The effects of lipoic acid and α-tocopherol supplementation on the lipid profile and insulin sensitivity of patients with type 2 diabetes mellitus: a randomized, double-blind, placebo-controlled trial

Systematic exploration of network pharmacology, in silico modeling and pharmacokinetic profiling for vitamin E in polycystic ovarian syndrome

Aim: This study seeks to explore the possibility of using vitamin E to alleviate the symptoms of polycystic ovarian syndrome (PCOS). Methods: Various computational methods were employed, including network pharmacology utilizing a compound-target-pathway approach, Swiss ADME, OSIRIS® property explorer, pkCSM, PASS online web resource and MOLINSPIRATION® software. In addition, in silico analysis of vitamin E was performed with ten receptors. Results & discussion: Our findings highlight the diverse potential of vitamin E in alleviating PCOS. The observed influence on hormones is in line with existing PCOS theories regarding cyst development, further enhancing the therapeutic promise of vitamin E. Conclusion: In conclusion, our computational analysis indicates that vitamin E shows potential as a therapeutic agent for alleviating PCOS in adolescents.

Lipoic acid alters the microRNA signature in breast cancer cells

BACKGROUND

Breast cancer, the deadliest disease affecting women globally, exhibits heterogeneity with distinct molecular subtypes. Despite advances in cancer therapy, the persistence of high mortality rates due to chemotherapy resistance remains a major challenge. Lipoic acid (LA), a natural antioxidant, has proven potent anticancer properties. Yet, the impact of LA on microRNA (miRNA) expression profile in breast cancer remains unexplored.

AIM

The aim of this study was to unravel the effect of LA on miRNA expression profiles in different breast cancer cell lines.

METHODS

The MiRCURY LNA miRNA miRNome qPCR Panel was used to compare the miRNA signature in MDA-MB-231 and MCF-7 cells treated or not with LA.

RESULTS

We identified six upregulated and six downregulated miRNAs in LA-treated MDA-MB-231 cells and 14 upregulated and four downregulated miRNAs in LA-treated MCF-7 cells compared to control cells. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis revealed that the deregulated miRNAs could alter different signaling cascades including FoxO, P53 and Hippo pathways.

CONCLUSION

The outcome of this study provides further insights into the molecular mechanisms underlying the therapeutic benefit of LA. This in turn could assist the amelioration of LA-based anticancer therapies.

NOX2 deficiency exacerbates diet-induced obesity and impairs molecular training adaptations in skeletal muscle

The production of reactive oxygen species (ROS) by NADPH oxidase (NOX) 2 has been linked to both insulin resistance and exercise training adaptations in skeletal muscle. This study explores the previously unexamined role of NOX2 in the interplay between diet-induced insulin resistance and exercise training (ET). Using a mouse model that harbors a point mutation in the essential NOX2 regulatory subunit, p47phox (Ncf1*), we investigated the impact of this mutation on various metabolic adaptations. Wild-type (WT) and Ncf1* mice were assigned to three groups: chow diet, 60% energy fat diet (HFD), and HFD with access to running wheels (HFD + E). After a 16-week intervention, a comprehensive phenotypic assessment was performed, including body composition, glucose tolerance, energy intake, muscle insulin signaling, redox-related proteins, and mitochondrial adaptations. The results revealed that NOX2 deficiency exacerbated the impact of HFD on body weight, body composition, and glucose intolerance. Moreover, in Ncf1* mice, ET did not improve glucose tolerance or increase muscle cross-sectional area. ET normalized body fat independently of genotype. The lack of NOX2 activity during ET reduced several metabolic adaptations in skeletal muscle, including insulin signaling and expression of Hexokinase II and oxidative phosphorylation complexes. In conclusion, these findings suggest that NOX2 mediates key beneficial effects of exercise training in the context of diet-induced obesity.

Effect of vitamin E intake on glycemic control and insulin resistance in diabetic patients: an updated systematic review and meta-analysis of randomized controlled trials

Since a 2014 meta-analysis, several randomized controlled trials (RCTs) evaluating the effect of vitamin E intake on glycemic indices and insulin resistance in adults with diabetes have reached inconsistent conclusions. Therefore, we updated the previous meta-analysis to summarize the current evidence in this regard. Online databases including PubMed, Scopus, ISI Web of Science, and Google Scholar were searched to identify relevant studies published up to September 30, 2021, using relevant keywords. Random-effects models were used to obtain overall mean difference (MD) comparing vitamin E intake with a control group. In total, 38 RCTs with a total sample size of 2171 diabetic patients (1110 in vitamin E groups and 1061 in control groups) were included. Combining the results from 28 RCTs on fasting blood glucose, 32 RCTs on HbA1c, 13 RCTs on fasting insulin, and 9 studies on homeostatic model assessment for insulin resistance (HOMA-IR) showed a summary MD of -3.35 mg/dL (95% CI: -8.10 to 1.40, P = 0.16), -0.21% (95% CI: -0.33 to -0.09, P = 0.001), -1.05 µIU/mL (95% CI: -1.53 to -0.58, P < 0.001), and -0.44 (95% CI: -0.82 to -0.05, P = 0.02), respectively. This indicates a significant lowering effect of vitamin E on HbA1c, fasting insulin and HOMA-IR, while no significant effect on fasting blood glucose in diabetic patients. However, in subgroup analyses, we found that vitamin E intake significantly reduced fasting blood glucose in studies with an intervention duration of < 10 weeks. In conclusion, vitamin E intake has a beneficial role in improving HbA1c and insulin resistance in a population with diabetes. Moreover, short-term interventions with vitamin E have resulted in lower fasting blood glucose in these patients. This meta-analysis was registered in PROSPERO with code CRD42022343118.

Efficacy and safety of oral alpha-lipoic acid supplementation for type 2 diabetes management: a systematic review and dose-response meta-analysis of randomized trials

Objective

To examine the dose-dependent influence of oral alpha-lipoic acid (ALA) supplementation on cardiometabolic risk factors in patients with type 2 diabetes (T2D).

Design

We followed the instructions outlined in the Cochrane Handbook for Systematic Reviews of Interventions and the Grading of Recommendations, Assessment, Development, and Evaluation Handbook to conduct our systematic review. The protocol of the study was registered in PROSPERO (CRD42021260587).

Method

We searched PubMed, Scopus, and Web of Science to May 2021 for trials of oral ALA supplementation in adults with T2D. The primary outcomes were HbA1c, weight loss, and LDL cholesterol (LDL-C). Secondary outcomes included fasting plasma glucose (FPG), triglyceride (TG), C-reactive protein (CRP), and blood pressure. We conducted a random-effects dose-response meta-analysis to calculate the mean difference (MD) and 95% CI for each 500 mg/day oral ALA supplementation. We performed a nonlinear dose-response meta-analysis using a restricted cubic spline.

Results

We included 16 trials with 1035 patients. Each 500 mg/day increase in oral ALA supplementation significantly reduced HbA1c, body weight, CRP, FPG, and TG. Dose-response meta-analyses indicated a linear decrement in body weight at ALA supplementation of more than 600 mg/day (MD600 mg/day: -0.30 kg, 95% CI: -0.04, -0.57). A relatively J-shaped effect was seen for HbA1c (MD: -0.32%, 95% CI: -0.45, -0.18). Levels of FPG and LDL-C decreased up to 600 mg/day ALA intake. The point estimates were below minimal clinically important difference thresholds for all outcomes.

Conclusion

Despite significant improvements, the effects of oral ALA supplementation on cardiometabolic risk factors in patients with T2D were not clinically important.

Could nutrient supplements provide additional glycemic control in diabetes management? A systematic review and meta-analysis of randomized controlled trials of as an add-on nutritional supplementation therapy

This systematic review and meta-analysis assessed the antidiabetic effect of pharmaconutrients as an add-on in type 2 diabetes mellitus patients by pooling data from currently available randomized controlled trials (RCTs). Data sources included the PubMed and EMBASE, Cochrane Central Register of Controlled Trials. RCTs reporting changes in glycosylated hemoglobin (HbA1c), fasting blood glucose (FBG), or homeostasis model assessment of insulin resistance (HOMA-IR) levels following add-on pharmaconutritional therapies for T2DM patients consuming antidiabetic drugs were targeted. Using random-effects meta-analyses, we identified pharmaconutrients with effects on glycemic outcomes. Heterogeneity among studies was presented using I² values. Among 9537 articles, 119 RCTs with nine pharmaconutrients (chromium; coenzyme Q10; omega-3 fatty acids; vitamins C, D, and E; alpha-lipoic acid; selenium; and zinc) were included. Chromium (HbA1c, FBG, and HOMA-IR), coenzyme Q10 (HbA1c and FBG), vitamin C (HbA1c and FBG), and vitamin E (HbA1c and HOMA-IR) significantly improved glycemic control. Baseline HbA1c level and study duration influenced the effects of chromium and vitamin E on HbA1c level. Sensitivity analyses did not modify the pooled effects of pharmaconutrients on glycemic control. Administration of chromium, coenzyme Q10, and vitamins C and E for T2DM significantly improved glycemic control. This study has been registered in PROSPERO (CRD42018115229).

Effects of alpha lipoic acid on metabolic syndrome: A comprehensive review

Metabolic syndrome (MetS) is a multifactorial disease with medical conditions such as hypertension, diabetes, obesity, dyslipidemia, and insulin resistance. Alpha-lipoic acid (α-LA) possesses various pharmacological effects, including antidiabetic, antiobesity, hypotensive, and hypolipidemia actions. It exhibits reactive oxygen species scavenger properties against oxidation and age-related inflammation and refines MetS components. Also, α-LA activates the 5' adenosine monophosphate-activated protein kinase and inhibits the NFκb. It can decrease cholesterol biosynthesis, fatty acid β-oxidation, and vascular stiffness. α-LA decreases lipogenesis, cholesterol biosynthesis, low-density lipoprotein and very low-density lipoprotein levels, and atherosclerosis. Moreover, α-LA increases insulin secretion, glucose transport, and insulin sensitivity. These changes occur via PI3K/Akt activation. On the other hand, α-LA treats central obesity by increasing adiponectin levels and mitochondrial biogenesis and can reduce food intake mainly by SIRT1 stimulation. In this review, the most relevant articles have been discussed to determine the effects of α-LA on different components of MetS with a special focus on different molecular mechanisms behind these effects. This review exhibits the potential properties of α-LA in managing MetS; however, high-quality studies are needed to confirm the clinical efficacy of α-LA.

Therapeutic Benefits of Alpha-Lipoic Acid Supplementation in Diabetes Mellitus: A Narrative Review

Elevated oxidative stress is a common denominator between pathways implicated in the pathogenesis of diabetes mellitus and diabetes complications, prompting the use of antioxidant compounds in diabetes therapy. Alpha-lipoic acid (ALA), has been investigated for its role as a potent antioxidant in diabetes treatment and the results from clinical trials indicate improved glucose metabolism, reduced oxidative stress, improved endothelial dysfunction, a decline in platelet reactivity and moderate improvements to weight loss yet conflicting data regarding insulin metabolism. ALA inhibits nuclear factor kappa B (NFkB), chelates divalent transient metal ions and induces the expression of adenosine monophosphate-activated protein kinase (AMPK). This narrative review explores the results from clinical trials investigating the role of ALA in the treatment of diabetes mellitus.

Alpha lipoic acid supplementation affects serum lipids in a dose and duration-dependent manner in different health status

Background: Many studies have investigated the effect of ALA supplementation on lipid profile, and different results have been obtained from these studies. The current systematic review and dose-response meta-analysis was conducted to achive a strong conclusion about the effect of ALA supplementation on lipid profile including total cholesterol (TC), low- and high-density lipoprotein cholesterol (LDL, HDL) and triglyceride (TG). Methods: A systematic search was performed in PubMed, SCOPUS, ProQuest and Embase for randomized placebo-controlled human trials that examined the effect of ALA supplementation on lipid profile up to November 2020. The dose and duration of ALA supplementation for included studies were ranged between 300-1200 mg/d and 2-16 weeks respectively. Weighted mean differences (WMD) and 95% confidence intervals (CIs) were used to evaluate the effect size. Cochran's Q and I² tests were also used to assess between-study's heterogeneity. In addition, subgroup analysis was performed to investigate potential sources of heterogeneity. Dose-response relationship was done using fractional polynomial modeling. Results: Among all eligible studies, 12 studies with a total number of 548 participants were selected. ALA caused a significant reduction on TC (WMD): -10.78 mg/dl, 95% CI: -20.81, -0.74, P=0.002), LDL (WMD: -10.88 mg/dl, 95% CI: -19.52, -2.24, P=0.014) and TG (WMD: -31.02 mg/dl, 95% CI: -49.63, -12.42, P<0.001). There was also a non-significant increaes in HDL concentrations. In addition, dose-response analysis showed a positive association between LDL (P_{non-linearity}=0.026), TG (P_{non-linearity}<0.001) and duration of intervention in a non-linear model. Conclusion: The present meta-analysis revealed the beneficial effects of ALA supplementation on TC, LDL and TG levels. Moreover, the beneficial effects of ALA supplementation on LDL and TG levels was duration-dependent.

Systematic review and meta-analyses of vitamin E (alpha-tocopherol) supplementation and blood lipid parameters in patients with diabetes mellitus

BACKGROUND AND AIMS

The studies have shown that α-tocopherol supplementation could improve lipid profile in diabetes mellitus (DM) patients. Nonetheless, the result remains inconsistent. Therefore, this meta-analysis was performed to evaluate the efficacy of α-tocopherol supplement on lipid parameters in DM patients.

METHODS

We conducted an extensive search via Cochrane Library, PubMed, Scopus, and Web of Science databases to acquire the reported RCTs up to October 2020.

RESULTS

The results showed no effects of α-tocopherol supplementation on lipid profile in DM patients except when used ≥12 weeks.

CONCLUSIONS

α-tocopherol supplementation in DM patients had no significant effect on lipid profiles.

An updated systematic review and dose-response meta-analysis of the effects of α-lipoic acid supplementation on glycemic markers in adults

This systematic review and dose-response meta-analysis was conducted to summarize data from available clinical trials on the effects of α-lipoic acid (ALA) supplementation on glycemic markers including glucose, hemoglobin A_1c (HbA_1c), insulin, homeostatic model assessment of insulin resistance (HOMA-IR), HOMA-β, and quantitative insulin check index in adults. A comprehensive literature search was conducted in the electronic databases of PubMed, Web of Science, ProQuest, Embase and SCOPUS from inception to February 2020. Among all of the eligible studies, 28 articles were selected. The weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to evaluate the pooled effect size. Between-study heterogeneity was evaluated using Cochran's Q test and I². Subgroup analysis was done to evaluate the potential sources of heterogeneity. The dose-response relationship was evaluated using fractional polynomial modeling. Twenty eight eligible studies with a total sample size of 1,016 participants were included in the current meta-analysis. The findings of the meta-analysis showed that ALA supplementation significantly reduced insulin (WMD: -0.64; CI: -1.287 to 0.004, P = .04), HOMA-IR (WMD: -0.48; 95% CI: -0.79 to -0.16; P = .002). No change in glucose or HbA1C was reported. Moreover, the effect of ALA on insulin was duration-dependent (P_{non-linearity} = 0.04). No evidence of departure from linearity was observed between dose and duration of the ALA supplementation on other markers. The subgrouping revealed that ALA dosage and duration of ALA supplementation, health status of participants, geographic locations and the studies' quality are possible sources of heterogeneity. In summary, ALA supplementation improves serum insulin and insulin resistance in a two-class and duration dependent non-linear analysis.

The Beneficial Effects of Alpha Lipoic Acid Supplementation on Lp-PLA2 Mass and Its Distribution between HDL and apoB-Containing Lipoproteins in Type 2 Diabetic Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

Lipoprotein-associated phospholipase A₂ (Lp-PLA2) is a new specific vascular inflammation biomarker that is carried by the lipoproteins in the blood and plays a prominent role in the pathogenesis of atherosclerosis. Increased Lp-PLA2 levels and impaired Lp-PLA2 distribution across high-density lipoprotein (HDL) and non-HDL lipoproteins have been reported in diabetic patients, which is associated with the increase in cardiovascular disease (CVD) risk. This study is aimed at investigating the effect of alpha lipoic acid (ALA), as an antioxidant with potential cardioprotective properties, on the Lp-PLA2 mass and its distribution in diabetic patients. In a double-blind, randomized, placebo-controlled clinical trial, seventy diabetic patients were randomly allocated to ALA (1200 mg ALA as two 600 mg capsules/day) and placebo (two maltodextrin capsules/day) groups. The serum levels of total Lp-PLA2 mass, HDL-Lp-PLA2, oxidized low-density lipoproteins (ox-LDL), apolipoprotein A1 (apo A1), lipid profiles, fasting blood sugar (FBS), and insulin were measured, and apolipoprotein B- (apoB-) associated Lp-PLA2 and homeostasis model of assessment index (HOMA-IR) were calculated at the baseline and after 8 weeks of intervention. ALA significantly decreased the ox-LDL, total Lp-PLA2 mass, apoB-associated Lp-PLA2, and percent of apoB-associated Lp-PLA2 and triglyceride and increased the percent of HDL-Lp-PLA2 compared with the placebo group but had no significant effect on HDL-Lp-PLA2 mass, apo A1, lipid profiles, and glycemic indices. There was a positive correlation between the reduction in the ox-LDL level and total Lp-PLA2 mass in the ALA group. In conclusion, ALA may decrease the CVD risk by reducing the ox-LDL and Lp-PLA2 mass and improving the Lp-PLA2 distribution among lipoproteins in type 2 diabetic patients.

Lipoic acid decreases breast cancer cell proliferation by inhibiting IGF-1R via furin downregulation

BACKGROUND

Breast cancer is the second most common cancer in the world. Despite advances in therapies, the mechanisms of resistance remain the underlying cause of morbidity and mortality. Lipoic acid (LA) is an antioxidant and essential cofactor in oxidative metabolism. Its potential therapeutic effects have been well documented, but its mechanisms of action (MOA) are not fully understood.

METHODS

The aim of this study is to validate the inhibitory LA effect on the proliferation of various breast cancer cell lines and to investigate the MOA that may be involved in this process. We tested LA effects by ex vivo studies on fresh human mammary tumour samples.

RESULTS

We demonstrate that LA inhibits the proliferation and Akt and ERK signalling pathways of several breast cancer cells. While searching for upstream dysregulations, we discovered the loss of expression of IGF-1R upon exposure to LA. This decrease is due to the downregulation of the convertase, furin, which is implicated in the maturation of IGF-1R. Moreover, ex vivo studies on human tumour samples showed that LA significantly decreases the expression of the proliferation marker Ki67.

CONCLUSION

LA exerts its anti-proliferative effect by inhibiting the maturation of IGF-1R via the downregulation of furin.

White adipose tissue mitochondrial metabolism in health and in obesity

White adipose tissue is one of the largest organs of the body. It plays a key role in whole-body energy status and metabolism; it not only stores excess energy but also secretes various hormones and metabolites to regulate body energy balance. Healthy adipose tissue capable of expanding is needed for metabolic well-being and to prevent accumulation of triglycerides to other organs. Mitochondria govern several important functions in the adipose tissue. We review the derangements of mitochondrial function in white adipose tissue in the obese state. Downregulation of mitochondrial function or biogenesis in the white adipose tissue is a central driver for obesity-associated metabolic diseases. Mitochondrial functions compromised in obesity include oxidative functions and renewal and enlargement of the adipose tissue through recruitment and differentiation of adipocyte progenitor cells. These changes adversely affect whole-body metabolic health. Dysfunction of the white adipose tissue mitochondria in obesity has long-term consequences for the metabolism of adipose tissue and the whole body. Understanding the pathways behind mitochondrial dysfunction may help reveal targets for pharmacological or nutritional interventions that enhance mitochondrial biogenesis or function in adipose tissue.

Mitoprotective Clinical Strategies in Type 2 Diabetes and Fanconi Anemia Patients: Suggestions for Clinical Management of Mitochondrial Dysfunction

Oxidative stress (OS) and mitochondrial dysfunction (MDF) occur in a number of disorders, and several clinical studies have attempted to counteract OS and MDF by providing adjuvant treatments against disease progression. The present review is aimed at focusing on two apparently distant diseases, namely type 2 diabetes (T2D) and a rare genetic disease, Fanconi anemia (FA). The pathogenetic links between T2D and FA include the high T2D prevalence among FA patients and the recognized evidence for OS and MDF in both disorders. This latter phenotypic/pathogenetic feature-namely MDF-may be regarded as a mechanistic ground both accounting for the clinical outcomes in both diseases, and as a premise to clinical studies aimed at counteracting MDF. In the case for T2D, the working hypothesis is raised of evaluating any in vivo decrease of mitochondrial cofactors, or mitochondrial nutrients (MNs) such as α-lipoic acid, coenzyme Q10, and l-carnitine, with possibly combined MN-based treatments. As for FA, the established knowledge of MDF, as yet only obtained from in vitro or molecular studies, prompts the requirement to ascertain in vivo MDF, and to design clinical studies aimed at utilizing MNs toward mitigating or delaying FA's clinical progression. Altogether, this paper may contribute to building hypotheses for clinical studies in a number of OS/MDF-related diseases.

Metabolic effects of α-lipoic acid supplementation in pre-diabetics: a randomized, placebo-controlled pilot study

Supplementation of health promoting nutraceuticals may be an effective adjunct strategy with other lifestyle and drug approaches to impede disease progression in prediabetic subjects. α-Lipoic acid, a naturally occurring short-chain fatty acid, has been extensively evaluated for its antioxidant and glycemic control properties but has rarely been investigated as a lipid-lowering strategy. We conducted a pilot study to examine the effects of α-lipoic acid supplementation on glycemic control and lipid profile in pre-diabetic, overweight/obese adults. The study was designed as a free-living, randomized, two-phase, placebo-controlled cross-over study with 12 pre-diabetic, dyslipidemic subjects. Eligible subjects completed two thirty-day phases (in random order) consisting of a placebo (600 mg cellulose per day) and α-lipoic acid treatment (600 mg day^-1). Although no change (p < 0.05) in serum glucose was observed, α-lipoic acid-supplemented subjects demonstrated reduced fasting serum insulin (p = 0.04) and HOMA-IR (p = 0.07) compared with the placebo group. However, no change (p > 0.05) in serum lipids (including total cholesterol, LDL-C, HDL-C, triglycerides, LDL-C/HDL-C, and TC/HDL-C) were observed. Study results suggest that α-lipoic acid supplementation may be a useful strategy to improve insulin sensitivity in pre-diabetic subjects but is not effective in modulating serum lipids.

Evaluating the Lipid-Lowering Effects of α-lipoic Acid Supplementation: A Systematic Review

Dietary supplementation of α-lipoic acid, an 8-carbon organosulfur compound, has been widely reported to lower blood glucose concentration and/or improve insulin sensitivity in previous randomized controlled trials. Although animal model studies further report fairly consistent lipid lowering in both blood and tissue pools in response to α-lipoic acid supplementation, results from human studies are mixed. According to PRISMA guidelines, we conducted a systematic review of published randomized controlled studies (RCTs) to assess the efficacy of α-lipoic acid supplementation as a strategy to improve dyslipidemia, with a focus on serum lipid endpoints including TC, low density lipoprotein cholesterol (LDL-C), HDL-C, and TG. PubMed, EMBASE, Cochrane Evidence-Based Medicine Reviews, Proquest, Web of Science, and Scopus were searched to identify RCTs that reported the effects of α-lipoic acid on blood lipid concentrations from 1970 to 2017. We included RCTs reporting blood lipid responses in adults supplemented with oral α-lipoic acid versus a placebo or control for at least one month. Studies were reviewed and data were extracted by two independent study authors. Seventeen studies were deemed eligible for inclusion. Overall, mean percent changes in blood lipid endpoints in response to α-lipoic acid varied considerably between studies for total cholesterol (-10.5 to +13.9), low-density lipoprotein cholesterol (-19.67 to +9.06), high-density lipoprotein cholesterol (-12.5 to +29.20), and triglycerides (-38.57 to +17.0). Results of this systematic review suggest little consistent benefit on serum lipids in response to α-lipoic acid supplementation. Further well-controlled studies designed and powered to detect improvements in blood lipids in hypercholesterolemic individuals are warranted (PROSPERO registration number: CRD42018105933).

The effects of alpha-lipoic acid supplementation on fasting glucose and lipid profiles among patients with stroke: a systematic review and meta-analysis of randomized controlled trials

Background and objective

Stroke is a devastating condition with long-term comorbidities including metabolic abnormalities. Alpha lipoic acid (ALA), with its antioxidant properties, might improve metabolic status of patients, though current evidence is still inclusive. This systematic review of randomized controlled trials (RCTs) was conducted to summarize the existing evidence regarding the effects of ALA supplementation on fasting glucose and lipid profiles among patients with stroke.

Methods

We searched Cochrane Library, EMBASE, MEDLINE, and Web of Science from 1990 until April 5th, 2018. The relevant randomized-controlled articles, based on defined key words, were included in the analyses. Two independent researchers investigated study eligibility, extracted data, and assessed the risk of bias for included studies. Heterogeneity among included studies was tested using Q-test and I² statistics. Random-effects models were applied to pool the data and standardized mean differences (WMD) were considered as summary effect size.

Results

A total of five studies (140 patients in each intervention group) were included in our meta-analysis. The findings showed that ALA supplementation significantly decreased fasting glucose levels (WMD -36.93 mg/dL; 95% CI, -65.58, -8.28; P = 0.01; I² = 85.0%) in patients with stroke. We found no significant effect of ALA supplementation on triglycerides (WMD -7.45 mg/dL; 95% CI, -51.35, 36.45; P = 0.739; I² = 83.9%), total cholesterol (WMD -23.23 mg/dL; 95% CI, -48.07, 1.62; P = 0.067; I² = 80.5%), LDL-cholesterol (WMD -10.46 mg/dL; 95% CI, -21.01, 0.09; P = 0.052; I² = 47.4%) and HDL-cholesterol levels (WMD -3.02 mg/dL; 95% CI, -20.18, 14.14; P = 0.730; I² = 85.8%).

Conclusions

This meta-analysis suggested the beneficial impacts of ALA supplementation in improving fasting glucose of patients diagnosed with stroke.

Oral α-lipoic acid supplementation in patients with non-alcoholic fatty liver disease: effects on adipokines and liver histology features

Considering the importance of adipokines in the pathophysiology of non-alcoholic fatty liver disease (NAFLD), and due to the possible beneficial effects of α-lipoic acid (α-LA) on these adipose-derived hormones, this study aimed to investigate the effect of α-LA supplementation on adipokines and liver steatosis in obese patients with NAFLD. In a double-blind, placebo-controlled randomized clinical trial with two parallel groups, fifty patients with NAFLD were randomized to receive daily supplementation with either two capsules of α-LA (each capsule containing 600 mg α-LA) or two placebo capsules, daily for 12 weeks. At the baseline, all participants received consultation on how to implement a healthy diet into their daily lives. Anthropometric measures, dietary intakes, liver enzymes and adipokines were assessed at the baseline and after 12 weeks of intervention. A significant reduction was observed in the serum levels of insulin (P = 0.024) and leptin (P = 0.019) in the α-LA group compared to the placebo group, but changes in anthropometric and body composition measures, serum glucose (FSG), resistin, irisin and liver enzymes did not differ between the groups. α-LA supplementation resulted in a statistically significant elevation in the quantitative insulin sensitivity check index (QUICKI) (P = 0.033), serum levels of adiponectin (P = 0.008) and adiponectin-to-leptin ratio (P = 0.007) compared to the placebo. The liver steatosis intensity improved significantly. Nonetheless, no significant differences were observed between the study groups in the liver steatosis intensity, at the end of the study. According to the results, α-LA supplementation for 12 weeks improved insulin resistance, serum levels of insulin, adiponectin and leptin without changing anthropometric measures, serum liver enzymes, resistin and irisin.

The Effect of 600 mg Alpha-lipoic Acid Supplementation on Oxidative Stress, Inflammation, and RAGE in Older Adults with Type 2 Diabetes Mellitus

Alpha-lipoic acid (ALA) has been used as a dietary supplement at different doses in patients with diabetes mellitus type 2 (T2DM) due to its antioxidant, anti-inflammatory, and hypoglycemic effects. However, the reports on the effects of ALA are controversial. For this reason, the purpose of the present study was to determine the effect of 600 mg/day of ALA on the markers of oxidative stress (OxS) and inflammation and RAGE in older adults with T2DM. A quasiexperimental study was carried out with a sample of 135 sedentary subjects (98 women and 37 men) with a mean age of 64 ± 1 years, who all had T2DM. The sample was divided into three groups: (i) experimental group (EG) with 50 subjects, (ii) placebo group (PG) with 50 subjects, and control group (CG) with 35 subjects. We obtained the following measurements in all subjects (pre- and posttreatment): glycosylated hemoglobin (HbA1c), receptor for advanced glycation end products (RAGE), 8-isoprostane, superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant status (TAS), and inflammatory (CRP, TNF-α, IL-6, IL-8, and IL-10) markers. Regarding the effect of ALA on HbA1c, a decrease was observed in the EG (baseline 8.9 ± 0.2 vs. posttreatment 8.6 ± 0.3) and the PG (baseline 8.8 ± 0.2 vs. posttreatment 8.4 ± 0.3) compared to the CG (baseline 8.8 ± 0.3 vs. six months 9.1 ± 0.3) although the difference was not statistically significant (p < 0.05). There was a statistically significant decrease (p < 0.05) in the blood concentration of 8-isoprostane in the EG and PG with respect to the CG (EG: baseline 100 ± 3 vs. posttreatment 57 ± 3, PG: baseline 106 ± 7 vs. posttreatment 77 ± 5, and CG: baseline 94 ± 10 vs. six months 107 ± 11 pg/mL). Likewise, a statistically significant decrease (p < 0.05) in the concentration of the RAGE was found in the EG (baseline 1636 ± 88 vs. posttreatment 1144 ± 68) and the PG (baseline 1506 ± 97 vs. posttreatment 1016 ± 82) compared to CG (baseline 1407 ± 112 vs. six months 1506 ± 128). A statistically significant decrease was also observed in all markers of inflammation and in the activity of SOD and GPx in the CG with respect to the EG and PG. Our findings suggest that the administration of ALA at a dose of 600 mg/day for six months has a similar effect to that of placebo on oxidative stress, inflammation, and RAGE in older adults with T2DM. Therefore, higher doses of ALA should be tried to have this effect. This trial is registered with trial registration number ISRCTN13159380.

Alpha-lipoic acid (ALA) supplementation effect on glycemic and inflammatory biomarkers: A Systematic Review and meta- analysis

BACKGROUND & AIMS

Several randomized clinical trials (RCTs) have investigated the effect of Alpha - Lipoic Acid (ALA) supplementation on metabolic parameters, with conflicting results. Therefore, the present study assessed the effect of ALA on some glycemic and inflammatory parameters.

METHODS

A comprehensive literature search was conducted up from inception to July 2018 on PubMed, Scopus, Cochrane databases, Google Scholar, ProQuest, Web of Science, and Embase. From among eligible trials, 41 articles were selected for the meta-analysis. Two reviewers independently assessed the risk of bias and extracted data from the included studies. Meta-analyses using the random-effects model were performed to analyze the data.

RESULTS

Based on the Cochrane risk of bias tool, 19 articles had a good quality, 16 trials had a poor quality and 6 trials had a fair quality. The results demonstrated the significant effect of ALA on Fasting Blood Sugar (FBS) (weighted mean difference (WMD)) = -6.57, 95% confidence interval (CI: -11.91 to -1.23, P = 0.016), Hemoglobin A1c (HbA1c) (WMD = -0.35, 95% CI: -0.55 to -0.15, P = 0.004), Tumor Necrosis Factor Alpha (TNF-α) (WMD = -1.57, 95% CI: -2.29 to -0.85, P < 0.05), Interleukin 6 levels (IL-6) (WMD = -1.15, 95% CI: -1.58 to -0.72, P < 0.001), and C-reactive protein (CRP) (WMD = -0.31, 95% CI: -0.47 to -0.16, P > 0.001). No effect was detected for ALA on insulin and the homeostatic model assessment of insulin resistance (HOMA-IR).

CONCLUSIONS

These findings suggest that ALA is a viable supplement to improve some of the glycemic and inflammatory biomarkers.

The Role of Tocotrienol in Protecting Against Metabolic Diseases

Obesity is a major risk factor for diabetes, and these two metabolic conditions cause significant healthcare burden worldwide. Chronic inflammation and increased oxidative stress due to exposure of cells to excess nutrients in obesity may trigger insulin resistance and pancreatic β-cell dysfunction. Tocotrienol, as a functional food component with anti-inflammatory, antioxidant, and cell signaling-mediating effects, may be a potential agent to complement the current management of obesity and diabetes. The review aimed to summarize the current evidence on the anti-obesity and antidiabetic effects of tocotrienol. Previous studies showed that tocotrienol could suppress adipogenesis and, subsequently, reduce body weight and fat mass in animals. This was achieved by regulating pathways of lipid metabolism and fatty acid biosynthesis. It could also reduce the expression of transcription factors regulating adipogenesis and increase apoptosis of adipocytes. In diabetic models, tocotrienol was shown to improve glucose homeostasis. Activation of peroxisome proliferator-activated receptors was suggested to be responsible for these effects. Tocotrienol also prevented multiple systemic complications due to obesity and diabetes in animal models through suppression of inflammation and oxidative stress. Several clinical trials have been conducted to validate the antidiabetic of tocotrienol, but the results were heterogeneous. There is no evidence showing the anti-obesity effects of tocotrienol in humans. Considering the limitations of the current studies, tocotrienol has the potential to be a functional food component to aid in the management of patients with obesity and diabetes.

Effects of α-Lipoic Acid, Carnosine, and Thiamine Supplementation in Obese Patients with Type 2 Diabetes Mellitus: A Randomized, Double-Blind Study

Type 2 diabetes mellitus (T2DM) is evolving to an epidemic of the modern world. T2DM is associated with a number of pathological complications, including cardiovascular disease that is mostly promoted by the increased oxidative stress in type 2 diabetic patients. We performed a randomized double-blind placebo-controlled trial to investigate the effectiveness of an individualized oral supplementation with α-lipoic acid (ALA), carnosine, and thiamine. For that purpose, 82 obese type 2 diabetic patients were randomly assigned to 2 groups, and were either supplemented daily with 7 mg ALA/kg body weight, 6 mg carnosine/kg body weight, and 1 mg thiamine/kg body weight or placebo for 8 weeks. An array of biochemical tests including the estimation of oxidative stress and platelet aggregation were performed at baseline and at follow-up. Moreover, the antiplatelet activity of each of the supplement's components was determined ex vivo at human and washed rabbit platelets. Glucose and HbA_1c levels were significantly reduced after supplementation (135.7 ± 19.5 mg/dL vs. 126.5 ± 16.8 mg/dL and 8.3% ± 0.3% vs. 6.03% ± 0.58%, respectively, P < .05); however, insulin was significantly increased (3.6 ± 0.7 μIU/mL vs. 6.8 ± 0.2 μIU/mL, P < .05). The patients treated with the supplement recorded higher follow-up values for HOMA-IR and HOMA-β, and a significant drop in serum hydroperoxide level. Only ALA inhibited platelets aggregation ex vivo through ADP, platelet activating factor, arachidonic acid, epinephrine, collagen, and thrombin pathways. Daily supplementation with an individualized ALA, carnosine, and thiamine supplement effectively reduced glucose concentration in type 2 diabetic patients, probably by increasing insulin production from the pancreas. In addition to that, the reduction of oxidative stress and inhibition of platelet aggregation could potentially provide greater cardiovascular protection. Further studies are needed to fine-tune the supplementation dose-response effects in T2DM patients.

The effects of alpha-lipoic acid supplementation on glucose control and lipid profiles among patients with metabolic diseases: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effect of alpha-lipoic acid (ALA) supplementation on glycemic control and lipid profiles among patients with metabolic diseases.

METHODS

We searched the following databases till October 2017: MEDLINE, EMBASE, Web of Science and Cochrane Central Register of Controlled Trials. The relevant data were extracted and assessed for quality of the studies according to the Cochrane risk of bias tool. Data were pooled using the inverse variance method and expressed as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Heterogeneity between studies was assessed by the Cochran Q statistic and I-squared tests (I²). Twenty-four studies were included in the meta-analyses.

RESULTS

The findings of this meta-analysis showed that ALA supplementation among patients with metabolic diseases significantly decreased fasting glucose (SMD -0.54; 95% CI, -0.89, -0.19; P = 0.003), insulin (SMD -1.01; 95% CI, -1.70, -0.31; P = 0.006), homeostasis model assessment of insulin resistance (SMD -0.76; 95% CI, -1.15, -0.36; P < 0.001) and hemoglobin A1c (SMD -1.22; 95% CI, -2.01, -0.44; P = 0.002), triglycerides (SMD -0.58; 95% CI, -1.00, -0.16; P = 0.006), total- (SMD -0.64; 95% CI, -1.01, -0.27; P = 0.001), low density lipoprotein-cholesterol (SMD -0.44; 95% CI, -0.76, -0.11; P = 0.008). We found no detrimental effect of ALA supplementation on high density lipoprotein-cholesterol (HDL-cholesterol) levels (SMD 0.57; 95% CI, -0.14, 1.29; P = 0.11).

CONCLUSIONS

Overall, the current meta-analysis demonstrated that ALA administration may lead to an improvement in glucose homeostasis parameters and lipid profiles except HDL-cholesterol levels.

Effect of alpha-lipoic acid supplementation on lipid profile: A systematic review and meta-analysis of controlled clinical trials

Several studies have shown the effect of alpha-lipoic acid (ALA) on lipid profile. However, findings remain controversial. This systematic review and meta-analysis was conducted to systematically summarize the available clinical trials that examined the effects ALA supplementation on the lipid profile of adults. A systematic search through PubMed and Scopus was done for studies published in English up to April 2017. Effect sizes were combined with fixed- or random-effects analysis, where appropriate. Between-study heterogeneity was evaluated by Cochran's Q test and I². Eleven clinical trials with 452 adults (51.5% women, 48.5% men) were included in this meta-analysis. Combining effect sizes of 10 studies on serum triacylglycerol (TG) concentrations revealed a significant effect of ALA supplementation on serum TG compared with the placebo group (weighted mean difference [WMD], -29.185 mg/dL; 95% confidence interval [CI], -51.454 to -6.916; P = 0.010). We also found significant changes in serum total cholesterol and low-density lipoprotein (WMD, -10.683 mg/dL; 95% CI, -19.816 to -1.550; P = 0.022, WMD, -12.906 mg/dL; 95% CI, -22.133 to -3.679; P = 0.006, respectively). Significant changes were not observed in serum high-density lipoprotein (WMD, -0.092 mg/dL; 95% CI, -3.014 to 2.831; P = 0.025). Supplementation dosage and body mass index were potential sources of heterogeneity, in which those with body mass index >30 kg/m² who received >600 mg/d ALA showed better improvements in lipid profile. Our findings showed that supplementation with ALA significantly decreased the serum concentrations of TG, total cholesterol, and low-density lipoprotein but did not affect serum levels of high-density lipoprotein in adults.

Effect of Tocotrienols enriched canola oil on glycemic control and oxidative status in patients with type 2 diabetes mellitus: A randomized double-blind placebo-controlled clinical trial

Background:

Tocotrienols have been shown to improve glycemic control and redox balance in an animal study, but their effects on patients with diabetes are unknown. The study aimed to investigate whether tocotrienols improves glycemic control, insulin sensitivity, and oxidative stress in individuals with type 2 diabetes mellitus (T2DM).

Materials and Methods:

This study was a double-blinded, placebo-controlled, randomized trial. A total of 50 patients, aged 35-60 years, with T2DM treated by noninsulin hypoglycemic drugs were randomly assigned to receive either 15 mL/day tocotrienols (200 mg) enriched canola oil (n = 25) or pure canola oil (n = 25) for 8 weeks. Fasting blood sugar (FBS), fasting insulin, total antioxidant capacity (TAC), malondialdehyde (MDA), and homeostatic model assessment for insulin resistance (HOMA-IR) were determined before and after the intervention. The data were compared between and within groups, before and after the intervention.

Results:

Baseline characteristics of participants including age, sex, physical activity, disease duration, and type of drug consumption were not significantly different between the two groups. In tocotrienol enriched canola oil, FBS (mean percent change: –15.4% vs. 3.9%; P = 0.006) and MDA (median percent change: –35.6% vs. 16.3%; P = 0.003) were significantly reduced while TAC was significantly increased (median percent change: 21.4% vs. 2.3%; P = 0.001) compared to pure canola oil. At the end of the study, patients who treated with tocotrienols had lower FBS (P = 0.023) and MDA (P = 0.044) compared to the pure canola oil group. However, tocotrienols had no effect on insulin concentrations and HOMA-IR.

Conclusion:

Tocotrienols can improve FBS concentrations and modifies redox balance in T2DM patients with poor glycemic control and can be considered in combination with hypoglycemic drugs to better control of T2DM.

Effect of vitamins C and E on insulin resistance in diabetes: a meta-analysis study

BACKGROUND

Data regarding the effect of vitamin C (VC) and vitamin E (VE) supplementation on insulin resistance in type 2 diabetes mellitus (T2DM) are controversial. We aimed to systematically review the current data on this topic.

MATERIALS AND METHODS

All randomized controlled trials (RCTs) conducted to assess the effect of VC and/or VE on insulin resistance in diabetes published in Google Scholar and PubMed web databases until January 2014 were included. Exclusion criteria were studies conducted in animal, type 1 DM, children or pregnant women. Main outcome measure was insulin resistance by homoeostasis model assessment (HOMA) index. According to degree of heterogeneity, fixed- or random-effect model was employed by stata software (11.0).

RESULTS

We selected 14 RCTs involving 735 patients with T2DM. VE or mixture-mode supplementation did not have any significant effect on HOMA with a standardized mean difference (SMD): 0·017, 95% CI: -0·376 to 0·411 (P = 0·932); and SMD: -0·035, 95% CI: -0·634 to 0·025 (P = 0·070), respectively, by random-effect model. VC supplement alone did not improve insulin resistance with a SMD: -0·150, 95% CI: -0·494 to 0·194 (P = 0·391), by fixed-effect model. Meta-regression test demonstrated that HOMA index may have not been influenced by the year of publication, dosage or duration of treatment.

CONCLUSIONS

The sole intake of VC, VE or their combination with other antioxidants could not improve insulin resistance in diabetes.

Lipoic acid decreases Mcl-1, Bcl-xL and up regulates Bim on ovarian carcinoma cells leading to cell death

Background

Ovarian carcinoma is the leading cause of death from gynecological cancer because there is risk of chemoresistance. As previously demonstrated in our laboratory, Alpha-lipoic acid (LA), a co-factor for metabolic enzymes, suppresses the tumor growth. In this study, we have researched the mechanisms that are responsible for the activity of LA.

Methods

We have studied the mechanisms of LA in two ovarian cancer cell lines, a cisplatin sensitive one, IGROV1 and its resistant counterpart, IGROV1-R10. These cells have been exposed to lipoic acid at various concentrations. Cell proliferation, cell cycle repartition and nuclear staining with DAPI were recorded. Western blot analyses were performed to detect various proteins implied in apoptotic cell death pathways. To investigate the formation of ROS, the oxidation of CM-DCFH₂-DA were also determined.

Findings

LA suppressed growth proliferation and induced apoptosis in both ovarian cell lines. Moreover, LA provoked a down regulation of two anti-apoptotic proteins, Mcl-1 and Bcl-x_L protein and a strong induction of the BH3-only protein Bim. Furthermore, LA induced ROS generation which could be involved in the CHOP induction which is known to activate the Bim translation.

Conclusions

Our results reveal novel actions of LA which could explain the anti-tumoral effects of the LA. Therefore, LA seems to be a promising compound for ovarian cancer treatment.

α-Lipoic acid as a triglyceride-lowering nutraceutical

Considering the current obesity epidemic in the United States (>100 million adults are overweight or obese), the prevalence of hypertriglyceridemia is likely to grow beyond present statistics of ∼30% of the population. Conventional therapies for managing hypertriglyceridemia include lifestyle modifications such as diet and exercise, pharmacological approaches, and nutritional supplements. It is critically important to identify new strategies that would be safe and effective in lowering hypertriglyceridemia. α-Lipoic acid (LA) is a naturally occurring enzyme cofactor found in the human body in small quantities. A growing body of evidence indicates a role of LA in ameliorating metabolic dysfunction and lipid anomalies primarily in animals. Limited human studies suggest LA is most efficacious in situations where blood triglycerides are markedly elevated. LA is commercially available as dietary supplements and is clinically shown to be safe and effective against diabetic polyneuropathies. LA is described as a potent biological antioxidant, a detoxification agent, and a diabetes medicine. Given its strong safety record, LA may be a useful nutraceutical, either alone or in combination with other lipid-lowering strategies, when treating severe hypertriglyceridemia and diabetic dyslipidemia. This review examines the current evidence regarding the use of LA as a means of normalizing blood triglycerides. Also presented are the leading mechanisms of action of LA on triglyceride metabolism.

Natural products for the management of type 2 diabetes mellitus and comorbid conditions

OBJECTIVE

To provide pharmacists with practical information to guide consumers in their choices of herbal products and dietary supplements for the management of type 2 diabetes mellitus (T2DM) and its comorbid disease states.

SUMMARY

The herbal and dietary supplement market has grown exponentially over the past decade as Americans increasingly use such agents for generalized health and the prevention and treatment of chronic disease states.1 Pharmacist advice is often requested on the use of these agents for the management of T2DM; however, this is an area that has insufficient evidence to support confident recommendations. Many published studies involving herbal agents and dietary supplements are small and poorly designed, with heterogeneous results. Pharmacists should be aware of the safety and efficacy data available for these agents, recognize potential drug interactions, and identify acceptable manufactured products.

CONCLUSION

The strongest scientific evidence for blood glucose lowering effect is associated with alpha-lipoic acid and fenugreek. There is also good evidence supporting the use of ivy gourd, gymnema, and vitamin E for management of hyperglycemia; however, caution should be used when recommending vitamin E. Pharmacists should advise consumers to disclose use of any of these products to all of their health care providers.

Effects of supplementation with the fat-soluble vitamins E and D on fasting flow-mediated vasodilation in adults: a meta-analysis of randomized controlled trials

The effects of fat-soluble vitamin supplementation on cardiovascular disease (CVD) risk are not clear. Therefore, we performed a meta-analysis to quantify effects of fat-soluble vitamin supplements on fasting flow-mediated vasodilation (FMD) of the brachial artery, a validated marker to assess CVD risk. Randomized placebo-controlled trials (RCTs) were identified by a systematic search till July 2014. Seven RCTs studying the effects of vitamin E supplements (range: 300 to 1800 IU per day) and nine RCTs examining the effects of vitamin D supplements, that involved, respectively, 303 and 658 adults, were included. No studies with carotenoid or vitamin K supplements were found. Vitamin E supplementation increased FMD vs. control by 2.42% (95% CI: 0.46% to 4.37%; p = 0.015). No effects of vitamin D supplementation were found (0.15%; 95% CI: −0.21% to 0.51%; p = 0.41). These effects did not depend on subject characteristics, treatment characteristics or technical aspects of the FMD measurement. However, no dose-response relationship was evident for vitamin E, statistical significance depended on one study, while the levels of supplement were far above recommended intakes. The current meta-analysis, therefore, does not provide unambiguous evidence to support the use of fat-soluble vitamin supplements to improve fasting FMD in adults.

Mitochondrial dysfunction and insulin resistance: an update

Mitochondrial dysfunction has been implicated in the development of insulin resistance (IR); however, a large variety of association and intervention studies as well as genetic manipulations in rodents have reported contrasting results. Indeed, even 39 years after the first publication describing a relationship between IR and diminished mitochondrial function, it is still unclear whether a direct relationship exists, and more importantly if changes in mitochondrial capacity are a cause or consequence of IR. This review will take a journey through the past and summarise the debate about the occurrence of mitochondrial dysfunction and its possible role in causing decreased insulin action in obesity and type 2 diabetes. Evidence is presented from studies in various human populations, as well as rodents with genetic manipulations of pathways known to affect mitochondrial function and insulin action. Finally, we have discussed whether mitochondria are a potential target for the treatment of IR.

Vitamins and type 2 diabetes mellitus

The present review evaluates the relationship between type 2 diabetes mellitus and individual or combined vitamins. Antioxidant vitamins A, C and E are found decreased in diabetic subjects, possibly due to an increased need to control the excessive oxidative stress produced by abnormalities in glucose metabolism. On the other hand, retinol binding protein exerts a modulating effect, as it has adipokine functions. With respect to the B group vitamins, thiamin, pyridoxine and biotin have been found decreased but the mechanisms are not clear, however supplementation has shown some improvement of the metabolic control in diabetic patients. The absorption of folic acid and vitamin B12 is importantly decreased by the prolongued use of metformin, which is the first choice drug in uncomplicated diabetes, thus these two nutrients have been found deficient in the disease and most probably need to be supplemented regularly. On the other hand, vitamin D is considered a risk factor for the development of diabetes as well as its complications, particularly cardiovascular ones. Although some studies have found an association of vitamin K intake with glucose metabolism further research is needed. Studies on the use of multivitamin supplements have shown unconclusive results. After reviewing the evidence, no real recommendation on the use of vitamin supplements in type 2 diabetes mellitus can be issued, however patients using metformin during prolongued periods may need folic acid and vitamin B12.

Current experience in testing mitochondrial nutrients in disorders featuring oxidative stress and mitochondrial dysfunction: rational design of chemoprevention trials

An extensive number of pathologies are associated with mitochondrial dysfunction (MDF) and oxidative stress (OS). Thus, mitochondrial cofactors termed "mitochondrial nutrients" (MN), such as α-lipoic acid (ALA), Coenzyme Q10 (CoQ10), and l-carnitine (CARN) (or its derivatives) have been tested in a number of clinical trials, and this review is focused on the use of MN-based clinical trials. The papers reporting on MN-based clinical trials were retrieved in MedLine up to July 2014, and evaluated for the following endpoints: (a) treated diseases; (b) dosages, number of enrolled patients and duration of treatment; (c) trial success for each MN or MN combinations as reported by authors. The reports satisfying the above endpoints included total numbers of trials and frequencies of randomized, controlled studies, i.e., 81 trials testing ALA, 107 reports testing CoQ10, and 74 reports testing CARN, while only 7 reports were retrieved testing double MN associations, while no report was found testing a triple MN combination. A total of 28 reports tested MN associations with "classical" antioxidants, such as antioxidant nutrients or drugs. Combinations of MN showed better outcomes than individual MN, suggesting forthcoming clinical studies. The criteria in study design and monitoring MN-based clinical trials are discussed.

Alpha-lipoic acid as a pleiotropic compound with potential therapeutic use in diabetes and other chronic diseases

Alpha-lipoic acid is a naturally occurring substance, essential for the function of different enzymes that take part in mitochondria's oxidative metabolism. It is believed that alpha-lipoic acid or its reduced form, dihydrolipoic acid have many biochemical functions acting as biological antioxidants, as metal chelators, reducers of the oxidized forms of other antioxidant agents such as vitamin C and E, and modulator of the signaling transduction of several pathways. These above-mentioned actions have been shown in experimental studies emphasizing the use of alpha-lipoic acid as a potential therapeutic agent for many chronic diseases with great epidemiological as well economic and social impact such as brain diseases and cognitive dysfunctions like Alzheimer disease, obesity, nonalcoholic fatty liver disease, burning mouth syndrome, cardiovascular disease, hypertension, some types of cancer, glaucoma and osteoporosis. Many conflicting data have been found concerning the clinical use of alpha-lipoic acid in the treatment of diabetes and of diabetes-related chronic complications such as retinopathy, nephropathy, neuropathy, wound healing and diabetic cardiovascular autonomic neuropathy. The most frequent clinical condition in which alpha-lipoic acid has been studied was in the management of diabetic peripheral neuropathy in patients with type 1 as well type 2 diabetes. Considering that oxidative stress, a imbalance between pro and antioxidants with excessive production of reactive oxygen species, is a factor in the development of many diseases and that alpha-lipoic acid, a natural thiol antioxidant, has been shown to have beneficial effects on oxidative stress parameters in various tissues we wrote this article in order to make an up-to-date review of current thinking regarding alpha-lipoic acid and its use as an antioxidant drug therapy for a myriad of diseases that could have potential benefits from its use.

Micronutrient status in type 2 diabetes: a review

Type 2 diabetes is characterized by significant losses of important micronutrients due to metabolic basis of the disease and its complications. Evidence of changes in trace mineral and vitamin metabolism as a consequence of type 2 diabetes is reviewed in this chapter. This review is not a meta-analysis but an overview of the micronutrient status, metabolic needs, and potential micronutrient requirements in type 2 diabetics. This chapter will not concentrate on vitamin D and type 2 diabetes as this is a topic that has been extensively reviewed before. The less well-known micronutrients notably zinc, magnesium, chromium, copper, manganese, iron, selenium, vanadium, B-group vitamins, and certain antioxidants are assessed. While some evidence is available to demonstrate the positive influence of micronutrient supplementation on glycemic control, much remains to be investigated. Additional research is necessary to characterize better biomarkers of micronutrient status and requirements in type 2 diabetics. The optimal level of micronutrient supplementation to achieve glucose homeostasis in type 2 diabetics remains a challenge.

Influence of vitamin E supplementation on glycaemic control: a meta-analysis of randomised controlled trials

Observational studies have revealed that higher serum vitamin E concentrations and increased vitamin E intake and vitamin E supplementation are associated with beneficial effects on glycaemic control in type 2 diabetes mellitus (T2DM). However, whether vitamin E supplementation exerts a definitive effect on glycaemic control remains unclear. This article involves a meta-analysis of randomised controlled trials of vitamin E to better characterise its impact on HbA1c, fasting glucose and fasting insulin. PubMed, EMBASE and the Cochrane Library were electronically searched from the earliest possible date through April 2013 for all relevant studies. Weighted mean difference (WMD) was calculated for net changes using fixed-effects or random-effects models. Standard methods for assessing statistical heterogeneity and publication bias were used. Fourteen randomised controlled trials involving individual data on 714 subjects were collected in this meta-analysis. Increased vitamin E supplementation did not result in significant benefits in glycaemic control as measured by reductions in HbA1c, fasting glucose and fasting insulin. Subgroup analyses revealed a significant reduction in HbA1c (-0.58%, 95% CI -0.83 to -0.34) and fasting insulin (-9.0 pmol/l, 95% CI -15.90 to -2.10) compared with controls in patients with low baseline vitamin E status. Subgroup analyses also demonstrated that the outcomes may have been influenced by the vitamin E dosage, study duration, ethnic group, serum HbA1c concentration, and fasting glucose control status. In conclusion, there is currently insufficient evidence to support a potential beneficial effect of vitamin E supplementation on improvements of HbA1c and fasting glucose and insulin concentrations in subjects with T2DM.

The role of antioxidants and other agents in alleviating hyperglycemia mediated oxidative stress and injury in liver

Several antioxidants and agents having similar antioxidant effects are known to exert beneficial effects in ameliorating the injurious effects of hyperglycemia on liver in different diabetic in vitro and in vivo models. The review deals with some of the agents which have been shown to exert protective effects on liver against hyperglycemic insult and the various mechanisms involved. The different classes of agents which protect the diabetic liver or decrease the severity of hyperglycemia mediated injury include flavonoids, catechins, and other polyphenolic compounds, curcumin and its derivatives, certain vitamins, hormones and drugs, trace elements, prototypical antioxidants and amino acids. Some of the pronounced changes mediated by the antioxidants in liver exposed to hyperglycemia include decreased oxidative stress, and alterations in carbohydrate and lipid metabolism. Other mechanisms through which the agents ameliorate hyperglycemia mediated liver injury include decrease in oxidative DNA and protein damage, restoration of mitochondrial structural and functional integrity, decrease in inflammation and improved insulin signaling. Thus, antioxidants may prove to be an important mode of defense in maintaining normal hepatic functions in diabetes.

Selenium inadequacy is not associated with oxidative stress in child and adolescent acute lymphocytic leukemia survivors

OBJECTIVE

Acute lymphocytic leukemia (ALL) and its subsequent treatment may provoke increased oxidative stress. The aim of this study was to investigate the antioxidant status of children and adolescents who had received ALL therapy, and to test the hypothesis that selenium (Se) inadequacy is correlated with reduced defenses against oxidative stress in this population.

METHODS

This case-control study involved 24 patients between ages 5 and 13 y who had been treated successfully for ALL (ALL group) and 60 children of similar age and socioeconomic background with no clinical history of leukemia (control group). Dietary intake of Se was evaluated by the 24-h recall method, and the concentrations of Se in plasma, erythrocytes, and urine determined. Antioxidant status was assessed by analysis of the oxidative stress markers, namely, superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), α-tocopherol, and 8-oxo-deoxyguanosine (8-oxo-dG).

RESULTS

There were no between-group differences with respect to plasma (P = 0.122), erythrocyte (P = 0.202), urinary (P = 0.608), or dietary (P = 0.757) levels of Se. GPx activity was significantly (P < 0.001) reduced in the ALL group compared with the control group, whereas SOD activity and MDA concentrations were similar. The concentrations of α-tocopherol and 8-oxo-dG were significantly increased in the ALL group compared with the control group (P < 0.001 and P = 0.031, respectively).

CONCLUSION

All participants were Se inadequate, but such inadequacy was not correlated with reduced defenses against oxidative stress. However, individuals of the ALL group were with increased oxidative stress compared with the control group, possibly due to previous disease and to intensive polychemotherapy.

Nutritional supplements for diabetes sold on the internet: business or health promotion?

Background

Diabetes is one of the most widespread chronic disease. Although many medications are available for the treatment and prevention of diabetes, many people turn to nutritional supplements (NSs). In these years, the online sales have contributed to the growth of use of nutritional supplement. The aim of the research was to investigate the type of information provided by sales websites on NSs, and analyse the existence of scientific evidence about some of the most common ingredients found in available NSs for diabetes.

Methods

A web search was conducted in April 2012 to identify web sites selling NSs in the treatment of diabetes using Google, Yahoo and Bing! and the key word used was “diabetes nutritional supplements”. Website content was evaluated for the quality of information available to consumers and for the presence of a complete list of ingredients in the first NS suggested by the site. Subsequently, in order to analyze the scientific evidence on the efficacy of these supplements a PubMed search was carried out on the ingredients that were shared in at least 3 nutritional supplements.

Results

A total of 10 websites selling NSs were selected. Only half of the websites had a Food and Drug Administration disclaimer and 40% declared clearly that the NS offered was not a substitute for proper medication. A total of 10 NS ingredients were searched for on PubMed. Systematic reviews, meta-analyses or randomized control trials were present for all the ingredients except one. Most of the studies, however, were of poor quality and/or the results were conflicting.

Conclusions

Easy internet access to NSs lacking in adequate medical information and strong scientific evidence is a matter of public health concern, mainly considering that a misleading information could lead to an improper prevention both in healthy people and people suffering from diabetes. There is a clear need for more trials to assess the efficacy and safety of these NSs, better quality control of websites, more informed physicians and greater public awareness of these widely used products.

The effect of lipoic acid and vitamin E therapies in individuals with the metabolic syndrome

The metabolic syndrome is associated with abnormal glucose and lipid metabolism, insulin resistance, increased oxidative stress and pro-inflammatory activity that increase the risk of type 2 diabetes and cardiovascular disease. The aim of this study was to investigate the effect of treatment with the antioxidant α-lipoic acid (ALA) with or without vitamin E supplementation, on markers of insulin resistance and systemic inflammation and plasma nonesterified fatty acid (NEFA) concentrations in individuals with the metabolic syndrome. In a randomized, double-blind, placebo-controlled trial, subjects with the metabolic syndrome received ALA (600 mg/day, n = 34), vitamin E (100 IU/day, n = 36), both ALA and vitamin E (n = 41), or matching placebo (n = 40) for 1 year. Fasting circulating concentrations of glucose and insulin were measure every 3 months and NEFA, markers of inflammation, adiponectin and vitamin E were measured at 6 monthly intervals. Plasma NEFA concentrations decreased [-10 (-18, 0)%] at a marginal level of significance (p = 0.05) in those who received ALA alone compared with placebo and decreased [-8 (-14, -1)% (95% CI)] significantly (P = 0.02) in participants who were randomised to ALA with and without vitamin E compared with those who did not receive ALA. Fasting glucose, insulin, homeostatic model assessment of insulin resistance, adiponectin, and markers of inflammation did not change significantly during the study. These data suggest that prolonged treatment with ALA may modestly reduce plasma NEFA concentrations but does not alter insulin or glucose levels in individuals with the metabolic syndrome.

A prescribed Chinese herbal medicine improves glucose profile and ameliorates oxidative stress in Goto-Kakisaki rats fed with high fat diet

Oxidative stress (OS) plays a role in hyperglycemia induced islet β cell dysfunction, however, studies on classic anti-oxidants didn’t show positive results in treating diabetes. We previously demonstrated that the prescribed Chinese herbal medicine preparation “Qing Huo Yi Hao” (QHYH) improved endothelial function in type 2 diabetic patients. QHYH protected endothelial cells from high glucose-induced damages by scavenging superoxide anion and reducing production of reactive oxygen species. Its active component protected C2C12 myotubes against palmitate-induced oxidative damage and mitochondrial dysfunction. In the present study, we investigated whether QHYH protected islet β cell function exacerbated by high fat diet (HFD) in hyperglycemic GK rats. 4-week-old male rats were randomly divided into high HFD feeding group (n = 20) and chow diet feeding group (n = 10). Each gram of HFD contained 4.8 kcal of energy, 52% of which from fat. Rats on HFD were further divided into 2 groups given either QHYH (3 ml/Kg/d) or saline through gastric tube. After intervention, serum glucose concentrations were monitored; IPGTTs were performed without anesthesia on 5 fasting rats randomly chosen from each group on week 4 and 16. Serum malondialdehyde (MDA) concentrations and activities of serum antioxidant enzymes were measured on week 4 and 16. Islet β cell mass and OS marker staining was done by immunohistochemistry on week 16. QHYH prevented the exacerbation of hyperglycemia in HFD feeding GK rats for 12 weeks. On week 16, it improved the exacerbated glucose tolerance and prevented the further loss of islet β cell mass induced by HFD. QHYH markedly decreased serum MDA concentration, increased serum catalase (CAT) and SOD activities on week 4. However, no differences of serum glucose concentration or OS were observed on week 16. We concluded that QHYH decreased hyperglycemia exacerbated by HFD in GK rats by improving β cell function partly via its antioxidant effect.