Effects of oral α-lipoic acid administration on body weight in overweight or obese subjects: a crossover randomized, double-blind, placebo-controlled trial

Alpha-lipoic acid on intermediate disease markers in overweight or obese adults: a systematic review and meta-analysis

OBJECTIVES

To evaluate the associations between alpha-lipoic acid (ALA) intake and intermediate disease markers in overweight or obese adults.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, EMBASE, Medline, APA PsycINFO, SocINDEX, CINAHL, SSRN, SocArXiv, PsyArXiv, medRxiv, and Google Scholar (from inception to October 2024).

ELIGIBILITY CRITERIA

This study included English-language randomised controlled trials (RCTs) on adults (body mass index ≥25 kg/m²) to assess the impact of ALA on intermediate disease markers. Studies lacking outcome data, duplicates or inaccessible full texts were excluded.

DATA EXTRACTION AND SYNTHESIS

Paired reviewers independently extracted the data. We used frequentist meta-analysis to summarise the evidence, employing the DerSimonian and Laird estimator to account for heterogeneity across study designs, settings and measurement methods. Heterogeneity was assessed via the I² statistic with CIs and τ² values. The risk of bias was independently assessed by two reviewers according to the Cochrane Handbook, covering domains such as randomisation, blinding and data completeness. Publication bias was assessed using Begg's test, while funnel plots and Egger's test were applied to outcomes with 10 or more studies.

RESULTS

This meta-analysis included 11 RCTs from an initial screening of 431 studies, encompassing a total of 704 adults. The meta-analysis results revealed no significant associations were detected between ALA supplementation and changes in intermediate disease markers, including triglyceride (TG) (standardised mean difference (SMD): -0.08, 95% CI: -0.24 to 0.09, p=0.36, I²=0.00%, τ²=0.00), total cholesterol (TC) (SMD: 0.08, 95% CI: -0.55 to 0.71, p=0.80, I²=87.50%, τ²=0.52), high-density lipoprotein cholesterol (HDL-C) (SMD: -0.05, 95% CI: -0.22 to 0.11, p=0.52, I²=0.00%, τ²=0.00), low-density lipoprotein cholesterol (LDL-C) (SMD: -0.13, 95% CI: -0.40 to 0.15, p=0.37, I²=0.00%, τ²=0.00), homeostasis model assessment of insulin resistance (HOMA-IR) (SMD: -0.23, 95% CI: -0.60 to 0.15, p=0.23, I²=26.20%, τ²=0.05) and fasting blood glucose (FBS) (SMD: 0.13, 95% CI: -0.16 to 0.41, p=0.39, I²=29.40%, τ²=0.04). According to the Grading of Recommendations Assessment, Development and Evaluation bias assessment approach, eight studies were rated as having low bias (grade A), and three studies were rated as having moderate bias (grade B). Begg's test indicated no evidence of publication bias.

CONCLUSIONS

No significant associations were detected between ALA intake and intermediate disease markers, including TG, TC, HDL-C, LDL-C, HOMA-IR and FBS levels, in overweight or obese adults. Further research is needed to explore the potential associations of ALA, especially in high-risk populations with metabolic disorders, by employing longer intervention durations, higher dosages and optimised formulations.

PROSPERO REGISTRATION NUMBER

CRD42023450239.

The effects of alpha-lipoic acid transdermal patch for local subcutaneous fat reduction: A randomized, placebo-controlled, clinical trial in overweight volunteers

Background

Combating obesity is challenging, as anti-obesity compounds lose effectiveness or cause severe side effects when delivered via conventional routes. Thus, there is a need for new, effective treatment routes that are home-based and safe for long-term use. This double-blind, placebo-controlled clinical trial aimed to investigate the efficacy of a biocellulose transdermal patch containing α-lipoic acid (ALA), an anti-obesity compound, in reducing subcutaneous fat accumulation.

Methods

One hundred and sixteen overweight participants (average age 37.96 ± 7.80 years) were recruited for the study. They were randomly assigned to apply either the calcium citrate nanoparticle-encapsulated ALA transdermal patch or a placebo on their arm. The participants' body weight, height, blood lipid profile (cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein), arm circumference, triceps skin fold, and subcutaneous fat thickness were recorded at baseline and at the 2-week follow-up.

Results

The mean arm circumference did not show any significant difference from baseline, whereas the triceps skinfold and subcutaneous fat thickness showed a significant reduction. The 2-week treatment did not significantly alter the plasma LDL, HDL, and triglyceride levels of the participants, but it significantly reduced the total cholesterol level.

Conclusion

This study reports the successful reduction of subcutaneous fat of the calcium citrate nanoparticle-encapsulated ALA transdermal patches. The transdermal patches could be used as a safe and effective home-based solution for combating obesity.

Alpha-Lipoic Acid Induces Adipose Tissue Browning through AMP-Activated Protein Kinase Signaling in Vivo and in Vitro

Background

AMP-activated protein kinase (AMPK) is a key enzyme for cellular energy homeostasis and improves metabolic disorders. Brown and beige adipose tissues exert thermogenesis capacities to dissipate energy in the form of heat. Here, we investigated the beneficial effects of the antioxidant alpha-lipoic acid (ALA) in menopausal obesity and the underlying mechanisms.

Methods

Female Wistar rats (8 weeks old) were subjected to bilateral ovariectomy (Ovx) and divided into four groups: Sham (n=8), Ovx (n=11), Ovx+ALA2 (n=10), and Ovx+ALA3 (n=6) (ALA 200 and 300 mg/kg/day, respectively; gavage) for 8 weeks. 3T3-L1 cells were used for in vitro study.

Results

Rats receiving ALA2 and ALA3 treatment showed significantly lower levels of body weight and white adipose tissue (WAT) mass than those of the Ovx group. ALA improved plasma lipid profiles including triglycerides, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. Hematoxylin & eosin staining of inguinal WAT showed that ALA treatment reduced Ovx-induced adipocyte size and enhanced uncoupling protein 1 (UCP1) expression. Moreover, plasma levels of irisin were markedly increased in ALA-treated Ovx rats. Protein expression of brown fat-specific markers including UCP1, PRDM16, and CIDEA was downregulated by Ovx but markedly increased by ALA. Phosphorylation of AMPK, its downstream acetyl-CoA carboxylase, and its upstream LKB1 were all significantly increased by ALA treatment. In 3T3-L1 cells, administration of ALA (100 and 250 μM) reduced lipid accumulation and enhanced oxygen consumption and UCP1 protein expression, while inhibition of AMPK by dorsomorphin (5 μM) significantly reversed these effects.

Conclusion

ALA improves estrogen deficiency-induced obesity via browning of WAT through AMPK signaling.

Alpha-lipoic acid, apocynin or probiotics influence glutathione status and selected inflammatory parameters in C57/BL6 mice when combined with a low-fat diet

BACKGROUND

The aim of the study was to determine the potential of a low-fat diet (LFD) to protect against oxidative and inflammatory damage in the course of asthma and obesity when combined with antioxidants (alpha-lipoic acid-ALA, apocynin-APO) or a probiotic (P) (Lactobacillus casei).

METHODS

The experiments were carried out on ten groups of male C57/BL6 mice that were fed standard fat (SFD), low-fat (LFD), or high-fat (HFD) diets. Ovalbumin (OVA, administered subcutaneously and by inhalation) was used to sensitize the animals. IL-1α, IL-10, eotaxin-1, leptin, and TNF-α concentrations were examined in blood, while total glutathione (GSHt), reduced glutathione (GSH), oxidized glutathione (GSSG) and -SH groups were measured in lung homogenates.

RESULTS

LFD in combination with the analyzed compounds (APO, P, ALA) significantly decreased the concentration of IL-1α compared to the OVA + HFD group (p < 0.01; p = 0.025; p = 0.002, respectively). Similarly, the treated mice demonstrated lower eotaxin-1 concentrations compared to the HFD group (p < 0.001). Moreover, supplementation of LFD with probiotics significantly increased the concentration of IL-10 vs. controls (p < 0.001) and vs. untreated OVA-sensitized and challenged/obese mice (p < 0.001). Animals administered APO/ALA with LFD displayed a significant decrease in TNF-α concentration compared to OVA + HFD mice (p = 0.013; p = 0.002 respectively). Those treated with ALA displayed significantly improved GSH levels (p = 0.035) compared to OVA + HFD mice.

CONCLUSIONS

Supplementation of the tested compounds with LFD appears to have a positive influence on the glutathione redox status of pulmonary tissues and selected inflammatory parameters in mouse blood.

Bioactive compounds in childhood obesity and associated metabolic complications: Current evidence, controversies and perspectives

Obesity represents the most frequent chronic disease among children worldwide, with a significant global burden on society. Metabolically unhealthy obesity (MUO) can affect children since their first years of life, and novel therapeutic strategies to tackle metabolic complications are under investigation. This review focuses on bioactive compounds and their possible beneficial effects on obesity, particularly omega-3, docosahexaenoic acid, vitamin D, biotics, polysaccharide macromolecules, polyphenols, inositols, alpha lipoic acid, and bromelaine. Our aim is to summarize current evidence about bioactive compounds in the treatment of obesity, highlighting recent findings on their use in children and adolescents. Most studied molecules are omega-3 and vitamin D, despite the heterogeneity between the studies. Moreover, given the emerging interest in the gut-brain axis in the link between metabolic health and microbiota, various studies on prebiotics, probiotics, synbiotics, postbiotics and polysaccharide macromolecules have been considered. Some preclinical studies seem to highlight a possible role of the polyphenols, even if their clinical evidence is still discussed. Lastly, we describe possible effects of inositols and alpha-lipoic acid. Despite some dietary supplements seem to be promising in overweight subjects, only in a few of them a dose/response efficacy has been found in the pediatric age. Innovative, well-designed and targeted clinical trials are then needed to prove the beneficial effects of these compounds that could support the standard behavioral therapy for obesity.

Alpha-Lipoic Acid and Glucose Metabolism: A Comprehensive Update on Biochemical and Therapeutic Features

Alpha-lipoic acid (ALA) is a natural compound with antioxidant and pro-oxidant properties which has effects on the regulation of insulin sensitivity and insulin secretion. ALA is widely prescribed in patients with diabetic polyneuropathy due to its positive effects on nerve conduction and alleviation of symptoms. It is, moreover, also prescribed in other insulin resistance conditions such as metabolic syndrome (SM), polycystic ovary syndrome (PCOS) and obesity. However, several cases of Insulin Autoimmune Syndrome (IAS) have been reported in subjects taking ALA. The aim of the present review is to describe the main chemical and biological functions of ALA in glucose metabolism, focusing on its antioxidant activity, its role in modulating insulin sensitivity and secretion and in symptomatic peripheral diabetic polyneuropathy. We also provide a potential explanation for increased risk for the development of IAS.

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.

Review of lipoic acid: From a clinical therapeutic agent to various emerging biomaterials

Lipoic acid (LA), an endogenous small molecule in organisms, has been extensively used for the highly efficient clinical treatment of malignant diseases, which include diabetes, Alzheimer's disease, and cancer over the past seven decades. Tremendous progresses have been made on the use of LA in nanomedicine for the development of various biomaterials because of its unique biological properties and highly adaptable structure since the first discovery. However, there are few reviews thus far, to our knowledge, summarizing this hot subject of research of LA and its derived biomaterials. For this purpose, we present herein the first comprehensive summary on the design and development of LA and its derived materials for biomedical applications. This review first discusses the therapeutic use of LA followed by the description of synthesis and preclinical study of LA-derived-small molecules. The applications of various LA and poly (lipoic acid) (PLA)-derived-biomaterials are next summarized in detail with an emphasis on the use of LA for the design of biomaterials and the diverse properties. This review describes the development of LA from a clinical therapeutic agent to a building unit of various biomaterials field, which will promote the further discovery of new therapeutic uses of LA as therapeutic agents and facile development of LA-based derivates with greater performance for biomedical applications.

Metabolic and clinical effect of alpha-lipoic acid administration in schizophrenic subjects stabilized with atypical antipsychotics: A 12-week, open-label, uncontrolled study

Background

Many of the atypical antipsychotics induce metabolic side effects, limiting their use in clinical practice. Alpha-lipoic acid (ALA) was proposed as a new approach in schizophrenia to improve metabolic effects of atypical antipsychotics. The aim of the study is to evaluate the effect of ALA on metabolic and clinical parameters among schizophrenic subjects.

Methods

15 schizophrenic subjects, in stable atypical antipsychotic monotherapy were included in the study. ALA was administrated at the oral daily dose of 600 ​mg/d in addition to antipsychotic therapy. Metabolic, clinical, and psychopathological parameters were measured at typical antipsychotics. e initial screening, and after 12 weeks.

Results

ALA produced a statistically significant reduction in QTc (p ​= ​0.012), blood glucose (p ​= 0.005), AST (p ​= ​0.021), γGT (p ​= ​0.035), CPK (p ​= ​0.005) and prolactinaemia (p ​= ​0.026). In contrast, there was a significant increase in HbA1c (p ​= ​0.026). No effects on body weight and blood lipid levels (triglycerides, total cholesterol, HDL, LDL) emerged.

Conclusions

ALA treatment appeared to be effective for reducing diabetes risk, liver functionality parameters, hyperprolactinaemia and QTC interval. ALA appears to be safe as adjunctive components in schizophrenia.

Diverse impact of N-acetylcysteine or alpha-lipoic acid supplementation during high-fat diet regime on fatty acid transporters in visceral and subcutaneous adipose tissue

PURPOSE

Adipose tissue's (AT) structural changes accompanying obesity may alter lipid transport protein expression and, thus, the fatty acids (FAs) transport and lipid balance of the body. Metabolic abnormalities within AT contribute to the elevated production of reactive oxygen species and increased oxidative/nitrosative stress. Although compounds such as N-acetylcysteine (NAC) and α-lipoic acid (ALA), which restore redox homeostasis, may improve lipid metabolism in AT, the mechanism of action of these antioxidants on lipid metabolism in AT is still unknown. This study aimed to examine the impact of NAC and ALA on the level and FA composition of the lipid fractions, and the expression of FA transporters in the visceral and subcutaneous AT of high-fat diet-fed rats.

MATERIALS AND METHODS

Male Wistar rats were randomly divided into four groups. The mRNA levels and protein expression of FA transporters were assessed using real-time PCR and Western Blot analyses. The collected samples were subjected to histological evaluation. The level of lipids (FFA, DAG, and TAG) was measured using gas-liquid chromatography.

RESULTS

We found that antioxidants affect FA transporter expressions at both the transcript and protein levels, and, therefore, they promote changes in AT's lipid pools. One of the most remarkable findings of our research is that different antioxidant molecules may have a varying impact on AT phenotype.

CONCLUSION

NAC and ALA exert different influences on AT, which is reflected in histopathological images, FA transport proteins expression patterns, or even the lipid storage capacity of adipocytes.

Chitosan Nanoparticles Containing Lipoic Acid with Antioxidant Properties as a Potential Nutritional Supplement

Simple Summary

Alfa-lipoic acid (ALA) is an important antioxidant that could be added to animal feed as a nutritional supplement. To improve its stability in the digestive system, ALA was encapsulated in chitosan nanoparticles. The nanoparticles containing ALA were stable in stomach-like conditions and were able to cross the intestinal barrier. Chitosan-based nanoparticles seem to be an attractive administration method for antioxidants, or other sensible additives, in food.

Abstract

The addition of the antioxidant α-lipoic acid (ALA) to a balanced diet might be crucial for the prevention of comorbidities such as cardiovascular diseases, diabetes, and obesity. Due to its low half-life and instability under stomach-like conditions, α-lipoic acid was encapsulated into chitosan nanoparticles (Ch-NPs). The resulting chitosan nanoparticles containing 20% w/w ALA (Ch-ALA-NPs) with an average diameter of 44 nm demonstrated antioxidant activity and stability under stomach-like conditions for up to 3 h. Furthermore, fluorescent Ch-ALA-NPs were effectively internalized into 3T3-L1 fibroblasts and were able to cross the intestinal barrier, as evidenced by everted intestine in vitro experiments. Thus, chitosan-based nanoparticles seem to be an attractive administration method for antioxidants, or other sensible additives, in food.

Alpha-lipoic acid did not affect lipid profile and blood pressure in critically ill patients: A randomized, double-blind clinical trial

BACKGROUND: Some researchers suggested a positive effect of Alpha-Lipoic Acid (ALA) on Blood Pressure (BP) and lipid profile. OBJECTIVE: The aim of this study was to determine the efficacy of ALA for improving BP and lipid profile in critically ill patients. METHODS: In the present study, eighty patients (aged 18–80 years old) were randomly assigned to receive daily either ALA (600 mg/day) or placebo for eight weeks. Systolic BP (SBP), Diastolic BP (DBP), Triglyceride (TG), Total cholesterol (TC), Low Density Lipoprotein (LDL), and High Density Lipoprotein (HDL) were measured before and after intervention. RESULTS: LDL decreased significantly in the ALA group (110.6±34.9 vs. 107.9±33.4 mg/dl; P <  0.05). There was also a significant difference in terms of HDL in both groups (Δ= +1.8 vs. Δ= –0.3 mg/dl; P <  0.05). A marginal non-significant reduction was also observed for SBP. There were no significant differences in other variables between the two groups. CONCLUSIONS: ALA supplementation did not improve the BP and some serum lipid markers in critically ill patients. Larger and longer trials will be needed to determine efficacy of ALA.

Mechanics Insights of Alpha-Lipoic Acid against Cardiovascular Diseases during COVID-19 Infection

Coronavirus disease 2019 (COVID-19) was first reported in Wuhan, China, in late December 2019. Since then, COVID-19 has spread rapidly worldwide and was declared a global pandemic on 20 March 2020. Cardiovascular complications are rapidly emerging as a major peril in COVID-19 in addition to respiratory disease. The mechanisms underlying the excessive effect of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on patients with cardiovascular comorbidities remain only partly understood. SARS-CoV-2 infection is caused by binding of the viral surface spike (S) protein to the human angiotensin-converting enzyme 2 (ACE2), followed by the activation of the S protein by transmembrane protease serine 2 (TMPRSS2). ACE2 is expressed in the lung (mainly in type II alveolar cells), heart, blood vessels, small intestine, etc., and appears to be the predominant portal to the cellular entry of the virus. Based on current information, most people infected with SARS-CoV-2 virus have a good prognosis, while a few patients reach critical condition, especially the elderly and those with chronic underlying diseases. The "cytokine storm" observed in patients with severe COVID-19 contributes to the destruction of the endothelium, leading to "acute respiratory distress syndrome" (ARDS), multiorgan failure, and death. At the origin of the general proinflammatory state may be the SARS-CoV-2-mediated redox status in endothelial cells via the upregulation of ACE/Ang II/AT1 receptors pathway or the increased mitochondrial reactive oxygen species (mtROS) production. Furthermore, this vicious circle between oxidative stress (OS) and inflammation induces endothelial dysfunction, endothelial senescence, high risk of thrombosis and coagulopathy. The microvascular dysfunction and the formation of microthrombi in a way differentiate the SARS-CoV-2 infection from the other respiratory diseases and bring it closer to cardiovascular diseases like myocardial infarction and stroke. Due the role played by OS in the evolution of viral infection and in the development of COVID-19 complications, the use of antioxidants as adjuvant therapy seems appropriate in this new pathology. Alpha-lipoic acid (ALA) could be a promising candidate that, through its wide tissue distribution and versatile antioxidant properties, interferes with several signaling pathways. Thus, ALA improves endothelial function by restoring the endothelial nitric oxide synthase activity and presents an anti-inflammatory effect dependent or independent of its antioxidant properties. By improving mitochondrial function, it can sustain the tissues' homeostasis in critical situation and by enhancing the reduced glutathione it could indirectly strengthen the immune system. This complex analysis could open a new therapeutic perspective for ALA in COVID-19 infection.

α-Lipoic Acid Alleviates Hepatic Lipid Deposition by Inhibiting FASN Expression via miR-3548 in Rats

Excessive liver lipid deposition is a vital risk factor for the development of many diseases. Here, we fed Sprague-Dawley rats with a control or α-lipoic acid-supplemented diet (0.2%) for 5 weeks to elucidate the effects of α-lipoic acid on preventive ability, hepatic lipid metabolism-related gene expression, and the involved regulatory mechanisms. In the current study, α-lipoic acid supplementation lowered plasma triglyceride level and hepatic triglyceride content. Reduced hepatic lipid deposition was closely associated with inhibiting fatty acid-binding protein 1 and fatty acid synthase expression, as well as increasing phosphorylated hormone-sensitive lipase expression at the protein level in α-lipoic acid-exposed rats. Hepatic miRNA sequencing revealed increased expression of miR-3548 targeting the 3'untranslated region of Fasn mRNA, and the direct regulatory link between miRNA-3548 and FASN was verified by dual-luciferase reporter assay. Taken together, α-lipoic acid lowered hepatic lipid accumulation, which involved changes in miRNA-mediated lipogenic genes.

Effects of alpha lipoic acid on iron overload, lipid profile and oxidative stress indices in β-thalassemia major patients: A cross-over randomised controlled clinical trial

AIMS

β-Thalassemia major (β-TM) is associated with iron overload, abnormal lipid levels and oxidative stress. Alpha lipoic acid (ALA) showed anti-oxidant and iron chelating properties, but its effect in β-TM patients is unclear. We investigated the effects of ALA on iron levels, lipid profile and oxidative stress.

METHODS

In this cross-over randomised clinical trial, 26 β-TM patients were assigned to receive 600 mg/d ALA or placebo (corn starch), for 8 weeks with a 21-days washout period. Serum ferritin, total cholesterol, triglycerides, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C, total antioxidant capacity, malondialdehyde (MDA) and MDA/LDL-C were assessed at baseline and the end of each intervention phase.

RESULTS

Twenty-two patients completed the study. Serum ferritin (P = .004), MDA (P = .025) and MDA/LDL-C ratio (P =.002) were decreased and HDL-C (P =.035) increased significantly during ALA consumption. In comparison with placebo, ALA decreased the serum ferritin significantly (P = .02). Also, the changes in serum ferritin between ALA and placebo (-123.1 ± 40.0 vs -34.3 ± 21.0, P =.03) was significant in women subgroup. ALA had no significant effects on the other biomarkers.

CONCLUSION

The results of this study indicated that supplementation with 600 mg/d ALA may decrease serum ferritin in β-TM. Further studies are needed to confirm the findings.

The Role of AMPK Signaling in Brown Adipose Tissue Activation

Obesity is becoming a pandemic, and its prevalence is still increasing. Considering that obesity increases the risk of developing cardiometabolic diseases, research efforts are focusing on new ways to combat obesity. Brown adipose tissue (BAT) has emerged as a possible target to achieve this for its functional role in energy expenditure by means of increasing thermogenesis. An important metabolic sensor and regulator of whole-body energy balance is AMP-activated protein kinase (AMPK), and its role in energy metabolism is evident. This review highlights the mechanisms of BAT activation and investigates how AMPK can be used as a target for BAT activation. We review compounds and other factors that are able to activate AMPK and further discuss the therapeutic use of AMPK in BAT activation. Extensive research shows that AMPK can be activated by a number of different kinases, such as LKB1, CaMKK, but also small molecules, hormones, and metabolic stresses. AMPK is able to activate BAT by inducing adipogenesis, maintaining mitochondrial homeostasis and inducing browning in white adipose tissue. We conclude that, despite encouraging results, many uncertainties should be clarified before AMPK can be posed as a target for anti-obesity treatment via BAT activation.

Epigenetics in NAFLD/NASH: Targets and therapy

Recently non-alcoholic fatty liver disease (NAFLD) has grabbed considerable scientific attention, owing to its rapid increase in prevalence worldwide and growing burden on end-stage liver diseases. Metabolic syndrome including obesity, diabetes, and hypertension poses a grave risk to NAFLD etiology and progression. With no drugs available, the mainstay of NAFLD management remains lifestyle changes with exercise and dietary modifications. Nonselective drugs such as metformin, thiazolidinediones (TZDs), ursodeoxycholic acid (UDCA), silymarin, etc., are also being used to target the interrelated pathways for treating NAFLD. Considering the enormous disease burden and the unmet need for drugs, fresh insights into pathogenesis and drug discovery are required. The emergence of the field of epigenetics offers a convincing explanation for the basis of lifestyle, environmental, and other risk factors to influence NAFLD pathogenesis. Therefore, understanding these epigenetic modifications to target the primary cause of the disease might prove a rational strategy to prevent the disease and develop novel therapeutic interventions. Apart from describing the role of epigenetics in the pathogenesis of NAFLD as in other reviews, this review additionally provides an elaborate discussion on exploiting the high plasticity of epigenetic modifications in response to environmental cues, for developing novel therapeutics for NAFLD. Besides, this extensive review provides evidence for epigenetic mechanisms utilized by several potential drugs for NAFLD.

Alpha-lipoic acid: A possible pharmacological agent for treating dry eye disease and retinopathy in diabetes

Alpha-lipoic acid (ALA) is a naturally occurring dithiol micronutrient which acts as a cofactor for mitochondrial enzyme activity. Due to its potential antioxidant activity, it is considered as "universal antioxidant". Previous studies reported the pharmacological benefits of ALA such as glycaemic control, improved insulin sensitivity and alleviation of diabetic complications such as neuropathy and cardiovascular diseases. Dry eye disease and retinopathy are prevalent in diabetic patients. Experimental studies demonstrated the beneficial effects of ALA in dry eye and diabetic retinopathy. ALA can prevent the dry eye by down regulating the expression of matrix metalloproteinase-9 in the corneal epithelial cells and activating the antioxidant status of the ocular surface. Furthermore, its direct antioxidant effect can also prevent oxidative stress-induced corneal surface erosion and lachrymal gland damage. ALA prevents diabetic retinopathy through inhibition of O-linked β-N-acetylglucosamine transferase and nuclear factor-kappa B activity and alleviation of oxidative stress. It can activate the nuclear factor erythroid-2-related factor 2 and AMP-activated protein kinase in retinal ganglion cells. Clinical trials conducted in pre-retinopathic diabetic patients showed ALA with genistein and vitamins could protect the retinal cells and decline the inflammatory effect in diabetic patients. However, studies are scant to explore its beneficial effects in dry eye disease and diabetic retinopathy. Therefore, this review article discusses an update on the role of ALA in dry eye disease and diabetic retinopathy, two ocular diseases prevalent in diabetic patients.

Alpha-lipoic acid supplementation significantly reduces the risk of obesity in an updated systematic review and dose response meta-analysis of randomised placebo-controlled clinical trials

BACKGROUND

There are numerous trials reported the effect of alpha-lipoic acid (ALA) on obesity measurements; while no summarised dose-response meta-analysis is available to address the effects of dose and duration of ALA supplementation on obesity measurements. We aimed to summarise the results of studies evaluating the effects of ALA supplementation on obesity measurements in a systematic review and dose-response meta-analysis.

METHODS AND MATERIALS

In a systematic search from Scopus, PubMed, Embase, Proquest electronic databases up to January 2020 relevant studies were retrieved. Randomised, placebo-controlled trials investigating the effect of ALA supplementation on obesity measurements including weight, body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and fat mass (FM) were included. Two class and dose-response meta-analysis were performed to data analysis.

RESULTS

Totally, 18, 21 and 8 studies were included for the meta-analysis of ALA-weight, ALA-BMI, ALA-WC, respectively. In the two-class meta-analysis, ALA treatment significantly reduced weight (WMD: -2.29 kg, 95% CI: -2.98, 1.60, P < .01) and BMI (WMD: -0.49 kg/m² , 95% CI:-0.83,-0.15, P = .005) but no effect on WC (WMD: -2.57 cm, 95% CI: -8.91, 3.76; P = .426). While the dose-response meta-analysis revealed that the duration of ALA treatment is a significant factor affecting WC reduction (P_{non-linearity}  = .047). While no evidence of departure from linearity was observed for other variables; moreover, subgrouping also revealed that gender could be an important factor affecting the ALA impact on WC which was significant among women (WMD: -4.099; CI: -7.837, -0.361; P = .032).

CONCLUSION

According to our finding, ALA treatment significantly reduced BMI, weight in a two-class meta-analysis without evidence of departure from linearity in terms of dose or duration. While the association of ALA treatment on WC is dependent to the duration of the study. Although further trials evaluating the other obesity measurements specially central obesity will be helpful to infer a more reliable result.

Effects of alpha lipoic acid as a supplement in obese children and adolescents

OBJECTIVES

Obesity is significantly associated with inflammatory process and oxidative stress. Alpha lipoic acid (ALA) is a potent antioxidant that has been reported for reducing weight in animals and obese adults in several studies but no data are available in pediatrics. We investigated the possible beneficial role of ALA in obese children.

PATIENTS AND METHODS

Eighty obese children and adolescents were randomized into two groups; the treatment group (n = 40) who received 300 mg of ALA twice daily for 3 months and the control group (n = 40) who received placebo for 3 months. Measurements of weight, body mass index (BMI), lipid profile, fasting blood glucose (FBG), malondialdhyde (MDA), tumor necrosis factor alpha (TNF-α), leptin and adiponectin were carried out before and 3 months after the treatment.

RESULTS

ALA treatment group had a significant reduction of the weight, BMI, MDA, TNF-α, and leptin levels but a significant increase of adiponectin level (P < 0.05) compared to the control group. However, it had no effect on FBG or lipid profile (P > 0.05).

CONCLUSION

ALA may be a promising supplement in the weight reduction in obese children and adolescents.

Alpha-lipoic acid effect on leptin and adiponectin concentrations: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

New evidence suggests that dysregulation of adipocytokines caused by excess adiposity plays an important role in the pathogenesis of various obesity comorbidities. Our aim in this meta-analysis was to determine the effect of alpha-lipoic acid (ALA) supplementation on serum levels of leptin and adiponectin.

METHODS

We searched Scopus, PubMed, Google Scholar, and ISI Web of Science from inception up to July 2019. Mean difference for leptin and adiponectin were calculated by subtracting the change from baseline in each study group. Summary estimates for the overall effect of ALA on serum leptin and adiponectin concentrations were calculated using random effects model. Results were presented as weighted mean difference (WMD) and their 95% confidence intervals (CI). Between-study heterogeneity was examined using the I² statistics.

RESULT

Eight studies were included in systematic review and seven studies in meta-analysis. The overall effect suggested a significant decrement in serum leptin concentrations (WMD = - 3.63; 95% CI, - 5.63, - 1.64 μg/ml; I² = 80.7%) and a significant increase in serum levels of adiponectin (WMD = 1.98 μg/ml; 95% CI, 0.92, 3.04; I² = 95.7%). Subgroup analyses based on age showed a significant reduction in leptin levels only in younger adults, and subgroup analysis based on duration indicated in studies with a duration of more than 8 weeks adiponectin levels increased significantly and leptin levels decreased significantly.

CONCLUSION

Our results revealed ALA decreased leptin and increased adiponectin especially in studies lasted more than 8 weeks. We still need more studies with different ALA dose, intervention duration, and separately on male and female.

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.

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).

Insights on the Use of α-Lipoic Acid for Therapeutic Purposes

α-lipoic acid (ALA, thioctic acid) is an organosulfur component produced from plants, animals, and humans. It has various properties, among them great antioxidant potential and is widely used as a racemic drug for diabetic polyneuropathy-associated pain and paresthesia. Naturally, ALA is located in mitochondria, where it is used as a cofactor for pyruvate dehydrogenase (PDH) and α-ketoglutarate dehydrogenase complexes. Despite its various potentials, ALA therapeutic efficacy is relatively low due to its pharmacokinetic profile. Data suggests that ALA has a short half-life and bioavailability (about 30%) triggered by its hepatic degradation, reduced solubility as well as instability in the stomach. However, the use of various innovative formulations has greatly improved ALA bioavailability. The R enantiomer of ALA shows better pharmacokinetic parameters, including increased bioavailability as compared to its S enantiomer. Indeed, the use of amphiphilic matrices has capability to improve ALA bioavailability and intestinal absorption. Also, ALA's liquid formulations are associated with greater plasma concentration and bioavailability as compared to its solidified dosage form. Thus, improved formulations can increase both ALA absorption and bioavailability, leading to a raise in therapeutic efficacy. Interestingly, ALA bioavailability will be dependent on age, while no difference has been found for gender. The present review aims to provide an updated on studies from preclinical to clinical trials assessing ALA's usages in diabetic patients with neuropathy, obesity, central nervous system-related diseases and abnormalities in pregnancy.

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.

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.

Alpha lipoic acid protects against chlorpyrifos-induced toxicity in Wistar rats via modulating the apoptotic pathway

The chronic exposure to chlorpyrifos (CPF) pesticide induces several human disorders including hepatotoxicity. Alpha-lipoic acid (ALA) is a natural antioxidant compound found in plants and animals. The present study aimed to investigate the possible protective effect of ALA against CPF-induced hepatotoxicity and the possible underlying molecular mechanism. Thirty-two male Wistar rats were divided into: Normal rats received only vehicle; ALA group received ALA (10 mg/kg, i.p.); CPF group received CPF (18 mg/kg, s.c.) and CPF-ALA group received CPF (18 mg/kg, s.c.) once daily for 14 days. The present results demonstrated that administration of ALA significantly improved liver functions (p < 0.05) and limited the histopathological lesions induced by CPF in liver tissues. Furthermore, ALA decreased hepatic malondialdehyde contents while increased the glutathione peroxidase, catalase, superoxide dismutase and acetylcholinesterase activities. Interestingly, ALA showed significant antiapoptotic effects through downregulation of Bax and Caspase-3 expression levels. In conclusion, ALA possess protective effects against CPF-induced liver injury through attenuation of apoptosis and oxidative stress.