Effect of vitamin D supplementation on cardiac-metabolic risk factors in elderly: a systematic review and meta-analysis of clinical trials.

BACKGROUND: There has been a longstanding interest in the potential effect of vitamin D in preventing cardiac-metabolic diseases. However, there are divergent results regarding the impact of vitamin D supplementation (VDS) on managing cardiac-metabolic outcomes in the elderly population. MATERIAL AND METHOD: We systematically searched electronic databases; Web of Science, PubMed, Scopus, EMBASE, Cochrane, and ProQuest. We included all trials that evaluated the effect of VDS on cardiac-metabolic risk factors in the elderly population, which were published until 30 September 2021. The effects of VDS on cardiac-metabolic outcomes were assessed using standardized mean difference (SMD). A random-effect model was used to pool the SMD and 95% confidence interval (CI). RESULT: The literature search identified 4409 studies, of which 12 trials met inclusion criteria. Results of random effect meta-analysis indicated a significant reduction in total cholesterol (TC) (SMD: - 0.14 mg/dl; 95% CI: - 0.25, - 0.02) and triglyceride (TG) (SMD: - 0.45 mg/dl; 95% CI: - 0.86, - 0.04) with VDS compared to the placebo. The subgroup analyses revealed that the reduction of TG in patients with diabetes and vitamin D deficiency was significant. Furthermore, short-term intervention (≤ 6 months) induced a significantly lower level of TG and insulin in comparison to longer duration (> 6 months). CONCLUSION: The study suggests that VDS could improve insulin concentration and dyslipidemia in the elderly population. The systematic review was registered in Alborz university of medical sciences with 2060-01-03-1397 number and the Ethics council IR.ABZUMS.REC.1397.207 number.

The effects of dietary selenium supplementation on inflammatory markers among patients with metabolic diseases: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: Selenium (Se) is a trace element having significant effects on human metabolism. Recent studies suggest that Se supplementation have a pivotal effect on the inflammatory markers. Therefore, the aim of this study was to assess the effect of Se supplementation on plasma inflammatory markers including C-reactive protein (CRP) and high-sensitivity C-reactive protein (hs-CRP) and nitric oxide (NO) as a stress oxidative index, among patients with metabolic diseases. METHODS: To assess the effects of Se on the inflammatory markers, following the PRISMA-P guidelines, we systematically searched ISI/WOS, PubMed/MEDLINE, and Scopus for studies that assessed the effect of Se supplementation on the inflammatory markers. Data extraction was performed by two independent investigators. Using the random effects or fixed-effects model depending on the results of heterogeneity tests was used to estimate the pooled standardized mean difference (SMD). Heterogeneity between studies was assessed using Cochran's Q test and I2 index. RESULTS: The initial search revealed 3,320 papers. After screening process and considering inclusion criteria, 7 publications were eligible for inclusion in the meta-analysis. The meta-analysis results showed that Se supplementation did not significantly affect CRP and hs-CRP concentrations (mean difference (MD) = -0.15; 95% CI: -0.55- 0.23; P = 0.43). Subgroup analysis of CRP type showed that Se supplementation significantly decreased hs-CRP level (pooled SMD = -0.44; 95% CI: -0.67-0.21). Moreover, no significant change was observed in NO level by continuing to take Se supplementation, (pooled SMD: 0.003, 95%CI: -0.26, 0.26). CONCLUSIONS: This study revealed that Se supplementation would have desirable effects on cardio-metabolic indicators through affecting the levels of inflammatory markers. Given the importance of concerns, more attention should be given to more prospective studies with longer follow-up.

Prevalence and determinants of vitamin D deficiency in Iranian children and adolescents: the CASPIAN-V study.

PURPOSE: To examine the prevalence and determinants of vitamin D deficiency in Iranian children and adolescents. METHODS: We used data from a national school-based surveillance program conducted among 7-18-year-old children and adolescents living in rural and urban areas in 30 provinces of Iran. Data on student's lifestyle, health behaviors, and health status was obtained through a validated questionnaire. Serum 25-hydroxy vitamin D (25-OH-D) level was measured by chemiluminescent immunoassay. Vitamin D deficiency was defined as serum 25-OH-D concentrations < 30 ng/ml. Determinants of vitamin D deficiency were identified using logistic regression analysis. RESULTS: Data of 2,596 participants were available for this study. Prevalence of vitamin D deficiency was 71.1 % (95 % Confidence interval (CI): 69.3-72.8 %), without significant difference between boys and girls (72.0 % vs. 70.1 %, respectively, p = 0.29). In the multivariate regression model, in both genders, those who reported having sun exposure for at least 30 min/day and those taking vitamin D supplementation had lower odds for vitamin D deficiency (all p values < 0.05). In boys, obesity increased the odds of vitamin D deficiency (adjusted OR, 95 % CI: 1.57, 1.08-2.27). The association of vitamin D deficiency with other demographic characteristics and food items was not statistically significant. CONCLUSIONS: This large population-based study revealed a high frequency of hypovitaminosis D in Iranian children and adolescents. Sun exposure for at least 30 min/day and taking vitamin D supplementation may reduce the risk of vitamin D deficiency.

Effect of glutamine supplementation on cardiometabolic risk factors and inflammatory markers: a systematic review and meta-analysis.

BACKGROUND: Evidence exists that glutamine plays multiple roles in glucose metabolism, insulin sensitivity, and anti-inflammatory effects. This systematic review and meta-analysis of controlled trials aimed to assess the effect of glutamine supplementation on cardio-metabolic risk factors and inflammatory markers. METHODS: The processes of systematic reviews and meta-analyses were performed according to the PRISMA checklist. PubMed, Web of Sciences, Cochrane library, and Scopus databases were search for relevant studies without time or language restrictions up to December 30, 2020. All randomized clinical trials which assessed the effect of glutamine supplementation on "glycemic indices", "level of triglyceride, "and "inflammatory markers" were included in the study. The effect of glutamine supplementation on cardio-metabolic risk factors and inflammatory markers was assessed using a standardized mean difference (SMD) and 95% confidence interval (CI). Heterogeneity between among studies was assessed using Cochran Q-statistic and I-square. Random/fixed-effects meta-analysis method was used to estimate the pooled SMD. The risk of bias for the included trials was evaluated using the Cochrane quality assessment tool. RESULTS: In total, 12 studies that assessed the effect of glutamine supplementation on cardio-metabolic risk factors were included in the study. Meta-analysis showed that glutamine supplementation significantly decreased significantly serum levels of FPG [SMD: - 0.73, 95% CI - 1.35, - 0.11, I2: 84.1%] and CRP [SMD: - 0.58, 95% CI - 0.1, - 0.17, I2: 0%]. The effect of glutamine supplementation on other cardiometabolic risk factors was not statistically significant (P > 0.05). CONCLUSION: Our findings showed that glutamine supplementation might have a positive effect on FPG and CRP; both of which are crucial as cardio-metabolic risk factors. However, supplementation had no significant effect on other cardio-metabolic risk factors.

The Effect of Oligopin Supplementation on Hormonal and Metabolic Profiles in the Polycystic Ovary Syndrome: A Randomized Controlled Trial.

Background: A double blind clinical trial was performed to evaluate whether the polycystic ovary syndrome (PCOS)-specific serum markers and metabolic parameters would change in the women with PCOS during the three-month administration of oligopin. Methods: In this double-blind multicenter trial, we randomly assigned 80 PCOS women, based on a 1:1 ratio, to receive oligopin (n= 40) or maltodextrin as placebo (n = 40) for up to 3 months. As PCOS-specific outcomes, we investigated the changes in testosterone, sex hormone binding globulin (SHBG), free androgen index (FAI), dehydroepiandrosterone (DHEA), follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Secondary end points were metabolic (fasting glycaemia, hemoglobin A1c (HbA1c), lipids, insulin resistance (HOMA-IR)), anthropometrics parameters and blood pressure from the baseline to the end of treatment. We investigated serum transaminase, alkaline phosphatase (ALP), creatinine (Cr) and blood urea nitrogen (BUN) levels as hepatic and kidney outcomes, respectively. Results: The first participant was enrolled on April 18, 2018, and the last study visit took place on May 14, 2019. PCOS-specific serum parameters did not change during the three-month administration of oligopin (p > 0.05), except for a small increase in the FSH levels (p=0.03). Oligopin neither changed the metabolic profile nor the anthropometric parameters or blood pressure. ALP levels was significantly increased in placebo group, as compared with oligopin (p=0.01). Conclusion: Oligopin supplementation does not seem to be exerting a beneficial effect on both hormonal and metabolic parameters in the women with PCOS. Clinical Trial Registration: www.irct.ir, identifier IRCT20140406017139N3.

Effect of selenium supplementation on glycemic indices: a meta-analysis of randomized controlled trials.

PURPOSE: The association between selenium supplementation and glycemic indices seems to be a controversial issue. This systematic review and meta-analysis was conducted to evaluate the effect of selenium supplementation on glycemic indices. METHODS: We systematically searched PubMed/MEDLINE, ISI/WOS, and Scopus (from their commencements up to Jan 2016) for relevant studies examining the association between intake of selenium and glycemic indices. The data were extracted from relevant qualified studies and estimated using the random-effect or pooled model and standardized mean difference (SMD) with 95% confidence interval (CI). RESULTS: Twelve articles published between 2004 and 2016 were included. In all the studies, the participants were randomly assigned to an intervention group (n = 757) or a control group(n = 684). All the studies were double blind, placebo controlled trials. Selenium supplementation resulted in a significant decrease in homeostasis model of assessment-estimated ß-cell function (HOMA-B) (SMD: -0.63; 95%CI: -0.89 to -0.38) and a significant increase in quantitative insulin sensitivity check index (QUICKI) (SMD: by 0.74; 95%CI: 0.49 to 0.1) as compared with the controls. There were no statistically significant improvements in glycemic indices, such as fasting plasma glucose (FPG), insulin, homeostasis model of assessment-estimated insulin resistance (HOMA-IR), Hemoglobin A1c (HbA1c) and adiponectin. CONCLUSION: This meta-analysis indicated that selenium supplementation significantly decreased HOMA-B and increased QUICKI score. There was no statistically significant improvement in FPG, insulin, HOMA-IR, HbA1c and adiponectin indices following selenium supplementation.

Effects of Selenium Supplementation on Cardiometabolic Risk Factors, Inflammatory, and Antioxidant Markers: A Systematic Review and Meta-analysis Protocol.

BACKGROUND: Selenium (Se) is considered as an antioxidant trace element involved in key activities in human metabolism. Recent investigations indicate that Se plays a pivotal role in human health. Se supplementation considered as an intervention is both cost-effective and simple-to-use that may play an important role in the prevention of cardiometabolic risk factors (CRFs), inflammatory, and antioxidant markers. METHODS: This paper is a protocol study on systematic review of probable effects of Se supplementation on CRFs, inflammatory, and antioxidant markers. The aim was to achieve three international databases available related to the current publications including, PubMed, ISI/WOS, and Scopus. We attempted to search for randomized clinical trials (RCT) and cross-over trials pertaining to human subjects without any restriction on language and time. In addition, there was no limitation on the age of participants. For RCTs were included all studies in different target groups comprising diabetic patients, patients with polycystic ovarian syndrome, obese subjects, or even healthy controls. To investigate the effect of Se, we included all studies which Se is used either as single therapy or as combination therapy. All studies associated with articles and meta-analyses would be evaluated to review their references. CONCLUSIONS: The current study contained numerous outcomes. The result of this study can be led to make reliable scientific evidence on the probable effects of Se supplementation on CRFs, inflammatory factors, and antioxidant factors. In addition to these findings, other technical documents developed for a systematic review can be used for future studies.