The association between plasma 25-hydroxyvitamin D3 concentrations, C-reactive protein levels, and coronary artery atherosclerosis in postmenopausal monkeys

Uncoupling proteins: are they involved in vitamin D3 protective effect against high-fat diet-induced cardiac apoptosis in rats?

This study aimed to assess the impact of high-fat diet (HFD) and vitamin D3 supplementation on cardiac apoptosis, inflammation, oxidative stress, and cardiac uncoupling proteins (UCPs) 2&3 expression. Forty rats were fed either (45%) or (10%) fat diet with or without vitamin D3 (500 U/kg/day) for 6 months, then cardiac tissue expression of Bax, Bcl2, Fas, Fas-L (markers for apoptotic pathways), TNF-α, MDA7, GPX1 (inflammatory and oxidative markers) and UCP 2&3 were assessed. Results revealed the enhancement of intrinsic and extrinsic cardiomyocyte apoptosis cascades and increased inflammatory and oxidative burdens on the heart in HFD rats. Downregulation of UCP2 and upregulation of UCP3 gene expression at 6 months. After vitamin D3 supplementation with HFD, cardiac apoptotic, inflammatory and oxidative markers were mitigated and expression of UCP3 was downregulated and UCP2 was upregulated. This work highlights the novel cardioprotective effect of vitamin D3 in the experimental model of HFD feeding through the downregulation of UCP3.

Assessment of the Relationship between Serum Vitamin D and Osteocalcin Levels with Metabolic Syndrome in Non-Osteoporotic Postmenopausal Women

Introduction The aim of this study was to compare serum vitamin D and osteocalcin levels in non-osteoporotic postmenopausal women with and without metabolic syndrome and to analyze the relationship between serum vitamin D and osteocalcin levels and the relationships between these two factors and other clinical/biochemical parameters.

Material and Method This cross-sectional study was carried out in 191 postmenopausal non-osteoporotic (T-score > − 2.5) women. Patients were divided into two groups according to the presence or absence of metabolic syndrome. Blood samples were obtained and evaluated for 25-hydroxyvitamin D, osteocalcin, insulin resistance (using a homeostatic model assessment of insulin resistance), glycosylated hemoglobin (HbA _1c ), calcium, phosphorus, deoxypyridinoline, thyroid-stimulating hormone, lipid profile, fasting insulin, fasting glucose and HbA _1c levels. Demographic and laboratory parameters were recorded for each woman.

Results Vitamin D was found to be lower in women with metabolic syndrome compared to controls (16.1 ± 11.2 vs. 20.4 ± 13.1 mg/dL; p = 0.013). Similarly, osteocalcin was found to be significantly lower in the metabolic syndrome group compared to the control group (4.2 ± 2.1 vs. 5.5 ± 3.0; p < 0.001). A significant positive correlation was observed between vitamin D and osteocalcin levels (r = 0.198; p = 0.008). There was an inverse correlation between vitamin D and some of the lipid parameters. However, osteocalcin levels were negatively correlated with C-reactive protein, insulin resistance, and HbA _1c in both groups (p = 0.003, p = 0.001 and p = 0.048, respectively).

Conclusion Vitamin D deficiency is common in postmenopausal women, even in women who are non-osteoporotic. Serum levels of vitamin D are significantly decreased in cases with metabolic syndrome. Vitamin D may directly improve serum lipid profiles and may indirectly decrease insulin resistance and subclinical systemic inflammation through the impact on the metabolic functions of osteocalcin.

Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data

BACKGROUND

A large number of observational studies have reported harmful effects of low 25-hydroxyvitamin D (25OHD) levels on non-skeletal outcomes. We performed a systematic quantitative review on characteristics of randomized clinical trials (RCTs) included in meta-analyses (MAs) on non-skeletal effects of vitamin D supplementation.

METHODS AND FINDINGS

We identified systematic reviews (SR) reporting summary data in terms of MAs of RCTs on selected non-skeletal outcomes. For each outcome, we summarized the results from available SRs and scrutinized included RCTs for a number of predefined characteristics. We identified 54 SRs including data from 210 RCTs. Most MAs as well as the individual RCTs reported null-findings on risk of cardiovascular diseases, type 2 diabetes, weight-loss, and malignant diseases. Beneficial effects of vitamin D supplementation was reported in 1 of 4 MAs on depression, 2 of 9 MAs on blood pressure, 3 of 7 MAs on respiratory tract infections, and 8 of 12 MAs on mortality. Most RCTs have primarily been performed to determine skeletal outcomes, whereas non-skeletal effects have been assessed as secondary outcomes. Only one-third of the RCTs had low level of 25OHD as a criterion for inclusion and a mean baseline 25OHD level below 50 nmol/L was only present in less than half of the analyses.

CONCLUSIONS

Published RCTs have mostly been performed in populations without low 25OHD levels. The fact that most MAs on results from RCTs did not show a beneficial effect does not disprove the hypothesis suggested by observational findings on adverse health outcomes of low 25OHD levels.

Vitamin D and cardiovascular disease: an appraisal of the evidence

BACKGROUND

Supplementation with vitamin D has received attention as a potential cardioprotective strategy. Biologically plausible mechanisms have been proposed to link vitamin D to coronary heart disease (CHD) prevention, and observational studies suggest an inverse association between serum 25-hydroxyvitamin D (25OHD) concentrations and CHD. Few randomized clinical trials of vitamin D supplementation and CHD have been conducted, however, and no trial with CHD as the primary prespecified outcome has been completed.

CONTENT

A search was conducted in PubMed to find prospective studies of the use of vitamin D supplementation and its relationship to cardiovascular risk factors (RFs) and/or cardiovascular disease (CVD). The exact search query was: ((vitamin D supplement*[Title/Abstract]) AND cardiovascular [Title/Abstract]) AND prospective [Title/Abstract]. This query yielded 42 results. "Randomized Controlled Trial" (article type) was used as a filter in a subsequent query with the same search terms. We review the evidence that vitamin D supplementation modifies coronary RFs, such as blood pressure, lipids, glucose tolerance, and/or affects the development of clinical CHD events. We address potential sources of confounding in observational epidemiologic studies of the relationship between serum 25OHD and CHD. We also address laboratory assay issues relevant to the reliable measurement of 25OHD.

SUMMARY

Most vitamin D supplementation trials have not demonstrated improvement in CVD, but they have tested relatively low vitamin D doses. Thus, the evidence remains inconclusive, highlighting the need for rigorous randomized trials of higher vitamin D doses with cardiovascular events as prespecified outcomes. While we await the results of ongoing trials, the recommended dietary allowances from the Institute of Medicine remain the best guidepost for nutritional requirements.

C-reactive protein, vitamin D deficiency, and slow gait speed

OBJECTIVES

To evaluate the independent and joint effects of C-reactive protein (CRP) and 25-OH vitamin D (25(OH)D) levels on mobility disability in older persons.

DESIGN

U.S. population-based cross-sectional study.

SETTING

National Health and Nutrition Examination Surveys (2001-2002).

PARTICIPANTS

Individuals aged 50 and older (N = 1,826).

MEASUREMENTS

C-reactive protein (mg/dL), with high CRP defined as ≥ 0.2 mg/dL, and 25(OH)D levels (ng/mL) operationalized as severe deficiency (<10 ng/mL), deficiency (10-19.9 ng/mL), insufficiency (20-29.9 ng/mL), and normal (≥ 30 ng/mL). Mobility disability was operationalized as gait speed of <0.8 m/s while completing a 20-foot walk (6.1 m).

RESULTS

High CRP and low 25(OH)D levels were associated with slow gait speed. Individuals with high CRP levels and severe vitamin D deficiency were more likely to have slow gait speed than were those with neither risk factor (odds ratio = 3.54, 95% confidence interval = 1.42-8.84, P = .007). A significant positive association between vitamin D level and gait speed was found only in those with high CRP in stratified analyses. Whites and blacks showed similar findings as the overall population.

CONCLUSION

These findings provide evidence of a potential joint effect of vitamin D and CRP on gait speed, suggesting that evaluation and correction of vitamin D levels may be especially important in individuals with high CRP levels.