The effect of vitamin D2 supplementation on vitamin D levels in humans: A time and dose-response meta-analysis of randomized controlled trials.

BACKGROUND: Inconsistencies exist regarding the influence of vitamin D2 (ergocalciferol) supplementation on serum vitamin D levels. These inconsistencies could be attributed to numerous factors, such as dosage, baseline vitamin D levels, and duration of intervention. Hence, this dose-response meta-analysis of randomized controlled trials was conducted to assess the efficacy of vitamin D2 supplementation on vitamin D levels. METHODS: Relevant studies were searched in PubMed/Medline, Web of Science, Embase, and Scopus, from their inception to 3 January 2023. Variable alterations were considered to calculate the pooled weighted mean difference (WMD) with 95% confidence interval (CI) using the random effects model. RESULTS: Pooled results from 33 study arms demonstrated that Vitamin D2 treatment significantly increases total vitamin D concentrations (WMD: 11.47 ng/mL, 95 %CI: 9.29 to 13.64, p < 0.001), 25(OH)D2 concentrations (WMD: 11.40 ng/mL, 95 %CI: 4.72 to 18.09, p = 0.001), and 1,25(OH)D concentrations (WMD: 5.61 ng/mL, 95 %CI: 0.74 to 10.48, p = 0.024), but decreases 25(OH)D3 concentrations (WMD: -4.63 ng/mL, 95 %CI: -6.46 to -2.81, p < 0.001). In subgroup analyses, increase in total vitamin D concentrations was more significant in vitamin D2 doses >2000 IU/day (WMD: 13.82 ng/mL), studies with duration ≤12 weeks (WMD: 12.53 ng/mL), participants aged ≥60 years (WMD: 14.40 ng/mL), and trials with basal 25(OH)D concentrations <20 ng/mL (WMD: 11.47 ng/mL). CONCLUSIONS: This meta-analysis indicates that the supplementation of vitamin D2 significantly increases the serum concentrations of total vitamin D, 25(OH)D2, and 1,25(OH)D, but decreases 25(OH)D3 concentrations. Careful consideration of patient characteristics, dosage, and treatment duration is recommended for vitamin D2 supplementation.

The Effects of Vitamin D Supplementation on C-Reactive Protein and Systolic and Diastolic Blood Pressure in Postmenopausal Women: A Meta-Analysis and Systematic Review of Randomized Controlled Trials.

BACKGROUND: An inverse relationship between vitamin D supplementation and C-reactive protein (CRP) and hypertension has been reported, mostly through observational data. This inverse relationship, however, has not been confirmed in randomized controlled trials (RCTs). A meta-analysis of RCTs is needed to provide more robust evidence. OBJECTIVE: This systematic review of RCTs was conducted to assess the effect of vitamin D supplementation on CRP, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in postmenopausal women. METHODS: Four databases (PubMed, Web of Science, Embase, and Scopus) were systemically searched to identify relevant RCTs published in international scientific journals up to January 2023. Changes from baseline and SDs of CRP, SBP, and DBP were compared between postmenopausal women who received vitamin D supplementation and those who did not (controls). These parameters were applied to compute the overall effect sizes using the random-effects model. Data were summarized as mean difference (MD) with 95% CI. Heterogeneity among arms was scrutinized using the Cochrane's Q test and I2 statistic. Publication bias was judged by means of funnel plots and Egger's test. RESULTS: Seven studies with 6 arms on CRP, 6 arms on SBP, and 6 arms on DBP were included in the meta-analysis. Combined effect sizes suggested a significant effect of vitamin D supplementation on CRP (MD = -0.65 mg/L; 95% CI -0.93 to -0.37 mg/L; P < .001). In addition, CRP concentrations were significantly reduced after vitamin D supplementation in studies with a duration of more than 3 months (MD = -0.91 mg/L; 95% CI -1.37 to -0.45 mg/L; P < .001) and studies involving doses of ≤1,000 IU/d (MD = -2.10 mg/L; 95% CI -2.51 to -1.68 mg/L; P < .001). Vitamin D supplementation did not reduce SBP significantly (MD = -1.06 mm Hg; 95% CI -2.43 to 0.30 mm Hg; P = .127) and DBP (MD = 0.003 mm Hg; 95% CI -0.86 to 0.86 mm Hg; P = .994) levels compared with control groups. CONCLUSIONS: This meta-analysis concluded that vitamin D supplementation is associated with reduced CRP concentrations among postmenopausal women.

The impact of medroxyprogesterone acetate on lipid profiles in Women: A time and dose-response meta-analysis of randomized controlled trials.

BACKGROUND: The effect of MPA on the lipid profile and CVD risk is still controversial; hence, this comprehensive dose-response meta-analysis of randomized controlled trials was conducted to assess the effect of MPA on lipid profiles in women. METHODS: A comprehensive search was conducted in the following databases: Web of Science, Scopus, PubMed/Medline, and Embase, up to October 20, 2023. A random-effects meta-analysis approach based on the DerSimonian and Laird method was used to compute the combined estimates of the intervention's impact on the lipid profile. RESULTS: 35 eligible studies with 58 arms were included in our meta-analyses analysis. Combined effect sizes suggested a significant effect of MPA on total cholesterol (TC) levels (WMD: -3.43 mg/dL, 95 % CI: -5.38 to -1.48, p < 0.001), HDL-C levels (WMD: -3.34 mg/dL, 95 % CI: -3.77 to -2.91, p < 0.001), and triglyceride (TG) levels (WMD: -9.13 mg/dL, 95 % CI: -10.92 to -7.33, p < 0.001). The subgroup meta-analysis revealed a more substantial reduction in TC in studies with dosages > 2.5 mg/day (WMD: -4.10 mg/dL), mean participant age lower than 60 years (WMD: -3.80 mg/dL), mean BMI lower than 25 kg/m2 (WMD: -5.61 mg/dL), duration of intervention of 12 months or more (WMD: -3.98 mg/dL), and when the baseline TC value was equal to or greater than 200 mg/dL (WMD: -4.13 mg/dL). CONCLUSIONS: The current meta-analysis showed a statistically significant decrease in TC, TG, and HDL-C levels and a non-significant increase in LDL-C levels after MPA administration in women.

The effect of green coffee extract supplementation on obesity indices: critical umbrella review of interventional meta-analyses.

Despite a multitude of investigations assessing the impact of green coffee extract supplementation on obesity indices, there is still a great deal of heated debate regarding the benefits of this intervention in obesity management. Therefore, in order to clarify the effect of green coffee extract on waist circumference (WC), body mass index (BMI) and body weight (BW), we conducted an umbrella review of interventional meta-analyses. The Web of Science, Scopus, PubMed/Medline, and Embase databases were searched using specific keywords and word combinations. The umbrella meta-analysis was performed using the Stata software version 17 (Stata Corp. College Station, Texas, USA). We pooled effect sizes (ES) and confidence intervals (CI) for the outcomes using the random effects model (the DerSimonian and Laird method). In total, 5 eligible meta-analyses were included in the final quantitative assessment. Data pooled from 5 eligible papers revealed that green coffee extract can reduce BW (WMD: -1.22 kg, 95% CI: -1.53 to -0.92, p < 0.001), BMI (WMD: -0.48 kg/m2, 95% CI: -0.67 to -0.29, p < 0.001) and WC (WMD: -0.55 cm, 95% CI: -0.80 to -0.31, p < 0.001). Subgroup analyses highlighted that green coffee extract supplementation in dosages ≤600 mg/day and interventions lasting >7 wk are more likely to decrease BW. The present umbrella meta-analysis confirms the beneficial effects of green coffee extract in reducing WC, BMI, and BW. Thus, we may infer that green coffee extract can be used as a complementary therapy in the management of obesity.

Does Omega-3 Fatty Acid Supplementation Have Favorable Effects on the Lipid Profile in Postmenopausal Women? A Systematic Review and Dose-response Meta-analysis of Randomized Controlled Trials.

PURPOSE: Menopause is associated with disturbances in the metabolism of lipids. Moreover, during the postmenopausal period, female subjects are more prone to develop dyslipidemia. Omega-3 fatty acids, which exert cardioprotective, anti-inflammatory, and lipid-lowering actions, are commonly recommended in postmenopausal women. However, their effect on serum lipids in this population remains unclear. This systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to clarify this research question. METHODS: We systematically searched the Web of Science, Scopus, PubMed/MEDLINE, and EMBASE databases from their inception until January 3, 2022. The DerSimonian and Laird random-effects model was used to combine effect sizes. FINDINGS: Omega-3 fatty acid supplementation resulted in a decrease in triglyceride concentrations (weighted mean difference [WMD], -17.8 mg/dL; 95% CI, -26 to -9.6; P < 0.001), particularly in the RCTs that lasted ≤16 weeks (WMD, -18.6 mg/dL), when the baseline triglyceride concentrations were ≥150 mg/dL (WMD, -22.8 mg/dL), in individuals with a body mass index ≥30 kg/m2 (WMD, -19.3 mg/dL), and when the dose of omega-3 fatty acids was ≥1 g/d (WMD, -21.10 mg/dL). LDL-C (WMD, 4.1 mg/dL; 95% CI, 1.80 to 6.36; P < 0.001) and HDL-C (WMD, 2.1 mg/dL; 95% CI, 0.97 to 3.2; P < 0.001) values increased. Total cholesterol levels (WMD, -0.15 mg/dL; 95% CI, -4 to 3.74; P = 0.94) remained unchanged after administration of omega-3 fatty acids. IMPLICATIONS: In postmenopausal women, supplementation with omega-3 fatty acids resulted in a significant reduction in triglyceride concentrations and a modest elevation in HDL-C and LDL-C levels, whereas this intervention did not affect total cholesterol values.

Comparing the effects of docosahexaenoic and eicosapentaenoic acids on cardiovascular risk factors: Pairwise and network meta-analyses of randomized controlled trials.

BACKGROUND: Evidence from clinical trial studies suggests that docosahexaenoic acids (DHA) may have greater potential effects on improving cardiovascular risk factors than eicosapentaenoic acid (EPA). However, this evidence has not yet been meta-analyzed and quantified. The aim of this study was to evaluate and compare the effect of DHA and EPA monotherapy on cardiovascular risk factors based on paired and network meta-analysis. METHODS: Relevant articles published up to January 2022 were systematically retrieved from relevant databases. We included all Randomized Controlled Trials (RCTs) on adults that directly compared the effects of DHA with EPA and RCTs of indirect comparisons (DHA and EPA monotherapy compared to control groups). Data were pooled by pairwise and network meta-analysis and expressed as mean differences (MDs) with 95% CIs. The study protocol was registered with PROSPERO (Registration ID: CRD42022328630). RESULTS: Network meta-analysis of comparisons of DHA and EPA suggested significant comparable effects only on LDL-C (MD EPA versus DHA = -8.51 mg/L; 95% CI: -16.67; -0.35). However, the Network meta-analysis not show a significant effect for other risk factors. Furthermore, pairwise meta-analysis of direct comparisons of DHA and EPA showed significant difference in their effects on plasma glucose (MD EPA versus DHA = -0.31 mg/L; 95% CI: -0.60, -0.02), Insulin (MD EPA versus DHA = -2.14 mg/L; 95% CI: -3.26, -1.02), but the results were not significant for risk factors. CONCLUSION: Our findings suggest that both EPA and DHA act similarly on the markers under study, with slight changes in plasma glucose, insulin, and LDL-C.

Wheat germ improves hepatic steatosis, hepatic enzymes, and metabolic and inflammatory parameters in patients with nonalcoholic fatty liver disease: A randomized, placebo-controlled, double-blind clinical trial.

Globally, Non-alcoholic fatty liver disease (NAFLD) has a rising prevalence with no definitive pharmacological treatments. The aim of this study was to assess the clinical effects of wheat germ in patients with NAFLD. Fifty participants with NAFLD were randomly allocated to take 40 g wheat germ (n = 25) or placebo (n = 25) in a randomized double-blind clinical trial over 12 weeks. Transient elastography (FibroScan) determined a diagnosis of NAFLD. After 12 weeks of intervention, reduction in serum alanine aminotransferase (p = 0.006) and γ-glutamyltransferase (p = 0.004), total cholesterol (p = 0.018), triglyceride (p = 0.046), and hepatic steatosis (p = 0.043) levels in the wheat germ group was significantly higher compared to the placebo group. Serum TAC levels in wheat germ group patients increased significantly higher than placebo group (p = 0.001). Reduction in serum hs-CRP level in the wheat germ group was significantly higher than in the placebo group (p = 0.031). In conclusion, our study shows that wheat germ consumption may improve total antioxidant capacity, hepatic steatosis, serum total cholesterol and triglyceride levels, alanine aminotransferase (ALT), and Gamma-glutamyl Transferase (GGT) in NAFLD patients. Longitudinal studies with larger sample sizes are needed to confirm biological effects of wheat germ on NAFLD patients.

The influence of omega-3 supplementation on vitamin D levels in humans: a systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND: Inconsistencies exist with regard to the influence of omega-3 supplementation on 25-hydroxyvitamin D (25(OH)D) levels, which could be attributed to many factors, such as the duration and dose of omega-3 supplementation, and individuals' baseline 25(OH)D levels. Therefore, to address the inconsistencies, we conducted a systematic review and dose-response meta-analysis to accurately determine the effect of omega-3 supplementation on 25(OH)D levels in humans. METHODS: We performed a comprehensive literature search in Web of Science, PubMed/Medline, Scopus, and Embase databases from inception up to January 2020. We included only randomized controlled trials (RCTs). We used weighted mean difference (WMD) with 95% confidence interval (CI) to assess the influence of omega-3 supplementation on serum 25(OH)D levels using the random-effects model. RESULTS: Our pooled results of 10 RCTs demonstrated an overall significant increase in 25(OH)D levels following omega-3 intake (WMD = 3.77 ng/ml, 95% CI: 1.29, 6.25). In addition, 25(OH)D levels were significantly increased when the intervention duration lasted >8 weeks and when the baseline serum 25(OH)D level was ˂20 ng/ml. Moreover, omega-3 intake ≤1000 mg/day resulted in higher 25(OH)D levels compared to omega-3 intake >1000 mg/day. CONCLUSION: In conclusion, omega-3 supplementation increased 25(OH)D concentrations, particularly with dosages ≤1000 mg/day and intervention durations >8 weeks.

Effects of dehydroepiandrosterone (DHEA) supplementation on cortisol, leptin, adiponectin, and liver enzyme levels: A systematic review and meta-analysis of randomised clinical trials.

BACKGROUND AND AIMS: Dehydroepiandrosterone (DHEA) supplementation has been investigated in patients with altered cortisol levels and is proposed to ameliorate the metabolic profile related to adipose tissue. However, further research is warranted and evidence is no compelling for liver safety. Hence, we aimed to meta-analyse the effects of DHEA supplementation on circulating levels of cortisol, liver enzymes, and adipokines. METHODS: We searched literature published in PubMed, Web of Science, Embase and Scopus, until December 2020. We obtained overall results using the generic inverse of variance method with a random-effects model. RESULTS: Through 10 arms, serum cortisol levels decreased significantly after DHEA supplementation [weighted mean difference (WMD): -53.581 nmol/L, 95% confidence interval (CI): -88.2, -18.9, P = .002], without significant heterogeneity (I2  = 36%, P = .117). In contrast, any significance was noted for adiponectin (WMD: -0.045 µg/mL, 95% CI: -0.56, 0.47; P = .865), leptin (WMD: -2.55 µg/mL, 95% CI: -6.2, 1.06; P = .166), aspartate transaminase (AST) (WMD: -3.7 U/L, 95% CI: -10.35, 2.95; P = .276), and alanine aminotransferase (ALT) (WMD: -1.7 U/L, 95% CI: -3.45, 0.06; P = .058). CONCLUSION: DHEA supplementation decreased circulating cortisol but did not alter adiponectin, leptin, AST, and ALT levels. Hence, DHEA supplementation could be considered as an adjunct in the management of hypercortisolaemia and is safe for the liver.

Clinical efficacy of zinc supplementation in improving antioxidant defense system: A comprehensive systematic review and time-response meta-analysis of controlled clinical trials.

Oxidative stress is a contributing factor to many chronic diseases. It has been investigated that zinc (Zn) may enhance the antioxidant defense. The current dose-response and time-response meta-analysis aims to determine the efficacy of Zn supplementation in improving antioxidant defense. Scopus, PubMed/Medline, Web of Science, and Embase databases were searched systematically up to December 30, 2020. Meta-analysis was performed on human controlled clinical trials using random effects method. To find any source of heterogeneity, subgroup analysis and meta-regression were performed. Trim and fill analysis was used for adjusting the publication bias. To find any non-linear relationship between variables and effect size, dose-response and time-response analyses were performed. Cochrane Collaboration's tool was used for evaluating the quality assessment. A total of 23 controlled clinical trials were analyzed. The range of Zn supplementation duration in various studies was within 4-24 weeks. Zn supplementation did not have beneficial effects on glutathione peroxidase (GPx) activity (SMD = -0.34 U/g; 95% CI: -0.93, 0.25; P = 0.258). There were significant increasing effects of Zn supplementation on glutathione (GSH) (SMD = 1.28 µmol/l; 95% CI: 0.42, 2.14; P = 0.003) and total antioxidant capacity (TAC) levels (SMD = 1.39 mmol/l; 95% CI: 0.44, 2.35; P = 0.004). Zn had ameliorative effects on superoxide dismutase (SOD) activity after elimination of publication bias (SMD: 0.84 U/g; 95% CI: 0.12, 1.56, P < 0.05). Zn could also elevate GSH and TAC levels, plus SOD activity after modifying the publication bias. Finally, Zn had no significant effect on GPx activity.

Trends in Serum Vitamin D Levels within 12 Months after One Anastomosis Gastric Bypass (OAGB).

PURPOSE: To assess serum vitamin D trend from baseline to 12 months after one anastomosis gastric bypass (OAGB). MATERIALS AND METHODS: In this observational cohort analysis of longitudinal data, we assessed the trend of serum vitamin D, and its associations with anthropometric, and biochemical measurements in 98 patients undergoing OAGB in a bariatric surgery center. All participants were on >800 IU/day vitamin D supplementation. RESULTS: Vitamin D, lipid profile, creatinine, and albumin levels significantly improved at 12 months post-surgery. Vitamin D concentrations significantly increased from 26.52 ± 12.32 to 54.52 ± 27.90 ng/mL at 12 months. The correlations between vitamin D concentrations and weight, body mass index, lipid profile, ferritin, glycemic indices, and albumin were not significant. In addition, the correlations between vitamin D and parathormone, vitamin D receptor, calcium, phosphorus, body composition, and basal metabolic rate (BMR) did not reach the threshold of statistical significance at 12 months following bariatric surgery. Although there was a significant correlation between body weight and body composition (P < 0.001) and basal metabolic rate (BMR) (r = 0.762, P < 0.001) at 12 months, there were no significant correlations between weight change percent and body composition (P > 0.05), BMR (r = -0.101, P = 0.350), and vitamin D (r = 0.120, P = 0.271) at 12 months. CONCLUSION: Our results showed that supplementation of vitamin D with dosage of >800 IU/day is sufficient for prevention of vitamin D deficiency within 12 months after OAGB surgery. Note: This data is mandatory.

Association between abnormal maternal serum levels of vitamin B12 and preeclampsia: a systematic review and meta-analysis.

CONTEXT: Some evidence has shown an association between maternal vitamin B12 levels and the development of preeclampsia in pregnant women, but the relationship between preeclampsia and vitamin B12 is not clear. OBJECTIVE: The aim of this systematic review was to compare serum vitamin B12 levels in women with preeclampsia with those in normotensive pregnant women. DATA SOURCES: The PubMed/MEDLINE, Scopus, and Web of Science databases were searched up to August 2019, along with the reference lists of included articles. STUDY SELECTION: The literature was searched for observational studies that investigated vitamin B12 levels in women with preeclampsia. DATA EXTRACTION: Data were extracted independently by 2 authors. Data were pooled using a random-effects model. RESULTS: Vitamin B12 levels in women with preeclampsia were significantly lower than those in healthy women (mean, -15.24 pg/mL; 95%CI, -27.52 to -2.954; P < 0.015), but heterogeneity between studies was high (I2 = 97.8%; P = 0.0103). Subgroup analyses based on folic acid supplementation, homocysteine concentrations, and gestational age at the time of sampling for vitamin B12 assessment did not identify the sources of heterogeneity. CONCLUSIONS: Women with preeclampsia had significantly lower vitamin B12 concentrations than normotensive pregnant women.

Effects of intermittent fasting diets on plasma concentrations of inflammatory biomarkers: A systematic review and meta-analysis of randomized controlled trials.

Intermittent fasting (IF) and energy-restricted diets (ERDs) have emerged as dietary approaches to decrease inflammatory status; however, there are no consistent results regarding humans. To achieve a comprehensive conclusion, we aimed to conduct a meta-analysis of randomized control trials (RCTs) to evaluate the effects of IF or ERDs on plasma concentrations of inflammatory biomarkers. We systematically searched online medical databases including Web of Sciences, PubMed, SCOPUS, and Google Scholar up to June 2019. Evaluations of effect sizes were described employing in weighted mean difference and 95% confidence intervals from the random-effects model. Eighteen eligible RCTs were included in this meta-analysis. The pooled estimation from the random-effect model showed that IF regimens and ERDs significantly reduced C-reactive protein (CRP) concentrations (WMD: -0.024 mg/dL; 95% CI: -0.044 to -0.005, I2 = 7.0%). Additionally, IF regimens (WMD: -0.029; 95% CI: -0.058 to -0.000, I2 = 17.9%) were more effective in reducing CRP levels than ERDs (WMD: -0.001 mg/dL; 95% CI: -0.037 to 0.034, I2 = 0.0%). Moreover, based on the treatment duration and types of the studies' population, a greater reduction was observed in overweight and obese individuals (WMD: -0.03 mg/dL; 95% CI: -0.05 to 0.01, I2 = 42.1%), and in treatment duration ≥8 wk (WMD: -0.03 mg/dL; 95% CI: -0.05 to 0.01, I2 = 0.0%) as well. However, IF and ERDs did not significantly reduced tumor necrosis factor-α (WMD: -0.158 pg/mL; P = 0.549, I2 = 98.3) and interleukin-6 (IL-6) concentrations (WMD: -0.541 pg/mL; P = 0.080, I2 = 94.7%). This meta-analysis demonstrated that IF regimens and ERDs may reduce CRP concentrations, particularly in overweight and obese individuals and through a considerable length of intervention (≥2 mo). However, neither dietary model affected the concentrations of tumor necrosis factor-α or interleukin-6.

The effects of astaxanthin supplementation on obesity, blood pressure, CRP, glycemic biomarkers, and lipid profile: A meta-analysis of randomized controlled trials.

BACKGROUND AND AIM: Previous studies lack consistent conclusions as to whether astaxanthin is actually linked to various health benefits as claimed. Here, we attempt to unravel the association of astaxanthin consumption with selected health benefits by performing a systematic review and meta-analysis. METHODS: Online literature search databases including Scopus, Web of Science, PubMed/Medline, Embase and Google Scholar were searched to discover relevant articles available up to 17 March 2020. We used mean changes and SD of the outcomes to assess treatment response from baseline and mean difference, and 95 % CI were calculated to combined data and assessment effect sizes in astaxanthin and control groups. RESULTS: 14 eligible articles were included in the final quantitative analysis. Current study revealed that astaxanthin consumption was not associated with FBS, HbA1c, TC, LDL-C, TG, BMI, BW, DBP, and SBP. We did observe an overall increase in HDL-C (WMD: 1.473 mg/dl, 95 % CI: 0.319-2.627, p = 0.012). As for the levels of CRP, only when astaxanthin was administered (i) for relatively long periods (≥ 12 weeks) (WMD: -0.528 mg/l, 95 % CI: -0.990 to -0.066), and (ii) at high dose (> 12 mg/day) (WMD: -0.389 mg/dl, 95 % CI: -0.596 to -0.183), the levels of CRP would decrease. CONCLUSION: In summary, our systematic review and meta-analysis revealed that astaxanthin consumption was associated with increase in HDL-C and decrease in CRP. Significant associations were not observed for other outcomes.

The effects of N-acetylcysteine on inflammatory and oxidative stress biomarkers: A systematic review and meta-analysis of controlled clinical trials.

Prolonged inflammation could be considered as the leading cause of chronic diseases such as cardiovascular disorders, type two diabetes, and obesity. N-acetylcysteine (NAC) is considered an antioxidant. The present meta-analysis aims to determine the efficacy of NAC in alleviating inflammation and oxidative stress. PubMed-Medline, SCOPUS, Web of Science and Embase databases and Google Scholar were searched up to Nov 2019. Random effect analysis was used to perform meta-analysis. Subgroup analyses were carried out to find heterogeneity sources. Meta-regression analysis was used to explore linear relationship between effect size and variables. Trim and fill analysis were performed in case of the presence of publication bias. Quality assessment was performed using Cochrane Collaboration's tool. A total of 28 studies were included in meta-analysis. NAC significantly decreased malondialdehyde (MDA) (SMD = -1.44 µmol/L; 95% CI: -2.05, -0.84; P < 0.001), IL-8 (WMD = -2.56 pg/ml; 95% CI: -3.89, -1.23; P < 0.001) and homocysteine (WMD = -1.45 pg/ml; 95% CI: -2.74, -0.17; P = 0.027) levels. There were no significant effects of NAC supplementation on CRP (SMD = -0.1 g/L; 95% CI: -0.52, 0.32; P = 0.647), TNF- α (WMD = -0.2 pg/ml; 95% CI: -0.65, 0.25; P = 0.378) and IL-6 (WMD = -0.41 pg/ml; 95% CI: -1.15, 0.32; P = 0.270) levels. However, NAC effects were significant in ameliorating TNF-α and IL-6 using sensitivity analysis. NAC significantly decreased MDA, IL-8, and homocysteine levels. The effects of NAC on amending TNF-α and IL-6 levels were significant after sensitivity analysis. No significant change was observed on CRP levels.

Effect of evening primrose oil supplementation on lipid profile: A systematic review and meta-analysis of randomized clinical trials.

BACKGROUND: Studies have shown that evening primrose oil (EPO) supplementation might be effective in improving lipid profile, however, the results are inconsistent. This study was performed to determine the direction and magnitude of the EPO effect on the lipid profile. METHODS: PubMed, Scopus, Cochrane Library, Embase and Web of Science databases and Google Scholar were searched up to September-2019. Meta-analysis was performed using the random-effects model. Lipid profile including high-density lipoprotein (HDL), total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) was considered as the primary outcome. RESULTS: A total of 926 articles were identified through database searching, of which, six RCTs were included in the meta-analysis. There were six studies on HDL, TC, and TG and four studies on LDL. EPO supplementation had no significant effect on TC, TG, LDL, and HDL. However, in subgroup analysis, a significant reduction in TG at a dose of ≤4 g/day (weighted mean difference [WMD] = -37.28 mg/dl; 95% CI: -73.53 to -1.03, p = .044) and a significant increase in HDL in hyperlipidemic subjects (WMD = 5.468 mg/dl; 95% CI: 1.323 to 9.614, p = .010) was found. CONCLUSION: Oral intake of EPO at a dose of ≤4 g/day significantly reduces serum TG levels and significantly increases HDL levels in hyperlipidemic subjects.

The effect of resistance training on serum insulin-like growth factor 1(IGF-1): A systematic review and meta-analysis.

BACKGROUND: Data about the effects of resistance exercise on level of IGF-1 in the serum are conflicting. To resolve this inconsistency, we performed a systematic review and meta-analysis to precisely examine the effects of resistance exercise on the levels of serum IGF-1. METHODS: PubMed, Scopus, Web of Science, and Embase databases were systematically searched from their inceptions until 10 December 2019 for randomized controlled trials (RCTs) comparing individuals who underwent resistance training and control participants. We applied a random-effects model to calculate the weighted mean difference (WMD). RESULTS: 33 trials reported IGF-1 level as an outcome measure. The pooled estimate demonstrated a significant increase in IGF-1 (WMD: 10.34 ng/ml, 95 % CI: 4.93, 15.74, p = 0.000, I2 = 90.3 %) after resistance training compared with the control group. Subgroup analysis demonstrated that the increase in IGF-1 levels following resistance training was only statistically significant in treatment duration ≤16 weeks (WMD: 8.04 ng/ml), participants aged more than 60 years old (WMD: 9.84 ng/ml); and in women (WMD: 17.27 ng/ml). Subsequent analysis of the relationship between participants' age with plasma IGF-1 alterations revealed a U shape correlation in non-liner dose response, in which resistance training resulted in a declined IGF-1 level up to 40 years of age. Beyond 40 years old, the IGF-1 level was increased following resistance training. CONCLUSION: We have successfully demonstrated that resistance training was associated with an increased IGF-1 level among those who received the training for ≤16 weeks, among participants older than 60 years old, and among women. Further studies are warranted to clarify the mechanisms underlying the influence of resistance training on IGF-1.

Effects of walnut intake on anthropometric characteristics: A systematic review and dose-response meta-analysis of randomized controlled trials.

BACKGROUND & OBJECTIVE: Effects of walnut intake on anthropometric measurements have been inconsistent among clinical studies. Thus, we conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate and quantify the effects of walnut intake on anthropometric characteristics. METHODS: We carried out a systematic search of all available RCTs up to June 2019 in the following electronic databases: PubMed, Scopus, Web of Science and Google Scholar. Pooled weight mean difference (WMD) of the included studies was estimated using random-effects model. RESULTS: A total of 27 articles were included in this meta-analysis, with walnuts dosage ranging from 15 to 108 g/d for 2 wk to 2 y. Overall, interventions with walnut intake did not alter waist circumference (WC) (WMD: -0.193 cm, 95 % CI: -1.03, 0.64, p = 0.651), body weight (BW) (0.083 kg, 95 % CI: -0.032, 0.198, p = 0.159), body mass index (BMI) (WMD: -0.40 kg/m,295 % CI: -0.244, 0.164, p = 0.703), and fat mass (FM) (WMD: 0.28 %, 95 % CI: -0.49, 1.06, p = 0.476). Following dose-response evaluation, reduced BW (Coef.= -1.62, p = 0.001), BMI (Coef.= -1.24, p = 0.041) and WC (Coef.= -5.39, p = 0.038) were significantly observed through walnut intake up to 35 g/day. However, the number of studies can be limited as to the individual analysis of the measures through the dose-response fashion. CONCLUSIONS: Overall, results from this meta-analysis suggest that interventions with walnut intake does not alter BW, BMI, FM, and WC. To date, there is no discernible evidence to support walnut intake for improving anthropometric indicators of weight loss.