Effect of soluble fiber on blood pressure in adults: a systematic review and dose-response meta-analysis of randomized controlled trials.

OBJECTIVES: Pervious epidemiologic evidence indicates that soluble fiber is protective against hypertention: however, randomized controlled trials (RCTs) have presented varying results. In the present study, we aimed to conduct a systematic review and dose-response meta-analysis to summarize published RCTs which assess the effect of soluble fiber supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP). METHODS: Scopus, PubMed, and ISI Web of Sciences were searched to identify relevant studies up to Aug 2022. We estimated the change in blood pressure for each 5 g/d increment in soluble fiber supplementation in each trial and then calculated the weighted mean difference (WMD) and 95%CI using a random-effects model. We estimated dose-dependent effects using a dose-response meta-analysis of differences in means. The risk of bias for study was assessed using the Cochrane tool. Publication bias was evaluated via funnel plot and Begg's test and Egger's test. RESULTS: Eighty-three eligible studies with total sample size of 5,985 participants were included in the meta-analysis. Soluble fiber supplementation significantly decreased SBP (WMD: -1.36 mmHg, 95% CI: -2.13 to -0.60, P < 0.001; I2 = 47.1%, P < 0.001) and DBP (WMD: -0.72 mmHg, 95% CI: -1.26 to -0.18, P = 0.009; I2 = 45.4%, P < 0.001). Each 5 g/d increment in soluble fiber supplementation had a significant reduction in SBP (WMD: -0.54 mmHg; 95%CI: -0.86, -0.22, P = 0.001; I2 = 52.2, Phet < 0.001) and DBP (WMD: -0.28 mmHg; 95%CI: -0.49, -0.80, P = 0.007; I2 = 43.1%, Phet < 0.001). The levels of SBP decreased proportionally with the increase in soluble fiber supplementation up to 20 g/d (MD20g/d: -1.79 mmHg, 95%CI: -2.86, -0.71). CONCLUSION: Current evidence indicated the beneficial effect of soluble fiber supplementation on blood pressure. Our findings suggest that soluble fiber supplementation could contribute to the management of hypertension and the reduction of cardiovascular disease risk.

Soluble Fiber Supplementation and Serum Lipid Profile: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials.

To present a comprehensive synthesis of the effect of soluble fiber supplementation on blood lipid parameters in adults, a systematic search was undertaken in PubMed, Scopus, and ISI Web of Science of relevant articles published before November 2021. Randomized controlled trials (RCTs) evaluating the effects of soluble fibers on blood lipids in adults were included. We estimated the change in blood lipids for each 5 g/d increment in soluble fiber supplementation in each trial and then calculated the mean difference (MD) and 95% CI using a random-effects model. We estimated dose-dependent effects using a dose-response meta-analysis of differences in means. The risk of bias and certainty of the evidence was evaluated using the Cochrane risk of bias tool and the Grading Recommendations Assessment, Development, and Evaluation methodology, respectively. A total of 181 RCTs with 220 treatment arms (14,505 participants: 7348 cases and 7157 controls) were included. There was a significant reduction in LDL cholesterol (MD: -8.28 mg/dL, 95% CI: -11.38, -5.18), total cholesterol (TC) (MD: -10.82 mg/dL, 95% CI: -12.98, -8.67), TGs (MD: -5.55 mg/dL, 95% CI: -10.31, -0.79), and apolipoprotein B (Apo-B) (MD: -44.99 mg/L, 95% CI: -62.87, -27.12) after soluble fiber supplementation in the overall analysis. Each 5 g/d increase in soluble fiber supplementation had a significant reduction in TC (MD: -6.11 mg/dL, 95% CI: -7.61, -4.61) and LDL cholesterol (MD: -5.57 mg/dl, 95% CI: -7.44, -3.69). In a large meta-analysis of RCTs, results suggest that soluble fiber supplementation could contribute to the management of dyslipidemia and the reduction of cardiovascular disease risk.

Effects of inulin-type fructans with different degrees of polymerization on inflammation, oxidative stress and endothelial dysfunction in women with polycystic ovary syndrome: A randomized, double-blind, placebo-controlled trial.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is associated with several cardiovascular risk factors. Prebiotics were proposed to beneficially affect risk factors associated with metabolic disorders. The aim of this study was to investigate and compare the effects of inulin-type fructans (ITFs), as well-studied prebiotics, with different degrees of polymerization, on markers of inflammation, oxidative stress and endothelial dysfunction in PCOS patients. DESIGN: A randomized, double-blind, placebo-controlled trial. PATIENTS: Seventy-five PCOS women were randomly assigned to receive 10 g/day of either high-performance inulin (HPI) or oligofructose-enriched inulin (OEI) or placebo for 12 weeks. MEASUREMENTS: Biochemical indices and blood pressure levelswere assessed before and after the intervention. RESULTS: In the intent-to-treat analysis, high-sensitive C-reactive protein (hs-CRP) decreased in HPI and OEI groups, over the 12 weeks, and the changes were significant in the HPI group, compared to placebo (changes from baseline in the HPI group: -0.11 vs. placebo group: 0.004 mg/L [conversion factor to SI units (nmol/L): 9/5238]; p = .007). Serum levels of nitric oxide (NO) increased, and endothelin-1 and total oxidant status decreased in HPI and OEI groups, at the end of the trial; however, these changes were not significantly compared to placebo (p = .07, .36 and .22, respectively). No differences in systolic and diastolic blood pressure were found. Per-protocol analysis (n = 68) yielded consistent results for all endpoints, with the exception that the significant effect of ITFs on serum hs-CRP levels in the unadjusted ITT analysis became nonsignificant in the per-protocol analysis (p = .06). CONCLUSION: A 12-week supplementation with long-chain ITFs had favourable effects on inflammatory status among PCOS patients.

Biological and pharmacological effects and nutritional impact of phytosterols: A comprehensive review.

Phytosterols (PSs), classified into plant sterols and stanols, are bioactive compounds found in foods of plant origin. PSs have been proposed to exert a wide number of pharmacological properties, including the potential to reduce total and low-density lipoprotein (LDL) cholesterol levels and thereby decreasing the risk of cardiovascular diseases. Other health-promoting effects of PSs include anti-obesity, anti-diabetic, anti-microbial, anti-inflammatory, and immunomodulatory effects. Also, anticancer effects have been strongly suggested, as phytosterol-rich diets may reduce the risk of cancer by 20%. The aim of this review is to provide a general overview of the available evidence regarding the beneficial physiological and pharmacological activities of PSs, with special emphasis on their therapeutic potential for human health and safety. Also, we will explore the factors that influence the physiologic response to PSs.

What is the Impact of Cinnamon Supplementation on Blood Pressure? A Systematic Review and Meta-Analysis.

AIM: This study was designed to make a systematic review and meta-analysis on randomized controlled trials (RCTs) assessing the effect of cinnamon on blood pressure (BP). METHODS: A systematic computerized literature search of PubMed, Scopus, Web of Science, Cochrane Library and Google Scholar databases was conducted up to August 2019. All RCTs using cinnamon supplements in adults were included in this systematic review and meta-analysis. RESULTS: Out of 927 records, 8 trials that enrolled 582 participants were included. The pooled effect size showed that SBP did not change following cinnamon supplementation. (WMD: -0.61mmHg; 95% CI: -1.36, 0.14, P= 0.111). Also cinnamon supplementation in long-duration (≥ 8weeks) had a significant effect on SBP (WMD: -1.25 mmHg; 95% CI: -2.22, -0.28, P= 0.012). Pooled analysis showed that cinnamon had a significant effect on DBP (WMD: -0.93mmHg, 95% CI: -1.55 to -0.32, P= 0.003). In addition, results from both duration subsets and high dose (>1500 mg/day) of cinnamon supplementation were significant. CONCLUSION: Our findings revealed that cinnamon supplementation has favorable effects on DBP although results of SBP were not the same. Nonetheless, further studies are required.

The effect of pomegranate (Punica granatum) supplementation on metabolic status in patients with type 2 diabetes: A systematic review and meta-analysis.

OBJECTIVE: Several randomized controlled clinical trials (RCTs) have investigated the effect of pomegranate (Punica granatum) supplementation in patients with type 2 diabetes mellitus (T2DM), with conflicting results. Therefore, the present study assessed the effect of pomegranate on metabolic status and oxidative stress in patients with T2DM. METHODS: A comprehensive search was conducted in Pubmed, EMBASE, ISI web of science, Cochrane library and Scopus databases until April 2020, to identify RCTs investigating the effect of pomegranate supplementation on glycemic markers (fasting blood glucose (FBG), homeostasis model assessment-estimated insulin resistance index (HOMA-IR), glycosylated hemoglobin percentage (HbA1c) and insulin levels), anthropometric indices (body mass index (BMI) and body weight (BW)), blood lipids (triglycerides (TG), total cholesterol (TC), high lipoprotein cholesterol (HDL-C) and low lipoprotein cholesterol (LDL-C)), inflammatory markers (high sensitive c-reactive protein (Hs-CRP)) and markers of oxidative stress (total antioxidant capacity (TAC)) in adults with T2DM. Mean difference was pooled using a random-effects model. RESULTS: Seven trials, comprising 350 participants, were included in the present systematic review and meta-analysis. The results of the meta-analysis revealed that pomegranate supplementation did not have any significant effects on metabolic status and oxidative stress biomarkers of subjects with T2DM. There were no evidence of publication bias regarding to selected outcomes. CONCLUSION: There were no significant favorable effects of pomegranate supplementation on metabolic parameters in patients with T2DM. Future well-designed, large scale RCTs, with longer duration are needed in this field.

Benefits and harms of ginseng supplementation on liver function? A systematic review and meta-analysis.

OBJECTIVE: Existing evidence on the possible effects of ginseng on liver function has not been fully established. Therefore, the present review was undertaken to evaluate the overall effects of ginseng supplementation on liver enzymes in adults. METHODS: A systematic computerized literature search of PubMed, Scopus, Web of Science, Cochrane Library and Google scholar databases was conducted up to May 2019. All RCTs using ginseng supplements in adults were included in this systematic review and meta-analysis. RESULTS: Overall, 14 randomized trials (with 20 arms) including 992 subjects were identified. Pooled analysis did not illustrate any significant changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and albumin (ALB) levels, however, it showed a minor significant increase in bilirubin (BIL) levels. Subgroup analysis by dosage and study population revealed significant increase of bilirubin after ginseng supplementation ≥3 g/day or in unhealthy individuals. CONCLUSION: Ginseng appears to have neither hepatoprotective nor hepatotoxic effects in conventional doses and duration. It is noteworthy that this seems applicable only for individuals with healthy liver function. Further largescale studies are warranted to confirm present findings.

Impact of flaxseed supplementation on plasma lipoprotein(a) concentrations: A systematic review and meta-analysis of randomized controlled trials.

The aim of the study was to investigate the impact of supplementation with flaxseed on plasma lipoprotein(a) [Lp(a)] levels through a systematic review and meta-analysis of eligible randomized placebo-controlled trials. PubMed, Scopus, Cochrane Library, and ISI Web of Science were searched for randomized controlled trials (RCTs) which have been published up to November 2019. RCTs that investigated the effect of flaxseed supplementation on plasma Lp(a) levels in adults were included for final analysis. The random effects model was used for calculating the overall effects. Meta-analysis of 7 selected RCTs with 629 individuals showed significant lowering effect of flaxseed supplementation on Lp(a) (MD -2.06 mg/dl; 95% CI: -3.846, -0.274, p = .024), without considerable heterogeneity between studies (p = .986, I2 = 0%). Subgroup analysis also revealed that longer duration only showed significant lowering effect of flaxseed supplementation on Lp(a). This meta-analysis has shown that flaxseed supplementation might significantly decrease plasma Lp(a) levels. Future well-designed and long-term clinical trials are required to confirm these results.

The efficacy of ginseng supplementation on plasma lipid concentration in adults: A systematic review and meta-analysis.

OBJECTIVE: We performed a meta-analysis to evaluate the efficacy of ginseng supplementation on plasma lipid concentration. METHODS: The search included PubMed, Scopus, ISI Web of Science, Cochrane library, and Google Scholar (up to April 2019) to identify randomized controlled trials (RCTs) investigating the effect of ginseng supplementation on serum lipid parameters. To estimate the overall summary effect, we used random-effects model. RESULTS: Twenty-seven studies comprising 35 treatment arms comprising 1245 participants fulfilled the inclusion criteria. The meta-analysis results showed that consumption of ginseng did not significantly change the concentrations of total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C), and high density lipoprotein-cholesterol (HDL-C). However, subgroup analyses showed a significant lowering effect in high dose ginseng supplementation on TC, LDL-C and TG. Also, the impact of ginseng on TC and TG was significant in long-term interventions. CONCLUSION: Further RCTs with longer supplementation durations in subjects with dyslipidemia are necessitated for a more robust assessment of the lipid-modulating properties of this plant.

Effects of phytosterols supplementation on blood pressure: A systematic review and meta-analysis.

Several reports have indicated a positive effect of phytosterols on blood pressure (BP), nevertheless these findings have been controversial. Therefore, a systematic review and meta-analysis of randomized controlled trials (RCTs) was aimed to investigate the effects of phytosterol supplementation on BP. An online search was carried out in PubMed, Scopus, ISI Web of Science, Cochrane library and Google Scholar up to May 2019. Weighted Mean difference (WMD) with 95% confidence intervals (CIs) were calculated using a fixed-effects model. The present meta-analysis of 19 RCTs showed that supplementation with phytosterols can decrease both systolic BP (WMD: -1.55 mmHg, 95% CI: -2.67 to -0.42, p = 0.007) and diastolic BP (WMD: -0.84 mmHg, 95% CI: -1.60 to -0.08, p = 0.03). Dose-response analysis revealed that phytosterol intake change SBP significantly based on treatment dose in nonlinear fashion. Subgroup analysis based on duration showed a significant effect of phytosterol on SBP and DBP in subsets of <12 weeks. In addition, a significant effect of phytosterol was observed in dosage of ≥2000 mg for SBP and <2000 mg for DBP. Based on current findings supplementation with phytosterol may be a beneficial adjuvant therapy in hypertensive patients as well as a complementary preventive option in prehypertensive and normotensive individuals. However, this issue is still open and requires further investigation in future studies.

The effect of nettle (Urtica dioica) supplementation on the glycemic control of patients with type 2 diabetes mellitus: A systematic review and meta-analysis.

Type 2 diabetes mellitus (T2DM) is a major health problem, worldwide, that is associated with increased morbidity and mortality. Several randomized controlled clinical trials (RCTs) have investigated the effect of nettle (Urtica dioica) supplementation on markers of glycemic status in patients with T2DM, with conflicting results. Therefore, the present study assessed the effect of nettle on some glycemic parameters in patients with T2DM. A comprehensive search was conducted in PubMed, Scopus, Cochrane Library, and Web of Science, from database inception up to June 2019, to identify RCTs investigating the effect of nettle supplementation on glycemic markers, including fasting blood sugar (FBS) concentrations, insulin levels, homeostasis model assessment-estimated insulin resistance index, and glycosylated hemoglobin percentage in adults with T2DM. The Cochrane Collaboration tool was used to assess the methodological quality of the included studies. Results of this meta-analysis were reported based on the random effects model. Eight RCTs, comprising 401 participants, were included in the present systematic review and meta-analysis. Based on the Cochrane Collaboration risk of bias tool, five studies were considered as good quality, one was fair, and two studies were poor, respectively. The results of the meta-analysis revealed a significant reduction in FBS concentrations (weighted mean difference [WMD]: -18.01 mg/dl, 95% confidence interval [CI]: -30.04 to -5.97, p < .001, I2 = 94.6%) following nettle supplementation. However, no significant reduction was observed in insulin levels (WMD: 0.83 Hedges' g, 95% CI: -0.26 to 1.92, p = .13, I2 = 89.4%), homeostasis model assessment-estimated insulin resistance index (WMD: -0.22, 95% CI: -0.83 to 0.40, p = .49, I2 = 69.2%), or glycosylated hemoglobin percentage (WMD: -0.77%, 95% CI: -1.77 to 0.22, p = .12, I2 = 83.0%). The findings of the present study suggest that nettle supplementation may be effective in controlling FBS for T2DM patients. However, further studies are needed to confirm the veracity of these results.

Effects of Coenzyme Q10 Supplementation on Anthropometric Indices in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Obesity is related to increase in the incidence of morbidity and mortality. Previous studies have led to conflicting results regarding the effect of coenzyme Q10 (CoQ10) supplementation on anthropometric indices. This study aimed to evaluate the efficacy of CoQ10 supplementation on body weight, body mass index (BMI), and waist circumference (WC) through a systematic review and meta-analysis of randomized controlled trials (RCTs). METHODS: PubMed, Scopus, Web of Science, and Cochrane Library as well as the reference lists of the identified relevant RCTs were searched up to March 2019, and weighted mean differences (WMDs) were pooled by using the random-effects model. RESULTS: Twenty RCTs (976 participants) were eligible to be included in the systematic review. The meta-analysis revealed that CoQ10 supplementation had no effect on body weight (WMD = -0.04 kg; 95% confidence interval [CI]: -1.96, 1.6; I 2 = 0.0%), BMI (WMD = -0.06 kg/m2; 95% CI: -0.54, 0.42; I 2 = 0.0%), and WC (WMD = 0.79 cm; 95% CI: -2.83, 0.04; I 2 = 0.0%). CONCLUSIONS: CoQ10 supplementation might not improve anthropometric indices. Future well-designed trials are still needed to confirm these results.

Effects of Spirulina supplementation on obesity: A systematic review and meta-analysis of randomized clinical trials.

OBJECTIVE: Evidence has suggested that Spirulina supplementation may affect anthropometric indices. Therefore, a systematic review and meta-analysis was performed to summarize published randomized clinical trials which assess the effect of Spirulina supplementation on obesity. SETTING: Pertinent studies were identified using Embase, Scopus, ISI Web of Science, PubMed and Cochrane library databases up to May 2019. Mean Differences (MD) were pooled using a random-effects model. Heterogeneity, sensitivity analysis and publication bias were reported using standard methods. RESULTS: Results of 5 studies (7 treatment arms) showed a significant reduction in weight (MD: -1.56 Kg, 95% CI: -1.98 to -1.14) after Spirulina supplementation. Subgroup analysis based on health status revealed that weight change in obese subjects (MD: -2.06 Kg, 95% CI: -2.45 to -1.68) was greater than overweight participants (MD: -1.28 Kg, 95% CI: -1.62 to -0.93) following Spirulina supplementation. Also, pooled analysis showed that Spirulina supplementation led to a significant reduction in body fat percent (MD: -1.02, 95% CI: -1.49 to -0.54) and waist circumference (MD: -1.40, 95% CI: -1.40 to -1.39), but not in body mass index and waist to hip ratio. CONCLUSION: Spirulina supplementation significantly reduces body weight, especially in obese individuals.