Relationship of 25-hydroxyvitamin D with all-cause and cardiovascular disease mortality in older community-dwelling adults

Vitamin D and cardiovascular disease

Vitamin D plays a classical hormonal role in skeletal health by regulating calcium and phosphorus metabolism. Vitamin D metabolites also have physiological functions in nonskeletal tissues, where local synthesis influences regulatory pathways via paracrine and autocrine mechanisms. The active metabolite of vitamin D, 1α,25-dihydroxyvitamin D, binds to the vitamin D receptor that regulates numerous genes involved in fundamental processes of potential relevance to cardiovascular disease, including cell proliferation and differentiation, apoptosis, oxidative stress, membrane transport, matrix homeostasis, and cell adhesion. Vitamin D receptors have been found in all the major cardiovascular cell types including cardiomyocytes, arterial wall cells, and immune cells. Experimental studies have established a role for vitamin D metabolites in pathways that are integral to cardiovascular function and disease, including inflammation, thrombosis, and the renin-angiotensin system. Clinical studies have generally demonstrated an independent association between vitamin D deficiency and various manifestations of degenerative cardiovascular disease including vascular calcification. However, the role of vitamin D supplementation in the management of cardiovascular disease remains to be established. This review summarizes the clinical studies showing associations between vitamin D status and cardiovascular disease and the experimental studies that explore the mechanistic basis for these associations.

Associations between serum 25-hydroxyvitamin D concentrations and multiple health conditions, physical performance measures, disability, and all-cause mortality: the Concord Health and Ageing in Men Project

OBJECTIVES

To explore associations between serum 25-hydroxyvitamin D (25(OH)D) levels and a wide range of health conditions, physical performance measures, disability, and mortality in a large epidemiological study to identify an optimum range for 25(OH)D concentrations.

DESIGN

Cross-sectional study, with additional prospective data on falls and mortality.

SETTING

Concord Health and Ageing in Men Project, Sydney, Australia.

PARTICIPANTS

Community-dwelling men aged 70 and older (N = 1,659).

MEASUREMENTS

Serum 25(OH)D levels, general health status, self-reported diseases, physical performance measures, disability (activities of daily living and instrumental activities of daily living) and falls.

RESULTS

Fair, poor, and very poor health; self-reported diabetes mellitus; hyperglycemia; depression; muscle weakness; poor balance; and all-cause mortality were all associated with serum 25(OH)D levels less than 50 nmol/L, even after adjustment for confounding. The findings also suggest that, in older men, for a wide range of health conditions, physical performance measures, disability, falls, and mortality, the optimum range of 25(OH)D is between 50.0 and 74.9 nmol/L, with no additional benefit for 25(OH)D levels of 75.0 nmol/L or greater.

CONCLUSION

Programs aimed at achieving an optimum range of serum 25(OH)D at levels between 50.0 and 74.9 nmol/L may have overall health benefits and such levels are adequate for older men.

Vitamin D deficiency in reproductive age Mongolian women: a cross sectional study

Vitamin D production is critical not only for rickets prevention but for its role in several chronic diseases of adulthood. Maternal vitamin D status also has consequences for the developing fetus. This study assessed the prevalence of vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D]<20ng/ml) and insufficiency [25(OH)D=20-29ng/ml] in spring, among reproductive age Mongolian women. Blood was drawn in March and April, 2009 from 420 Mongolian women, 18-44 years of age. Serum 25(OH)D concentrations were measured, anthropometric measurements were performed and information was collected by interview on lifestyle, dietary and reproductive factors. Logarithm-transformed 25(OH)D levels were compared across risk factor categories by analysis of variance. Linear regression analysis was used to assess the independent associations of factors with vitamin D status. Cutaneous vitamin D3 synthesis was assessed between December and July using a standard 7-dehydrocholesterol ampoule model. The vast majority of women 415 (98.8%) had serum 25(OH)D<20ng/ml (50nmol/l) with an additional 4 women (<1%) in the insufficient range (20-29ng/ml); only one women (0.2%) had sufficient levels (>30ng/ml or 75nmol/l). 25(OH)D concentrations were positively and independently associated with educational status and use of vitamin D supplements, but not with other demographic, lifestyle, reproductive, or anthropometric factors. 25(OH)D levels were not associated with dietary factors in this population, as there is little access to foods containing vitamin D in Mongolia. No production of previtamin D3 was observed until March and was maximally effective in April and was sustained through July. These data suggest that the prevalence of vitamin D deficiency in spring among reproductive age women in Mongolia is high. Given the lack of naturally vitamin D-rich food in the diet and limited use of vitamin D supplements, food fortification and/or supplementation with vitamin D should be considered among these women.

Effect of diet on vascular health

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in the Western world in older people. Diet and lifestyle change can reduce CVD risk in older people, and this evidence base is reviewed. For example, diets low in trans fats can reduce CVD risk, while for saturated fats the CVD-lowering effect depends on what is substituted for the saturated fat. Diets rich in fish reduce CVD risk, although n-3 supplements have not been shown to have a consistent effect on CVD end-points. Antioxidant and B-group vitamin supplementation are unlikely to reduce CVD risk, but diets rich in these micronutrients (e.g. rich in fruits and vegetables and the Mediterranean diet) are associated with lower CVD risk, while, for the Mediterranean diet, this has been supported by randomized controlled trials. Maintaining a healthy weight and being physically active reduce CVD risk factors and CVD incidence and mortality.

Inverse association between circulating vitamin D and mortality--dependent on sex and cause of death?

BACKGROUND AND AIMS

In various populations, vitamin D deficiency is associated with chronic diseases and mortality. We examined the association between concentration of circulating 25-hydroxyvitamin D [25(OH)D], a marker of vitamin D status, and all-cause as well as cause-specific mortality.

METHODS AND RESULTS

The study included 3404 participants of the general adult Swiss population, who were recruited between November 1988 and June 1989 and followed-up until the end of 2008. Circulating 25(OH)D was measured by protein-bound assay. Cox proportional hazards regression was used to examine the association between 25(OH)D concentration and all-cause and cause-specific mortality adjusting for sex, age, season, diet, nationality, blood pressure, and smoking status. Per 10 ng/mL increase in 25(OH)D concentration, all-cause mortality decreased by 20% (HR = 0.83; 95% CI 0.74-0.92). 25(OH)D concentration was inversely associated with cardiovascular mortality in women (HR = 0.68, 95% CI 0.46-1.00 per 10 ng/mL increase), but not in men (HR = 0.97; 95% CI 0.77-1.23). In contrast, 25(OH)D concentration was inversely associated with cancer mortality in men (HR = 0.72, 95% CI 0.57-0.91 per 10 ng/mL increase), but not in women (HR = 1.14, 95% CI 0.93-1.39). Multivariate adjustment only slightly modified the 25(OH)D-mortality association.

CONCLUSION

25(OH)D was similarly inversely related to all-cause mortality in men and women. However, we observed opposite effects in women and men with respect to cardiovascular and cancer mortality.

A systematic review of vitamin D status in populations worldwide

Vitamin D deficiency is associated with osteoporosis and is thought to increase the risk of cancer and CVD. Despite these numerous potential health effects, data on vitamin D status at the population level and within key subgroups are limited. The aims of the present study were to examine patterns of 25-hydroxyvitamin D (25(OH)D) levels worldwide and to assess differences by age, sex and region. In a systematic literature review using the Medline and EMBASE databases, we identified 195 studies conducted in forty-four countries involving more than 168 000 participants. Mean population-level 25(OH)D values varied considerably across the studies (range 4·9-136·2 nmol/l), with 37·3 % of the studies reporting mean values below 50 nmol/l. The highest 25(OH)D values were observed in North America. Although age-related differences were observed in the Asia/Pacific and Middle East/Africa regions, they were not observed elsewhere and sex-related differences were not observed in any region. Substantial heterogeneity between the studies precluded drawing conclusions on overall vitamin D status at the population level. Exploratory analyses, however, suggested that newborns and institutionalised elderly from several regions worldwide appeared to be at a generally higher risk of exhibiting lower 25(OH)D values. Substantial details on worldwide patterns of vitamin D status at the population level and within key subgroups are needed to inform public health policy development to reduce risk for potential health consequences of an inadequate vitamin D status.

Vitamin D and subsequent all-age and premature mortality: a systematic review

Background

All-cause mortality in the population < 65 years is 30% higher in Glasgow than in equally deprived Liverpool and Manchester. We investigated a hypothesis that low vitamin D in this population may be associated with premature mortality via a systematic review and meta-analysis.

Methods

Medline, EMBASE, Web of Science, the Cochrane Library and grey literature sources were searched until February 2012 for relevant studies. Summary statistics were combined in an age-stratified meta-analysis.

Results

Nine studies were included in the meta-analysis, representing 24,297 participants, 5,324 of whom died during follow-up. The pooled hazard ratio for low compared to high vitamin D demonstrated a significant inverse association (HR 1.19, 95% CI 1.12-1.27) between vitamin D levels and all-cause mortality after adjustment for available confounders. In an age-stratified meta-analysis, the hazard ratio for older participants was 1.25 (95% CI 1.14-1.36) and for younger participants 1.12 (95% CI 1.01-1.24).

Conclusions

Low vitamin D status is inversely associated with all-cause mortality but the risk is higher amongst older individuals and the relationship is prone to residual confounding. Further studies investigating the association between vitamin D deficiency and all-cause mortality in younger adults with adjustment for all important confounders (or using randomised trials of supplementation) are required to clarify this relationship.

Racial differences in the association of serum 25-hydroxyvitamin D concentration with coronary heart disease events

IMPORTANCE

Low circulating concentrations of 25-hydroxyvitamin D (25[OH]D) have been consistently associated with an increased risk of coronary heart disease (CHD) in white populations. This association has not been rigorously evaluated in other races or ethnicities, in which the distributions of 25(OH)D concentration and possibly other aspects of 25(OH)D metabolism differ.

OBJECTIVE

To examine the association of serum 25(OH)D concentration with risk of CHD in a multiethnic population.

DESIGN, SETTING, AND PARTICIPANTS

We studied 6436 participants in the Multi-Ethnic Study of Atherosclerosis (MESA), recruited from July 2000 through September 2002, who were free of known cardiovascular disease at baseline. We measured baseline serum 25(OH)D concentrations using a mass spectrometry assay calibrated to established standards. We tested associations of 25(OH)D with adjudicated CHD events assessed through May 2012.

MAIN OUTCOME AND MEASURES

Primary outcome measure was time to first adjudicated CHD event, defined as myocardial infarction, angina, cardiac arrest, or CHD death.

RESULTS

During a median follow-up of 8.5 years, 361 participants had an incident CHD event (7.38 events per 1000 person-years). Associations of 25(OH)D with CHD differed by race/ethnicity (P for interaction < .05). After adjustment, lower 25(OH)D concentration was associated with a greater risk of incident CHD among participants who were white (n = 167 events; hazard ratio [HR], 1.26 [95% CI, 1.06-1.49] for each 10-ng/mL decrement in 25(OH)D) or Chinese (HR, 1.67 [95% CI, 1.07-2.61]; n = 27). In contrast, 25(OH)D was not associated with risk of CHD in participants who were black (HR, 0.93 [95% CI, 0.73-1.20]; n = 94) or Hispanic (HR, 1.01 [95% CI, 0.77-1.33]; n = 73).

CONCLUSIONS AND RELEVANCE

Lower serum 25(OH)D concentration was associated with an increased risk of incident CHD events among participants who were white or Chinese but not black or Hispanic. Results evaluating 25(OH)D in ethnically homogeneous populations may not be broadly generalizable to other racial or ethnic groups.

Is there a reverse J-shaped association between 25-hydroxyvitamin D and all-cause mortality? Results from the U.S. nationally representative NHANES

CONTEXT

A reverse J-shaped association between serum 25-hydroxyvitamin D (25[OH]D) concentration and all-cause mortality was suggested in a 9-year follow-up (1991-2000) analysis of the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994).

OBJECTIVE

Our objective was to repeat the analyses with 6 years additional follow-up to evaluate whether the association persists through 15 years of follow-up.

PARTICIPANTS

The study included 15 099 participants aged ≥ 20 years with 3784 deaths.

MAIN OUTCOME MEASURE

Relative risk (RR) of death from all causes was adjusted for age, sex, race/ethnicity, and season using 2 Poisson regression approaches: traditional categorical and cubic splines. Results were given for 9 25(OH)D levels: <20, 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 74, 75 to 99 (reference), 100 to 119, and ≥ 120 nmol/L.

RESULTS

The reverse J-shaped association became stronger with longer follow-up and was not affected by excluding deaths within the first 3 years of follow-up. Similar results were found from both statistical approaches for levels <20 through 119 nmol/L. Adjusted RR (95% confidence interval [CI]) estimates for all levels <60 nmol/L were significantly >1 compared with the reference group. The nadir of risk was 81 nmol/L (95% CI, 73-90 nmol/L). For 25(OH)D ≥ 120 nmol/L, results (RR, 95% CI) were slightly different using traditional categorical (1.5, 1.02-2.3) and cubic splines approaches (1.2, 0.9-1.4). The association appeared in men, women, adults ages 20 to 64 years, and non-Hispanic whites but was weaker in older adults. The study was too small to evaluate the association in non-Hispanic black and Mexican-American adults.

CONCLUSIONS

A reverse J-shaped association between serum 25(OH)D and all-cause mortality appears to be real. It is uncertain whether the association is causal.

Vitamin D status and incident cardiovascular disease and all-cause mortality: a general population study

Low vitamin D status has been associated with cardiovascular disease (CVD) and mortality primarily in selected groups, smaller studies, or with self-reported vitamin D intake. We investigated the association of serum vitamin D status with the incidence of a registry-based diagnosis of ischemic heart disease (IHD), stroke, and all-cause mortality in a large sample of the general population. A total of 9,146 individuals from the two population-based studies, Monica10 and Inter99, were included. Measurements of serum 25-hydroxyvitamin D at baseline were carried out using the IDS ISYS immunoassay system in Monica10 and High-performance liquid chromatography in Inter99. Information on CVDs and causes of death was obtained from Danish registries until 31 December 2008. There were 478 cases of IHD, 316 cases of stroke, and 633 deaths during follow-up (mean follow-up 10 years). Cox regression analyses with age as underlying time axis showed a significant association between vitamin D status and all-cause mortality with a HR = 0.95 (P = 0.005) per 10 nmol/l higher vitamin D level. We found no association between vitamin D status and incidence of IHD or stroke (HR = 1.01, P = 0.442 and HR = 1.00, P = 0.920, respectively). In this large general population study, the observed inverse association between serum vitamin D status and all-cause mortality was not explained by a similar inverse association with IHD or stroke.

Vitamin D, calcium, and atherosclerotic risk: evidence from serum levels and supplementation studies

Vitamin D and calcium have traditionally been viewed in relation to bone health. However, recent research has suggested relations between these nutrients and cardiovascular disease (CVD). Specifically, evidence from both observational studies and clinical trials suggests that vitamin D may be related to lower risk of CVD. The picture for calcium is more complex. Dietary intake of calcium may be associated with lower CVD risk, while calcium supplementation may elevate CVD risk. In this review, we summarize evidence of these relations, and comment on the recent Institute of Medicine (IOM) recommendations regarding use of vitamin D and calcium supplements.

The effect of vitamin D status on risk factors for cardiovascular disease

Vitamin-D-related pathways are implicated in various endocrine, inflammatory and endothelial functions. An estimated 1 billion people in the world have vitamin D deficiency or insufficiency, and undiagnosed vitamin D deficiency is common. Vitamin D deficiency is associated with substantial increases in the incidence of hypertension, hyperlipidaemia, myocardial infarction and stroke, as well as in diseases such as chronic kidney disease and type 2 diabetes. Low vitamin D levels also upregulate the renin-angiotensin-aldosterone system, increase inflammation and cause endothelial dysfunction. However, the role of vitamin D deficiency in cardiovascular morbidity and mortality is an emerging and hotly debated topic. Epidemiological studies suggest an association between low vitamin D levels and risk factors for cardiovascular disease, but a causal relationship has not been established, and clinical trials and meta-analyses have not demonstrated convincing evidence that vitamin D therapy improves cardiovascular outcomes. Some evidence suggests that vitamin D status is a biomarker of lifestyle, since unhealthy and sedentary lifestyles are associated with vitamin D insufficiency or deficiency and are also risk factors for cardiovascular complications.

Fibroblast growth factor 23, mineral metabolism and mortality among elderly men (Swedish MrOs)

Background

Fibroblast growth factor 23 (FGF23) is the earliest marker of disturbed mineral metabolism as renal function decreases. Its serum levels are associated with mortality in dialysis patients, persons with chronic kidney disease (CKD) and prevalent cardiovascular disease (CVD), and it is associated with atherosclerosis, endothelial dysfunction and left ventricular hypertrophy in the general population. The primary aim of this study is to examine the association between FGF23 and mortality, in relation to renal function in the community. A secondary aim is to examine the association between FGF23 and CVD related death.

Methods

The population-based cohort of MrOS Sweden included 3014 men (age 69–81 years). At inclusion intact FGF23, intact parathyroid hormone (PTH), 25 hydroxyl vitamin D (25D), calcium and phosphate were measured. Mortality data were collected after an average of 4.5 years follow-up. 352 deaths occurred, 132 of CVD. Association between FGF23 and mortality was analyzed in quartiles of FGF23. Kaplan-Meier curves and Log-rank test were used to examine time to events. Cox proportional hazards regression was used to examine the association between FGF23, in quartiles and as a continuous variable, with mortality. The associations were also analyzed in the sub-cohort with estimated glomerular filtration rate (eGFR) above 60 ml/min/1.73 m².

Results

There was no association between FGF23 and all-cause mortality, Hazard ratio (HR) 95% confidence interval (CI): 1.02 (0.89-1.17). For CVD death the HR (95% CI) was 1.26 (0.99 - 1.59)/(1-SD) increase in log(10)FGF23 after adjustment for eGFR, and other confounders. In the sub-cohort with eGFR > 60 ml/min/1.73 m² the HR (95% CI) for CVD death was 55% (13–111)/(1-SD) increase in log(10)FGF23.

Conclusions

FGF23 is not associated with mortality of all-cause in elderly community living men, but there is a weak association with CVD death, even after adjustment for eGFR and the other confounders. The association with CVD death is noticeable only in the sub-cohort with preserved renal function.

Vitamin D supplementation in elderly or postmenopausal women: a 2013 update of the 2008 recommendations from the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO)

BACKGROUND

Vitamin D insufficiency has deleterious consequences on health outcomes. In elderly or postmenopausal women, it may exacerbate osteoporosis.

SCOPE

There is currently no clear consensus on definitions of vitamin D insufficiency or minimal targets for vitamin D concentrations and proposed targets vary with the population. In view of the potential confusion for practitioners on when to treat and what to achieve, the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) convened a meeting to provide recommendations for clinical practice, to ensure the optimal management of elderly and postmenopausal women with regard to vitamin D supplementation.

FINDINGS

Vitamin D has both skeletal and extra-skeletal benefits. Patients with serum 25-hydroxyvitamin D (25-(OH)D) levels <50 nmol/L have increased bone turnover, bone loss, and possibly mineralization defects compared with patients with levels >50 nmol/L. Similar relationships have been reported for frailty, nonvertebral and hip fracture, and all-cause mortality, with poorer outcomes at <50 nmol/L.

CONCLUSION

The ESCEO recommends that 50 nmol/L (i.e. 20 ng/mL) should be the minimal serum 25-(OH)D concentration at the population level and in patients with osteoporosis to ensure optimal bone health. Below this threshold, supplementation is recommended at 800 to 1000 IU/day. Vitamin D supplementation is safe up to 10,000 IU/day (upper limit of safety) resulting in an upper limit of adequacy of 125 nmol/L 25-(OH)D. Daily consumption of calcium- and vitamin-D-fortified food products (e.g. yoghurt or milk) can help improve vitamin D intake. Above the threshold of 50 nmol/L, there is no clear evidence for additional benefits of supplementation. On the other hand, in fragile elderly subjects who are at elevated risk for falls and fracture, the ESCEO recommends a minimal serum 25-(OH)D level of 75 nmol/L (i.e. 30 ng/mL), for the greatest impact on fracture.

25-Hydroxyvitamin D concentrations and risk of venous thromboembolism in the general population with 18,791 participants

BACKGROUND

Vitamin D has potential antithrombotic effects, suggesting that vitamin D analogs could be used as adjunctive antithrombotic agents. However, epidemiologic evidence of an association between reduced 25-hydroxyvitamin D concentrations and the risk of venous thromboembolism is lacking.

OBJECTIVES

To test the hypothesis that reduced plasma 25-hydroxyvitamin D concentrations are associated with an increased risk of venous thromboembolism in the general population.

METHODS

We prospectively studied 18 791 participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. During up to 30 years of follow-up, 950 participants were diagnosed with venous thromboembolism. Plasma 25-hydroxyvitamin D concentrations were adjusted for seasonal variation.

RESULTS

The cumulative incidence of venous thromboembolism as a function of age increased with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D (log-rank trend: P = 4 × 10(-4) ). On comparison of participants in the lowest and the highest tertile of plasma 25-hydroxyvitamin D concentrations, the crude risk estimate in a model adjusted for age and sex was a 37% (95% confidence interval [CI] 15-64%) increased risk of venous thromboembolism. The corresponding risk increase in a model adjusted for age, sex, body mass index, smoking and cancer was 26% (95% CI 5-51%), and in a multivariable-adjusted model also including physical activity, hormone replacement therapy, menopausal status, oral contraception use and lipid-lowering therapy it was 28% (95% CI 6-53%). Furthermore, corresponding risk increases with attempts to correct for regression dilution bias were 103% (95% CI 37-202%), 70% (95% CI 14-155%) and 73% (95% CI 15-160%) in the three models, respectively.

CONCLUSION

In these large general population studies, we observed a stepwise increasing risk of venous thromboembolism with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D concentrations.

Serum 25-hydroxyvitamin D levels and overall mortality. A systematic review and meta-analysis of prospective cohort studies

OBJECTIVE

To provide a systematic review and meta-analysis of prospective, population-based cohort studies on the association of serum 25-hydroxyvitamin D (25(OH)D) and all-cause mortality.

METHODS

Relevant studies were identified by systematically searching Medline, EMBASE and ISI Web of Knowledge. Reported hazard ratios (HRs) for 25(OH)D categories were recalculated employing comprehensive trend estimation from summarized dose-response data and pooled in a random effects model meta-analysis.

RESULTS

Overall, 12 original studies were included in the review and meta-analysis comprising 32,142 mainly elderly study participants with measured 25(OH)D of whom 6921 died during follow-up. An inverse association between 25(OH)D levels and all-cause mortality was found in all but two studies that was statistically significant in several of the individual studies. In meta-analysis, 25(OH)D levels were significantly inversely associated with all-cause mortality with a pooled HR of 0.92 (95% confidence interval: 0.89-0.95) for a 20 nmol/l increase in 25(OH)D levels.

CONCLUSION

In this meta-analysis of prospective, population-based cohort studies, a 20 nmol/l increase in 25(OH)D levels was associated with an 8% lower mortality in the general elderly population. This agrees with results from meta-analyses on randomized controlled trials that found a decrease in mortality with vitamin D3 supplementation of a comparable magnitude.

A prospective study of serum 25-hydroxyvitamin d levels and mortality among African Americans and non-African Americans

The beneficial biologic effects attributed to vitamin D suggest a potential to influence overall mortality. Evidence addressing this hypothesis is limited, especially for African Americans who have a high prevalence of vitamin D insufficiency. The authors conducted a nested case-control study within the prospective Southern Community Cohort Study to relate baseline serum levels of 25-hydroxyvitamin D (25(OH)D) with subsequent mortality. Cases were 1,852 participants who enrolled from 2002 to 2009 and died >12 months postenrollment. Controls (n = 1,852) were matched on race, sex, age, enrollment site, and blood collection date. The odds ratios for quartile 1 (<10.18 ng/mL) versus quartile 4 (>21.64 ng/mL) levels of 25(OH)D were 1.60 (95% confidence interval (CI): 1.20, 2.14) for African Americans and 2.11 (95% CI: 1.39, 3.21) for non-African Americans. The effects were strongest for circulatory disease death, where quartile 1 versus quartile 4 odds ratios were 2.53 (95% CI: 1.44, 4.46) and 3.25 (95% CI: 1.33, 7.93) for African Americans and non-African Americans, respectively. The estimated odds of total mortality were minimized in the 25(OH)D range of 35-40 ng/mL. These findings provide support for the hypothesis that vitamin D status may have an important influence on mortality for both African Americans and non-African Americans.

Vitamin D status and cause-specific mortality: a general population study

Background

Vitamin D deficiency is associated with an increased risk of all-cause mortality in observational studies. The specific causes of death underlying this association lack clarity. We investigated the association between vitamin D status and cause-specific mortality.

Methods

We included a total of 9,146 individuals from the two population-based studies, Monica10 and Inter99, conducted in 1993–94 and 1999–2001, respectively. Vitamin D status was assessed as serum 25-hydroxyvitamin D. Information on causes of death was obtained from The Danish Register of Causes of Death until 31 December 2009. There were a total of 832 deaths (median follow-up 10.3 years).

Results

Multivariable Cox regression analyses with age as underlying time axis and vitamin D quartiles showed significant associations between vitamin D status and death caused by diseases of the respiratory system, the digestive system, and endocrine, nutritional and metabolic diseases with hazard ratios (HRs) 0.26 (p_trend = 0.0042), 0.28 (p_trend = 0.0040), and 0.21 (p_trend = 0.035), respectively, for the fourth vitamin D quartile compared to the first. We found non-significantly lower HRs for death caused by mental and behavioural diseases and diseases of the nervous system, but no association between vitamin D status and death caused by neoplasms or diseases of the circulatory system.

Conclusion

The associations of vitamin D status and cause-specific mortality suggest that we also look elsewhere (than to cardiovascular disease and cancer) to explain the inverse association between vitamin D status and mortality.

Circulating 25OHD, dietary vitamin D, PTH, and calcium associations with incident cardiovascular disease and mortality: the MIDSPAN Family Study

CONTEXT

Observational studies relating circulating 25-hydroxyvitamin D (25OHD) and dietary vitamin D intake to cardiovascular disease (CVD) have reported conflicting results.

OBJECTIVE

Our objective was to investigate the association of 25OHD, dietary vitamin D, PTH, and adjusted calcium with CVD and mortality in a Scottish cohort.

DESIGN AND SETTING

The MIDSPAN Family Study is a prospective study of 1040 men and 1298 women from the West of Scotland recruited in 1996 and followed up for a median 14.4 yr.

PARTICIPANTS

Locally resident adult offspring of a general population cohort were recruited from 1972-1976.

MAIN OUTCOME MEASURES

CVD events (n = 416) and all-cause mortality (n = 100) were evaluated.

RESULTS

25OHD was measured using liquid chromatography-tandem mass spectrometry in available plasma (n = 2081). Median plasma 25OHD was 18.6 ng/ml, and median vitamin D intake was 3.2 μg/d (128 IU/d). Vitamin D deficiency (25OHD <15 ng/ml) was present in 689 participants (33.1%). There was no evidence that dietary vitamin D intake, PTH, or adjusted calcium were associated with CVD events or with mortality. Vitamin D deficiency was not associated with CVD (fully adjusted hazard ratio = 1.00; 95% confidence interval = 0.77-1.31). Results were similar after excluding patients who reported an activity-limiting longstanding illness at baseline (18.8%) and those taking any vitamin supplements (21.7%). However, there was some evidence vitamin D deficiency was associated with all-cause mortality (fully adjusted hazard ratio = 2.02; 95% confidence interval = 1.17-3.51).

CONCLUSION

Vitamin D deficiency was not associated with risk of CVD in this cohort with very low 25OHD. Future trials of vitamin D supplementation in middle-aged cohorts should be powered to detect differences in mortality outcomes as well as CVD.

Circulating 25-hydroxy-vitamin D and risk of cardiovascular disease: a meta-analysis of prospective studies

BACKGROUND

Vitamin D status has been linked to the risk of cardiovascular disease (CVD). However, the optimal 25-hydroxy-vitamin D (25[OH]-vitamin D) levels for potential cardiovascular health benefits remain unclear.

METHODS AND RESULTS

We searched MEDLINE and EMBASE from 1966 through February 2012 for prospective studies that assessed the association of 25(OH)-vitamin D concentrations with CVD risk. A total of 24 articles met our inclusion criteria, from which 19 independent studies with 6123 CVD cases in 65 994 participants were included for a meta-analysis. In a comparison of the lowest with the highest 25(OH)-vitamin D categories, the pooled relative risk was 1.52 (95% confidence interval, 1.30-1.77) for total CVD, 1.42 (95% confidence interval, 1.19-1.71) for CVD mortality, 1.38 (95% confidence interval, 1.21-1.57) for coronary heart disease, and 1.64 (95% confidence interval, 1.27-2.10) for stroke. These associations remained strong and significant when analyses were limited to studies that excluded participants with baseline CVD and were better controlled for season and confounding. We used a fractional polynomial spline regression analysis to assess the linearity of dose-response association between continuous 25(OH)-vitamin D and CVD risk. The CVD risk increased monotonically across decreasing 25(OH)-vitamin D below ≈60 nmol/L, with a relative risk of 1.03 (95% confidence interval, 1.00-1.06) per 25-nmol/L decrement in 25(OH)-vitamin D.

CONCLUSIONS

This meta-analysis demonstrated a generally linear, inverse association between circulating 25(OH)-vitamin D ranging from 20 to 60 nmol/L and risk of CVD. Further research is needed to clarify the association of 25(OH)-vitamin D higher than 60 nmol/L with CVD risk and assess causality of the observed associations.

Vitamin D and overall mortality

Vitamin D is a steroid molecule, mainly produced in the skin that regulates the expression of a large number of genes. Several meta-analyses of epidemiological studies support the evidence that low vitamin D serum level, which is highly prevalent worldwide, could be a 'new' risk factor for many chronic diseases including cancer, and for all-cause mortality. A meta-analysis in healthy subjects suggested that current doses of vitamin D supplements could be associated with decrease in total mortality rates. However, these associations are insufficient to establish causality between vitamin D and all-cause mortality. Furthermore, long-term health effects of high doses of vitamin D, that is, prolonged supplementation and association with different baseline vitamin D levels, remain to be investigated. Several trials are ongoing but population-based, placebo-controlled randomized trials with total mortality as the main endpoint should be planned to confirm a real beneficial effect of vitamin D for non-skeletal diseases and to prove causality.

25-Hydroxyvitamin D, parathyroid hormone, and mortality in black and white older adults: the health ABC study

CONTEXT

Previous 25-hydroxyvitamin D [25(OH)D] and mortality studies have included mostly individuals of European descent. Whether the relationship is similar in Blacks and to what extent differences in 25(OH)D explain racial disparities in mortality is unclear.

OBJECTIVE

The objective of the study was to examine the relationship between 25(OH)D, PTH, and mortality in Black and white community-dwelling older adults over 8.5 yr of follow-up.

DESIGN AND SETTING

Health ABC is a prospective cohort study conducted in Memphis, TN, and Pittsburgh, PA.

PARTICIPANTS

Well-functioning Blacks and whites aged 71-80 yr with measured 25(OH)D and PTH (n = 2638; 49% male, 39% Black) were included in the study.

MAIN OUTCOME MEASURE

Multivariate-adjusted proportional hazards models estimated the hazard ratios (HR) for all-cause, cardiovascular, cancer, and noncancer, noncardiovascular mortality (n = 691 deaths).

RESULTS

Mean 25(OH)D concentrations were higher in whites than in Blacks [mean (sd): 29.0 (9.9) and 20.8 (8.7) ng/ml, respectively; P < 0.001]. Serum 25(OH)D by race interactions were not significant, however. Lower 25(OH)D concentrations were associated with higher mortality in Blacks and whites combined [HR (95% confidence interval [CI] 2.27 (1.59-3.24), 1.48 (1.20-1.84), and 1.25 (1.02-1.52) for < 10, 10 to < 20, and 20 to < 30 vs. ≥30 ng/ml]. In the multivariate model without 25(OH)D, Blacks had 22% higher mortality than whites [HR (95% CI) 1.22 (1.01, 1.48)]; after including 25(OH)D in the model, the association was attenuated [1.09 (0.90-1.33)]. The mortality population attributable risks (95% CI) for 25(OH)D concentrations less than 20 ng/ml and less than 30 ng/ml in Blacks were 16.4% (3.1-26.6%) and 37.7% (11.6-55.1%) and in whites were 8.9% (3.9-12.7%) and 11.1% (-2.7 to 22.0%), respectively. PTH was also associated with mortality [HR (95% CI) 1.80 (1.33-2.43) for ≥70 vs. <23 pg/ml].

CONCLUSIONS

Low 25(OH)D and high PTH concentrations were associated with increased mortality in Black and white community-dwelling older adults. Because 25(OH)D concentrations were much lower in Blacks, the potential impact of remediating low 25(OH)D concentrations was greater in Blacks than whites.

Arterial stiffness and vitamin D levels: the Baltimore longitudinal study of aging

CONTEXT

The importance of vitamin D for bone health has long been acknowledged. Recent evidence suggests that vitamin D can also play a role in reducing the risk of several other diseases, including cardiovascular disease.

OBJECTIVE

The aim of this study is to test the hypothesis that 25-hydroxyvitamin D (25-OH D) is an independent cross-sectional correlate of central arterial stiffness in a normative aging study population.

DESIGN AND SETTINGS

We conducted a cross-sectional analysis.

SUBJECTS

We studied 1228 healthy volunteers (50% males; age, 70±12 yr) of the Baltimore Longitudinal Study of Aging.

MAIN OUTCOME MEASURES

We measured carotid-femoral pulse wave velocity (PWV) and 25-OH D levels.

RESULTS

We found a significant inverse association between PWV and 25-OH D levels (adjusted r2=0.27; β=-0.43; P=0.001). After adjusting for age, gender, ethnicity, season of blood draw, estimated glomerular filtration rate, physical activity level, cardiovascular risk factors score (smoking, visceral obesity, hypercholesterolemia, hypertension, and diabetes), calcium/vitamin D supplementation, serum calcium, and PTH levels, the association between PWV and 25-OH D levels was only slightly reduced and remained statistically significant (adjusted r2=0.34; β=-0.34; P=0.04).

CONCLUSIONS

Vitamin D levels are inversely associated with increased arterial stiffness in a normative aging population, irrespective of traditional risk factor burden. Further research is needed to understand the mechanism of this association and to test the hypothesis that vitamin D supplementation can reduce arterial stiffness.

Vitamin D status and changes in cardiovascular risk factors: a prospective study of a general population

OBJECTIVES

A low vitamin D level has been associated with increased cardiovascular disease risk but possible mechanisms remain unclear. We investigated the association between vitamin D levels and 5-year changes in blood pressure, lipid profile and incidence of the metabolic syndrome, hypertension and hypercholesterolemia.

METHODS

A random sample of 6,784 individuals aged 30-60 years from a general population was investigated in the Inter99 study in 1999-2001. Vitamin D (serum 25-hydroxyvitamin D) was measured at baseline by high-performance liquid chromatography, and 4,330 individuals participated at the 5-year follow-up and were included in the present study.

RESULTS

The median baseline vitamin D concentration was 48.0 nmol/l. In multivariable linear regression analyses, a 10 nmol/l higher baseline level of vitamin D was associated with a decrease in triglycerides and very low density lipoprotein cholesterol by 0.52 (p = 0.03) and 0.66% (p = 0.005), respectively. In multivariable logistic regression analyses, the odds ratios per 10 nmol/l higher baseline vitamin D level were 0.95 (p < 0.05) and 0.94 (p = 0.01) for the development of the metabolic syndrome and hypercholesterolemia, respectively. There was no association between vitamin D and blood pressure.

CONCLUSIONS

An optimal vitamin D status may influence cardiovascular health by changing the lipid profile in a favorable direction and decreasing the incidence of the metabolic syndrome.

25-hydroxyvitamin d levels and risk of ischemic heart disease, myocardial infarction, and early death: population-based study and meta-analyses of 18 and 17 studies

OBJECTIVE

We tested the hypothesis that reduced plasma 25-hydroxyvitamin D associates with increased risk of ischemic heart disease, myocardial infarction, and early death.

METHODS AND RESULTS

We measured baseline plasma 25-hydroxyvitamin D in 10 170 women and men from the Danish general population without vitamin D-fortified food. During 29 years of follow-up, 3100 persons developed ischemic heart disease, 1625 myocardial infarction, and 6747 died. Decreasing plasma 25-hydroxyvitamin D levels were associated with increasing risk of ischemic heart disease, myocardial infarction, and early death as a function of seasonally adjusted percentile categories (P for trend, 2×10(-4)-3×10(-53)). Comparing individuals with plasma 25-hydroxyvitamin D levels at the 1st to 4th percentile with individuals with levels at the 50th to 100th percentile, the multivariable adjusted risk was increased by 40% (95% CI, 14%-72%) for ischemic heart disease, by 64% (25%-114%) for myocardial infarction, by 57% (38%-78%) for early death, and by 81% (40%-135%) for fatal ischemic heart disease/myocardial infarction. In the meta-analyses of 18 and 17 studies, risk of ischemic heart disease and early death were increased by 39% (25%-54%) and 46% (31%-64%) for lowest versus highest quartile of 25-hydroxyvitamin D level.

CONCLUSIONS

We observed increasing risk of ischemic heart disease, myocardial infarction, and early death with decreasing plasma 25-hydroxyvitamin D levels. These findings were substantiated in meta-analyses.

A global representation of vitamin D status in healthy populations

PURPOSE

This paper visualizes the available data on vitamin D status on a global map, examines the existing heterogeneities in vitamin D status and identifies research gaps.

METHODS

A graphical illustration of global vitamin D status was developed based on a systematic review of the worldwide literature published between 1990 and 2011. Studies were eligible if they included samples of randomly selected males and females from the general population and assessed circulating 25-hydroxyvitamin D [25(OH)D] levels. Two different age categories were selected: children and adolescents (1-18 years) and adults (>18 years). Studies were chosen to represent a country based on a hierarchical set of criteria.

RESULTS

In total, 200 studies from 46 countries met the inclusion criteria, most coming from Europe. Forty-two of these studies (21 %) were classified as representative. In children, gaps in data were identified in large parts of Africa, Central and South America, Europe, and most of the Asia/Pacific region. In adults, there was lack of information in Central America, much of South America and Africa. Large regions were identified for which the mean 25(OH)D levels were below 50 nmol/L.

CONCLUSIONS

This study provides an overview of 25(OH)D levels around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to musculoskeletal growth, development, and preservation, and of its potential importance in other tissues, we strongly encourage new research to clearly define 25(OH)D status around the world.

25-Hydroxyvitamin D is lower in deprived groups, but is not associated with carotid intima media thickness or plaques: results from pSoBid

OBJECTIVE

The association of the circulating serum vitamin D metabolite 25-hydroxyvitamin D (25OHD) with atherosclerotic burden is unclear, with previous studies reporting disparate results.

METHOD

Psychological, social and biological determinants of ill health (pSoBid) is a study of participants aged 35-64 years from Glasgow who live at extremes of the socioeconomic spectrum. Vitamin D deficiency was defined as 25OHD < 25nmol/L, as per convention. Cross-sectional associations between circulating 25OHD concentrations and a range of socioeconomic, lifestyle, and biochemistry factors, as well as carotid intima media thickness (cIMT) and plaque presence were assessed in 625 participants.

RESULTS

Geometric mean levels of circulating 25OHD were higher among the least deprived (45.6 nmol/L, 1-SD range 24.4-85.5) versus most deprived (34.2 nmol/L, 1-SD range 16.9-69.2; p < 0.0001). In the least deprived group 15% were "deficient" in circulating 25OHD versus 30.8% in the most deprived (χ(2)p < 0.0001). Log 25OHD was 27% lower among smokers (p < 0.0001), 20% higher among the physically active versus inactive (p = 0.01), 2% lower per 1 kg/m(2) increase in body mass index (BMI) (p < 0.0001), and showed expected seasonal variation (χ(2)p < 0.0001). Log 25OHD was 13% lower in the most versus least deprived independent of the aforementioned lifestyle confounding factors (p = 0.03). One unit increase in log 25OHD was not associated with atherosclerotic burden in univariable models; cIMT (effect estimate 0.000 mm [95% CI -0.011, 0.012]); plaque presence (OR 0.88 [0.75, 1.03]), or in multivariable models.

CONCLUSION

There is no strong association of 25OHD with cIMT or plaque presence, despite strong evidence 25OHD associates with lifestyle factors and socioeconomic deprivation.

Serum 25-hydroxyvitamin D levels and all-cause and cardiovascular disease mortality among US adults with hypertension: the NHANES linked mortality study

OBJECTIVES

Research suggests that serum concentrations of 25-hydroxyvitamin D [25(OH)D] are inversely associated with hypertension incidence. This study examined whether concentrations of 25(OH)D are inversely associated with mortality risk among US adults with hypertension.

METHODS

We analyzed data from the 2001-2004 National Health and Nutrition Examination Survey with mortality data obtained through 2006. Hazard ratios with 95% confidence intervals (CIs) for all-cause and cardiovascular disease (CVD) mortality were estimated using Cox proportional hazard models.

RESULTS

Of 2609 participants with hypertension, 191 died (including 68 CVD deaths) during an average of 3.7-year follow-up. Compared with participants with 25(OH)D concentrations in the highest quartile (≥29 ng/ml), the hazard ratios for all-cause mortality were 1.93 (95% CI 1.06-3.49), 1.32 (95% CI 0.85-2.04), and 1.36 (95% CI 0.84-2.22), respectively (P for trend <0.05), and the hazard ratios for CVD mortality were 3.21 (95% CI 1.14-8.99), 2.42 (95% CI 0.85-6.90), and 2.33 (95% CI 0.88-6.12), respectively (P for trend <0.05), in the first (<17 ng/ml), second (17-<23 ng/ml) and third (23-<29 ng/ml) quartiles of 25(OH)D after adjustment for potential confounding variables. Additionally, concentrations of 25(OH)D as a continuous variable were linearly and inversely associated with the risk of mortality from all causes (P = 0.012) and from CVD (P = 0.010). These relationships were not affected much by adjustment for baseline blood pressure and use of antihypertension medications.

CONCLUSION

Concentrations of 25(OH)D were inversely associated with all-cause and CVD mortality among adults with hypertension in the US. Enhancing vitamin D intake may contribute to a lower risk for premature death.

Vitamin D: an essential component for skeletal health

Vitamin D deficiency is increasing worldwide. Ultraviolet rays are supposed to provide humans over 80% of our vitamin D requirement; the rest is received through diet and supplements. In addition to enhancing calcium absorption from the intestine and mineralization of the osteoid tissue, vitamin D has many other physiological effects, including neuromodulation, improving muscle strength and coordination, insulin release, immunity and prevention of infections, and curtailing cancer. Whether the increased incidence of vitamin D deficiency is related to increased incidences of nonskeletal disorders remains to be determined. Serum levels of 25-hydroxyvitamin [25(OH)D] above 30 ng/mL indicate vitamin D sufficiency. An additional 1,000 IU of vitamin D/day is sufficient for most lighter-skinned individuals, whereas an extra 2,000 IU/day is needed by the elderly and dark-skinned individuals to maintain normal 25(OH)D levels. Additional research is needed to clarify the relationship between vitamin D and the nonskeletal systems, nonclassic functions, and targets of vitamin D.

Effect of follow-up time on the relation between prediagnostic serum 25-hydroxyvitamin D and all-cause mortality rate

Evidence continues to mount that vitamin D reduces the risk and mortality rates of many types of disease. However, evidence from prospective cohort studies is sometimes weaker than that from case-control and ecological studies. A suggested reason for this discrepancy is that, because serum levels of 25-hydroxyvitamin D [25(OH)D] change over time, a single 25(OH)D concentration measurement taken at study enrollment does not reliably indicate 25(OH)D concentration related to the health outcome. To evaluate this suggestion further, this paper plots results from 12 prospective cohort studies of all-cause mortality rate vs. follow-up time. The regression fit to the hazard ratio per 20-nmol/l increase in serum 25(OH)D concentration vs. time increased from 0.82 (95% CI, 0.67-1.02) for 6 y to 0.96 (95% CI, 0.90-1.01) for 14 y. The value extrapolated for zero follow-up time was 0.72 (95% CI, 0.50-1.03), giving a hazard ratio reduction 3.5 times higher than the standard result from the meta-analysis [0.92 (95% CI, 0.89-0.95)]. Using the example of the Vitamin D Pooling Project of Rarer Cancers, this paper also discusses follow-up time's effect in interpreting prospective cohort studies of cancer outcome. This paper recommends that meta-analyses of prospective cohort studies account for follow-up time and, if possible, that studies measure serum 25(OH)D concentration every 2-4 y.

Low serum vitamin D is associated with increased mortality in elderly men: MrOS Sweden

In elderly man, low serum 25-hydroxyvitamin D (25(OH)D) was associated with a substantial excess risk of death compared to 25(OH)D values greater than 50-70 nmol/l, but the association attenuated with time.

INTRODUCTION

The aim of the present study was to determine whether poor vitamin D status was associated with an increase in the risk of death in elderly men.

METHODS

We studied the relationship between serum 25(OH)D and the risk of death in 2,878 elderly men drawn from the population and recruited to the MrOS study in Sweden. Baseline data included general health and lifestyle measures and serum 25(OH)D measured by competitive RIA. Men were followed for up to 8.2 years (average 6.0 years).

RESULTS

Mortality adjusted for comorbidities decreased by 5% for each SD increase in 25(OH)D overall (gradient of risk 1.05; 95% confidence interval 0.96-1.14). The predictive value of 25(OH)D for death was greatest below a threshold value of 50-70 nmol/l, was greatest at approximately 3 years after baseline and thereafter decreased with time.

CONCLUSIONS

Low serum 25(OH)D is associated with a substantial excess risk of death compared to 25(OH)D values greater than 50-70 nmol/l, but the association attenuates with time. These findings, if causally related, have important implications for intervention in elderly men.

Determinants of vitamin D status in a general population of Danish adults

BACKGROUND AND AIMS

Danish legislation regarding food fortification has been very restrictive and vitamin D deficiency is thought to be common in Denmark due to inadequate dietary intakes and the fact that in Denmark (latitude 56°N) vitamin D is only synthesized in the skin after exposure to solar radiation during summertime (April-September). The purpose of this study was to evaluate the vitamin D status of a general adult population in Denmark and, in addition, associations between vitamin D status and distinct lifestyle factors were studied.

METHODS

A random sample of 6784 persons from a general population aged 30-60 years participated in a health examination in 1999-2001. Serum samples from all participants were stored and levels of 25-hydroxyvitamin D (25(OH)D) were measured by HPLC in 2009. The method was compared to another HPLC method. Information on dietary intake of vitamin D and other lifestyle factors were obtained by questionnaires. A total of 6146 persons defined as ethnic Danes and with successful measurements of 25(OH)D were included in the analyses.

RESULTS

The overall prevalence of vitamin D deficiency (25(OH)D<25 nmol/l) and insufficiency (25(OH)D<50 nmol/l) were 13.8% and 52.2%, respectively. A marked seasonal fluctuation was seen in serum levels of 25(OH)D - median values of 25(OH)D were lowest in February and highest in August. In multiple logistic regression models (n=5506), low vitamin D status was significantly associated with obesity (BMI≥30), daily smoking and a sedentary lifestyle. However, measurements of 25(OH)D were not associated with the estimated dietary intake of vitamin D. Comparison of two HPLC methods demonstrated considerable differences in accuracy.

DISCUSSION AND CONCLUSIONS

Our results suggest that poor vitamin D status is common among adults in a Northern European country without food fortification with vitamin D. Methodological issues are, however, of great importance when using cut-off values to define poor vitamin D status. In addition, we demonstrated that low serum levels of 25(OH)D were associated with several lifestyle factors.

Vitamin D in the new millennium

The incidence of vitamin D deficiency is rising worldwide, yet in the vast majority of patients, the condition remains undiagnosed and untreated. Current evidence overwhelmingly indicates that supplemental doses greater than 800 IU/day have beneficial effects on the musculoskeletal system, improving skeletal homeostasis, thus leading to fewer falls and fractures. Evidence is also accumulating on the beneficial effects of vitamin D on extraskeletal systems, such as improving immune health, autoimmune disorders, cancer, neuromodulation, diabetes, and metabolic syndrome. The cause-effect relationship of vitamin D deficiency with increasing incidences of nonskeletal disorders is being investigated. Published reports support the definition of sufficiency, serum levels of 25-hydroxyvitamin D [25(OH)D] greater than 30 ng/mL (75 nmol/L). To achieve this, most people need vitamin D supplementation ranging from 600 to 2000 IU/day; consumption up to of 5000 international units (IU) per day of vitamin D is reported as safe. Although light-skinned individuals need 1000 IU/day of vitamin D, elderly and dark-skinned individuals are likely to need approximately 2000 IU/day to maintain serum 25(OH)D levels greater than 30 ng/mL. Other vulnerable patients, such as the obese, those who have undergone bariatric surgery, and those with gastrointestinal malabsorption syndromes, may require higher doses of vitamin D to maintain normal serum levels and be healthy.

Serum 25-hydroxyvitamin D, transitions between frailty states, and mortality in older adults: the Invecchiare in Chianti Study

OBJECTIVES

To assess whether serum 25-hydroxyvitamin D (25(OH)D) concentrations relate to transitions between the states of robustness, prefrailty, and frailty and to mortality in older adults.

DESIGN

The Invecchiare in Chianti (InCHIANTI) Study, a prospective cohort study.

SETTING

Tuscany, Italy.

PARTICIPANTS

Adults aged 65 and older (N = 1,155).

MEASUREMENTS

Serum 25(OH)D concentrations measured at baseline; frailty state (robust, prefrail, frail) assessed at baseline and 3 and 6 years after enrollment; and vital status determined 3 and 6 years after enrollment.

RESULTS

The median (interquartile range) 25(OH)D concentration was 16.0 ng/mL (10.4-25.6 ng/mL; multiply by 2.496 to convert to nmol/L). Prefrail participants with 25(OH)D levels less than 20 ng/mL were 8.9% (95% confidence interval (CI) = 2.5-15.2%) more likely to die, 3.0% (95% CI = -5.6-14.6%) more likely to become frail, and 7.7% (95% CI = -3.5-18.7%) less likely to become robust than prefrail participants with 25(OH)D levels of 20 ng/mL or more. In prefrail participants, each 5-ng/mL decrement of continuous 25(OH)D was associated with 1.46 times higher odds of dying (95% CI = 1.18-2.07) and 1.13 higher odds of incident frailty (95% CI = 0.90-1.39) than with recovery of robustness. Transitions from robustness or frailty were not associated with 25(OH)D levels.

CONCLUSION

Results provide evidence that prefrailty is an "at risk" state from which older adults with high 25(OH)D levels are more likely to recover than to decline, but high 25(OH)D levels were not associated with recovery from frailty. Thus, 25(OH)D levels should be investigated as a potential therapy to treat prefrailty and prevent further decline.

Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies

BACKGROUND

Low vitamin D status may increase mortality risk.

OBJECTIVE

We used nonparametric ("highest compared with lowest" categories) and parametric (>2 categories) statistical models to evaluate associations of 25-hydroxyvitamin D [25(OH)D] serum concentrations and mortality in observational studies among general populations.

DESIGN

We searched PubMed, EMBASE, Web of Science, and reference lists for relevant articles. We included studies that contained data on relative risks (RRs) for mortality for different 25(OH)D concentrations, which included a corresponding measure of uncertainty, and this yielded 14 prospective cohort studies that involved 5562 deaths out of 62,548 individuals. We applied log-transformed RRs and CIs, adjusted for the maximal number of confounding variables. In the parametric model, which is based on 11 studies and 59,231 individuals, we used the lowest quantile as the reference category.

RESULTS

For "highest compared with lowest" categories of 25(OH)D, the estimated summary RR of mortality was 0.71 (95% CI: 0.50, 0.91). In the parametric model, the estimated summary RRs (95% CI) of mortality were 0.86 (0.82, 0.91), 0.77 (0.70, 0.84), and 0.69 (0.60, 0.78) for individuals with an increase of 12.5, 25, and 50 nmol 25(OH)D serum values/L, respectively, from a median reference category of ∼27.5 nmol/L. There was, however, no significant decrease in mortality when an increase of ∼87.5 nmol/L above the reference category occurred.

CONCLUSION

Data suggest a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ∼75-87.5 nmol/L.

Vitamin D and cardiovascular disease and cancer: not too much and not too little? The need for clinical trials

Low vitamin D levels are more common in women than in men. Low vitamin D levels have been implicated in numerous disease processes including fracture risk, falls, cardiovascular disease, hypertension, diabetes mellitus and cancers. In this article we review recent evidence regarding associations between low vitamin D levels and cancers and cardiovascular disease. We also review evidence regarding associations between high vitamin D levels and vascular calcifications and pancreatic cancer. It appears that there is probably an optimal level of vitamin D that is neither too high nor too low that is required to maximize health. On going clinical trials should aid in elucidating the optimal levels of 25-hydroxyvitamin D for numerous health outcomes.

Vitamin D, cardiovascular disease and mortality

A poor vitamin D status, i.e. low serum levels of 25-hydroxyvitamin D [25(OH)D], is common in the general population. This finding is of concern not only because of the classic vitamin D effects on musculoskeletal outcomes, but also because expression of the vitamin D receptor (VDR) and vitamin D metabolizing enzymes in the heart and blood vessels suggests a role of vitamin D in the cardiovascular system. VDR-knockout mice suffer from cardiovascular disease (CVD), and various experimental studies suggest cardiovascular protection by vitamin D, including antiatherosclerotic, anti-inflammatory and direct cardio-protective actions, beneficial effects on classic cardiovascular risk factors as well as suppression of parathyroid hormone (PTH) levels. In epidemiological studies, low levels of 25(OH)D are associated with increased risk of CVD and mortality. Data from randomized controlled trials (RCTs) are sparse and have partially, but not consistently, shown some beneficial effects of vitamin D supplementation on cardiovascular risk factors (e.g. arterial hypertension). We have insufficient data on vitamin D effects on cardiovascular events, but meta-analyses of RCTs indicate that vitamin D may modestly reduce all-cause mortality. Despite accumulating data suggesting that a sufficient vitamin D status may protect against CVD, we still must wait for results of large-scale RCTs before raising general recommendations for vitamin D in the prevention and treatment of CVD. In current clinical practice, the overall risks and costs of vitamin D supplementation should be weighed against the potential adverse consequences of untreated vitamin D deficiency.

Increased telomerase activity and vitamin D supplementation in overweight African Americans

OBJECTIVE

We aimed to investigate whether vitamin D supplementation modulates peripheral blood mononuclear cell (PBMC) telomerase activity in overweight African Americans.

DESIGN

A double blind, randomized and placebo-controlled clinical trial (#NCT01141192) was recently conducted.

SUBJECTS AND METHODS

African-American adults were randomly assigned to either the placebo, or the vitamin D group (60,000 IU per month (equivalent to ~2000 IU per day) oral vitamin D3 supplementation). Fresh PBMCs were collected from 37 subjects (18 in the placebo group and 19 in the vitamin D group), both at baseline and 16 weeks. PBMC telomerase activity was measured by the telomeric repeat amplification protocol.

RESULTS

Serum 25 hydroxyvitamin D levels increased from 40.7±15.7 at baseline to 48.1±17.5 nmol l(-1) at posttest (P=0.004) in the placebo group, and from 35.4±11.3 at baseline to 103.7±31.5 nmol l(-1) at posttests (P<0.0001) in the vitamin D group. In the vitamin D group, PBMC telomerase activity increased by 19.2% from baseline (1.56±0.29 absorbance reading unit (AU)) to posttest (1.86±0.42 AU, P<0.0001). The significance persisted after controlling for age, sex and body mass index (P=0.039). PBMC telomerase activity in the placebo group did not change from baseline (1.43±0.26 AU) to posttest (1.46±0.27 AU, P=0.157).

CONCLUSION

Vitamin D supplementation significantly increased PBMC telomerase activity in overweight African Americans. Our data suggest that vitamin D may improve telomere maintenance and prevent cell senescence and counteract obesity-induced acceleration of cellular aging.

Vitamin D status and risk of cardiovascular events: lessons learned via systematic review and meta-analysis

Accumulating data linking hypovitaminosis D to cardiovascular (CV) events has contributed to large increases in vitamin D testing and supplementation. To evaluate the merits of this practice, we conducted a systematic review with meta-analysis providing a framework for interpreting the literature associating hypovitaminosis D with increased CV events. Prospective studies were identified by search of MEDLINE and EMBASE from inception to January 2010, restricted to English language publications. Two authors independently extracted data and graded study quality. Pooled relative risks (RR) were calculated using a random effects model. Ten studies met criteria for review and 7 were included in meta-analysis. Pooled RR for CV events using FAIR and GOOD quality studies was 1.67 (95% confidence interval, 1.23-2.28) during an average follow-up of 11.8 years. There was evidence of significant heterogeneity across studies (Q statistics = 16.6, P = 0.01, I = 63.8%), which was eliminated after omitting 2 studies identified by sensitivity analysis (RR, 1.34 [1.08-1.67]; P for heterogeneity =0.33). When restricting analysis to GOOD quality studies (RR, 1.27 [1.04-1.56]), no significant heterogeneity was found (P = 0.602). Systematic review identified significant shortcomings in the literature, including variability in defining vitamin D status, seasonal adjustments, defining and determining CV outcomes, and the use of baseline vitamin D levels. In conclusion, a modest increased risk of CV events associated with hypovitaminosis D is tempered by significant limitations within the current literature. These findings underscore the importance of critical appraisal of the literature, looking beyond reported risk estimates before translating results into clinical practice.

Coronary heart disease prevention: nutrients, foods, and dietary patterns

Diet is a key modifiable risk factor in the prevention and risk reduction of coronary heart disease (CHD). Results from the Seven Countries Study in the early 1970s spurred an interest in the role of single nutrients such as total fat in CHD risk. With accumulating evidence, we have moved away from a focus on total fat to the importance of considering the quality of fat. Recent meta-analyses of intervention studies confirm the beneficial effects of replacing saturated fat with polyunsaturated fatty acids on CHD risk. Scientific evidence for a detrimental role of trans fat intake from industrial sources on CHD risk has led to important policy changes including listing trans fatty acid content on the "Nutrition Facts" panel and banning the use of trans fatty acids in food service establishments in some cities. The effects of such policy changes on changes in CHD incidence are yet to be evaluated. There has been a surging interest in the protective effects of vitamin D in primary prevention. Yet, its associations with secondary events have been mixed and intervention studies are needed to clarify its role in CHD prevention. Epidemiological and clinical trial evidence surrounding the benefit of B vitamins and antioxidants such as carotenoids, vitamin E, and vitamin C, have been contradictory. While pharmacological supplementation of these vitamins in populations with existing CHD has been ineffective and, in some cases, even detrimental, data repeatedly show that consumption of a healthy dietary pattern has considerable cardioprotective effects for primary prevention. Results from these studies and the general ineffectiveness of nutrient-based interventions have shifted interest to the role of foods in CHD risk reduction. The strongest and most consistent protective associations are seen with fruit and vegetables, fish, and whole grains. Epidemiological and clinical trial data also show risk reduction with moderate alcohol consumption. In the past decade, there has been a paradigm shift in nutritional epidemiology to examine associations between dietary patterns and health. Several epidemiological studies show that people following the Mediterranean style diet or the Dietary Approaches to Stop Hypertension (DASH) diet have lower risk of CHD and lower likelihood of developing hypertension. Studies using empirical or data driven dietary patterns have frequently identified two patterns - "Healthy or Prudent" and "Western". In general, the "Healthy", compared to the "Western" pattern has been associated with more favorable biological profiles, slower progression of atherosclerosis, and reduced incidence. Evidence on changes in dietary patterns and changes in CHD risk is still emerging. With the emergence of the concept of personalized nutrition, studies are increasingly considering the role of genetic factors in the modulation of the association between nutrients and CHD. More studies of genetic variation and dietary patterns in relation to CHD are needed.

Shining D' light on chronic kidney disease: mechanisms that may underpin the cardiovascular benefit of vitamin D

Hypovitaminosis D is a significant health-care burden worldwide, particularly in susceptible populations such as those with chronic kidney disease (CKD). Recent epidemiological studies have identified that both higher serum vitamin D concentrations and use of vitamin D supplements may confer a survival benefit both in terms of all-cause and cardiovascular mortality. There is potential to investigate this inexpensive therapy for the CKD population, which suffers excessive cardiovascular events, although the mechanisms explaining this link have yet to be fully elucidated. This review discusses potential mechanisms identified in the basic science literature that may provide important insights into how vitamin D may orchestrate a change in cardiovascular risk profile through such diverse mechanisms as inflammation, atherogenesis, glucose homeostasis, vascular calcification, renin-angiotensin regulation and alterations in cardiac physiology. Where available, the clinical translation of these concepts to intervention trials in the CKD population will be reviewed.

Vitamin D, cognitive dysfunction and dementia in older adults

The physiologically active form of vitamin D, 1,25-dihydroxyvitamin D(3), is a fat-soluble steroid hormone with a well established role in skeletal health. A growing body of evidence suggests low vitamin D levels also play a role in the pathogenesis of a wide range of non-skeletal, age-associated diseases including cancer, heart disease, type 2 diabetes mellitus and stroke. Low levels of serum 25-hydroxyvitamin D [25(OH)D], a stable marker of vitamin D status, are also associated with increased odds of prevalent cognitive dysfunction, Alzheimer's disease and all-cause dementia in a number of studies, raising the possibility that vitamin D plays a role in the aetiology of cognitive dysfunction and dementia. To date, the majority of human studies reporting associations between vitamin D and cognition or dementia have been cross-sectional or case-control designs that do not permit us to exclude the possibility that such associations are a result of disease progression rather than being causal. Animal and in vitro experiments have identified a number of neuroprotective mechanisms that might link vitamin D status to cognitive dysfunction and dementia, including vasoprotection and amyloid phagocytosis and clearance, but the clinical relevance of these mechanisms in humans is not currently clear. Two recent, large, prospective studies go some way to establish the temporal relationship with cognitive decline. The relative risk of cognitive decline was 60% higher (relative risk = 1.6, 95% CI 1.2, 2.0) in elderly Italian adults with severely deficient 25(OH)D levels (<25 nmol/L) when compared with those with sufficient levels (≥75 nmol/L). Similarly, the odds of cognitive decline were 41% higher (odds ratio = 1.4, 95% CI 0.9, 2.2) when elderly US men in the lowest quartile (≤49.7 nmol/L) were compared with those in the highest quartile (≥74.4 nmol/L). To our knowledge, no prospective studies have examined the association between 25(OH)D levels and incident dementia or neuroimaging abnormalities. The possible therapeutic benefits of vitamin D have attracted considerable interest as over 1 billion people worldwide are thought to have insufficient 25(OH)D levels and these levels can be increased using inexpensive and well tolerated dietary supplements. However, no large randomized controlled trials have yet examined the effect of vitamin D supplements on cognitive decline or incident dementia. Further studies are urgently needed to establish which mechanisms have clinical relevance in human populations and whether vitamin D supplements are effective at minimizing cognitive decline or preventing dementia.

Vitamin D: epidemiology of cardiovascular risks and events

Vitamin D may influence blood pressure through the renin-angiotensin system, parathyroid hormone levels, myocardial function, inflammation, and vascular calcification. In the past several years, a number of high-quality prospective studies have examined 25(OH)vitamin D (25(OH)D) levels in relation to risk of cardiovascular disease (CVD). Studies consistently show that levels of 25(OH)D below 20-25 ng/mL are associated with an increased risk of CVD incidence or mortality. Risk appears especially elevated at 25(OH)D levels below 10 or 15 ng/mL. It is unclear if levels higher that 25 ng/mL provide further benefits for CVD disease. Currently, results from randomized clinical trials are sparse and do not allow a definitive conclusion. Given other potential benefits of vitamin D, and low potential for toxicity, deficient levels below 25-30 ng/mL should be avoided and treated when identified. Further observational and randomized clinical trial data are important to better characterize the optimal range for 25(OH)D.

The prevalence of vitamin D deficiency and relationship with fracture risk in older women presenting in Australian general practice

AIM

To investigate vitamin D status among older women and to explore relationships between vitamin D and fracture risk and vertebral fractures.

METHODS

A total of 267 general practitioners recruited 2466 women aged >70 years with no known osteoporosis or fragility fracture. Serum 25-hydroxy vitamin D (25(OH)D), bone mineral density by dual-energy X-ray absorptiometry (DXA) and vertebral fracture on thoracolumbar X-ray were determined.

RESULTS

A total of 2368 women, median age 76 years, provided data and of these 13% were on vitamin D supplements. 25(OH)D levels were available for 907 (44.1%) of those not taking vitamin D. 88.3% of these had a level below 75 nmol/L. Serum 25(OH)D was negatively associated with age (P = 0.003) and body mass index (P < 0.001), and positively associated with lower latitude, femoral neck DXA T-score (P = 0.044) and being Caucasian (P < 0.001).

CONCLUSIONS

The vitamin D status of community-dwelling older Australian women is inadequate, yet the use of supplements is low.