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Effects of tocotrienols supplementation on markers of inflammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials.

ABSTRACT: Studies investigating the effects of tocotrienols on inflammation and oxidative stress have yielded inconsistent results. This systematic review and meta-analysis aimed to evaluate the effects of tocotrienols supplementation on inflammatory and oxidative stress biomarkers. We searched PubMed, Scopus, and Cochrane Central Register of Controlled Trials from inception until 13 July 2020 to identify randomized controlled trials supplementing tocotrienols and reporting circulating inflammatory or oxidative stress outcomes. Weighted mean difference (WMD) and corresponding 95% confidence interval (CI) were determined by pooling eligible studies. Nineteen studies were included for qualitative analysis, and 13 studies were included for the meta-analyses. A significant reduction in C-reactive protein levels (WMD: -0.52 mg/L, 95% CI: -0.73, -0.32, p < 0.001) following tocotrienols supplementation was observed, but this finding was attributed to a single study using δ-tocotrienols, not mixed tocotrienols. There were no effects on interleukin-6 (WMD: 0.03 pg/mL, 95% CI: -1.51, 1.58, p = 0.966), tumor necrosis factor-alpha (WMD: -0.28 pg/mL, 95% CI: -1.24, 0.68, p = 0.571), and malondialdehyde (WMD: -0.42 μmol/L, 95% CI: -1.05, 0.21, p = 0.189). A subgroup analysis suggested that tocotrienols at 400 mg/day might reduce malondialdehyde levels (WMD: -0.90 μmol/L, 95% CI: -1.20, -0.59, p < 0.001). Future well-designed studies are warranted to confirm the effects of tocotrienols on inflammatory and oxidative stress biomarkers, particularly on different types and dosages of supplementation. PROSPERO registration number: CRD42020198241.

SUBMITTER: Khor BH

PROVIDER: S-EPMC8301652 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PURPOSE:The role of oxidative stress in pathogenesis of diabetes is well established. In addition, an association between gut microbiota and type 2 diabetes mellitus (T2DM) is widely observed in previously published reports. This meta-analysis critically examines the association between gut microbiota, and oxidative stress in T2DM. METHODS:A systematic search for clinical trials was performed in PubMed, Web of Science and Scopus web databases up to 1 Jan 2019. Primary search terms include "microbiota", "diabetes", and "oxidative stress". Study was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline. All clinical trials that compared the effects of probiotic supplementations with a control group using end points serum levels of fasting blood sugar (FBS), hemoglobin A1C (HbA1C) and oxidative stress biomarkers were included. Two independent researchers screened the data extracted from the relevant studies. The pooled standardized mean difference (SMD) was estimated using the random or fixed effects model. Heterogeneity among the studies was assessed using Q-test. RESULTS:Overall, 13 randomized clinical trials (RCTs) involving 840 subjects with T2DM were included in the meta-analysis. The analysis showed that probiotics intake resulted in significant improvement in serum levels of FBS [SMD: -0.35, 95% CI: (-0.59, -0.12)], total antioxidant status (TAS) [SMD: 0.33, 95% CI: (0.11, 0.55)], total glutathione (GSH) [SMD: 0.41, 95% CI: (0.26, 0.56)] and malondialdehyde (MDA) [SMD: -0.54, 95% CI: (-0.83, -0.26)]. No significant improvement was found in HbA1C [SMD: -0.06, 95% CI:(-0.82, 0.69)], and nitric oxide (NO) [SMD:-0.24, 95% CI:(-1.10, 0.62)] levels. CONCLUSION:It seems that gut microbiota can exert beneficial effects in diabetic patients via altering oxidative stress' biomarkers. The beneficial effect of gut microbiota however was modest on FBS and non-significant on HbA1C. These results need to be confirmed by conducting more reliable RCTs. PROSPERO REGISTRATION NUMBER:CRD42019134905. Graphical abstract Flow diagram of the study selection process.

Project description:To determine the efficacy of calcium supplementation in reducing the recurrence of colorectal adenomas.We conducted a systematic review and meta-analysis of published studies. We searched PubMed, Scopus, the Cochrane Library, the WHO International Clinical Trials Registry Platform, and the ClinicalTrials.gov website, through December 2015. Randomized, placebo-controlled trials assessing supplemental calcium intake for the prevention of recurrence of adenomas were eligible for inclusion. Two reviewers independently selected studies based on predefined criteria, extracted data and outcomes (recurrence of colorectal adenomas, and advanced or "high-risk" adenomas), and rated each trial's risk-of-bias. Between-study heterogeneity was assessed, and pooled risk ratio (RR) estimates with their 95% confidence intervals (95%CI) were calculated using fixed- and random-effects models. To express the treatment effect in clinical terms, we calculated the number needed to treat (NNT) to prevent one adenoma recurrence. We also assessed the quality of evidence using GRADE.Four randomized, placebo-controlled trials met the eligibility criteria and were included. Daily doses of elemental calcium ranged from 1200 to 2000 mg, while the duration of treatment and follow-up of participants ranged from 36 to 60 mo. Synthesis of intention-to-treat data, for participants who had undergone follow-up colonoscopies, indicated a modest protective effect of calcium in prevention of adenomas (fixed-effects, RR = 0.89, 95%CI: 0.82-0.96; random-effects, RR = 0.87, 95%CI: 0.77-0.98; high quality of evidence). The NNT was 20 (95%CI: 12-61) to prevent one colorectal adenoma recurrence within a period of 3 to 5 years. On the other hand, the association between calcium treatment and advanced adenomas did not reach statistical significance (fixed-effects, RR = 0.92, 95%CI: 0.75-1.13; random-effects, RR = 0.92, 95%CI: 0.71-1.18; moderate quality of evidence).Our results suggest a modest chemopreventive effect of calcium supplements against recurrent colorectal adenomas over a period of 36 to 60 mo. Further research is warranted.

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Effects of tocotrienols supplementation on markers of inflammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials.

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