Vitamin D and fracture prevention

Effects of vitamin D and calcium supplementation on bone mineral density among Thai youth using daily HIV pre-exposure prophylaxis

INTRODUCTION

Tenofovir disoproxil fumarate with emtricitabine (TDF/FTC) is used for HIV pre-exposure prophylaxis (PrEP). TDF may affect bone mineral density (BMD), particularly in youth who are at a stage of peak bone mass accrual. The objective of this study was to evaluate the effect of vitamin D and calcium supplementation on BMD among Thai youth receiving daily oral PrEP.

METHODS

This open-label randomized trial was conducted in male youth aged between 15 and 24 years. Participants were randomized to Arm A who received once-daily TDF/FTC plus vitamin D3 and calcium supplementation with meals twice daily (400 units of vitamin D3 and 1200 mg of elemental calcium/day) or Arm B who received once-daily TDF/FTC only. PrEP users were defined as taking at least two tablets/week (tenofovir-diphosphate level of >350 fmol/punch). Adherence to vitamin D/calcium supplementation was defined as self-reported adherence of >50%. Lumbar spine (L2-L4) BMD (LSBMD) was evaluated by dual-energy X-ray absorptiometry scan zero and six months after PrEP initiation.

RESULTS

From March 2019 to March 2020, 100 youth were enrolled. Baseline characteristics between the two arms were similar. Median (IQR) age was 18 (17 to 20) years. At entry, median (IQR) LSBMD z-score was -0.8 (-1.5 to -0.3), 17% had low LSBMD (Z-score < -2). The median amount of calcium intake from nutritional three-day recall was 167 (IQR 94 to 272) mg/day, 39% of participants had vitamin D deficiency, defined as 25(OH)D levels <20 IU/mL. At six months, 79 participants were evaluated. Of these, 42 (52%) were PrEP takers and 25 of 38 (66%) of arm A participants had good adherence to vitamin D/calcium supplementation. Significantly higher proportions of youth in arm A compared to arm B had >3% increase in LSBMD at month 6 compared to baseline (67.6% vs. 42.9% respectively; p = 0.03). There were significantly higher increases in LSBMD among youth with vitamin D deficiency who were supplemented; arm A + 0.05 (0 to 0.05) compared to arm B + 0.03 (-0.1 to 0.03), p = 0.04.

CONCLUSIONS

Increases in LSBMD over six months among youth using PrEP who received vitamin D/calcium supplementation was greater than those not supplemented. Long-term follow-up should be considered to explore long-term outcomes.

Vitamin D3 Supplementation Increases Spine Bone Mineral Density in Adolescents and Young Adults With Human Immunodeficiency Virus Infection Being Treated With Tenofovir Disoproxil Fumarate: A Randomized, Placebo-Controlled Trial

Background

Tenofovir disoproxil fumarate (TDF) decreases bone mineral density (BMD). We hypothesized that vitamin D3 (VITD3) would increase BMD in youth receiving TDF.

Methods

This was a randomized, double-blind, placebo-controlled trial of directly observed VITD3 vs placebo every 4 weeks for 48 weeks in youth aged 16-24 years with HIV, RNA load <200 copies/mL, taking TDF-containing combination antiretroviral therapy (TDF-cART) for ≥180 days. Participants (N = 214) received a daily multivitamin containing VITD3 400 IU and calcium 162 mg, plus monthly randomized VITD3 50000 IU (n = 109) or placebo (n = 105). Outcome was change from baseline to week 48 in lumbar spine BMD (LSBMD). Data presented are median (Q1, Q3).

Results

Participants were aged 22.0 (21.0, 23.0) years, 84% were male, and 74% were black/African American. At baseline, 62% had 25-hydroxy vitamin D (25-OHD) <20 ng/mL. Multivitamin adherence was 49% (29%, 69%), and VITD3/placebo adherence 100% (100%, 100%). Vitamin D intake was 2020 (1914, 2168) and 284 (179, 394) IU/day, and serum 25-OHD concentration was 36.9 (30.5, 42.4) and 20.6 (14.4, 25.8) ng/mL at 48 weeks in VITD3 and placebo groups, respectively (P < .001). From baseline to week 48, LSBMD increased by 1.15% (-0.75% to 2.74%) in the VITD3 group (n = 99; P < .001) and 0.09% (-1.49% to 2.61%) in the placebo group (n = 89; P = .25), without between-group difference (P = .12). VITD3 group changes occurred with baseline 25-OHD <20 ng/mL (1.17% [-.82% to 2.90%]; P = .004) and ≥20 ng/mL (0.93% [-.26% to 2.15%]; P = .033).

Conclusions

For youth taking TDF-cART, LSBMD increased through 48 weeks with VITD3 plus multivitamin, but not with placebo plus multivitamin, independent of baseline vitamin D status.

Clinical Trials Registration

NCT01751646.

Prediction of insufficient serum vitamin D status in older women: a validated model

We developed an externally validated simple prediction model to predict serum 25(OH)D levels < 30, < 40, < 50 and 60 nmol/L in older women with risk factors for fractures. The benefit of the model reduces when a higher 25(OH)D threshold is chosen.

INTRODUCTION

Vitamin D deficiency is associated with increased fracture risk in older persons. General supplementation of all older women with vitamin D could cause medicalization and costs. We developed a clinical model to identify insufficient serum 25-hydroxyvitamin D (25(OH)D) status in older women at risk for fractures.

METHODS

In a sample of 2689 women ≥ 65 years selected from general practices, with at least one risk factor for fractures, a questionnaire was administered and serum 25(OH)D was measured. Multivariable logistic regression models with backward selection were developed to select predictors for insufficient serum 25(OH)D status, using separate thresholds 30, 40, 50 and 60 nmol/L. Internal and external model validations were performed.

RESULTS

Predictors in the models were as follows: age, BMI, vitamin D supplementation, multivitamin supplementation, calcium supplementation, daily use of margarine, fatty fish ≥ 2×/week, ≥ 1 hours/day outdoors in summer, season of blood sampling, the use of a walking aid and smoking. The AUC was 0.77 for the model using a 30 nmol/L threshold and decreased in the models with higher thresholds to 0.72 for 60 nmol/L. We demonstrate that the model can help to distinguish patients with or without insufficient serum 25(OH)D levels at thresholds of 30 and 40 nmol/L, but not when a threshold of 50 nmol/L is demanded.

CONCLUSIONS

This externally validated model can predict the presence of vitamin D insufficiency in women at risk for fractures. The potential clinical benefit of this tool is highly dependent of the chosen 25(OH)D threshold and decreases when a higher threshold is used.

Evolution of Serum 25OHD in Response to Vitamin D3-Fortified Yogurts Consumed by Healthy Menopausal Women: A 6-Month Randomized Controlled Trial Assessing the Interactions between Doses, Baseline Vitamin D Status, and Seasonality

BACKGROUND

Adequate vitamin D status contributes to bone fragility risk reduction and possibly other pathological conditions that occur with aging. In response to pharmaceutical vitamin D3 supplements, several studies have documented the influence of doses, baseline status, and seasonality on serum 25-hydroyvitamin D (s25OHD).

OBJECTIVE

Using fortified yogurt, we investigated in one randomized controlled trial how both baseline status, as assessed by measuring s25OHD prior the onset of the trial, and the season of enrollment quantitatively influenced the response to the supplemented (Suppl.) of vitamin D3 (VitD3) in healthy community-dwelling women.

METHODS

A 24-week controlled trial was conducted in menopausal women (mean age: 61.5). Participants were randomized into 3 groups (Gr): Gr.Suppl.0, time controls maintaining dietary habits; Gr.Suppl.5 and Gr.Suppl.10 consuming one and two 125-g servings of VitD3-fortified yogurts with 5- and 10-µg daily doses, respectively. The 16 intervention weeks lasted from early January to mid-August, the 8 follow-up weeks, without product, from late August to mid-October. Before enrollment, subjects were randomized into 2 s25OHD strata: low stratum (LoStr): 25-50 nmol/L; high stratum (HiStr): >50-75 nmol/L.

RESULTS

All enrolled participants adhered to the protocol throughout the 24-week study: Gr.Suppl.0 (n = 45), Gr.Suppl.5 (n = 44), and Gr.Suppl.10 (n = 44). Over the 16 intervention and 8 follow-up weeks, s25OHD increased in both supplemented groups, more in Gr.Suppl.10 than in Gr.Suppl.5. At the end of the intervention, the subject proportion with s25OHD ≥ 50 nmol/L was 37.8, 54.5, and 63.6% in Gr.Suppl.0, Gr.Suppl.5, and Gr.Suppl.10, respectively. The constant rate of s25OHD per supplemental VitD3 microgram was greater in LoStr than HiStr. The s25OHD increase was greater with late (mid-March) than early (mid-January) inclusion.

CONCLUSION

This randomized trial demonstrates (1) a dose-dependent s25OHD improvement related to fortified yogurt consumption; (2) an inversely baseline-dependent increase in s25OHD; and (3) a seasonal effect that highlights the importance of VitD3-fortified foods during winter, even at 5 µg/d, in healthy menopausal women.

Vitamin D deficiency was common among nursing home residents and associated with dementia: a cross sectional study of 545 Swedish nursing home residents

Background

Residents of nursing homes may have low 25-hydroxyvitamin D (25OHD) concentrations. Associations between vitamin D and cognitive performance, dementia and susceptibility to infections are not clearly established. The aim of this study was to investigate the prevalence of vitamin D deficiency and to identify associated factors among residents of nursing homes for elderly.

Methods

In this cross-sectional study blood samples for analysis of 25OHD were collected from all participating residents of Swedish nursing homes for the elderly from January to March 2012.

Exclusion criteria: dementia too severe to collect a blood test, terminally ill or refusing participation. Outcome Measures: Serum 25OHD concentrations. Logistic regression to evaluate factors associated with vitamin D deficiency (25OHD < 25 nmol/L).

Results

Blood samples were obtained from 545 of 901 residents of 22 nursing homes. Mean age 86 years (SD 6.9), 68% were women. Prevalence of vitamin D supplementation 17%, dementia 55%, lack of appetite ≥3 months 45% and any antibiotic treatment during the last 6 months 30%. Serum 25OHD concentrations: mean 34 nmol/L (SD 21, median 27, range 4–125), 82% (448/545) had 25OHD < 50 nmol/L and 41% (224/545) had 25OHD < 25 nmol/L. Adjusted OR (95% CI; p-value) for possible predictors of vitamin D deficiency (25OHD < 25 nmol/L): vitamin D supplementation 0.075 (0.031–0.18; p < 0.001), lack of appetite ≥3 months 0.75 (0.50–1.1; p = 0.15), hours outdoors/week 0.99 (0.96–1.0; p = 0.62), Fitzpatrick skin phototype (4–6) 0.69 (0.44–1.1; p = 0.12); dementia 2.3 (1.5–3.4; p < 0.001) and antibiotics last 6 months 1.6 (1.1–2.6; p < 0.029), adjusted for age and gender.

Conclusions

Vitamin D deficiency was common among nursing home residents and strongly associated with dementia. Regardless of causality or not, it is important to be alert for vitamin D deficiency in nursing homes residents with dementia. As expected vitamin D supplementation was associated with less vitamin D deficiency, however lack of appetite, staying outdoors and skin phototype were not significant predictors. Antibiotic treatments during the last 6 months were associated with vitamin D deficiency, potentially supporting the hypothesis that vitamin D deficiency is associated with infections.

Vitamin D deficiency is associated with a poor prognosis in advanced non-small cell lung cancer patients treated with platinum-based first-line chemotherapy

OBJECTIVES

This study aimed to examine the prognostic role of the plasma 25-hydroxyvitamin D (25(OH)D) level in advanced non-small cell lung cancer (NSCLC) patients treated with platinum-based doublet first-line chemotherapy.

METHODS

A total of 195 advanced NSCLC patients were consecutively and prospectively hospitalized to receive platinum-based first-line chemotherapy. The baseline 25(OH)D level was measured at the time of diagnosis. Main outcome measures included overall survival (OS) and progression-free survival (PFS).

RESULTS

With 10 ng/mL as the cutoff value for the baseline plasma 25(OH)D level, patients with 25(OH)D < 10 ng/mL (n = 54) and those with 25(OH)D ≥ 10 ng/mL (n = 141) were found to have similar characteristics in terms of age, sex, smoking status, pathological type, Eastern Cooperative Oncology Group (ECOG) performance status, and clinical staging (all P-values > 0.05). The median OS values of patients with 25(OH)D < 10 ng/mL and ≥ 10 ng/mL were 17.9 months (95% confidence interval [CI], 14.4-21.4 months) and 20.8 months (95%CI, 17.9-23.8 months), respectively; the median PFS values were 9.4 months (95%CI, 8.2-10.5 months) and 9.4 months (95%CI, 8.3-10.5 months), respectively. Both univariate and multivariate analyses showed that having a plasma 25(OH)D level < 10 ng/mL was associated with a significantly shorter OS (P = 0.003; P = 0.009), while the baseline plasma 25(OH)D level was not significantly associated with PFS.

CONCLUSION

Deficiency of 25(OH)D is an independent prognostic factor for a poor OS in advanced NSCLC patients treated with platinum-based first-line chemotherapy.

Do studies reporting 'U'-shaped serum 25-hydroxyvitamin D-health outcome relationships reflect adverse effects?

Several reports describe U-shaped 25-hydroxyvitamin D [25(OH)D] concentration-health outcomes, including musculo-skeletal disorders such as falls and fractures, several cancers, cardiovascular disease (CVD), cognitive function, all-cause mortality rates, birth outcomes, allergic reactions, frailty, and some other disorders. This paper reviews reports of U-shaped outcome associations with vitamin D status for evidence of underlying pathophysiological processes, or of confounding, finding that some U-shaped associations appear to be biologically meaningful, but that many could well reflect confounding by factors such as lifestyle, or hypovitaminosis D-related disease onset being masked by self-supplementation that was begun too late to correct developing health problems but before baseline vitamin D status assessment. However, the various U-shaped associations for allergic reactions may be due to vitamin D modulation of the phenotype of the immune response, shifting the Th1-Th2 balance toward Th2 formation. For prostate cancer, there seems to be little effect of 25(OH)D concentration on incidence; however, there is an inverse correlation between 25(OH)D concentration and mortality rates. Future observational studies, and randomized controlled trial data analyses, should include adjustment for data collected on prior long-term vitamin D supplementation and solar UVB exposure, as well as other potential confounders.

Does vitamin-D intake during resistance training improve the skeletal muscle hypertrophic and strength response in young and elderly men? - a randomized controlled trial

Introduction

Recent studies have shown that vitamin-D intake can improve skeletal muscle function and strength in frail vitamin-D insufficient individuals. We investigated whether vitamin-D intake can improve the muscular response to resistance training in healthy young and elderly individuals, respectively.

Methods

Healthy untrained young (n = 20, age 20–30) and elderly (n = 20, age 60–75) men were randomized to 16 weeks of daily supplementary intake of either 48 μg of vitamin-D + 800 mg calcium (Vitamin-D-group) or 800 mg calcium (Placebo-group) during a period and at a latitude of low sunlight (December-April, 56°N). During the last 12 weeks of the supplementation the subjects underwent progressive resistance training of the quadriceps muscle. Muscle hypertrophy, measured as changes in cross sectional area (CSA), and isometric strength of the quadriceps were determined. Muscle biopsies were analyzed for fiber type morphology changes and mRNA expression of vitamin-D receptor (VDR), cytochrome p450 27B1 (CYP27B1) and Myostatin.

Results

In the vitamin-D groups, serum 25(OH)D concentration increased significantly and at week 12 was significantly different from placebo in both young men (71.6 vs. 50.4 nmol/L, respectively) and elderly men (111.2 vs. 66.7 nmol/L, respectively). After 12 weeks of resistance training, quadriceps CSA and isometric strength increased compared to baseline in young (CSA p < 0.0001, strength p = 0.005) and elderly (CSA p = 0.001, strength p < 0.0001) with no difference between vitamin-D and placebo groups. Vitamin-D intake and resistance training increased strength/CSA in elderly compared to young (p = 0.008). In the young vitamin-D group, the change in fiber type IIa percentage was greater after 12 weeks training (p = 0.030) and Myostatin mRNA expression lower compared to the placebo group (p = 0.006). Neither resistance training nor vitamin-D intake changed VDR mRNA expression.

Conclusion

No additive effect of vitamin-D intake during 12 weeks of resistance training could be detected on either whole muscle hypertrophy or muscle strength, but improved muscle quality in elderly and fiber type morphology in young were observed, indicating an effect of vitamin-D on skeletal muscle remodeling.

Trial registration

ClinicalTrials with nr. NCT01252381

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-015-0029-y) contains supplementary material, which is available to authorized users.

Vitamin D deficiency is common in HIV-infected southern Australian adults

BACKGROUND

Vitamin D deficiency can have serious health consequences and may be particularly important for those living with HIV. It is unknown whether HIV infection is a risk factor for vitamin D deficiency. The aim of the study was to determine whether vitamin D deficiency is more common in HIV-infected than in HIV-uninfected individuals.

METHODS

This was a cross-sectional study of HIV-infected and uninfected individuals. A total of 997 HIV-infected participants were from a sexual health clinic in Melbourne with 25(OH)D measurements taken between 2008 and 2012. 3,653 HIV-uninfected individuals were participants in a statewide Victorian survey with 25(OH)D measurements taken between 2009 and 2010. Logistic regression models evaluated the association of HIV status with vitamin D deficiency (25[OH]D<50 nmol/l).

RESULTS

The frequency of vitamin D deficiency was significantly more common in HIV-infected (39% [95% CI 36%, 42%]) compared with HIV-uninfected individuals 23% (95% CI 15%, 31%). In multivariable analysis, males (adjusted odds ratio [aOR] 0.8; 95% CI 0.6, 0.9; P=0.001), Caucasian country of origin (aOR 0.4; 95% CI 0.3, 0.4; P<0.001), summer/autumn (aOR for autumn 0.2; 95% CI 0.1, 0.3; P<0.001), total cholesterol to high-density lipoprotein ratio >5 (aOR 1.4; 95% CI 1.2, 1.8; P<0.001) and HIV infection (aOR 1.7; 95% CI 1.4, 2.1; P<0.001) were associated with vitamin D deficiency.

CONCLUSIONS

Adults living in southern Australia with HIV were more likely to be vitamin D deficient than the general population.

Osteoporosis in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a lifestyle-related chronic inflammatory pulmonary disease associated with significant morbidity and mortality worldwide. COPD is associated with various comorbidities found in all stages of COPD. The comorbidities have significant impact in terms of morbidity, mortality, and economic burden in COPD. Management of comorbidities should be incorporated into the comprehensive management of COPD as this will also have an effect on the outcome in COPD patients. Various comorbidities reported in COPD include cardiovascular disease, skeletal muscle dysfunction, anemia, metabolic syndrome, and osteoporosis. Osteoporosis is a significant comorbidity in COPD patients. Various risk factors, such as tobacco smoking, systemic inflammation, vitamin D deficiency, and the use of oral or inhaled corticosteroids (ICSs) are responsible for its occurrence in patients with COPD. This review will focus on the prevalence, pathogenesis, risk factors, diagnosis, and treatment of osteoporosis in COPD patients.

Biochemical markers for assessment of calcium economy and bone metabolism: application in clinical trials from pharmaceutical agents to nutritional products

Nutrition plays an important role in osteoporosis prevention and treatment. Substantial progress in both laboratory analyses and clinical use of biochemical markers has modified the strategy of anti-osteoporotic drug development. The present review examines the use of biochemical markers in clinical research aimed at characterising the influence of foods or nutrients on bone metabolism. The two types of markers are: (i) specific hormonal factors related to bone; and (ii) bone turnover markers (BTM) that reflect bone cell metabolism. Of the former, vitamin D metabolites, parathyroid hormone, and insulin-like growth factor-I indicate responses to variations in the supply of bone-related nutrients, such as vitamin D, Ca, inorganic phosphate and protein. Thus modification in bone remodelling, the key process upon which both pharmaceutical agents and nutrients exert their anti-catabolic or anabolic actions, is revealed. Circulating BTM reflect either osteoclastic resorption or osteoblastic formation. Intervention with pharmacological agents showed that early changes in BTM predicted bone loss and subsequent osteoporotic fracture risk. New trials have documented the influence of nutrition on bone-tropic hormonal factors and BTM in adults, including situations of body-weight change, such as anorexia nervosa, and weight loss by obese subjects. In osteoporosis-prevention studies involving dietary manipulation, randomised cross-over trials are best suited to evaluate influences on bone metabolism, and insight into effects on bone metabolism may be gained within a relatively short time when biochemical markers are monitored.

Vitamin D deficiency among children with epilepsy in South Queensland

This study evaluated prevalence and risk factors for vitamin D deficiency among children with epilepsy on long-term antiepileptic drugs treated in South Queensland, Australia. Children with epilepsy seen in a tertiary neurology clinic were contacted requesting bone health blood tests during winter of 2011. Vitamin D deficiency was defined as 25-hydroxy vitamin D levels <20 ng/mL, and insufficiency between 21 and 29 ng/mL. One hundred thirty letters were sent, with 111 (85%) subsequently having blood tests performed. Vitamin D deficiency was identified in 24 (22%) of 111 and an additional 45 (41%) of 111 had vitamin D insufficiency. Multiple logistic regression analysis identified children on >2 antiepileptic drugs or with underlying genetic etiologies were more likely to have vitamin D deficiency. High proportion of children on long-term antiepileptic drugs in Queensland risk vitamin D deficiency and insufficiency despite living in the subtropics. Vitamin D monitoring and supplementation is important in the management of children on long-term antiepileptic drugs requiring tertiary care in Queensland.

Tackling the aging process with bio-molecules: a possible role for caloric restriction, food-derived nutrients, vitamins, amino acids, peptides, and minerals

Aging is a multifactorial process leading to general deterioration in many tissues and organs, accompanied by an increased incidence and severity of a wide variety of chronic, incurable, and often fatal diseases. A possibility of slowing down the aging process and improving the quality of life in old age by nutritional intervention has renewed the interest of the scientific world in anti-aging therapies. These include potential dietary interventions, adherence to nutrition, hormonal and cell-based therapies, genetic manipulations, and anti-aging supplements or nutrients. This review addresses strategies to slow the aging process by caloric restriction and the use of nutritional supplements.

Vitamin D status and its association with morbidity including wasting and opportunistic illnesses in HIV-infected women in Tanzania

Vitamin D has a potential role in preventing HIV-related complications, based on its extensive involvement in immune and metabolic function, including preventing osteoporosis and premature cardiovascular disease. However, this association has not been examined in large studies or in resource-limited settings. Vitamin D levels were assessed in 884 HIV-infected pregnant women at enrollment in a trial of multivitamin supplementation (excluding vitamin D) in Tanzania. Information on HIV related complications was recorded during follow-up (median, 70 months). Proportional hazards models and generalized estimating equations were used to assess the relationship of vitamin D status with these outcomes. Women with low vitamin D status (serum 25-hydroxyvitamin D<32 ng/mL) had 43% higher risk of reaching a body mass index (BMI) less than 18 kg/m(2) during the first 2 years of follow-up, compared to women with adequate vitamin D levels (hazard ratio [HR]: 1.43; 95% confidence intervals: [1.03-1.99]). The relationship between continuous vitamin D levels and risk of BMI less than 18 kg/m(2) during follow-up was inverse and linear (p=0.03). Women with low vitamin D levels had significantly higher incidence of acute upper respiratory infections (HR: 1.27 [1.04-1.54]) and thrush (HR: 2.74 [1.29-5.83]) diagnosed during the first 2 years of follow-up. Low vitamin D status was a significant risk factor for wasting and HIV-related complications such as thrush during follow-up in this prospective cohort in Tanzania. If these protective associations are confirmed in randomized trials, vitamin D supplementation could represent a simple and inexpensive method to improve health and quality of life of HIV-infected patients, particularly in resource-limited settings.

Short-term and long-term orthopaedic issues in patients with fragility fractures

BACKGROUND

Patients with impaired bone quality who suffer a fragility fracture face substantial challenges in both their short- and long-term care. In addition to poor bone quality, many of these patients have multiple medical comorbidities that alter their surgical risk and affect their ultimate functional recovery. Some medical issues can contribute to the altered bone quality and must be addressed to prevent future fractures.

QUESTIONS/PURPOSES

This review summarizes the modifications in perioperative management and fracture fixation in patients with common fragility fractures who have impaired bone quality. It also summarizes the postoperative diagnosis and treatment of secondary causes of impaired bone quality in these patients.

METHODS

We performed a PubMed search, and literature published after 2000 was prioritized, with the exception of benchmark clinical trial studies published before 2000.

RESULTS

Patients with altered bone quality require rapid perioperative management of multiple medical comorbidities. Implant selection in patients with poor quality bone should permit early weightbearing, and constructs should maximize surface area contact with the remaining bone. Long-term diagnosis and treatment of other disease states contributing to poor bone quality (vitamin D deficiency/insufficiency, hypothyroidism, hyperthyroidism, hyperparathyroidism, Cushing's disease, and hypogonadism) must occur to minimize the chances of future fractures.

CONCLUSIONS

Recognition of patients with impaired bone quality and proper treatment of their special needs in both the short and long term are essential for their best opportunity for maximal functional recovery and prevention of future fractures.

1,25(OH)2vitamin D3 stimulates myogenic differentiation by inhibiting cell proliferation and modulating the expression of promyogenic growth factors and myostatin in C2C12 skeletal muscle cells

Skeletal muscle wasting is an important public health problem associated with aging, chronic disease, cancer, kidney dialysis, and HIV/AIDS. 1,25-Dihydroxyvitamin D (1,25-D3), the active form of vitamin D, is widely recognized for its regulation of calcium and phosphate homeostasis in relation to bone development and maintenance and for its calcemic effects on target organs, such as intestine, kidney, and parathyroid glands. Emerging evidence has shown that vitamin D administration improves muscle performance and reduces falls in vitamin D-deficient older adults. However, little is known of the underlying mechanism or the role 1,25-D3 plays in promoting myogenic differentiation at the cellular and/or molecular level. In this study, we examined the effect of 1,25-D3 on myoblast cell proliferation, progression, and differentiation into myotubes. C(2)C(12) myoblasts were treated with 1,25-D3 or placebo for 1, 3, 4, 7, and 10 d. Vitamin D receptor expression was analyzed by quantitative RT-PCR, Western blottings and immunofluorescence. Expression of muscle lineage, pro- and antimyogenic, and proliferation markers was assessed by immunocytochemistry, PCR arrays, quantitative RT-PCR, and Western blottings. Addition of 1,25-D3 to C(2)C(12) myoblasts 1) increased expression and nuclear translocation of the vitamin D receptor, 2) decreased cell proliferation, 3) decreased IGF-I expression, and 4) promoted myogenic differentiation by increasing IGF-II and follistatin expression and decreasing the expression of myostatin, the only known negative regulator of muscle mass, without changing growth differentiation factor 11 expression. This study identifies key vitamin D-related molecular pathways for muscle regulation and supports the rationale for vitamin D intervention studies in select muscle disorder conditions.

An ecological study of cancer incidence and mortality rates in France with respect to latitude, an index for vitamin D production

France has unexplained large latitudinal variations in cancer incidence and mortality rates. Studies of cancer rate variations in several other countries, as well as in multicountry studies, have explained such variations primarily in terms of gradients in solar ultraviolet-B (UVB) doses and vitamin D production. To investigate this possibility in France, I obtained data on cancer incidence and mortality rates for 21 continental regions and used this information in regression analyses with respect to latitude. This study also used dietary data. Significant positive correlations with latitude emerged for breast, colorectal, esophageal (males), lung (males), prostate, both uterine cervix and uterine corpus, all and all less lung cancer. Although correlations with latitude were similar for males and females, the regression variance for all and all less lung cancer was about twice as high for males than for females. Lung cancer incidence and mortality rates for females had little latitudinal gradient, indicating that smoking may have also contributed to the latitudinal gradients for males. On the basis of the available dietary factor, micro- and macronutrient data, dietary differences do not significantly affect geographical variation in cancer rates. These results are consistent with solar UVB's reducing the risk of cancer through production of vitamin D. In the context of serum 25-hydroxyvitamin D level-cancer incidence relations, cancer rates could be reduced significantly in France if everyone obtained an additional 1,000 IU/day of vitamin D. Many other benefits of vitamin D exist as well.