis factor receptor 2 (sTNFR-2). Data were derived from 2 cohorts of 15,551 women (Nurses' Health Study) and 7397 men (Health Professionals Follow-Up Study), who provided detailed dietary data before blood draw and were free of diabetes, cardiovascular disease, or cancer at the time of blood draw. Multivariable linear regression was used to calculate the percentage difference of biomarker concentrations comparing coffee drinkers with nondrinkers, after adjusting for a variety of demographic, clinical, and lifestyle factors.

RESULTS

Compared with nondrinkers, participants who drank ≥4 cups of total coffee/d had lower concentrations of C-peptide (-8.7%), IGFBP-3 (-2.2%), estrone (-6.4%), total estradiol (-5.7%), free estradiol (-8.1%), leptin (-6.4%), CRP (-16.6%), IL-6 (-8.1%), and sTNFR-2 (-5.8%) and higher concentrations of SHBG (5.0%), total testosterone (7.3% in women and 5.3% in men), total adiponectin (9.3%), and HMW adiponectin (17.2%). The results were largely similar for caffeinated and decaffeinated coffee.

CONCLUSION

Our data indicate that coffee consumption is associated with favorable profiles of numerous biomarkers in key metabolic and inflammatory pathways. This trial was registered at clinicaltrials.gov as NCT03419455.

The Effect of Acute Consumption of Energy Drinks on Blood Pressure, Heart Rate and Blood Glucose in the Group of Young Adults

Background: Energy drinks (EDs) are very popular among young people, who consume them for various reasons. A standard ED typically contains 80 mg of caffeine, as well as glucose, taurine, vitamins and other ingredients. Excessive consumption of EDs and accumulation of the above ingredients, as well as their mutual interactions, can be hazardous to the health of young adults. The purpose of this study was to assess the effect of acute consumption of energy drinks on blood pressure, heart rate and blood glucose. Methods: The study involved 68 volunteers, healthy young adults (mean age 25 years), who were divided into two groups: the first consumed three EDs at one-hour intervals, and the second drank the same amount of water. All participants had their blood pressure (BP)—systolic and diastolic (SBP and DBP)—as well as heart rate (HR) and blood glucose (BG) measured. In addition, participants could report any health problems before and after consuming each portion of ED. Results: In the above experiment, having consumed three portions of ED (240 mg of caffeine), the participants presented a significant increase in DBP (p = 0.003), by over 8%, which coincided with a lack of any significant impact on SBP (p = 0.809). No significant changes were noted in HR (p = 0.750). Consumption of EDs caused a significant increase (p < 0.001) in BG, by ca. 21%, on average. Some participants reported various discomforts, which escalated after 2 and 3 EDs. Conclusions: Acute consumption of EDs contributed to increased diastolic blood pressure, blood glucose and level of discomfort in healthy young people. Our results reinforce the need for further studies on a larger population to provide sufficient evidence.

Association between coffee or caffeine consumption and fecundity and fertility: a systematic review and dose-response meta-analysis

Objective

The aim was to investigate whether coffee or caffeine consumption is associated with reproductive endpoints among women with natural fertility (ie, time to pregnancy [TTP] and spontaneous abortion [SAB]) and among women in fertility treatment (ie, clinical pregnancy rate or live birth rate).

Design

This study was a systematic review and dose-response meta-analysis including data from case-control and cohort studies.

Methods

An extensive literature search was conducted in MEDLINE and Embase, with no time and language restrictions. Also, reference lists were searched manually. Two independent reviewers assessed the manuscript quality using the Newcastle-Ottawa Scale (NOS). A two-stage dose-response meta-analysis was applied to assess a potential association between coffee/caffeine consumption and the outcomes: TTP, SAB, clinical pregnancy, and live birth. Heterogeneity between studies was assessed using Cochrane Q-test and I² statistics. Publication bias was assessed using Egger's regression test.

Results

The pooled results showed that coffee/caffeine consumption is associated with a significantly increased risk of SAB for 300 mg caffeine/day (relative risk [RR]: 1.37, 95% confidence interval [95% CI]: 1.19; 1.57) and for 600 mg caffeine/day (RR: 2.32, 95% CI: 1.62; 3.31). No association was found between coffee/caffeine consumption and outcomes of fertility treatment (based on two studies). No clear association was found between exposure to coffee/caffeine and natural fertility as measured by fecundability odds ratio (based on three studies) or waiting TTP (based on two studies).

Conclusion

Results from this meta-analysis support the growing evidence of an association between coffee/caffeine intake and the risk of SAB. However, viewing the reproductive capacity in a broader perspective, there seems to be little, if any, association between coffee/caffeine consumption and fecundity. In general, results from this study are supportive of a precautionary principle advised by health organizations such as European Food Safety Authority (EFSA) and World Health Organization (WHO), although the advised limit of a maximum of two to three cups of coffee/200-300 mg caffeine per day may be too high.

Association between tea consumption and osteoporosis: A meta-analysis

BACKGROUND

Previous reports have suggested a potential association of tea consumption with the risk of osteoporosis. As such association is controversial, we conducted a meta-analysis to assess the relationship between tea consumption and osteoporosis.

METHODS AND FINDINGS

We systematically searched PubMed, EMBASE and WanFang databases until March 30, 2016, using the keywords "tea and osteoporosis," without limits of language. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were derived by using random-effects models throughout the analyses. We conducted the analysis of the statistical heterogeneity using Cochrane I. The funnel plot was used to speculate the publication bias, while the subgroup analysis and multiround elimination method were employed.

RESULTS

Our study was based on 17 journal articles, including 2 prospective cohort studies, 4 case-control studies, and 11 cross-sectional studies. In the present study, the total OR of osteoporosis for the highest versus the lowest categories of tea consumption was 0.62 (95% CI, 0.46-0.83), with significant heterogeneity among studies (I = 94%, P < .01). There was, however, no publication bias of the meta-analysis about tea consumption and osteoporosis. Subgroup analysis showed that tea consumption could reduce the risk of osteoporosis in all examined subgroups.

CONCLUSION

In the present study, it can be concluded from the results that tea consumption can reduce the risk of osteoporosis.

Cross-sectional association of coffee and caffeine consumption with sex hormone-binding globulin in healthy nondiabetic women

OBJECTIVE

Low sex hormone-binding globulin (SHBG) is a consistent risk factor for type 2 diabetes, particularly in women. Coffee consumption has been associated with a lower risk of type 2 diabetes, but its effects on SHBG are less known.

DESIGN AND METHODS

This was a cross-sectional study of 2377 nondiabetic pre- and postmenopausal women from the E3N cohort study whose baseline SHBG was measured. Information on diet (including coffee and caffeine consumption), lifestyle and medical conditions was collected through questionnaires. The relationship between coffee and caffeine consumption and SHBG was modelled, with adjustment for covariates and stratification by body mass index (BMI) categories (< or ≥25 kg/m² ) and menopausal status.

RESULTS

The mean age was 57.2±6.4 years and 61% of the 2377 women were postmenopausal. High coffee (≥3 cups/day) and caffeine (≥265 mg/day) intakes were associated with a reduced risk of being in the 1st quartile of the SHBG level distribution (<46.3 nmol/L) in a multivariate adjusted model (OR: 0.72 [95% CI: 0.52-1.01] and OR: 0.71 [95% CI: 0.53-0.95], respectively). No association was found between tea consumption and SHBG levels. In multivariate models stratified on BMI categories and menopausal status, associations were restricted to women with a BMI ≥25 kg/m² or being postmenopausal. The association with SHBG was consistently noted with consumption of both caffeinated coffee and caffeine, but not decaffeinated coffee.

CONCLUSIONS

Consumption of high coffee and caffeine is associated with a reduced risk of low SHBG, an established risk marker for T2DM, which might contribute to the protective effects of coffee for type 2 diabetes.

Dietary and pharmacological compounds altering intestinal calcium absorption in humans and animals

The intestine is the only gate for the entry of Ca to the body in humans and mammals. The entrance of Ca occurs via paracellular and intracellular pathways. All steps of the latter pathway are regulated by calcitriol and by other hormones. Dietary and pharmacological compounds also modulate the intestinal Ca absorption process. Among them, dietary Ca and P are known to alter the lipid and protein composition of the brush-border and basolateral membranes and, consequently, Ca transport. Ca intakes are below the requirements recommended by health professionals in most countries, triggering important health problems. Chronic low Ca intake has been related to illness conditions such as osteoporosis, hypertension, renal lithiasis and incidences of human cancer. Carbohydrates, mainly lactose, and prebiotics have been described as positive modulators of intestinal Ca absorption. Apparently, high meat proteins increase intestinal Ca absorption while the effect of dietary lipids remains unclear. Pharmacological compounds such as menadione, dl-butionine-S,R-sulfoximine and ursodeoxycholic acid also modify intestinal Ca absorption as a consequence of altering the redox state of the epithelial cells. The paracellular pathway of intestinal Ca absorption is poorly known and is under present study in some laboratories. Another field that needs to be explored more intensively is the influence of the gene × diet interaction on intestinal Ca absorption. Health professionals should be aware of this knowledge in order to develop nutritional or medical strategies to stimulate the efficiency of intestinal Ca absorption and to prevent diseases.

Coffee consumption and periodontal disease in males

BACKGROUND

Coffee is a major dietary source of antioxidants as well as of other anti-inflammatory factors. Given the beneficial role of such factors in periodontal disease, whether coffee intake is associated with periodontal disease in adult males was explored.

METHODS

Existing data collected by a prospective, closed-panel cohort study of aging and oral health in adult males was used. Participants included the 1,152 dentate males in the Veterans Affairs (VA) Dental Longitudinal Study who presented for comprehensive medical and dental examinations from 1968 to 1998. Mean age at baseline was 48 years; males were followed for up to 30 years. Participants are not VA patients; rather, they receive their medical and dental care in the private sector. Periodontal status was assessed by probing depth (PD), bleeding on probing, and radiographic alveolar bone loss (ABL), measured on intraoral periapical radiographs with a modified Schei ruler method. Moderate-to-severe periodontal disease was defined as cumulative numbers of teeth exhibiting PD ≥4 mm or ABL ≥40%. Coffee intake was obtained from participant self-reports using the Cornell Medical Index and food frequency questionnaires. Multivariate repeated-measures generalized linear models estimated mean number of teeth with moderate-to-severe disease at each examination by coffee intake level.

RESULTS

It was found that higher coffee consumption was associated with a small but significant reduction in number of teeth with periodontal bone loss. No evidence was found that coffee consumption was harmful to periodontal health.

CONCLUSION

Coffee consumption may be protective against periodontal bone loss in adult males.

A closer examination of the interaction among risk factors for low back pain

PURPOSE

To evaluate the interactions of risk factors and identify their most powerful discrimination pathway for the occurrence of low back pain (LBP).

DESIGN

A cross-sectional study.

SETTING

Taiwan.

SUBJECTS

Taiwanese population of 30 to 64 years old.

MEASURES

A self-reported question, "Have you experienced LBP within the last 3 months?" was used to evaluate LBP. The study variables included demographics (age, gender, occupation, education level, marital status, and household income), biometric health measures (bone mineral density and body mass index), dietary habits (weekly milk, coffee, tea, and soybean consumption), and other lifestyle factors (smoking habits, alcohol consumption, betel nut chewing, body weight control, exercise regularity, and stress management).

ANALYSIS

Logistic regression and classification tree analyses.

RESULTS

A total of 969 Taiwanese participants were analyzed. Primary logistic regression analysis identified three critical risk factors (gender, bone mineral density, and exercise regularity) for the occurrence of LBP. By classification tree analysis, demographic factors, dietary habits, and lifestyle factors had modifying effects on LBP.

CONCLUSIONS

Various factors contribute to the risk of LBP. Interactions between risk factors should be considered when developing future strategies for the prevention and management of LBP.

Caffeine regulates osteogenic differentiation and mineralization of primary adipose-derived stem cells and a bone marrow stromal cell line

Caffeine consumption reportedly influences bone mineral density and body weight. However, the effects of caffeine on bone metabolism are still controversial, and whether the dosage of caffeine influences osteogenic differentiation is yet to be clarified. In the present study, we cultured primary adipose-derived stem cells (ADSCs) and a bone marrow stromal cell line (M2-10B4) in osteogenic differentiation media containing varying concentrations of caffeine. Caffeine had biphasic effects: 0.1 mM caffeine significantly enhanced mineralization and alkaline phosphatase (ALP) activity. Consistent with these observations, a caffeine concentration of 0.1 mM upregulated the osteogenic differentiation marker genes ALP and osteocalcin (OCN), and elevated osteoprotegerin (OPG), Runt-related transcription factor 2 (RUNX2) and Sirtuin 1 (SIRT1) levels. However, a concentration of caffeine greater than 0.3 mM suppressed the differentiation of both the cell types. These findings indicate that caffeine has a beneficial effect on ADSCs and bone marrow stromal cells, enhancing differentiation to osteoblasts; this effect, which is mediated via RUNX2 activation at low doses is significantly suppressed at high doses.

The effects of caffeinated and decaffeinated coffee on sex hormone-binding globulin and endogenous sex hormone levels: a randomized controlled trial

Background

Findings from observational studies suggest that sex hormone-binding globulin (SHBG) and endogenous sex hormones may be mediators of the putative relation between coffee consumption and lower risk of type 2 diabetes. The objective of this study was to evaluate the effects of caffeinated and decaffeinated coffee on SHBG and sex hormone levels.

Findings

After a two-week run-in phase with caffeine abstention, we conducted an 8-week parallel-arm randomized controlled trial. Healthy adults (n = 42) were recruited from the Boston community who were regular coffee consumers, nonsmokers, and overweight. Participants were randomized to five 6-ounce cups of caffeinated or decaffeinated instant coffee or water (control group) per day consumed with each meal, mid-morning, and mid-afternoon. The main outcome measures were SHBG and sex hormones [i.e., testosterone, estradiol, dehydroepiandrosterone sulfate].

No significant differences were found between treatment groups for any of the studied outcomes at week 8. At 4 weeks, decaffeinated coffee was associated with a borderline significant increase in SHBG in women, but not in men. At week 4, we also observed several differences in hormone concentrations between the treatment groups. Among men, consumption of caffeinated coffee increased total testosterone and decreased total and free estradiol. Among women, decaffeinated coffee decreased total and free testosterone and caffeinated coffee decreased total testosterone.

Conclusions

Our data do not indicate a consistent effect of caffeinated coffee consumption on SHBG in men or women, however results should be interpreted with caution given the small sample size. This is the first randomized trial investigating the effects of caffeinated and decaffeinated coffee on SHBG and sex hormones and our findings necessitate further examination in a larger intervention trial.

Bone mineral density, polyphenols and caffeine: a reassessment

Several studies have shown beneficial associations between tea consumption and bone mineral density (BMD) and fracture risk. Current investigations into potential mechanisms of benefit are focused upon the F and polyphenol components of tea. However, previous studies have pointed towards caffeine consumption as a potential risk factor for low BMD and high fracture risk. Tea, therefore, represents an interesting paradox as a mildly caffeinated beverage that may enhance bone health. Fruit and vegetable intake has also been associated with BMD, and it is now apparent that several fruit and vegetable components, including polyphenols, may contribute positively to bone health. Evidence surrounding the function(s) of polyphenol-rich foods in bone health is examined, along with more recent studies challenging the relevance of caffeine consumption to in vivo Ca balance. Plant foods rich in polyphenols such as tea, fruit and vegetables, as significant factors in a healthy diet and lifestyle, may have positive roles in bone health, and the negative role of caffeine may have been overestimated. The present review covers evidence of dietary mediation in positive and negative aspects of bone health, in particular the roles of tea, fruit and vegetables, and of caffeine, flavonoids and polyphenols as components of these foods. Since the deleterious effects of caffeine appear to have been overstated, especially in respect of the positive effects of flavonoids, it is concluded that a reassessment of the role of caffeinated beverages may be necessary.

Assessing caffeine intake in the United Kingdom diet

Caffeine occurs naturally in the leaves and seeds of many plants and is artificially added to some beverages. Consumption of caffeine has been linked to both positive and adverse health outcomes. We incorporated estimates of caffeine content (mg/100g or ml) of foods and drinks, taken from the published literature, to provide a preliminary estimate of caffeine intake for the UK population, based on data collected in the National Diet and Nutrition Survey 2008-10. Among consumers mean total caffeine intakes of adult men 19+ y were significantly greater than intakes by boys 4-10y and 11-18y (p<0.05), with the same age-related differences seen for females. 4.1% of men 19+ y and 3.8% of women 19+ y had caffeine intakes in excess of 300mg/d. The addition of caffeine to UK food composition databases will allow more detailed study of the health effects of caffeine consumption.

Male risk factors for hip fracture-a 30-year follow-up study in 7,495 men

SUMMARY

Risk factors for hip fracture were studied in 7,495 randomly selected men during 30 years; 451 men had a hip fracture. High degree of leisure-time, but not work-related, physical activity, high occupational class, and high body mass index (BMI) protected against hip fracture. Smoking, tall stature, interim stroke, and dementia increased the risk.

PURPOSE

The purpose was to prospectively study risk factors for hip fracture in men.

METHODS

We studied midlife determinants of future hip fractures in 7,495 randomly selected men aged 46-56 years in Gothenburg, Sweden. The subjects were investigated in 1970-1973 and followed for over 30 years. Questionnaires were used regarding lifestyle factors, psychological stress, occupational class, and previous myocardial infarction, stroke, and diabetes mellitus. Alcohol problems were assessed with the aid of registers. Using the Swedish hospital discharge register, data were collected on intercurrent stroke and dementia diagnoses and on first hip fractures (X-ray-verified).

RESULTS

Four hundred fifty-one men (6%) had a hip fracture. Age, tall stature, low occupational class, tobacco smoking, alcoholic intemperance, and interim stroke or dementia were independently associated with the risk of hip fracture. There were inverse associations with leisure-time physical activity, BMI, and coffee consumption. The gradient of risk for one standard deviation of multivariable risk decreased with time since measurement yet was a good alternative to dual energy X-ray absorptiometry measurements.

CONCLUSIONS

High degree of leisure-time physical activity, high occupational class, and high BMI protected against hip fracture. However, work-related physical activity was not protective. Smoking, tall stature, and interim stroke or dementia increased the risk.

Coffee consumption and CYP1A2 genotype in relation to bone mineral density of the proximal femur in elderly men and women: a cohort study

Background

Drinking coffee has been linked to reduced calcium conservation, but it is less clear whether it leads to sustained bone mineral loss and if individual predisposition for caffeine metabolism might be important in this context. Therefore, the relation between consumption of coffee and bone mineral density (BMD) at the proximal femur in men and women was studied, taking into account, for the first time, genotypes for cytochrome P450 1A2 (CYP1A2) associated with metabolism of caffeine.

Methods

Dietary intakes of 359 men and 358 women (aged 72 years), participants of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS), were assessed by a 7-day food diary. Two years later, BMD for total proximal femur, femoral neck and trochanteric regions of the proximal femur were measured by Dual-energy X-ray absorptiometry (DXA). Genotypes of CYP1A2 were determined. Adjusted means of BMD for each category of coffee consumption were calculated.

Results

Men consuming 4 cups of coffee or more per day had 4% lower BMD at the proximal femur (p = 0.04) compared with low or non-consumers of coffee. This difference was not observed in women. In high consumers of coffee, those with rapid metabolism of caffeine (C/C genotype) had lower BMD at the femoral neck (p = 0.01) and at the trochanter (p = 0.03) than slow metabolizers (T/T and C/T genotypes). Calcium intake did not modify the relation between coffee and BMD.

Conclusion

High consumption of coffee seems to contribute to a reduction in BMD of the proximal femur in elderly men, but not in women. BMD was lower in high consumers of coffee with rapid metabolism of caffeine, suggesting that rapid metabolizers of caffeine may constitute a risk group for bone loss induced by coffee.

Patient responses to an integrated service, initiated by community pharmacists, for the prevention of osteoporosis

Objective

This study aimed to develop, implement and evaluate an integrated service provided by pharmacists to consumers based on the results of a risk-assessment survey carried out by the pharmacist and testing of bone mineral density (BMD) by a radiographer. It also investigated whether measurement of BMD in the pharmacy increased the effectiveness of the service and pharmacist referral in terms of adherence to advice and uptake of referral compared with the same service offered without BMD testing.

Setting

Community pharmacists in urban and rural settings in New South Wales, Australia, delivered the service.

Method

The adherence to advice or referral given by 12 community pharmacists during 2003 to 217 participants about the prevention of osteoporosis following screening with either a BMD test plus risk-assessment questionnaire or a risk-assessment questionnaire only was compared.

Key findings

No significant between-group differences in adherence to advice or referral were found. However, participants valued the BMD service significantly more highly than the non-BMD service as measured by satisfaction scores.

Conclusions

Consumers were interested in receiving information about osteoporosis and their own risk of it and even greater interest in BMD testing in the pharmacy. There was no difference in uptake of referral or advice following either questionnaire only or questionnaire plus BMD testing. Low uptake of referral and advice overall by those deemed to be at high risk is of concern. Far greater education and encouragement for consumers to follow through is required.

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

This study assessed associations between habitual caffeine intake and bone mass among young women. Analyses of the entire study population revealed no significant associations, while analyses restricted to women using depot medroxyprogesterone acetate (DMPA) showed modest inverse associations between caffeine intake and bone mineral content (BMC).

INTRODUCTION

Some previous investigations among postmenopausal women suggest an inverse relationship between caffeine intake and bone mass, yet studies of this association among young women are few.

METHODS

The association between habitual caffeine intake and bone mass was evaluated prospectively in a population-based cohort of 625 females, aged 14 to 40 years, adjusting for relevant biological and lifestyle factors. Caffeinated beverage intake was self-reported, and bone mineral content (BMC) and bone mineral density (BMD) were measured at baseline and every 6 months throughout a 24-month follow-up period using dual-energy x-ray absorptiometry.

RESULTS

Cross-sectional analyses revealed no significant differences in mean BMC or BMD at baseline. Mean percentage and absolute changes in BMC and BMD were not associated with caffeine use. Repeated measures analyses similarly showed no significant association between caffeine intake at baseline and mean BMC or BMD measured during follow-up. However, among women using depot medroxyprogesterone acetate (DMPA), modest inverse associations between caffeine and BMC (but not BMD) were detected.

CONCLUSIONS

Our data suggest that heavy habitual consumption of caffeinated beverages does not adversely impact bone mass among young women in general. Greater caffeine intake may be associated with lower BMC among DMPA users.

Diet and lifestyle associated with increased bone mineral density: cross-sectional study of Japanese elderly women at an osteoporosis outpatient clinic

BACKGROUND

Several studies have already demonstrated that lifestyle characteristics, such as physical activity, smoking, and alcohol intake, are associated with bone mineral density (BMD). Coffee intake was shown to be negatively associated with BMD, whereas tea drinking was reported to be associated with increased BMD. A review of the literature, however, revealed that few studies have described the association between BMD and lifestyle, including characteristic Japanese foods such as fish, natto, and Japanese green tea. The aim of this study was to identify lifestyle factors associated with BMD.

METHODS

A total of 632 women age > or =60 years were enrolled in this study. Subjects were interviewed about their lifestyle by means of a questionnaire regarding the consumption pattern of dietary items. BMD was measured at the lumbar spine by dual energy X-ray absorptiometry.

RESULTS

The BMD was higher in subjects with the habits of alcohol drinking, green tea drinking, and physical activity and lower in those with the habits of smoking and cheese consumption. Multiple regression analysis showed that factors associated with BMD were smoking, alcohol consumption, green tea drinking, and physical activity after adjusting for age and body mass index (BMI).

CONCLUSIONS

In this cross-sectional study at an osteoporosis outpatient clinic, patients with the habits of alcohol drinking, green tea drinking, and physical activity had significantly higher BMD, and those who smoked had significantly lower BMD than patients without each habit after adjusting for age, BMI, and other variables regarding lifestyle.

Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells

Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D(3) (1,25(OH)(2)D(3)) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)(2)D(3), VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)(2)D(3) mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10mM) on 1,25(OH)(2)D(3) induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)(2)D(3) induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)(2)D(3) induced VDR expression and at concentrations of 1 and 10mM, VDR expression was decreased by about 50-70%, respectively. In addition, the 1,25(OH)(2)D(3) induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)(2)D(3) stimulated VDR protein expression and 1,25(OH)(2)D(3) mediated actions in human osteoblast cells.

Effect of caffeine on the risk of coronary heart disease- A re-evaluation

The effect of caffeine intake on the risk of coronary heart disease was studied. Twenty-one rats used were randomly divided into three experimental groups, the first group served as the control while the second and third groups were administered caffeine orally at doses of 10mg/kg body weight and 20mg/kg body weight respectively for fourteen days. Caffeine, at 10mg/kg body weight, significantly increased (P<0.05) serum LDL- cholesterol concentration and coronary heart disease risk ratio while it significantly reduced (P<0.05) serum triacylglycerol concentration when compared with controls. At 20mg/kg body weight, caffeine significantly increased (P<0.05) coronary heart disease risk ratio while it significantly reduced (P<0.05) serum HDL-cholesterol concentration and serum triacylgycerol concentration when compared with controls. No dose response effect was observed possibly suggestive of a threshold effect. These results suggest that caffeine predisposes consumers of caffeine containing beverages to coronary heart disease.

Direct effects of caffeine on osteoblastic cells metabolism: the possible causal effect of caffeine on the formation of osteoporosis

BACKGROUND

Caffeine consumption has been reported to decrease bone mineral density (BMD), increase the risk of hip fracture, and negatively influence calcium retention. In this study, we investigated the influence of caffeine on the osteoblasts behaviour.

METHOD

Osteoblasts derived from newborn Wistar-rat calvaria was used in this study. The effects of various concentrations of caffeine on bone cell activities were evaluated by using MTT assay. Alkaline phosphatase (ALP) staining, von Kossa staining and biochemical parameters including ALP, lactate dehydrogenase (LDH), prostaglandin E2 (PGE2) and total protein were performed at day 1, 3, and 7. DNA degradation analysis under the caffeine influence was also performed.

RESULTS AND DISCUSSION

The results showed that the viability of the osteoblasts, the formation of ALP positive staining colonies and mineralization nodules formation in the osteoblasts cultures decreased significantly in the presence of 10 mM caffeine. The intracellular LDH, ALP and PGE2 content decreased significantly, the LDH and PGE2 secreted into the medium increased significantly. The activation of an irreversible commitment to cell death by caffeine was clearly demonstrated by DNA ladder staining.

CONCLUSION

In summary, our results suggest that caffeine has potential deleterious effect on the osteoblasts viability, which may enhance the rate of osteoblasts apoptosis.

Catabolic pathways and biotechnological applications of microbial caffeine degradation

Catabolism of caffeine (1,3,7-trimethylxanthine) in microorganisms commences via two possible mechanisms: demethylation and oxidation. Through the demethylation route, the major metabolite formed in fungi is theophylline (1,3-dimethylxanthine), whereas theobromine (3,7-dimethylxanthine) is the major metabolite in bacteria. In certain bacterial species, caffeine has also been oxidized directly to trimethyl uric acid in a single step. The conversion of caffeine to its metabolites is primarily brought about by N-demethylases (such as caffeine demethylase, theobromine demethylase and heteroxanthinedemethylase), caffeine oxidase and xanthine oxidase that are produced by several caffeine-degrading bacterial species such as Pseudomonas putida and species within the genera Alcaligenes, Rhodococcus and Klebsiella. Development of biodecaffeination techniques using these enzymes or using whole cells offers an attractive alternative to the present existing chemical and physical methods removal of caffeine, which are costly, toxic and non-specific to caffeine. This review mainly focuses on the biochemistry of microbial caffeine degradation, presenting recent advances and the potential biotechnological application of caffeine-degrading enzymes.

Caffeine-mediated enhancement of glucocorticoid receptor activity in human osteoblastic cells

Caffeine-containing beverage consumption has been reported to be associated with an increased risk for osteoporosis. Since the glucocorticoid receptor (GR) is a major factor in the induction of osteoporosis we analyzed whether caffeine may act via altering GR function. Applying a reporter gene assay we provide evidence that caffeine drastically amplifies GR transcriptional activity in human osteoblastic cells. Substances that increase the intracellular cyclic AMP-concentration also strengthen the transactivity of the GR and coincubation with caffeine further reinforces this potentiation, indicating that caffeine-mediated enhancement of GR transcriptional function is due to the inhibitory activity of caffeine on the cyclic AMP phosphodiesterase. Our data suggest evidence for a hitherto unrecognized crosstalk between caffeine-modulated signalling and GR-initiated gene expression in human osteoblastic cells and could provide the molecular basis for the role of caffeine in osteoporosis.

Bone mineral density and serum 25-hydroxyvitamin D level: is there any difference according to the dressing style of the female university students

Nutrition plays a role in the etiology of osteoporosis. Two of the most important nutrients for bone health are calcium and vitamin D. Plasma 25-hydroxyvitamin D [25-(OH)D] is the most sensitive clinical index of vitamin D status and has been found to be positively related to bone mineral density (BMD) in middle-aged and elderly women, and positive relations exist between the BMD of adult women and their calcium consumption throughout life. The aim of the present study was to determine relationships between BMD, serum vitamin D levels and dietary calcium intake of female young adult students who dressed in different styles. We studied two groups of volunteer female students (total = 67). Students in the first group dressed in a style that exposed the skin to sunlight, students in the second group wore dresses completely covering the skin except for the face and hands. Serum 25-(OH)D levels were measured by radioimmunoassay, BMDs were determined at the lumbar spine and femoral neck by dual-energy X-ray absorptiometry, and calcium intakes were estimated with a 3-day food recording questionnaire. The serum 25-(OH)D level was significantly lower in the second group. There was no significant difference in BMD between the two groups. The dietary calcium intake of the two groups were lower than the adequate intake of 1000 mg daily for this age. There was a correlation between the serum 25-(OH)D level and BMD at the femoral neck in the first group. Our results indicate that vitamin D and calcium requirements for normal bone mineral accrual in young adults may advance until a certain age, and the covered dressing style causes vitamin D insufficiency and most of the students were under risk for osteoporosis in later life.

Calcium, vitamin D, and nutrition in elderly adults

The nutritional needs for optimizing bone health easily can be met by a diet that is high in fruits and vegetables (five or more servings/day), adequate in protein but moderate in animal protein, and with adequate calcium and vitamin D intakes through the consumption of low fat dairy or calcium-fortified foods. Foods are a preferred source to maintaining calcium balance because there are other essential nutrients that are found in high-calcium foods. For those individuals in whom there is inadequate calcium intake from diet, supplemental calcium can be used. Supplemental or dietary calcium should be spread out throughout the day, with 500 mg or less being consumed at each meal to optimize absorption. In all individuals older than 70 years, vitamin D intakes of at least 600 IU per day (up to 1000 IU/day) are recommended, in addition to the calcium requirement of 1200 mg per day. Vitamin D from foods, supplements, and/or multivitamins can be used to meet the vitamin D requirement. In frail elderly individuals with malabsorption and alcoholics, there may be a need to supplement magnesium. Some elderly individuals with indications of poor nutritional status (low albumin levels) or after hip fracture might benefit from protein supplementation and a multivitamin to ensure adequacy of other nutrients.

Effects of caffeine on human health

Caffeine is probably the most frequently ingested pharmacologically active substance in the world. It is found in common beverages (coffee, tea, soft drinks), in products containing cocoa or chocolate, and in medications. Because of its wide consumption at different levels by most segments of the population, the public and the scientific community have expressed interest in the potential for caffeine to produce adverse effects on human health. The possibility that caffeine ingestion adversely affects human health was investigated based on reviews of (primarily) published human studies obtained through a comprehensive literature search. Based on the data reviewed, it is concluded that for the healthy adult population, moderate daily caffeine intake at a dose level up to 400 mg day(-1) (equivalent to 6 mg kg(-1) body weight day(-1) in a 65-kg person) is not associated with adverse effects such as general toxicity, cardiovascular effects, effects on bone status and calcium balance (with consumption of adequate calcium), changes in adult behaviour, increased incidence of cancer and effects on male fertility. The data also show that reproductive-aged women and children are 'at risk' subgroups who may require specific advice on moderating their caffeine intake. Based on available evidence, it is suggested that reproductive-aged women should consume </=300 mg caffeine per day (equivalent to 4.6 mg kg(-1) bw day(-1) for a 65-kg person) while children should consume </=2.5 mg kg(-1) bw day(-1).

Bone metabolism and the perimenopause overview, risk factors, screening, and osteoporosis preventive measures

In summary, FDA-approved therapies for prevention and treatment of osteoporosis are all antiresorptive agents. There are no approved therapies at this time that stimulate bone formation, although one such agent (PTH) is awaiting approval. Screening perimenopausal women at risk should identify osteopenic women early in the menopause before the accelerated bone loss of estrogen deficiency causes further irreversible erosion in bone density. The National Osteoporosis Foundation advocates initiating therapy to reduce fracture risk in postmenopausal women with T scores below -2 in the absence or factors and with T scores below -1.5 if other risk factors are present. Estrogen, alendronate, residronate, and raloxifene have all been shown to reduce the incidence of radiographic vertebral fractures in women at risk. Only alendronate and residronate have been shown in large randomized trials to reduce the incidence of nonvertebral fractures including hip fractures in women with postmenopausal osteoporosis. These antiresorptive therapies provide benefits above and beyond those of calcium and vitamin D alone. There is insufficient published evidence from randomized controlled trials convincingly to support a role for soy products, androgens, calcitonin, or fluoride in prevention of postmenopausal osteoporosis or reduction of fracture rates in women at risk.

Effects of caffeine on bone and the calcium economy

Caffeine-containing beverage consumption has been reported to be associated with reduced bone mass and increased fracture risk in some, but not most, observational studies. Human physiological studies and controlled balance studies show a clear but only a very small depressant effect of caffeine itself on intestinal calcium absorption, and no effect on total 24-h urinary calcium excretion. The epidemiologic studies showing a negative effect may be explained in part by an inverse relationship between consumption of milk and caffeine-containing beverages. Low calcium intake is clearly linked to skeletal fragility, and it is likely that a high caffeine intake is often a marker for a low calcium intake. The negative effect of caffeine on calcium absorption is small enough to be fully offset by as little as 1-2 tablespoons of milk. All of the observations implicating caffeine-containing beverages as a risk factor for osteoporosis have been made in populations consuming substantially less than optimal calcium intakes. There is no evidence that caffeine has any harmful effect on bone status or on the calcium economy in individuals who ingest the currently recommended daily allowances of calcium.

Fatores de risco da osteoporose: prevenção e detecção através do monitoramento clínico e genético

A osteoporose é uma doença sistêmica caracterizada pela baixa massa óssea e deterioração da micro arquitetura do tecido ósseo. Consequentemente existe um aumento na fragilidade do osso e suscetibilidade à fratura, que é considerada o efeito clínico mais importante deste processo. Muitos estudos que se utilizam de modelos em gêmeos ou pais e seus descendentes têm confirmado o papel da herança genética no pico de massa óssea, na verdade o maior fator de risco da fratura. Neste artigo de revisão, são enfocados os prováveis genes envolvidos no processo de osteoporose, ressaltando a importância das interações entre gene- gene e gene-ambiente. Concernente à influência isolada do ambiente, são abordados os hábitos relacionados ao estilo de vida, à nutrição e ao tabagismo envolvidos no aparecimento dessa doença. Durante os próximos anos, o conhecimento baseado na genética molecular elucidará o processo osteoporótico. Do mesmo modo, os estudos clínicos se expandirão, visando contribuir para a detecção precoce da doença, permitindo assim a aplicação de medidas preventivas e terapêuticas adequadas.

Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes

BACKGROUND

The role of caffeine as a risk factor for bone loss is controversial.

OBJECTIVE

Our goals were 1) to compare in both a cross-sectional study and a 3-y longitudinal study the bone mineral density (BMD) of postmenopausal women consuming high or low amounts of caffeine and 2) to study the interaction between caffeine intake, vitamin D receptor (VDR) polymorphism, and BMD in the longitudinal study.

DESIGN

The results are derived from cross-sectional measurements of BMD in 489 elderly women (aged 65-77 y) and from longitudinal measurements made in 96 of these women who were treated with a placebo for 3 y. Changes in BMD were adjusted for confounding factors and were compared between groups with either low (< or =300 mg/d) or high (>300 mg/d) caffeine intakes and between the VDR genotype subgroups of the low- and high-caffeine groups.

RESULTS

Women with high caffeine intakes had significantly higher rates of bone loss at the spine than did those with low intakes (-1.90 +/- 0.97% compared with 1.19 +/- 1.08%; P = 0.038). When the data were analyzed according to VDR genotype and caffeine intake, women with the tt genotype had significantly (P = 0.054) higher rates of bone loss at the spine (-8.14 +/- 2.62%) than did women with the TT genotype (-0.34 +/- 1.42%) when their caffeine intake was >300 mg/d.

CONCLUSIONS

Intakes of caffeine in amounts >300 mg/d ( approximately 514 g, or 18 oz, brewed coffee) accelerate bone loss at the spine in elderly postmenopausal women. Furthermore, women with the tt genetic variant of VDR appear to be at a greater risk for this deleterious effect of caffeine on bone.

Effect of coffee consumption on bone metabolism

The effects of coffee on bone metabolism are still controversial, although several studies have suggested that caffeine and/or heavy coffee consumption is associated with a significant increase in risk of fracture, osteoporosis, and periodontal disease. Therefore, we sought to clarify the relationship between coffee consumption and bone metabolism using male Wistar rats. Forty-eight male Wistar rats were assigned to three treatment groups including a control-diet group (control, n = 16, coffee-free diet), a 0.62% coffee-diet group (low caffeine, n = 16, diet supplemented with 6.2 g/kg of the control diet), and a 1.36% coffee-diet group (high caffeine, n = 16, diet supplemented with 13.6 g/kg of the control diet), and animals were maintained on an experimental diet for 140 days. Although caffeine in serum was not detected in rats fed the control diet, low-intake coffee for 140 days led to an increase in caffeine concentration to 0.53 +/- 0.11 microg/mL and high-intake coffee led to an increase of 1.77 +/- 0.22 microg/mL. No significant differences in body weight change, serum and urinary biochemical markers of bone metabolism, and bone histomorphometry were found between the coffee-diet groups and the control-diet group, except that urinary phosphorus excretion after 140 days of both coffee diets was significantly increased compared with controls (p < 0.05). In addition, the coffee diets were not associated with differences in tumor necrosis factor-alpha and interleukin-6, which have been implicated in the pathogenesis of bone loss together with interleukin-1beta. In conclusion, the present study strongly indicates that coffee does not stimulate bone loss in rats.

Tea drinking and bone mineral density in older women

BACKGROUND

High caffeine intake is reportedly a risk factor for reduced bone mineral density (BMD) in women. Most studies, however, are from populations in which coffee drinking predominates and is the major caffeine source. Tea contains caffeine but also has other nutrients, such as flavonoids, that may influence bone mass in different ways.

OBJECTIVE

We examined the relation between tea drinking and BMD in older women in Britain, where tea drinking is common.

METHODS

We measured BMD at the lumbar spine, femoral neck, greater trochanter, and Ward's triangle in 1256 free-living women aged 65-76 y in Cambridge, United Kingdom. Tea drinking was assessed by self-completed questionnaire and women were categorized as tea drinkers or non-tea drinkers.

RESULTS

There were 1134 tea drinkers (90.3%) and 122 non-tea drinkers (9.7%). Compared with non-tea drinkers, tea drinkers had significantly greater ( approximately 5%) mean BMD measurements, adjusted for age and body mass index, at the lumbar spine (0.033 g/cm(2); P = 0.03), greater trochanter (0.028 g/cm(2); P = 0.004), and Ward's triangle (0.025 g/cm(2); P = 0.02). Differences at the femoral neck (0.013 g/cm(2)) were not significant. These findings were independent of smoking status, use of hormone replacement therapy, coffee drinking, and whether milk was added to tea.

CONCLUSIONS

Older women who drank tea had higher BMD measurements than did those who did not drink tea. Nutrients found in tea, such as flavonoids, may influence BMD. Tea drinking may protect against osteoporosis in older women.

Effects of caffeine on fluoride, calcium and phosphorus metabolism and calcified tissues in the rat

This 6-week study was designed to determine the effects of graded doses of caffeine intake (3, 25 or 100 mg/kg per day) on the metabolic balance and tissue concentrations of fluoride, calcium and phosphorus in Sprague-Dawley rats. Caffeine intake did not affect the absorption, urinary excretion or balance of fluoride, the plasma, bone or enamel concentrations of fluoride, nor the occurrence of incisor enamel fluorosis. Neither did it affect the metabolism of calcium or phosphorus except that the urinary excretion of calcium was increased. This effect, however, was not sufficient to influence significantly calcium balance. The ash content of the femur epiphysis and bone mineral content of the tibia were significantly reduced only in the group exposed to the highest dose of caffeine. These effects on bone were not significantly related to the balance of calcium or phosphorus. It was concluded that caffeine, even at an extremely high level of intake, has no detectable effect on the balance or tissue concentrations of fluoride, calcium or phosphorus in the rat.

Caffeine and the elderly

The most common source of dietary caffeine among the elderly is coffee, with consumption averaging about 200 mg/day. Because of the greater proportion of adipose tissue to lean body mass in older humans, and because caffeine is distributed essentially only through lean body mass, a dose of caffeine expressed as mg/kg total bodyweight may result in a higher plasma and tissue concentration in elderly compared with younger individuals. The metabolism of, and physiological responses to, caffeine is similar in elderly and younger individuals. However, there is a limited amount of evidence that responses to caffeine in some physiological systems may be greater in the elderly at doses in the 200 to 300 mg range. Although caffeine consumption increases urinary calcium levels similarly in both younger and older individuals, the preponderance of data suggest that caffeine has a greater impact on calcium metabolism and bone in older people. Evidence also suggests that increasing age is associated with increasing sensitivity to the pressor effects of caffeine. Caffeine appears to affect metabolic and neurological responses similarly in both young and elderly individuals, when differences in baseline performance are taken into account.