Oral carnitine supplementation reduces body weight and insulin resistance in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

Improved insulin sensitivity and reproductive profile in overweight/obese PCOS patients undergoing integrative treatment with carnitines, L-arginine, L-cysteine and myo-inositol

OBJECTIVE

To evaluate the effects of a combination of carnitines, L-arginine, L-cysteine and myo-inositol on metabolic and reproductive parameters in PCOS overweight/obese patients.

METHODS

This was a retrospective study analyzing information of a group of PCOS (n = 25) overweight/obesity patients, not requiring hormonal treatment, selected from the database of the ambulatory clinic of the Gynecological Endocrinology Center at the University of Modena and Reggio Emilia, Modena, Italy. The hormonal profile, routine exams and insulin and C-peptide response to oral glucose tolerance test (OGTT) were evaluated before and after 12 weeks of a daily oral complementary treatment with L-carnitine (500 mg), acetyl-L-carnitine (250 mg), L-arginine (500 mg), L-cysteine (100 mg) and myo-inositol (1 gr). The hepatic insulin extraction index was also calculated.

RESULTS

The mix of complementary substances significantly improved metabolic parameters, homeostatic model assessment for insulin resistance index values and gonadotropin plasma levels. Glucose, C-peptide and insulin response to OGTT was significantly reduced as well as the hepatic insulin extraction index.

CONCLUSION

The administration of a combination of carnitines, L-arginine, L-cysteine and myoinositol improved gonadotropin plasma levels and insulin sensitivity in overweight/obese PCOS patients and restored hepatic clearance of insulin as demonstrated by the decreased hepatic insulin extraction index.

The Effect of the L-Carnitine Supplementation on Obesity Indices: An Umbrella Meta-Analysis

AIMS

Obesity, one of the most frequent health risks, represents a global public health problem. The potential impact of L-carnitine, a vital nutrient for energy metabolism, on weight loss is worth considering. However, given the inconclusive results from recent meta-analyses on L-carnitine, we conducted an umbrella meta-analysis of placebo-controlled and controlled trials to evaluate the effect of L-carnitine on anthropometric indices.

METHODS

Data synthesis: A comprehensive search approach using the relevant keywords was performed in PubMed, Web of Science, Scopus databases, and Google Scholar up to March 2023. Meta-analyses published in English that provided quantitative statistical analyses regarding the effects of L-carnitine on body weight, waist circumference (WC), and body mass index (BMI) were included. A random-effects model and subgroup analysis were performed based on the L-carnitine dosage and study population.

RESULTS

A total of 16,352 participants were included. Intervention durations ranged from 8 to 30 weeks, with L-carnitine dosages ranging between 150 and 4000 mg/day. The pooled results of the eight included meta-analyses indicated that L-carnitine supplementation can significantly decrease weight (effect size (ES) = -1.11; 95% confidence intervals (CIs): -1.90, -0.33, p = 0.005; I2 = 90.6%, p < 0.001), BMI (ES = -0.33; 95% CI: -0.61, -0.04, p = 0.026; I2 = 89.8%, p < 0.001), and WC (ES = -1.34; 95% CI: -1.83, -0.85, p < 0.001; I2 = 00.0%, p = 0.442).

CONCLUSION

The findings of this umbrella meta-analysis support that supplementation of L-carnitine supplementation can successfully manage weight, BMI, and WC reduction. Therefore, L-carnitine might help treat obesity. PROSPERO Registration Number: CRD42022307951.

Carnitine traffic and human fertility

Carnitine is a vital molecule in human metabolism, prominently involved in fatty acid β-oxidation within mitochondria. Predominantly sourced from dietary intake, carnitine also derives from endogenous synthesis. This review delves into the complex network of carnitine transport and distribution, emphasizing its pivotal role in human fertility. Together with its role in fatty acid oxidation, carnitine modulates the acety-CoA/CoA ratio, influencing carbohydrate metabolism, lipid biosynthesis, and gene expression. The intricate regulation of carnitine homeostasis involves a network of membrane transporters, notably OCTN2, which is central in its absorption, reabsorption, and distribution. OCTN2 dysfunction, results in Primary Carnitine Deficiency (PCD), characterized by systemic carnitine depletion and severe clinical manifestations, including fertility issues. In the male reproductive system, carnitine is crucial for sperm maturation and motility. In the female reproductive system, carnitine supports mitochondrial function necessary for oocyte quality, folliculogenesis, and embryonic development. Indeed, deficiencies in carnitine or its transporters have been linked to asthenozoospermia, reduced sperm quality, and suboptimal fertility outcomes in couples. Moreover, the antioxidant properties of carnitine protect spermatozoa from oxidative stress and help in managing conditions like polycystic ovary syndrome (PCOS) and endometriosis, enhancing sperm viability and fertilization potential of oocytes. This review summarizes the key role of membrane transporters in guaranteeing carnitine homeostasis with a special focus on the implications in fertility and possible treatments of infertility and other related disorders.

Morphological and Redox/Glycative Alterations in the PCOS Oviducts: Modulating Effects of Carnitines in PCOS Mice

Polycystic ovarian syndrome (PCOS) is a heterogeneous condition characterized by hyperandrogenism (HA), polycystic ovaries, and dysfunctional ovulation, and it is associated with metabolic problems such as insulin resistance (IR) and obesity. After having investigated the morphological and antioxidant/antiglycative alterations on mouse ovaries and uteri, we here focus on PCOS oviducts, a tract of the reproductive system essential for the nourishment and transport of gametes and embryos. The modulating effects of L-carnitine (LC) and acetyl-L-carnitine (ALC) were also assessed. CD1 mice were administered or not with dehydroepiandrosterone (DHEA, 6 mg/100 g body weight) for 20 days, alone or with 0.40 mg of L-carnitine (LC) and 0.20 mg of acetyl-L-carnitine (ALC). Oviducts were then subjected to histology and immunohistochemistry to evaluate their morphology and collagen deposition, and steroidogenesis. Oxidative, mitochondrial, and methylglyoxal (MG)-dependent damage was also investigated. Transmission electron microscopy was used to detect ultrastructural alterations. The PCOS oviducts were affected by hyperfibrosis, hyperplasia, hypertrophy, and altered steroidogenesis, with oxidative alterations associated with MethylGlyoxal-Advanced Glycation End product (MG-AGE) accumulation. A reduced ciliary coverage and numerous dilated intercellular spaces were found in the epithelium. LC-ALC administration mitigated PCOS oviductal alterations. These results provide evidence for the detrimental action of oxidative and glycative stress in PCOS oviducts, confirming a protective role of carnitines on the PCOS phenotype.

Investigating genetic links between blood metabolites and preeclampsia

BACKGROUND

Observational studies have revealed that metabolic disorders are closely related to the development of preeclampsia (PE). However, there is still a research gap on the causal role of metabolites in promoting or preventing PE. We aimed to systematically explore the causal association between circulating metabolites and PE.

METHODS

Single nucleotide polymorphisms (SNPs) from genome-wide association study (GWAS) of 486 blood metabolites (7,824 participants) were extracted as instrumental variables (P < 1 × 10- 5), GWAS summary statistics for PE were obtained from FinnGen consortium (7,212 cases and 194,266 controls) as outcome, and a two-sample Mendelian randomization (MR) analysis was conducted. Inverse variance weighted (IVW) was set as the primary method, with MR-Egger and weighted median as auxiliary methods; the instrumental variable strength and confounding factors were also assessed. Sensitivity analyses including MR-Egger, Cochran's Q test, MR-PRESSO and leave-one-out analysis were performed to test the robustness of the MR results. For significant associations, repeated MR and meta-analysis were performed by another metabolite GWAS (8,299 participants). Furthermore, significantly associated metabolites were subjected to a metabolic pathway analysis.

RESULTS

The instrumental variables for the metabolites ranged from 3 to 493. Primary analysis revealed a total of 12 known (e.g., phenol sulfate, citrulline, lactate and gamma-glutamylglutamine) and 11 unknown metabolites were associated with PE. Heterogeneity and pleiotropy tests verified the robustness of the MR results. Validation with another metabolite GWAS dataset revealed consistency trends in 6 of the known metabolites with preliminary analysis, particularly the finding that genetic susceptibility to low levels of arachidonate (20:4n6) and citrulline were risk factors for PE. The pathway analysis revealed glycolysis/gluconeogenesis and arginine biosynthesis involved in the pathogenesis of PE.

CONCLUSIONS

This study identifies a causal relationship between some circulating metabolites and PE. Our study presented new perspectives on the pathogenesis of PE by integrating metabolomics with genomics, which opens up avenues for more accurate understanding and management of the disease, providing new potential candidate metabolic molecular markers for the prevention, diagnosis and treatment of PE. Considering the limitations of MR studies, further research is needed to confirm the causality and underlying mechanisms of these findings.

Efficacy of antioxidant supplementation in improving endocrine, hormonal, inflammatory, and metabolic statuses of PCOS: a meta-analysis and systematic review

Background and aim: A large number of recent studies have reported on the use of antioxidants in patients with polycystic ovary syndrome (PCOS). This study aimed to evaluate the antioxidant effects on PCOS. Methods: We searched PubMed, Embase, Web of Science, and The Cochrane Library to identify randomized controlled trials investigating the use of antioxidants in treating PCOS. Statistical analysis was performed using Review Manager 5.4. Stata17.0 software was used to conduct sensitivity analyses. Results: This meta-analysis included 49 articles and 62 studies. The sample comprised 1657 patients with PCOS from the antioxidant group and 1619 with PCOS from the placebo group. The meta-analysis revealed that the fasting blood glucose levels [standardized mean difference (SMD): -0.31, 95% confidence interval (CI): -0.39 to -0.22, P < 0.00001], the homeostatic model assessment of insulin resistance (SMD: -0.68, 95% CI: -0.87 to -0.50], P < 0.00001), and insulin levels (SMD: -0.68, 95% CI: -0.79 to -0.58, P < 0.00001) were significantly lower in patients with PCOS taking antioxidants than those in the placebo group. Further, total cholesterol levels (SMD: -0.38, 95% CI: -0.56 to -0.20, P < 0.001), low-density lipoprotein cholesterol levels (SMD: -0.24, 95% CI: -0.37 to -0.10, P = 0.0008), and very low-density lipoprotein levels (SMD: -0.53, 95% CI: -0.65 to -0.41, P < 0.00001) were lower in patients with PCOS taking antioxidant supplements compared with the placebo group. Total testosterone (TT) level (SMD: -0.78, 95% CI: -1.15 to -0.42, P < 0.0001), dehydroepiandrosterone level (SMD: -0.42, 95% CI: -0.58 to -0.25, P < 0.00001), and mean standard deviation modified Ferriman-Gallway (MF-G scores) (SMD: -0.63, 95% CI: -0.98 to -0.28, P = 0.0004) were lower in patients taking antioxidant supplements. C-reactive protein (CRP) levels (SMD: -0.48, 95% CI: -0.63 to -0.34, P < 0.000001), body mass index [mean difference (MD): -0.27, 95% CI: -0.50 to -0.03, P = 0.03], weight (MD: -0.73, 95% CI: -1.35 to -0.11, P = 0.02), and diastolic blood pressure (MD: -3.78, 95% CI: -6.30 to -1.26, P = 0.003) were significantly lower. Moreover, the levels of sex hormone-binding protein (SMD: 0.23, 95% CI: 0.07-0.38, P = 0.004), high-density lipoprotein cholesterol (SMD: 0.11, 95% CI: 0.01-0.20, P = 0.03), total antioxidant capacity (SMD: 0.59, 95% CI: 0.31-0.87, P < 0.0001), and quantitative insulin sensitivity index (SMD: 0.01, 95% CI: 0.01-0.02, P < 0.00001) were higher in patients with PCOS who took antioxidant supplements compared with the placebo group. Antioxidant supplements did not affect other analyzed parameters in these patients, including follicle-stimulating hormone, free androgen index, nitric oxide, glutathione, malondialdehyde, and diastolic blood pressure. Conclusions: Antioxidants are beneficial in treating PCOS. Our study might provide a new treatment strategy for patients with clinical PCOS. We hope that more high-quality studies evaluating the effects of antioxidants on patients with PCOS will be conducted in the future. Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023448088.

Adding L-carnitine to antagonist ovarian stimulation doesn't improve the outcomes of IVF/ ICSI cycle in patients with polycystic ovarian syndrome: a double-blind randomized clinical trial

OBJECTIVE

To investigate the effect of L-carnitine supplementation during the controlled ovarian stimulation (COS) cycle with antagonist protocol in patients with polycystic ovary syndrome (PCOS) diagnosis undergoing IVF/ICSI treatment.

METHODS AND MATERIALS

This was a double-blind clinical trial study including 110 patients with PCOS attended to Royan Institute between March 2020 and February 2023. At the beginning of the COS cycle, the eligible patients were allocated into two groups randomly according to the coding list of the drugs prepared by the statistical consultant. In the experimental group, patients received 3 tablets daily (L-carnitine 1000 mg) from the second day of menstruation of the previous cycle until the puncture day in the cases of freeze-all embryos (6 weeks) or until the day of the pregnancy test (8 weeks) in fresh embryo transfer cycle. In the control group, patients received 3 placebo tablets for the same period of time. Weight assessment and fasting blood sugar and insulin tests, as well as serum lipid profile were also measured at the baseline and ovum pick-up day. The results of the COS cycle as well as the implantation and pregnancy rates were compared between groups.

RESULTS

Finally, 45 cases in L-carnitine group versus 47 cases in the placebo group were completed study per protocol. Data analysis showed that the two groups were homogeneous in terms of demographic characteristics and baseline laboratory tests and severity of PCOS. There is no statistically significant difference in terms of the oocyte recovery ratio and oocyte maturity rate, and the number and quality of embryos, as well as the rates of the fertilization, chemical and clinical pregnancy between groups. However, the means of weight (P < 0.001) and serum levels of fasting blood sugar (P = 0.021), fasting insulin (P = 0.004), triglyceride (P < 0.001) and cholesterol (P < 0.001), LDL (P < 0.001) have significantly decreased in women after consuming L-carnitine supplementation.

CONCLUSION

The oral intake of L-carnitine during COS in PCOS women for 6 weeks had no effect on COS and pregnancy outcomes. However, taking this supplement for 6 weeks has been associated with weight loss and improved lipid profile and serum glucose.

TRIAL REGISTRATION

The study was registered in the Clinicaltrials.gov site on December 17, 2020 (NCT04672720).

Causal Effects of Blood Metabolites and Obstructive Sleep Apnea: A Mendelian Randomization Study

BACKGROUND

Obstructive sleep apnea (OSA) is one of the most common forms of sleep-disordered breathing. Studies have shown that certain changes in metabolism play an important role in the pathophysiology of OSA. However, the causal relationship between these metabolites and OSA remains unclear.

AIMS

We use a mendelian randomization (MR) approach to investigate the causal associations between the genetic liability to metabolites and OSA.

METHODS

We performed a 2-sample inverse-variance weighted mendelian randomization analysis to evaluate the causal effects of genetically determined 486 metabolites on OSA. Multiple sensitivity analyses were performed to assess pleiotropy. We used multivariate mendelian randomization analyses to assess confounding factors and mendelian randomization Bayesian model averaging to rank the significant biomarkers by their genetic evidence. We also conducted a metabolic pathway analysis to identify potential metabolic pathways.

RESULTS

We identified 14 known serum metabolites (8 risk factors and 6 protective factors) and 12 unknown serum metabolites associated with OSA. These 14 known metabolites included 8 lipids( 1-arachidonoylglycerophosphoethanolamine, Tetradecanedioate, Epiandrosteronesulfate, Acetylca Glycerol3-phosphate, 3-dehydrocarnitine, Margarate17:0, Docosapentaenoaten3;22:5n3), 3 Aminoacids (Isovalerylcarnitine,3-methyl-2-oxobutyrate,Methionine), 2 Cofactors and vitamins [Bilirubin(E,ZorZ,E),X-11593--O-methylascorbate], 1Carbohydrate(1,6-anhydroglucose). We also identified several metabolic pathways that involved in the pathogenesis of OSA.

CONCLUSION

MR (mendelian randomization) approach was performed to identify 6 protective factors and 12 risk factors for OSA in the present study. 3-Dehydrocarnitine was the most significant risk factors for OSA. Our study also confirmed several significant metabolic pathways that were involved in the pathogenesis of OSA. Valine, leucine and isoleucine biosynthesis metabolic pathways were the most significant metabolic pathways that were involved in the pathogenesis of OSA.

The effect of adding L-Carnitine to the GnRH-antagonist protocol on assisted reproductive technology outcome in women with polycystic ovarian syndrome: a randomized clinical trial

OBJECTIVE

This study aimed to investigate the effect of adding L-Carnitine to the gonadotropins on ART outcome in frozen-thawed embryo transfer cycles among PCOS women.

METHODS

In this randomized clinical trial, 83 patients with PCOS were randomized to either L-Carnitine supplemented (n = 42) or control (n = 41) groups. The L-Carnitine group was given 3000 mg of oral L-Carnitine daily until the final day of ovulation. The numbers of metaphase II (MII) oocytes, 2-pronuclears (2PNs), oocyte maturity rate, fertilization rate, fertilization proportion as well as implantation, chemical and clinical pregnancy rates were compared between the two groups.

RESULTS

Even though the duration of stimulation and endometrial thickness were comparable between groups (p > .05), serum estradiol level on the day of oocyte triggering, was significantly higher in the L-Carnitine group compared to the control group (p < .05). In contrast, the number of retrieved and MII oocytes as well as the number of 2PNs and obtained embryos were similar between groups (p > .05). Moreover, oocyte maturity rate (0.85 ± 0.38 vs. 1.02 ± 0.90), fertilization proportion (0.62 ± 0.44 vs. 0.80 ± 0.86), fertilization rate (0.70 ± 0.22 vs. 0.76 ± 0.19) along with implantation rate (18.1 vs. 13.7%), chemical (26.8 vs. 30.7%) and clinical (24.3 vs. 25.6%) pregnancy rates, were all comparable between L-Carnitine and control groups respectively (p > .05).

CONCLUSIONS

Our result showed that oral L-Carnitine administration during induction of ovulation among PCOS women could not improve laboratory and pregnancy outcome.

Effects of carnitine on glucose and lipid metabolic profiles and fertility outcomes in women with polycystic ovary syndrome: A systematic review and meta-analysis

OBJECTIVES

To quantify the effect of carnitine on glucose and lipid metabolic profiles and fertility outcomes in women with Polycystic ovary syndrome (PCOS).

DESIGN

A systematic review and meta-analysis were conducted.

PATIENTS

Women with PCOS diagnosed by Rotterdam or Androgen Excess Society (AES) criteria and taking carnitine supplement were assessment.

MEASUREMENTS

Fertility outcomes (ovulation, clinical pregnancy, live birth, and miscarriage), lipid parameters (BMI, triglyceride, total cholesterol, high-density lipoprotein, low-density lipoprotein), fasting glucose and insulin, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR).

RESULTS

In total, 839 participants were included in this analysis. The dosage of carnitine and treatment duration reported by studies varied from 250 mg to 3000 mg daily and 84 to 90 days, respectively. The publication bias was absent. Compared with placebo, carnitine significantly improved ovulation rates (RR 3.42, 95% CI 2.39 to 4.89, I2 = 0%) and pregnancy rates (RR 11.05, 95% CI 1.21 to 100.58, I2 = 79%). None of included studies reported live birth. After treatment, carnitine resulted in significant reductions relative to baseline in body mass index (BMI, MD -0.93 kg/m2, 95% CI -1.15 to -0.70, I2 = 55.0%), insulin levels (MD -2.47 mIU/L, 95% CI -4.49 to -0.45, I2 = 0%) and the Homeostasis Model Assessment index (MD -0.67, 95% CI -1.20 to -0.14, I2 = 0%) than placebo, but not for lipid profiles including triglyceride, total cholesterol, and low-density lipoprotein.

CONCLUSION

With the available literature, carnitine seems to improve ovulation and clinical pregnancy and insulin resistance, BMI in women with PCOS. These effects are warranted to be further validated, due to insufficient statistical power.

l-carnitine: Nutrition, pathology, and health benefits

Carnitine is a medically needful nutrient that contributes in the production of energy and the metabolism of fatty acids. Bioavailability is higher in vegetarians than in people who eat meat. Deficits in carnitine transporters occur as a result of genetic mutations or in combination with other illnesses such like hepatic or renal disease. Carnitine deficit can arise in diseases such endocrine maladies, cardiomyopathy, diabetes, malnutrition, aging, sepsis, and cirrhosis due to abnormalities in carnitine regulation. The exogenously provided molecule is obviously useful in people with primary carnitine deficits, which can be life-threatening, and also some secondary deficiencies, including such organic acidurias: by eradicating hypotonia, muscle weakness, motor skills, and wasting are all improved l-carnitine (LC) have reported to improve myocardial functionality and metabolism in ischemic heart disease patients, as well as athletic performance in individuals with angina pectoris. Furthermore, although some intriguing data indicates that LC could be useful in a variety of conditions, including carnitine deficiency caused by long-term total parenteral supplementation or chronic hemodialysis, hyperlipidemias, and the prevention of anthracyclines and valproate-induced toxicity, such findings must be viewed with caution.

Insulin resistance in polycystic ovary syndrome across various tissues: an updated review of pathogenesis, evaluation, and treatment

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by chronic ovulation dysfunction and overabundance of androgens; it affects 6-20% of women of reproductive age. PCOS involves various pathophysiological factors, and affected women usually have significant insulin resistance (IR), which is a major cause of PCOS. IR and compensatory hyperinsulinaemia have differing pathogeneses in various tissues, and IR varies among different PCOS phenotypes. Genetic and epigenetic changes, hyperandrogenaemia, and obesity aggravate IR. Insulin sensitization drugs are a new treatment modality for PCOS. We searched PubMed, Google Scholar, Elsevier, and UpToDate databases in this review, and focused on the pathogenesis of IR in women with PCOS and the pathophysiology of IR in various tissues. In addition, the review provides a comprehensive overview of the current progress in the efficacy of insulin sensitization therapy in the management of PCOS, providing the latest evidence for the clinical treatment of women with PCOS and IR.

The effects of L-carnitine supplementation on glycemic markers in adults: A systematic review and dose-response meta-analysis

Background and aims

Hyperglycemia and insulin resistance are concerns today worldwide. Recently, L-carnitine supplementation has been suggested as an effective adjunctive therapy in glycemic control. Therefore, it seems important to investigate its effect on glycemic markers.

Methods

PubMed, Scopus, Web of Science, and the Cochrane databases were searched in October 2022 for prospective studies on the effects of L-carnitine supplementation on glycemic markers. Inclusion criteria included adult participants and taking oral L-carnitine supplements for at least seven days. The pooled weighted mean difference (WMD) was calculated using a random-effects model.

Results

We included the 41 randomized controlled trials (RCTs) (n = 2900) with 44 effect sizes in this study. In the pooled analysis; L-carnitine supplementation had a significant effect on fasting blood glucose (FBG) (mg/dl) [WMD = -3.22 mg/dl; 95% CI, -5.21 to -1.23; p = 0.002; I ² = 88.6%, p < 0.001], hemoglobin A1c (HbA1c) (%) [WMD = -0.27%; 95% CI, -0.47 to -0.07; p = 0.007; I ² = 90.1%, p < 0.001] and homeostasis model assessment-estimate insulin resistance (HOMA-IR) [WMD = -0.73; 95% CI, -1.21 to -0.25; p = 0.003; I ² = 98.2%, p < 0.001] in the intervention compared to the control group. L-carnitine supplementation had a reducing effect on baseline FBG ≥100 mg/dl, trial duration ≥12 weeks, intervention dose ≥2 g/day, participants with overweight and obesity (baseline BMI 25-29.9 and >30 kg/m²), and diabetic patients. Also, L-carnitine significantly affected insulin (pmol/l), HOMA-IR (%), and HbA1c (%) in trial duration ≥12 weeks, intervention dose ≥2 g/day, and participants with obesity (baseline BMI >30 kg/m²). It also had a reducing effect on HOMA-IR in diabetic patients, non-diabetic patients, and just diabetic patients for insulin, and HbA1c. There was a significant nonlinear relationship between the duration of intervention and changes in FBG, HbA1c, and HOMA-IR. In addition, there was a significant nonlinear relationship between dose (≥2 g/day) and changes in insulin, as well as a significant linear relationship between the duration (weeks) (coefficients = -16.45, p = 0.004) of intervention and changes in HbA1C.

Conclusions

L-carnitine could reduce the levels of FBG, HbA1c, and HOMA-IR.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022358692.

Effect of L-carnitine supplementation on lipid accumulation product and cardiovascular indices in women with overweight/obesity who have knee osteoarthritis: a randomized controlled trial

Background

Osteoarthritis is associated with obesity, dyslipidemia and cardiovascular diseases. It has been hypothesized that L-carnitine can improve cardiovascular risk factors. We aimed to investigate the effect of L-carnitine supplementation on lipid accumulation product (LAP) and atherogenic indices in women with overweight/obesity who have knee osteoarthritis.

Methods

In this double-blind randomized controlled trial, seventy-six women with overweight/obesity who had knee osteoarthritis were assigned into the intervention group and control group for 12 weeks. The intervention group received 1000 mg/day L-carnitine as capsule, and the control group received placebo. The primary outcomes were LAP, atherogenic index of plasma (AIP), atherogenic coefficient (AC) and Castelli risk index II (CRI-II).

Results

We found no significant difference between the groups in baseline values of LAP, AIP, AC and CRI-II. After the intervention, a significant reduction in LAP was observed in intervention group compared to the control group (− 11.05 (− 28.24 to 0.40) vs. − 5.82 (− 24.44 to 2.68); P = 0.03). However, there was no significant difference between two groups in AIP (− 0.05 ± 0.16 vs. − 0.01 ± 0.13; P = 0.19), AC (− 0.40 ± 0.81 vs. − 0.30 ± 0.67; P = 0.67) and CRI-II (− 0.20 ± 0.76 vs. − 0.21 ± 0.47; P = 0.11).

Conclusions

L-carnitine supplementation for 12 weeks can improve LAP, but it has no effect on cardiovascular outcomes. To reach a definitive conclusion, further clinical trials with larger sample sizes and higher dosages of L-carnitine are needed.

Trial registration

Registered on 27/4/2017 at Iranian Registry of Clinical Trials IRCT2017011932026N2.

Effects of L-carnitine supplementation for women with polycystic ovary syndrome: a systematic review and meta-analysis

Background

Polycystic ovary syndrome (PCOS) is a disorder in reproductive age women and is characterized by hyperandrogenic anovulation and oligo-amenorrhea, which leads to infertility. Anovulation in PCOS is associated with low follicle-stimulating hormone levels and the arrest of antral follicle development in the final stages of maturation. L-carnitine (LC) plays a role in fatty acid metabolism, which is found to be lacking in PCOS patients. This systematic review and meta-analysis aimed to determine the effectiveness of LC supplementation for patients with PCOS.

Methods

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Psychological Information Database (PsycINFO), and the World Health Organization International Clinical Trials Registry Platform for all randomized control trials, comparing LC alone or in combination with other standard treatments for the treatment of PCOS from inception till June 2021. We independently screened titles and abstracts to identify available trials, and complete texts of the trials were checked for eligibility. Data on the methods, interventions, outcomes, and risk of bias from the included trials were independently extracted by the authors. The estimation of risk ratios and mean differences with a 95 percent confidence interval (CI) was performed using a random-effects model.

Results

Nine studies with 995 participants were included in this review. Five comparison groups were involved. In one comparison group, LC reduced the fasting plasma glucose (FPG) (mean differences (MD) -5.10, 95% CI [-6.25 to -3.95]; P = 0.00001), serum low-density lipoprotein (LDL) (MD -25.00, 95% CI [-27.93 to -22.07]; P = 0.00001), serum total cholesterol (MD -21.00, 95% CI [-24.14 to -17.86]; P = 0.00001), and serum triglyceride (TG) (MD -9.00, 95% CI [-11.46 to -6.54]; P = 0.00001) with moderate certainty of evidence. Another comparison group demonstrated that LC lowers the LDL (MD -12.00, 95% CI [-15.80 to -8.20]; P = 0.00001), serum total cholesterol (MD -24.00, 95% CI [-27.61 to -20.39]; P = 0.00001), and serum TG (MD -19.00, 95% CI [-22.79 to -15.21]; P = 0.00001) with moderate certainty of evidence.

Conclusion

There was low to moderate certainty of evidence that LC improves Body Mass Index (BMI) and serum LDL, TG, and total cholesterol levels in women with PCOS.

A machine-learning approach for predicting the effect of carnitine supplementation on body weight in patients with polycystic ovary syndrome

The present study aimed to explore the effect of carnitine supplementation on body weight in patients with polycystic ovary syndrome (PCOS) and predict an appropriate dosage schedule using a machine-learning approach. Data were obtained from literature mining and the rates of body weight change from the initial values were selected as the therapeutic index. The maximal effect (E_max) model was built up as the machine-learning model. A total of 242 patients with PCOS were included for analysis. In the machine-learning model, the E_max of carnitine supplementation on body weight was -3.92%, the ET₅₀ was 3.6 weeks, and the treatment times to realize 25%, 50%, 75%, and 80% (plateau) E_max of carnitine supplementation on body weight were 1.2, 3.6, 10.8, and 14.4 weeks, respectively. In addition, no significant relationship of dose-response was found in the dosage range of carnitine supplementation used in the present study, indicating the lower limit of carnitine supplementation dosage, 250 mg/day, could be used as a suitable dosage. The present study first explored the effect of carnitine supplementation on body weight in patients with PCOS, and in order to realize the optimal therapeutic effect, carnitine supplementation needs 250 mg/day for at least 14.4 weeks.

Putative Complementary Compounds to Counteract Insulin-Resistance in PCOS Patients

Polycystic ovary syndrome (PCOS) is the most frequent endocrine-metabolic disorder among women at reproductive age. The diagnosis is based on the presence of at least two out of three criteria of the Rotterdam criteria (2003). In the last decades, the dysmetabolic aspect of insulin resistance and compensatory hyperinsulinemia have been taken into account as the additional key features in the etiopathology of PCOS, and they have been widely studied. Since PCOS is a complex and multifactorial syndrome with different clinical manifestations, it is difficult to find the gold standard treatment. Therefore, a great variety of integrative treatments have been reported to counteract insulin resistance. PCOS patients need a tailored therapeutic strategy, according to the patient’s BMI, the presence or absence of familiar predisposition to diabetes, and the patient’s desire to achieve pregnancy or not. The present review analyzes and discloses the main clinical insight of such complementary substances.

Carnitines as Mitochondrial Modulators of Oocyte and Embryo Bioenergetics

Recently, the importance of bioenergetics in the reproductive process has emerged. For its energetic demand, the oocyte relies on numerous mitochondria, whose activity increases during embryo development under a fine regulation to limit ROS production. Healthy oocyte mitochondria require a balance of pyruvate and fatty acid oxidation. Transport of activated fatty acids into mitochondria requires carnitine. In this regard, the interest in the role of carnitines as mitochondrial modulators in oocyte and embryos is increasing. Carnitine pool includes the un-esterified l-carnitine (LC) and carnitine esters, such as acetyl-l-carnitine (ALC) and propionyl-l-carnitine (PLC). In this review, carnitine medium supplementation for counteracting energetic and redox unbalance during in vitro culture and cryopreservation is reported. Although most studies have focused on LC, there is new evidence that the addition of ALC and/or PLC may boost LC effects. Pathways activated by carnitines include antiapoptotic, antiglycative, antioxidant, and antiinflammatory signaling. Nevertheless, the potential of carnitine to improve energetic metabolism and oocyte and embryo competence remains poorly investigated. The importance of carnitine as a mitochondrial modulator may suggest that this molecule may exert a beneficial role in ovarian disfunctions associated with metabolic and mitochondrial alterations, including PCOS and reproductive aging.

The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation

Mitochondria control cellular fate by various mechanisms and are key drivers of cellular metabolism. Although the main function of mitochondria is energy production, they are also involved in cellular detoxification, cellular stabilization, as well as control of ketogenesis and glucogenesis. Conditions like neurodegenerative disease, insulin resistance, endocrine imbalances, liver and kidney disease are intimately linked to metabolic disorders or inflexibility and to mitochondrial dysfunction. Mitochondrial dysfunction due to a relative lack of micronutrients and substrates is implicated in the development of many chronic diseases. l-carnitine is one of the key nutrients for proper mitochondrial function and is notable for its role in fatty acid oxidation. l-carnitine also plays a major part in protecting cellular membranes, preventing fatty acid accumulation, modulating ketogenesis and glucogenesis and in the elimination of toxic metabolites. l-carnitine deficiency has been observed in many diseases including organic acidurias, inborn errors of metabolism, endocrine imbalances, liver and kidney disease. The protective effects of micronutrients targeting mitochondria hold considerable promise for the management of age and metabolic related diseases. Preventing nutrient deficiencies like l-carnitine can be beneficial in maintaining metabolic flexibility via the optimization of mitochondrial function. This paper reviews the critical role of l-carnitine in mitochondrial function, metabolic flexibility and in other pathophysiological cellular mechanisms.

Clinical evidence of the effects of carnitine supplementation on body weight, glycemic control and serum lipids in women with polycystic ovary syndrome: a systematic review and meta-analysis

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders in women of reproductive age. Several clinical trials have investigated the influence of carnitine on metabolic variables in PCOS, but have yielded conflicting results. This study aimed to summarize the clinical evidence of the effects of carnitine on weight management, glycemic and serum lipids controls in women with PCOS by conducting a meta-analysis of randomized control trials (RCTs). PubMed, Embase, Web of Sciences, Scopus, and the CENTRAL database were searched from inception to March 2021 for eligible articles. Study selection and assessment of quality were conducted independently by two investigators. Effect sizes for each outcome were reported with the weighted mean differences (WMDs) and 95% confidence intervals (CIs). The statistical heterogeneity of the included clinical trials was tested using the I² statistic. Six studies with 672 PCOS participants were included for meta-analysis. Our results revealed that carnitine supplements significantly decreased total cholesterol, low-density lipoprotein-cholesterol, triglycerides, body weight, body mass index, hip circumference, and waist circumference (All p < .05). In addition, carnitine intervention also improved the levels of high-density lipoprotein cholesterol. However, no significant changes were seen in glucose homeostasis parameters. These results were stable after sensitivity analysis, and no significant publication biases were detected. Based on current evidence, carnitine supplementation in women with PCOS had beneficial effects on weight loss and lipid profiles. Further large-scale, well-designed RCTs are required to confirm these results.

Effect of l-carnitine supplementation on liver fat content and cardiometabolic indices in overweight/obese women with polycystic ovary syndrome: A randomized controlled trial

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine disorder among reproductive-age women, and is associated with cardiovascular diseases as well as non-alcoholic fatty liver disease. The recent evidence suggested the beneficial effects of l-carnitine in women with PCOS.

OBJECTIVE

The present study aimed to investigate the effect of l-carnitine supplementation on liver fat content and cardiometabolic outcomes in overweight/obese women with PCOS.

METHODS

The present study was designed as a 12-week double-blind, randomized controlled clinical trial. Sixty-two overweight/obese women with PCOS were assigned into the treatment (received 1000 mg/d l-carnitine capsule) and the control (received placebo capsule) groups. The outcomes included lipid accumulation product (LAP), atherogenic index of plasma (AIP), atherogenic coefficient (AC) and Castelli II indices.

RESULTS

At the end of the trial, there was no significant difference between the treatment and the control groups in terms of LAP (-1.1 vs. -4.0; P = 0.45), AIP (0.0 vs. -0.09; P = 0.14), AC (-0.2 vs. -0.8; P = 0.06) and Castelli II index (-0.2 vs. -0.6; P = 0.07) after controlling the mean change of waist circumference.

CONCLUSION

l-carnitine supplementation for 12 weeks has no beneficial effect on liver fat content and cardiometabolic outcomes in overweight or obese women with PCOS.

TRIAL REGISTRATION

Registered on 30 December 2019 at Iranian Registry of Clinical Trials IRCT20191016045131N1.

Female Fertility and the Nutritional Approach: The Most Essential Aspects

Infertility is an increasing problem that affects couples attempting pregnancy. A growing body of evidence points to a link between diet and female fertility. In fact, data show that a diet high in trans fats, refined carbohydrates, and added sugars can negatively affect fertility. Conversely, a diet based on the Mediterranean dietary patterns, i.e., rich in dietary fiber, omega-3 (ɷ-3) fatty acids, plant-based protein, and vitamins and minerals, has a positive impact on female fertility. An unhealthy diet can disrupt microbiota composition, and it is worth investigating whether the composition of the gut microbiota correlates with the frequency of infertility. There is a lack of evidence to exclude gluten from the diet of every woman trying to become pregnant in the absence of celiac disease. Furthermore, there are no data concerning adverse effects of alcohol on female fertility, and caffeine consumption in the recommended amounts also does not seem to affect fertility. On the other hand, phytoestrogens presumably have a positive influence on female fertility. Nevertheless, there are many unanswered questions with regard to supplementation in order to enhance fertility. It has been established that women of childbearing age should supplement folic acid. Moreover, most people experience vitamin D and iodine deficiency; thus, it is vital to control their blood concentrations and consider supplementation if necessary. Therefore, since diet and lifestyle seem to be significant factors influencing fertility, it is valid to expand knowledge in this area.

The effect of L-carnitine supplementation on insulin resistance, sex hormone-binding globulin and lipid profile in overweight/obese women with polycystic ovary syndrome: a randomized clinical trial

PURPOSE

Polycystic ovary syndrome (PCOS) is a common endocrine disorder among reproductive-age women. Insulin resistance and dyslipidemia are linked to PCOS. L-Carnitine supplementation as a management strategy for women with PCOS has been proposed. The effect of L-carnitine supplementation on insulin resistance, sex hormone-binding globulin (SHBG) and lipid profile in overweight/obese women with PCOS was investigated.

METHODS

This randomized, double-blind, controlled clinical trial, was conducted on 62overweight/obese women with PCOS. Participants were randomly assigned into two groups to receive 1000 mg/day L-carnitine or placebo (1000 mg starch) for 12 weeks.

RESULTS

L-Carnitine supplementation compared to the placebo showed a significant improvement in insulin [- 0.7 (- 7.3 to 4.0) vs. 0.7 (- 3.0 to 5.2); P = 0.001], homeostatic model assessment for insulin resistance [- 0.4 (- 1.7 to 1.1) vs. 0.0 (- 0.7 to 1.3); P = 0.002], quantitative insulin sensitivity check index (+ 0.01 ± 0.02 vs. - 0.01 ± 0.01; P = 0.02) and a non-significant change toward improvement in SHBG (+ 11.5 ± 40.2 vs. - 3.2 ± 40.2; P = 0.2). However, there was no significant differences between the two groups in serum levels of fasting plasma glucose, total cholesterol, triglyceride, low density lipoprotein-cholesterol and high density lipoprotein cholesterol (P > 0.05).

CONCLUSION

12-week L-carnitine supplementation in overweight or obese women with PCOS ameliorate insulin resistance, but has no effect on SHBG and lipid profile. Studies with higher dosages and duration of L-carnitine intake are required. The trial was registered on 30 December 2019 at Iranian Registry of Clinical Trials IRCT20191016045131N1.

TRIAL REGISTRATION

Registered on 30th December 2019 at Iranian Registry of Clinical Trials (IRCT20191016045131N1).

Antioxidant supplementations ameliorate PCOS complications: a review of RCTs and insights into the underlying mechanisms

Polycystic ovary syndrome (PCOS) is one of the most important gynecological disorders of women in the age of reproduction. Different hormonal and inflammatory cross-talks may play in the appearance of its eventual complications as a leading cause of infertility. Excessive production of reactive oxygen species over the power of the antioxidant system as oxidative stress is known to contribute to a variety of diseases like PCOS. Thus, the utilization of antioxidants can be efficient in preventing or assistant in treating these diseases. In this review, we describe the clinical trial studies that have examined the efficiency of antioxidant strategies against PCOS and the possible underlying mechanisms. The investigations presented here lead us to consider that targeting oxidative stress pathways is probably a powerful promising therapeutic approach towards PCOS. There is preparatory evidence of the effectiveness of antioxidant interventions in ameliorating some of the PCOS complications, including metabolic and hormonal disorders. Due to limited data and relatively few clinical trials, many of these interventions need further investigation before they can be considered effective agents for routine clinical use.

Neuroendocrine Effects of Carnitines on Reproductive Impairments

Carnitines are quaternary amines involved in various cellular processes such as fatty acid uptake, β-oxidation and glucose metabolism regulation. Due to their neurotrophic activities, their integrative use has been studied in several different physio-pathological conditions such as anorexia nervosa, chronic fatigue, vascular diseases, Alzheimer’s disease and male infertility. Being metabolically active, carnitines have also been proposed to treat reproductive impairment such as functional hypothalamic amenorrhea (FHA) and polycystic ovary syndrome (PCOS) since they improve both hormonal and metabolic parameters modulating the neuroendocrine impairments of FHA. Moreover, they are capable of improving the lipid profile and the insulin sensitivity in patients with PCOS.

Acetyl-L-Carnitine Ameliorates Metabolic and Endocrine Alterations in Women with PCOS: A Double-Blind Randomized Clinical Trial

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder and the main cause of infertility in women of reproductive age. Affected women suffer from insulin resistance and present with an intense stress response. Treatment with insulin sensitizers alone and in combination is used to ameliorate the signs and symptoms associated with the disease. This study was designed to compare the endocrine and metabolic parameters as well as subjective and objective measures of stress in women with PCOS before and after treatment with acetyl-L-carnitine (ALC) and metformin plus pioglitazone.

METHODS

A total of 147 women with PCOS were randomly assigned into two groups: the combo group (n = 72) received a combination of metformin, pioglitazone, and ALC (500 mg, 15 mg, and 1500 mg, respectively), twice daily; the Met + Pio group (n = 75) received metformin plus pioglitazone (500 mg, 15 mg, respectively) and placebo (citric acid plus calcium carbonate), twice daily for 12 weeks. Medications were discontinued when pregnancy was confirmed. The Perceived Stress Scale (PSS14) and Profile of Mood States (POMS) were employed as subjective measures of stress. The endocrine and metabolic functions of women with PCOS were assessed by measuring insulin, leutinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, and adiponectin levels in fasting blood samples. Insulin resistance was calculated by Homeostatic Model Assessment of Insulin Resistance (HOMA-IR).

RESULTS

Women at baseline had significantly elevated circulating concentration of insulin and low level of adiponectin. Treatment decreased insulin in both groups; however, the combo group showed a significant decrease (p = 0.001). Serum adiponectin level was raised significantly after treatment in both groups (p < 0.001). HOMA-IR also decreased in both groups (both p < 0.001). Testosterone, FSH, and LH significantly improved in both groups. LH also decreased in both groups; however, the change was significant only in the combo (metformin plus pioglitazone plus ALC) group (p = 0.013). Interestingly, there was a significant improvement in body circumference (p < 0.001) in the combo group. The PSS scores of the patients improved significantly (p < 0.001) in the combo group. Interestingly, regular menstrual cycles were found (97.2%) in the carnitine group, but in only 12.9% of the other group.

CONCLUSION

We conclude that addition of ALC therapy is superior to metformin plus pioglitazone in ameliorating insulin resistance, polycystic ovaries, menstrual irregularities, and hypoadiponectinemia in women with PCOS.

TRIAL REGISTRATION

Trial registration: clinicalTrial.gov NCT04113889. Registered 3 October, 2019. https://clinicaltrials.gov/ct2/show/NCT04113889 .

Can Nutrition Help in the Treatment of Infertility?

Infertility is defined as the inability to conceive after 12 months of unprotected intercourse or six months for women aged 35 years or older. The physical, emotional, psychological, and financial statuses of infertile couples are tremendously affected especially after undergoing diagnostic and/or curative treatments. Human fertility is influenced by multiple factors including female or male, and modifiable or non-modifiable factors. There is growing evidence that nutri-tion may play an important role in adjusting fertility-related outcomes in both men and women. The objective of our study was to summarize the latest data on nutritional factors (specific food groups, nutrients, and nutritional supplements) that have an impact on female or male sexual and reproductive function. PubMed and Google Scholar platforms were used to collect appropriate articles for the review using several combinations of keywords (infertility, diet, dietary supplements, antioxidants, and beverages). Adherence to a healthy dietary pattern favoring fish, poultry, whole grains, fruits, vegetables, and healthy fats, was related to better fertility in both genders. Despite the multifactorial etiology of sexual infertility, nutrition may affect the sexual/reproductive function in both women and men.

Metabolomic Biomarkers in Polycystic Ovary Syndrome: A Review of the Evidence

Polycystic ovary syndrome (PCOS) is an endocrinologic condition affecting one in five women of reproductive age. PCOS is often characterized by disruptions to the menstrual cycle, development of male-pattern hair growth (hirsutism), and polycystic ovary morphology. Recently, PCOS has been linked to metabolic dysfunction, with 40 to 80% of women characterized as overweight or obese. Despite these well-known negative health effects of PCOS, 75% of sufferers remain undiagnosed. This is most likely due to the variability in symptom presentation and the lack of a definitive test for the condition. Metabolomics, which is a platform used to analyze and characterize a large number of metabolites, has recently been proposed as a potential tool for investigating the metabolic pathways that could be involved in the pathophysiology of PCOS. In doing so, novel biomarkers could be identified to improve diagnosis and treatment of PCOS. This review aims to summarize the findings of recent metabolomic studies that highlight metabolic-specific molecules which are deranged in PCOS, to identify potential biomarkers for the condition. Current limitations for metabolomic studies are discussed, as well as future directions to progress the field toward further validation and integration into clinical practice.

Improvement of Insulin Sensitivity Increases Pregnancy Rate in Infertile PCOS Women: A Systemic Review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of infertility in reproductive-age women. Insulin increases steroidogenesis, deranges granulosa cell differentiation, and affects follicle growth. However, results from randomized control trials (RCTs) were heterogeneous, and little strong evidence associated actual achievement of insulin sensitivity (IS) improvement with reproductive outcomes.

OBJECTIVES

To identify evidence of the reproductive benefit of IS improvement in infertile PCOS women by analyzing eligible RCTs.

SEARCH STRATEGY

Different search strategies with unlimited keywords, including treatment, therapy, intervention, polycystic ovary syndrome/PCOS, insulin resistance, pregnancy, conceive, live birth, and randomized controlled trials/RCT were used in databases including Pubmed, Embase, and Web of Science to November 20th, 2021.

DATA COLLECTION AND ANALYSIS

Two authors independently abstracted study details and assessed study quality.

MAIN RESULTS

Ten RCTs that covered different races and met the inclusion criteria were included for analysis and discussion. Clinical pregnancy rate was increased in infertile PCOS women when they had significant improvement of IS after treatment regardless of the various interventions (non-surgical). The benefits of IS improvement appeared superior in PCOS women without severe obesity. The effect of IS improvement on pregnancy rate was independent of the change of BMI.

CONCLUSIONS

Nonsurgical therapeutic strategies that promote superior IS improvement may aid infertile PCOS women to increase their possibility of successful pregnancy regardless of the various interventions. The improvement of IS might be more important than the reduction of BMI in the improvement of pregnancy rate in infertile PCOS women.

The effect of L-Carnitine supplementation on clinical symptoms, C-reactive protein and malondialdehyde in obese women with knee osteoarthritis: a double blind randomized controlled trial

BACKGROUNDS

L-carnitine decreases oxidation and inflammation by reducing the fatty acid in plasma and using oxygen in ATP synthesis. As such, knee osteoarthritis (KOA) can be improved by reducing apoptotic chondrocytes. This study was designed to compare the effect of L-carnitine supplementation and low-calorie diet on improving KOA among obese women. We further investigated the effect of L- carnitine on improvement of KOA in obese women on low calorie diet.

METHODS

To conduct the study, 76 obese women with KOA were randomly assigned into two low-calorie diet groups: the first received 1000 mg of LCG and the second took the placebo (PLG) (n = 38). Anthropometry indices, body composition, lipid profile, C-reactive Protein (CRP), Malondialdehyde (MDA), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) were assessed at the baseline condition and after 12 weeks.

RESULTS

The mean change of body mass index (BMI) (- 1.21 ± 0.84 vs. -0.79 ± 0.70; P = 0.02) and weight (- 2.76 ± 1.69 vs. -1.95 ± 1.73; P = 0.05) were significant in the LCG compared with the PLG. Likewise, LCG compared to the PLG showed insignificant improvement in waist circumference (WC) (- 5.65 ± 5.85 vs. -3.64 ± 3.37; P = 0.08). Total cholesterol (P = 0.02), MDA (P = 0.03), fat mass (P = 0.03) and visceral fat (P = 0.001) only showed decreased levels in LCG in comparison to the baseline condition. There was no significant difference between LCG and PLG, in the mean changes of hip circumference, visceral fat, free fat mass, fat mass, lipid profiles, CRP, MDA as well as stiffness, physical function, decrease of pain and total scores (P > 0.05).

CONCLUSION

The 12-week L-carnitine supplementation could improve BMI, but had no significant effect on other anthropometric and body composition measures as well as clinical symptoms, CRP, MDA, and lipid profile in women with KOA. Further trials with higher doses and longer durations are required. IRCT registration number: IRCT2017011932026N2. Registration date: 2017-04-27.

Loss of Muscle Carnitine Palmitoyltransferase 2 Prevents Diet-Induced Obesity and Insulin Resistance despite Long-Chain Acylcarnitine Accumulation

To assess the effects of acylcarnitine accumulation on muscle insulin sensitivity, a model of muscle acylcarnitine accumulation was generated by deleting carnitine palmitoyltransferase 2 (CPT2) specifically from skeletal muscle (Cpt2^Sk-/- mice). CPT2 is an irreplaceable enzyme for mitochondrial long-chain fatty acid oxidation, converting matrix acylcarnitines to acyl-CoAs. Compared with controls, Cpt2^Sk-/- muscles do not accumulate anabolic lipids but do accumulate ∼22-fold more long-chain acylcarnitines. High-fat-fed Cpt2^Sk-/- mice resist weight gain, adiposity, glucose intolerance, insulin resistance, and impairments in insulin-induced Akt phosphorylation. Obesity resistance of Cpt2^Sk-/- mice could be attributed to increases in lipid excretion via feces, GFD15 production, and energy expenditure. L-carnitine supplement intervention lowers acylcarnitines and improves insulin sensitivity independent of muscle mitochondrial fatty acid oxidative capacity. The loss of muscle CPT2 results in a high degree of long-chain acylcarnitine accumulation, simultaneously protecting against diet-induced obesity and insulin resistance.

Ameliorating Effects of Natural Antioxidant Compounds on Female Infertility: a Review

The prevalence of female infertility cases has been increasing at a frightening rate, affecting approximately 48 million women across the world. However, oxidative stress has been recognized as one of the main mediators of female infertility by causing various reproductive pathologies in females such as endometriosis, PCOS, preeclampsia, spontaneous abortion, and unexplained infertility. Nowadays, concerned women prefer dietary supplements with antioxidant properties over synthetic drugs as a natural way to lessen the oxidative stress and enhance their fertility. Therefore, the current review is an attempt to explore the efficacy of various natural antioxidant compounds including vitamins, carotenoids, and plant polyphenols and also of some medicinal plants in improving the fertility status of females. Our summarization of recent findings in the current article would pave the way toward the development of new possible antioxidant therapy to treat infertility in females. Natural antioxidant compounds found in fruits, vegetables, and other dietary sources, alone or in combination with other antioxidants, were found to be effective in ameliorating the oxidative stress-mediated infertility problems in both natural and assisted reproductive settings. Numerous medicinal plants showed promising results in averting the various reproductive disorders associated with female infertility, suggesting a plant-based herbal medicine to treat infertility. Although optimum levels of natural antioxidants have shown favorable results, however, their excessive intake may have adverse health impacts. Therefore, larger well-designed, dose-response studies in humans are further warranted to incorporate natural antioxidant compounds into the clinical management of female infertility.

Regulatory Functions of L-Carnitine, Acetyl, and Propionyl L-Carnitine in a PCOS Mouse Model: Focus on Antioxidant/Antiglycative Molecular Pathways in the Ovarian Microenvironment

Polycystic ovary syndrome (PCOS) is a complex metabolic disorder associated with female infertility. Based on energy and antioxidant regulatory functions of carnitines, we investigated whether acyl-L-carnitines improve PCOS phenotype in a mouse model induced by dehydroepiandrosterone (DHEA). CD1 mice received DHEA for 20 days along with two different carnitine formulations: one containing L-carnitine (LC) and acetyl-L-carnitine (ALC), and the other one containing also propionyl-L-carnitine (PLC). We evaluated estrous cyclicity, testosterone level, ovarian follicle health, ovulation rate and oocyte quality, collagen deposition, lipid droplets, and 17ß-HSD IV (17 beta-hydroxysteroid dehydrogenase type IV) expression. Moreover, we analyzed protein expression of SIRT1, SIRT3, SOD2 (superoxide dismutase 2), mitochondrial transcriptional factor A (mtTFA), RAGE (receptor for AGEs), GLO2 (glyoxalase 2) and ovarian accumulation of MG-AGEs (advanced glycation end-products formed by methylglyoxal). Both carnitine formulations ameliorated ovarian PCOS phenotype and positively modulated antioxidant molecular pathways in the ovarian microenvironment. Addition of PLC to LC-ALC formulation mitigated intraovarian MG-AGE accumulation and increased mtTFA expression. In conclusion, our study supports the hypothesis that oral administration of acyl-L-carnitines alleviates ovarian dysfunctions associated with this syndrome and that co-administration of PLC provides better activity. Molecular mechanisms underlying these effects include anti-oxidant/glycative activity and potentiation of mitochondria.

Effects of l-carnitine supplementation on weight loss and body composition: A systematic review and meta-analysis of 37 randomized controlled clinical trials with dose-response analysis

BACKGROUND AND AIM

Clinical evidence which investigated the effects of l-carnitine, a vitamin-like substance, on weight loss had led to inconsistent results. This study therefore aimed to examine the effect of l-carnitine supplementation on body weight and composition by including the maximum number of randomized controlled trials (RCTs) and to conduct a dose-response analysis, for the first time.

METHODS AND RESULTS

Online databases were searched up to January 2019. In total, 37 RCTs (with 2292 participants) were eligible. Meta-analysis showed that l-carnitine supplementation significantly decreased body weight [Weighted mean difference (WMD) = -1.21 kg, 95% confidence interval (CI): -1.73, -0.68; P < 0.001], body mass index (BMI) (WMD = -0.24 kg/m2, 95% CI: -0.37, -0.10; P = 0.001), and fat mass (WMD = -2.08 kg, 95% CI: -3.44, -0.72; P = 0.003). No significant effect was seen for waist circumference (WC) and body fat percent. The meta-analysis of high-quality RCTs only confirmed the effect on body weight. A non-linear dose-response association was seen between l-carnitine supplementation and body weight reduction (P < 0.001) suggesting that ingestion of 2000 mg l-carnitine per day provides the maximum effect in adults. This association was not seen for BMI, WC and body fat percent.

CONCLUSIONS

l-carnitine supplementation provides a modest reducing effect on body weight, BMI and fat mass, especially among adults with overweight/obesity.

The effects of combined magnesium and zinc supplementation on metabolic status in patients with type 2 diabetes mellitus and coronary heart disease

Background

The present research aimed to analyze the impacts of magnesium and zinc supplements on glycemic control, serum lipids, and biomarkers of oxidative stress and inflammation in patients suffering from coronary heart disease (CHD) and type 2 diabetes mellitus (T2DM).

Methods

According to the research design, a randomized, double-blind, placebo-controlled trial has been implemented on 60 subjects suffering from CHD and T2DM. Therefore, participants have been randomly divided into 2 groups for taking placebo (n = 30) or 250 mg magnesium oxide plus 150 mg zinc sulfate (n = 30) for 12 weeks.

Results

Magnesium and zinc significantly decreased fasting plasma glucose (FPG) (β − 9.44 mg/dL, 95% CI, − 18.30, − 0.57; P = 0.03) and insulin levels (β − 1.37 μIU/mL, 95% CI, − 2.57, − 0.18; P = 0.02). Moreover, HDL-cholesterol levels significantly enhanced (β 2.09 mg/dL, 95% CI, 0.05, 4.13; P = 0.04) in comparison to the placebo. There was an association between magnesium and zinc intake, and a significant decrease of C-reactive protein (CRP) (β − 0.85 mg/L, 95% CI, − 1.26, − 0.45; P < 0.001), a significant increase in total nitrite (β 5.13 μmol/L, 95% CI, 1.85, 8.41; P = 0.003) and total antioxidant capacity (TAC) (β 43.44 mmol/L, 95% CI, 3.39, 83.50; P = 0.03) when compared with placebo. Furthermore, magnesium and zinc significantly reduced the Beck Depression Inventory index (BDI) (β − 1.66; 95% CI, − 3.32, − 0.009; P = 0.04) and Beck Anxiety Inventory (BAI) (β − 1.30; 95% CI, − 2.43, − 0.16; P = 0.02) when compared with the placebo.

Conclusions

In patients with T2DM and CHD, the 12-week intake of magnesium plus zinc had beneficial effects on FPG, HDL-cholesterol, CRP, insulin, total nitrite, TAC levels, and BDI and BAI score. This suggests that magnesium and zinc co-supplementation may be beneficial for patients with T2DM and CHD. Further studies on more patients and lasting longer are needed to determine the safety of magnesium and zinc co-supplementation.

Trial registration

Current Controlled Trials http://www.irct.ir: IRCT20130211012438N31 at 11 May 2019 of registration. This study retrospectively registered.

The effect of berberine supplementation on obesity parameters, inflammation and liver function enzymes: A systematic review and meta-analysis of randomized controlled trials

INTRODUCTION

So far, no study has summarized the findings on the effects of berberine intake on anthropometric parameters, C-reactive protein (CRP) and liver enzymes. This systematic review and meta-analysis were done based upon randomized controlled trials (RCTs) to analyze the effects of berberine on anthropometric parameters, CRP and liver enzymes.

METHOD

Following databases were searched for eligible studies published from inception to 30 July 2019: MEDLINE, EMBASE, Web of Science, Cochrane Library, PubMed and Google scholar. Necessary data were extracted. Data were pooled by the inverse variance method and expressed as mean difference with 95% Confidence Intervals (95% CI).

RESULT

12 studies were included. Berberine treatment moderately but significantly decreased body weight (WMD = -2.07 kg, 95% CI -3.09, -1.05, P < 0.001), body mass index (BMI) (WMD = -0.47 kg/m², 95% CI -0.70, -0.23, P < 0.001), waist circumference (WC) (WMD = -1.08 cm, 95% CI -1.97, -0.19, P = 0.018) and C-reactive protein (CRP) concentrations (WMD = -0.42 mg/L, 95% CI -0.82, -0.03, P = 0.034). However, berberine intake did not affect liver enzymes, including alanine aminotransferase (ALT) (WMD = -1.66 I/U, 95% CI -3.98, 0.65, P = 0.160) and aspartate aminotransferase (AST) (WMD = -0.87 I/U, 95% CI -2.56, 0.82, P = 0.311).

CONCLUSION

This meta-analysis found a significant reduction of body weight, BMI, WC and CRP levels associated with berberine intake which may have played an indirect role in improved clinical symptoms in diseases with metabolic disorders. Berberine administration had no significant effect on ALT and AST levels.

The Nutraceutical Value of Carnitine and Its Use in Dietary Supplements

Carnitine can be considered a conditionally essential nutrient for its importance in human physiology. This paper provides an updated picture of the main features of carnitine outlining its interest and possible use. Particular attention has been addressed to its beneficial properties, exploiting carnitine's properties and possible use by considering the main in vitro, in animal, and human studies. Moreover, the main aspects of carnitine-based dietary supplements have been indicated and defined with reference to their possible beneficial health properties.

Effects of Chromium and Carnitine Co-supplementation on Body Weight and Metabolic Profiles in Overweight and Obese Women with Polycystic Ovary Syndrome: a Randomized, Double-Blind, Placebo-Controlled Trial

The primary aim of our study was to determine the influence of taking chromium plus carnitine on insulin resistance, with a secondary objective of evaluating the influences on lipid profiles and weight loss in overweight subjects with polycystic ovary syndrome (PCOS). In a 12-week randomized, double-blind, placebo-controlled clinical trial, 54 overweight women were randomly assigned to receive either supplements (200 μg/day chromium picolinate plus 1000 mg/day carnitine) or placebo (27/each group). Chromium and carnitine co-supplementation decreased weight (- 3.6 ± 1.8 vs. - 1.0 ± 0.7 kg, P < 0.001), BMI (- 1.3 ± 0.7 vs. - 0.3 ± 0.3 kg/m², P < 0.001), fasting plasma glucose (FPG) (- 5.1 ± 6.0 vs. - 1.1 ± 4.9 mg/dL, P = 0.01), insulin (- 2.0 ± 1.4 vs. - 0.2 ± 1.2 μIU/mL, P < 0.001), insulin resistance (- 0.5 ± 0.4 vs. - 0.04 ± 0.3, P < 0.001), triglycerides (- 18.0 ± 25.2 vs. + 5.5 ± 14.4 mg/dL, P < 0.001), total (- 17.0 ± 20.3 vs. + 3.6 ± 12.0 mg/dL, P < 0.001), and LDL cholesterol (- 13.3 ± 19.2 vs. + 1.4 ± 13.3 mg/dL, P = 0.002), and elevated insulin sensitivity (+ 0.007 ± 0.005 vs. + 0.002 ± 0.005, P < 0.001). In addition, co-supplementation upregulated peroxisome proliferator-activated receptor gamma (P = 0.02) and low-density lipoprotein receptor expression (P = 0.02). Overall, chromium and carnitine co-supplementation for 12 weeks to overweight women with PCOS had beneficial effects on body weight, glycemic control, lipid profiles except HDL cholesterol levels, and gene expression of PPAR-γ and LDLR. Clinical trial registration number: http://www.irct.ir: IRCT20170513033941N38.

Causal Effects of Genetically Determined Metabolites on Risk of Polycystic Ovary Syndrome: A Mendelian Randomization Study

Background: Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder that is influenced by both genetic and environmental factors. However, the etiology of PCOS remains unclear. Methods: We conducted a two-sample Mendelian randomization (MR) analysis to assess the causal effects of genetically determined metabolites (GDMs) on the risk of PCOS. We used summary level data of a genome-wide association study (GWAS) on 486 metabolites (n = 7,824) as exposure and a PCOS GWAS consisting of 4,138 cases and 20,129 controls as the outcome. Both datasets were obtained from publicly published databases. For each metabolite, a genetic instrumental variable was generated to assess the relationship between the metabolite and PCOS. For MR analysis, we primarily used the standard inverse variance weighted (IVW) method, while three additional methods-the MR-Egger, weighted median, and MR-PRESSO (pleiotropy residual sum and outlier) methods-were performed as sensitivity analyses. Results: Using genetic variants as predictors, we observed a robust relationship between epiandrosterone sulfate (EPIA-S) and PCOS (P_IVW = 0.0186, P_MR-Egger = 0.0111; P_{Weighted-median} = 0.0154, and P_MR-PRESSO = 0.0290). Similarly, 3-dehydrocarnitine, 4-hydroxyhippurate, hexadecanedioate, and β-hydroxyisovalerate may also have causal effects on PCOS development. Conclusions: We identified metabolites that might have causal effects on PCOS development. Our study emphasizes the role of genetic factors underlying the causal relationships between metabolites and PCOS and provides novel insights through the integration of metabolomics and genomics to better understand the mechanisms involved in human disease pathogenesis.

L-Carnitine improves endocrine function and folliculogenesis by reducing inflammation, oxidative stress and apoptosis in mice following induction of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is related to low levels of serum l-carnitine, which has antioxidant, anti-inflammatory and antiapoptotic properties. The aim of this study was to investigate the effect of l-carnitine on folliculogenesis in mice following induction of PCOS. PCOS was induced by daily injections of testosterone enanthate (1mg per 100g, s.c., for 35 days). NMRI mice (21 days old) were divided into four groups (n=6 per group): Control, Control+l-carnitine, PCOS and PCOS+l-carnitine. Mice were treated with 500mgkg-1, i.p., l-carnitine every second day for 28 days. Ovaries were studied stereologically and serum concentrations of FSH, LH, testosterone, interleukin (IL)-6 and tumour necrosis factor (TNF)-α were determined using ELISA kits. Serum concentrations of malondialdehyde (MDA) and the ferric ion reducing antioxidant power (FRAP) were also analysed. Apoptosis of follicles was evaluated by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL). CD31 was assessed immunohistochemically. Data were analysed using one-way analysis of variance (ANOVA) and Tukey's test, differences considered significant at P<0.05.The total volume of the ovary, cortex volume, oocyte volume, zona pellucida thickness and the number of antral follicles increased significantly, whereas the number of primary and preantral follicles decreased significantly, in the PCOS+l-carnitine versus PCOS group. In the PCOS+l-carnitine group, serum concentrations of FSH and FRAP increased significantly, whereas there were significant decreases in serum concentrations of testosterone, LH, MDA, IL-6 and TNF-α, as well as in the percentage of TUNEL-positive apoptotic cells, compared with the PCOS group. l-Carnitine improves folliculogenesis and is therefore suggested as a therapeutic supplement in the treatment of PCOS.

The Effects of L-Carnitine Supplementation on Serum Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background:

The findings of trials investigating the effects of L-carnitine administration on serum lipids are inconsistent. This meta-analysis of randomized controlled trials (RCTs) was performed to summarize the effects of L-carnitine intake on serum lipids in patients and healthy individuals.

Methods:

Two authors independently searched electronic databases including MEDLINE, EMBASE, Cochrane Library, Web of Science, PubMed and Google Scholar from 1990 until August 1, 2019, in order to find relevant RCTs. The quality of selected RCTs was evaluated using the Cochrane Collaboration risk of bias tool. Cochrane’s Q test and I-square (I2) statistic were used to determine the heterogeneity across included trials. Weight mean difference (SMD) and 95% CI between the two intervention groups were used to determine pooled effect sizes. Subgroup analyses were performed to evaluate the source of heterogeneity based on suspected variables such as, participant’s health conditions, age, dosage of L-carnitine, duration of study, sample size, and study location between primary RCTs.

Results:

Out of 3460 potential papers selected based on keywords search, 67 studies met the inclusion criteria and were eligible for the meta-analysis. The pooled results indicated that L-carnitine administration led to a significant decrease in triglycerides (WMD: -10.35; 95% CI: -16.43, -4.27), total cholesterol (WMD: -9.47; 95% CI: - 13.23, -5.70) and LDL-cholesterol (LDL-C) concentrations (WMD: -6.25; 95% CI: -9.30, -3.21), and a significant increase in HDL-cholesterol (HDL-C) levels (WMD: 1.39; 95% CI: 0.21, 2.57). L-carnitine supplementation did not influence VLDL-cholesterol concentrations. When we stratified studies for the predefined factors such as dosage, and age, no significant effects of the intervention on triglycerides, LDL-C, and HDL-C levels were found.

Conclusion:

This meta-analysis demonstrated that L-carnitine administration significantly reduced triglycerides, total cholesterol and LDL-cholesterol levels, and significantly increased HDL-cholesterol levels in the pooled analyses, but did not affect VLDL-cholesterol levels; however, these findings were not confirmed in our subgroup analyses by participant’s health conditions, age, dosage of L-carnitine, duration of study, sample size, and study location.

Possible role of l-carnitine in improvement of metabolic and hepatic changes in hyperuricemic and hyperuricemic-Fructose-supplemented rats

Hyperuricemia was linked to diabetes mellitus, metabolic syndrome, and oxidative stress, and could be induced by higher fructose consumption through altering energy status in liver. l-Carnitine is an antioxidant, affecting mitochondria and cellular energetics; however, little is known about its effects in hyperuricemic states. This study investigated metabolic and hepatic effects of hyperuricemia and fructose feeding, and demonstrated the role of l-Carnitine in such states. Fifty adult male Wistar rats were randomly divided into control, untreated hyperuricemic, fructose-supplemented hyperuricemic, l-Carnitine-treated hyperuricemic, and l-Carnitine-treated fructose-supplemented hyperuricemic groups. The separated plasma was used for determination of the glycemic control, lipid profile, liver function tests, uric acid level, and oxidative stress markers. Atherogenic index, HOMA-IR, and body mass index (BMI) were calculated. Left liver lobe and left kidney specimen from all groups were used for histopathological studies. Hyperuricemic rats exhibited significantly hypoalbuminemia, dyslipidemia, insulin resistance, and oxidative stress compared to the controls. Fructose-supplemented hyperuricemic group showed obesity and more deleterious effects, as well as, steatosis, and renal tubular damage compared to the hyperuricemic rats. Concomitant l-Carnitine treatment with hyperuricemia improved such effects, despite causing adiposity. While combined l-Carnitine treatment and fructose supplementation in hyperuricemia limited the aggressive hyperuricemic picture of fructose supplementation. It is concluded that hyperuricemia has detrimental metabolic and hepatic effects. Artificial fructose supplementation worsened such effects, while l-Carnitine was efficient in ameliorating these hyperuricemia and/or excess fructose-induced hyperuricemia effects, through its anti-inflammatory, antisteatotic, and antioxidant properties.

Efficacy of l-carnitine supplementation for management of blood lipids: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND AND AIM

l-carnitine has an important role in fatty acid metabolism and could therefore act as an adjuvant agent in the improvement of dyslipidemia. The purpose of present systematic review and meta-analysis was to critically assess the efficacy of l-carnitine supplementation on lipid profiles.

METHODS AND RESULTS

We performed a systematic search of all available randomized controlled trials (RCTs) in the following databases: Scopus, PubMed, ISI Web of Science, The Cochrane Library. Mean difference (MD) of any effect was calculated using a random-effects model. In total, there were 55 eligible RCTs included with 58 arms, and meta-analysis revealed that l-carnitine supplementation significantly reduced total cholesterol (TC) (56 arms-MD: -8.53 mg/dl, 95% CI: -13.46, -3.6, I²: 93%), low-density lipoprotein-cholesterol (LDL-C) (47 arms-MD: -5.48 mg/dl, 95% CI: -8.49, -2.47, I²: 94.5) and triglyceride (TG) (56 arms-MD: -9.44 mg/dl, 95% CI: -16.02, -2.87, I²: 91.8). It also increased high density lipoprotein-cholesterol (HDL-C) (51 arms-MD:1.64 mg/dl, 95% CI:0.54, 2.75, I²: 92.2). l-carnitine supplementation reduced TC in non-linear fashion based on dosage (r = 21.11). Meta-regression analysis indicated a linear relationship between dose of l-carnitine and absolute change in TC (p = 0.029) and LDL-C (p = 0.013). Subgroup analyses showed that l-carnitine supplementation did not change TC, LDL-C and TG in patients under hemodialysis treatment. Intravenous l-carnitine and lower doses (>2 g/day) had no effect on TC, LDL-C and triglycerides.

CONCLUSION

l-carnitine supplementation at doses above 2 g/d has favorable effects on patients' lipid profiles, but is modulated on participant health and route of administration.

Effects of L-carnitine on Polycystic Ovary Syndrome

Objective:

Polycystic ovary syndrome (PCOS) is a common disorder in women of reproductive age. This study investigated the effects of L-carnitine on the clinical and laboratory findings of women with PCOS.

Methods:

Eighty women diagnosed with PCOS between 2017 and 2018 by the Rotterdam Criteria were enrolled in the study; six were lost during the study. The participants were given L-carnitine 3 g daily (Pursinapharma, Iran) for three months. Blood samples were taken after overnight fasting at baseline and three months into the study to assess the levels of fasting glucose, insulin, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), free testosterone, dehydroepiandrosterone (DHEA), and the insulin resistance index (HOMA-IR). The patients were weighed before and after treatment and had their body mass index (BMI) calculated. Menstrual cycles and manifestations of hirsutism were also assessed.

Results:

The data showed a significant improvement in insulin sensitivity and decreases in serum LDL levels and the BMI after three months of treatment. There was a significant increase in serum HDL levels. More regular menstrual cycles and decreased hirsutism were also observed.

Conclusion:

It appears that treatment with L-carnitine might decrease the risk of cardiovascular events by normalizing metabolic profiles and the BMI.