Effects of Phytosterols supplementation on blood glucose, glycosylated hemoglobin (HbA1c) and insulin levels in humans: a systematic review and meta-analysis of randomized controlled trials

Octadecyl and sulfonyl modification of diatomite synergistically improved the immobilization efficiency of lipase and its application in the synthesis of pine sterol esters

Phytosterols usually have to be esterified to various phytosterol esters to avoid their disadvantages of unsatisfactory solubility and low bioavailability. The enzymatic synthesis of phytosterol esters in a solvent-free system has advantages in terms of environmental friendliness, sustainability, and selectivity. However, the limitation of the low stability and recyclability of the lipase in the solvent-free system, which often requires a relatively high temperature to induce the viscosity, also increased the industrial production cost. In this context, a low-cost material, namely diatomite, was employed as the support in the immobilization of Candida rugosa lipase (CRL) due to its multiple modification sites. The Fe3 O4 was also then introduced to this system for quick and simple separation via the magnetic field. Moreover, to further enhance the immobilization efficiency of diatomite, a modification strategy which involved the octadecyl and sulfonyl group for regulating the hydrophobicity and interaction between the support and lipase was successfully developed. The optimization of the ratio of the modifiers suggested that the -SO3 H/C18 (1:1.5) performed best with an enzyme loading and enzyme activity of 84.8 mg·g-1 and 54 U·g-1 , respectively. Compared with free CRL, the thermal and storage stability of CRL@OSMD was significantly improved, which lays the foundation for the catalytic synthesis of phytosterol esters in solvent-free systems. Fortunately, a yield of 95.0% was achieved after optimizing the reaction conditions, and a yield of 70.0% can still be maintained after six cycles.

The effect of phytosterol supplementation on lipid profile: A critical umbrella review of interventional meta-analyses

Despite multiple investigations assessing the impact of phytosterol supplementation on serum lipid levels, there is still a great deal of debate regarding the benefits of this intervention in the management of dyslipidemia. Therefore, we aimed at clarifying this dilemma by conducting the present umbrella review of interventional meta-analyses. Scopus, PubMed, Web of Science, and EMBASE were used to search for pertinent publications on the effect of phytosterol supplementation on the lipid profile in humans up to June 2023. To compute the overall effect size (ES) and confidence intervals (CI), the random-effects model was used. The I2 statistic and Cochrane's Q-test were applied to estimate the heterogeneity among the studies. Seventeen meta-analyses with 23 study arms were included in the umbrella meta-analysis. Data pooled from the 23 eligible arms revealed that phytosterol supplementation reduces low-density lipoprotein cholesterol (LDL-C) (ES = -11.47 mg/dL; 95% CI: -12.76, -10.17, p < 0.001), total cholesterol (TC) (ES = -13.02 mg/dL; 95% CI: -15.68, -10.37, p < 0.001), and triglyceride (TG) (ES = -3.77 mg/dL; 95% CI: -6.04, -1.51, p = 0.001). Subgroup analyses showed that phytosterol administration with dosage ≥2 g/day and duration over 8 weeks and in hypercholesterolemic subjects was more likely to decrease LDL-C, TC, and TG. Phytosterol administration did not significantly modify HDL-C (ES = 0.18 mg/dL; 95% CI: -0.13, -0.51, p = 258) levels when compared to controls. The present umbrella meta-analysis confirms that phytosterol administration significantly reduces LDL-C, TC, and TG, with a greater effect with doses of ≥2 g/day and treatment duration >8 weeks, suggesting its possible application as a complementary therapy for cardiovascular risk reduction. Further studies are needed to determine the efficacy of phytosterols in patients with specific health conditions, as well as to ascertain the adverse effects, the maximum tolerable dose, and the maximum recommended duration of phytosterol administration.

Health outcomes associated with phytosterols: An umbrella review of systematic reviews and meta-analyses of randomized controlled trials

BACKGROUND

Phytosterols (PS), as a kind of plant active ingredients, have many benefits to human health. However, there is currently no comprehensive overview of the clinical evidence and an assessment of the evidence quality.

PURPOSE

We conducted an umbrella review, which incorporated verification spanning a number of meta-analyses and systematic reviews to clarify the link that existed between PS consuming and health outcomes.

METHODS

The databases PubMed, Embase, Web of Science and The Cochrane Library were searched for appropriate research and ultimately included 23 articles involving 79 results. Methodological quality and the validity of evidence received designation in the included meta-analyses leveraging the Assessment of Multiple Systematic Reviews (AMSTAR-2) and the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE).

RESULTS

The consumption of PS makes a contribution to the alleviation of metabolic conditions such as hypercholesterolemia, diabetes, obesity, and hypertension. Its most essential function is to decrease cholesterol absorption, leading to dramatically reductions in total cholesterol and low density lipoprotein cholesterol. Furthermore, utilizing PS products can have a favorable impact on managing apolipoprotein levels along with decreasing the probability of obtaining atherosclerotic cardiovascular disease.

CONCLUSION

This umbrella review summarized a range of beneficial functions of PS to humans, highlighting the promising potential for the development of PS into functional foods.

Plant Sterols and Plant Stanols in Cholesterol Management and Cardiovascular Prevention

Atherosclerotic cardiovascular disease (ASCVD) remains the major mortality cause in developed countries with hypercholesterolaemia being one of the primary modifiable causes. Lifestyle intervention constitutes the first step in cholesterol management and includes dietary modifications along with the use of functional foods and supplements. Functional foods enriched with plant sterols/stanols have become the most widely used nonprescription cholesterol-lowering approach, despite the lack of randomized trials investigating their long-term safety and cardiovascular efficacy. The cholesterol-lowering effect of plant-sterol supplementation is well-established and a potential beneficial impact on other lipoproteins and glucose homeostasis has been described. Nevertheless, experimental and human observational studies investigating the association of phytosterol supplementation or circulating plant sterols with various markers of atherosclerosis and ASCVD events have demonstrated controversial results. Compelling evidence from recent genetic studies have also linked elevated plasma concentrations of circulating plant sterols with ASCVD presence, thus raising concerns about the safety of phytosterol supplementation. Thus, the aim of this review is to provide up-to-date data on the effect of plant sterols/stanols on lipid-modification and cardiovascular outcomes, as well as to discuss any safety issues and practical concerns.

The Role of Phytochemicals and Plant-Based Diets in Gestational Diabetes: Evidence from Clinical Trials

Gestational diabetes mellitus (GDM) is defined as glucose intolerance identified during pregnancy. The increased risk of pregnancy complications and the adverse health effects for the mother and baby associated with GDM require urgent and effective ways to control the condition. The primary goal of this semi-quantitative review was to examine the effects of phytochemicals and plant-based diets on GDM in clinical studies involving women undergoing pregnancy and to summarize the findings for application in clinical practice and disease management. The articles included in this review show that intervention strategies, including fruits, vegetables, whole grains, nuts and seeds, and tea, may be beneficial in the management of GDM and lower blood glucose and improve adverse pregnancy outcomes in these women. The randomized controlled trials reviewed collectively show improved glycemic control markers, blood lipid values, and body weight and composition when supplemented with phytochemical-rich supplements and foods compared to those in the control groups. The findings support the clinical observations of lower GDM risks in women consuming plant-derived diets rich in phytochemicals. Nutrition interventions involving plant-based foods and diets are thus a practical way to reduce hyperglycemia both in patients diagnosed with GDM and those at high risk for the development of GDM.

Biogenic Phytochemicals Modulating Obesity: From Molecular Mechanism to Preventive and Therapeutic Approaches

The incidence of obesity and over bodyweight is emerging as a major health concern. Obesity is a complex metabolic disease with multiple pathophysiological clinical conditions as comorbidities are associated with obesity such as diabetes, hypertension, cardiovascular disorders, sleep apnea, osteoarthritis, some cancers, and inflammation-based clinical conditions. In obese individuals, adipocyte cells increased the expression of leptin, angiotensin, adipocytokines, plasminogen activators, and C-reactive protein. Currently, options for treatment and lifestyle behaviors interventions are limited, and keeping a healthy lifestyle is challenging. Various types of phytochemicals have been investigated for antiobesity potential. Here, we discuss pathophysiology and signaling pathways in obesity, epigenetic regulations, regulatory mechanism, functional ingredients in natural antiobesity products, and therapeutic application of phytochemicals in obesity.

Impact of walnut consumption on cardio metabolic and anthropometric parameters in metabolic syndrome patients: GRADE-assessed systematic review and dose-response meta-analysis of data from randomized controlled trials

BACKGROUND

In recent years, the effect of walnut consumption on various components of metabolic syndrome (Mets) in different populations has been investigated. However, the findings on the alterations of cardiometabolic and anthropometric indices following walnut consumption in adults with Mets have not been fully conclusive.

METHODS

The current study of eight randomized controlled trials (RCTs) examined the effects of walnut consumption on glucose homeostasis factors (fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1c)), lipid profile (triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), and high-density lipoprotein cholesterol (HDL-c)), high sensitivity C-reactive protein (hs-CRP) concentrations and anthropometric indices (body weight (BW), body mass index (BMI), and waist circumference (WC)) in trials of 549 participants. A systematic search was conducted in online databases including MEDLINE, Scopus, and Clarivate Analytics Web of Science uses related keywords to detect eligible studies until December 2021. To calculate the weighted mean difference (WMD) and 95% confidence intervals (CIs), a random-effects model was used.

RESULTS

Results from the pooled analysis showed that serum TG concentration was significantly reduced (WMD, - 0.1 mmol/L; 95%CI (- 0.3 to - 0.02); p = 0.02; I2 = 38.6%; p = 0.10), although other lipid profile components (TC, LDL-c, and HDL-c), glucose homeostasis markers (FPG, insulin, and HbA1c), hs-CRP levels, anthropometric indices (BW, BMI, and WC) and blood pressure (SBP and DBP) were not influenced by walnut consumption. A significant dose-response association was detected between the dose of walnut intake and serum concentrations of FPG (Pnon-linearity < 0.03, Pdose-response < 0.001) and HDL-c (Pnon-linearity = 0.01, Pdose-response = 0.006).

CONCLUSIONS

Walnut consumption reduces serum TG levels in individuals with metabolic syndrome, but it cannot affect other cardiometabolic indices. Future well-designed and large RCTs are required to clarify further beneficial effects of walnut consumption on the cardiometabolic profile.

The effects of melatonin administration on carotid intima-media thickness and pulse wave velocity in diabetic nephropathy: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Previous studies have reported that melatonin intake is inversely associated with reduced markers of atherosclerosis development such as carotid intima-media thickness (CIMT).

OBJECTIVE

This study was designed to assess the effects of melatonin administration on CIMT and pulse wave velocity (PWV) in patients with diabetic nephropathy (DN).

MATERIALS AND METHODS

This randomized, double-blind, placebo-controlled trial was conducted on 32 DN patients. Subjects were assigned to receive melatonin or placebo (starch) for 24 weeks. Individuals in the melatonin group (n = 19) received 10 mg/day. CIMT and PWV levels were taken at the study baseline and after 24 weeks of intervention.

RESULTS

After 24 weeks of intervention, melatonin intake did not affect mean levels of left (P = 0.51) and right (P = 0.16) CIMT and maximum levels of left (P = 0.76) and right (P = 0.15) CIMT, and PWV (P = 0.55) compared with the placebo. In addition, within-group difference demonstrated a significant reduction in mean levels of right CIMT (P = 0.01) in the melatonin group. We did not observe any significant change in C-reactive protein (CRP) concentrations after melatonin intake (P = 0.81).

CONCLUSIONS

Melatonin intake did not affect mean levels of left and right CIMT and maximum levels of left and right CIMT, PWV, CRP levels compared with the placebo. In addition, within-group difference demonstrated a significant reduction in mean levels of right CIMT in the melatonin group. This trial was registered at www.irct.ir as http://www.irct.ir: IRCT20200527047584N2.

Therapeutic Properties and Use of Extra Virgin Olive Oil in Clinical Nutrition: A Narrative Review and Literature Update

Extra virgin olive oil (EVOO) is a cornerstone of the Mediterranean diet (MedD). In this narrative review, we synthesize and illustrate the various characteristics and clinical applications of EVOO and its components—such as oleic acid, hydroxytyrosol, and oleuropein—in the field of clinical nutrition and dietetics. The evidence is split into diet therapy, oleic acid-based enteral nutrition formulations and oral supplementation formulations, oleic acid-based parenteral nutrition, and nutraceutical supplementation of minor components of EVOO. EVOO has diverse beneficial health properties, and current evidence supports the use of whole EVOO in diet therapy and the supplementation of its minor components to improve cardiovascular health, lipoprotein metabolism, and diabetes mellitus in clinical nutrition. Nevertheless, more intervention studies in humans are needed to chisel specific recommendations for its therapeutic use through different formulations in other specific diseases and clinical populations.

The effects of raloxifene on endothelial function and Inflammation in Postmenopausal women: A Meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Raloxifene treatment has been reported to be associated with cardiovascular benefits if prescribed to women during the postmenopausal period. However, a final conclusion regarding this hypothesis has not yet been achieved. We conducted a systematic review and meta-analysis to evaluate the effect of raloxifene on the endothelial function and inflammation in postmenopausal women.

METHODS

We systematically searched the following 4 databases from inception to 23 January 2021 without any language restrictions: Web of Science, PubMed/Medline, Embase and Scopus. The eligible randomized controlled trials (RCTs) reporting the effects of raloxifene on the flow-mediated dilatation (FMD), C-reactive protein (CRP), carotid intima-media thickness (CIMT), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and E-selectin levels, were included in the final meta-analysis.

RESULTS

A total of 16 RCTs were included in the final analysis. Raloxifene administration had no significant effect on ICAM-1 and E-selectin levels. However, we observed a decrease of the CIMT (WMD: -0.071 mm, 95% CI: -0.09 to -0.04, P = 0.000), CRP (WMD: -0.342 mg/L, 95% CI: -0.591, -0.094, p = 0.007), and VCAM-1 (WMD: -197.90 mg/L, 95% CI: -269.58 to -126.23, P = 0.000) levels in the intervention versus control groups following the prescription of this pharmacological agent. Moreover, raloxifene treatment resulted in a significant elevation of the FMD (WMD: 1.64%, 95% CI: 0.46 to 2.81, P = 0.006), particularly if the intervention was equal to or exceeded 12 weeks.

CONCLUSION

Raloxifene might emerge as a potential therapeutic option in the management of endothelial dysfunction and inflammation in postmenopausal women.

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.

Phytonutrient supplements and metabolic biomarkers of cardiovascular disease: An umbrella review of meta-analyses of clinical trials

Phytonutrients exert several pharmacological effects on humans. In this study, we performed an umbrella review of the association of phytonutrient supplements (PNSs) with biomarkers of cardiovascular disease. Relevant published systematic reviews and meta-analyses of clinical trials were identified by searching PubMed, Embase, and Cochrane Library until July 4, 2020. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) for summarized effects and I² statistics of heterogeneity were extracted from individual studies or reanalyzed using a random-effects model. Of the 50 included studies, pooled effects of PNSs on blood pressure, lipid profiles, and glycemic control were reported in 16, 25, and 14 articles, respectively. The findings appeared to be highly heterogeneous among individual trials of included systematic reviews and meta-analyses. Ginger (WMD = -6.36 mmHg, 95% CI = -11.27, -1.46) and Hibiscus sabdariffa (WMD = -7.58 mmHg, 95% CI = -9.69, -5.46) were associated with lowered systolic blood pressure, whereas Aloe vera, Nigella sativa, and spirulina were associated with beneficial effects on both lipid profiles and glycemic control. In summary, this umbrella review has provided up-to-date evidence for the effect of PNSs on biomarkers related to hypertension, dyslipidemia, and diabetes. The results must be interpreted with caution due to potential heterogeneity.

Effects of a Single Oral Megadose of Vitamin D3 on Inflammation and Oxidative Stress Markers in Overweight and Obese Women: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

AIM

The study aimed to evaluate the effects of vitamin D3 (VD3) supplementation on inflammation and oxidative stress markers in overweight and obese women with deficiency or insufficiency of vitamin D.

METHODS

Twenty-nine overweight or obese women who had a deficiency or insufficiency of vitamin D were placed into two groups according to VD3 intervention. Patients in the supplemented group received a single oral megadose of VD3 (VD3, n=14). Patients in placebo group received a single oral identical capsule without vitamin D (placebo, n = 15). Anthropometric and biochemical variables were assessed at baseline and after 4-weeks intervention.

RESULTS

Anthropometric variables (waist circumference, waist-hip ratio, waist-height ratio and body mass index) were similar between groups (p > 0.05). VD3 supplementation increased the serum levels of 25-hydroxyvitamin D (p=0.000), malondialdehyde (p=0.021) and C-reactive protein (p=0.043) in overweight and obese women. Additionally, VD3 supplementation reduced the serum levels of aspartate aminotransferase (AST, p=0.035), alanine aminotransferase (ALT, p<0.0001) in overweight and obese women. Despite this, the serum levels of parathyroid hormone (PTH), fasting glucose (FG), and alpha-1- acid glycoprotein (A1GPA), total antioxidant capacity (TAC) were similar between groups.

CONCLUSION

In summary, a single oral megadose of VD3 increased 25-hydroxyvitamin D serum levels but did not improve oxidative stress and inflammation markers.

Adipogenesis as a Potential Anti-Obesity Target: A Review of Pharmacological Treatment and Natural Products

Obesity is recognized as a severe threat to overall human health and is associated with type 2 diabetes mellitus, dyslipidemia, hypertension, and cardiovascular diseases. Abnormal expansion of white adipose tissue involves increasing the existing adipocytes' cell size or increasing the number through the differentiation of new adipocytes. Adipogenesis is a process of proliferation and differentiation of adipocyte precursor cells in mature adipocytes. As a key process in determining the number of adipocytes, it is a possible therapeutic approach for obesity. Therefore, it is necessary to identify the molecular mechanisms involved in adipogenesis that could serve as suitable therapeutic targets. Reducing bodyweight is regarded as a major health benefit. Limited efficacy and possible side effects and drug interactions of available anti-obesity treatment highlight a constant need for finding novel efficient and safe anti-obesity ingredients. Numerous studies have recently investigated the inhibitory effects of natural products on adipocyte differentiation and lipid accumulation. Possible anti-obesity effects of natural products include the induction of apoptosis, cell-cycle arrest or delayed progression, and interference with transcription factor cascade or intracellular signaling pathways during the early phase of adipogenesis.

Impact of dehydroepiandrosterone (DHEA) supplementation on testosterone concentrations and BMI in elderly women: A meta-analysis of randomized controlled trials

BACKGROUND

Despite the fact that numerous clinical studies have evaluated the positive effects of dehydroepiandrosterone (DHEA) supplementation on testosterone concentrations and on the body mass index (BMI), more evidence is needed to certify that DHEA is a BMI-reducing agent in the elderly. This meta-analysis aims to clarify the various incompatible results and investigate the impact of DHEA supplementation on serum testosterone levels and lean body mass in elderly women.

METHODS

Four scientific databases (EMBASE, PubMed/MEDLINE, Scopus and Web of Science) were searched from inception until 20 August 2020 for trials comparing DHEA with placebo. Results were presented as weighted mean differences (WMDs) and 95 % confidence intervals (CIs) based on the random effects model (DerSimonian-Laird approach).

RESULTS

Nine arms with 793 subjects reported testosterone as an outcome measure. The overall results demonstrated that testosterone levels increased significantly after DHEA administration in elderly women (WMD: 17.52 ng/dL, 95 % CI: 6.61, 28.43, P = 0.002). In addition, DHEA administration significantly decreased the BMI (WMD:-0.39 kg/m², I² = 0.0 %).

CONCLUSION

The results of the current meta-analysis support the use of DHEA supplementation for increasing testosterone concentrations in elderly women.