Oral carnitine supplementation influences mental health parameters and biomarkers of oxidative stress in women with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

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.

Comparison of nutritional supplements in improving glycolipid metabolism and endocrine function in polycystic ovary syndrome: a systematic review and network meta-analysis

Objective

To explore the comparative effectiveness of nutritional supplements in improving glycolipid metabolism and endocrine function in patients with polycystic ovary syndrome (PCOS).

Method

Randomized controlled clinical trials on the effects of nutritional supplements in PCOS patients were searched in PubMed, Embase, Cochrane Library, and Web of Science from their establishments to March 15, 2023. Then, literature screening, data extraction, and network meta-analysis were performed. This study was registered at PROSPERO (registration number CRD 42023441257).

Result

Forty-one articles involving 2,362 patients were included in this study. The network meta-analysis showed that carnitine, inositol, and probiotics reduced body weight and body mass index (BMI) compared to placebo, and carnitine outperformed the other supplements (SUCRAs: 96.04%, 97.73%, respectively). Omega-3 lowered fasting blood glucose (FBG) (SUCRAs: 93.53%), and chromium reduced fasting insulin (FINS) (SUCRAs: 72.90%); both were superior to placebo in improving insulin resistance index (HOMA-IR), and chromium was more effective than Omega-3 (SUCRAs: 79.99%). Selenium was potent in raising the quantitative insulin sensitivity index (QUICKI) (SUCRAs: 87.92%). Coenzyme Q10 was the most effective in reducing triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels (SUCRAs: 87.71%, 98.78%, and 98.70%, respectively). Chromium and probiotics decreased TG levels, while chromium and vitamin D decreased TC levels. No significant differences were observed in high-density lipoprotein cholesterol (HDL-C), total testosterone (TT), sex-hormone binding globulin (SHBG), and C-reactive protein (CRP) between nutritional supplements and placebo.

Conclusion

Carnitine was relatively effective in reducing body mass, while chromium, Omega-3, and selenium were beneficial for improving glucose metabolism. Meanwhile, coenzyme Q10 was more efficacious for improving lipid metabolism. However, publication bias may exist, and more high-quality clinical randomized controlled trials are needed.

The effects of L-carnitine supplementation on inflammatory and anti-inflammatory markers in adults: a systematic review and dose-response meta-analysis

L-carnitine supplementation may be beneficial in improving inflammatory conditions and reducing the level of inflammatory cytokines. Therefore, according to the finding of randomized controlled trials (RCTs), the systematic review and meta-analysis aimed to investigate the effect of L-carnitine supplementation on inflammation in adults. To obtain acceptable articles up to October 2022, a thorough search was conducted in databases including PubMed, ISI Web of Science, the Cochrane Library, and Scopus. A random-effects model was used to estimate the weighted mean difference (WMD). We included the 48 RCTs (n = 3255) with 51 effect sizes in this study. L-carnitine supplementation had a significant effect on C-reactive protein (CRP) (p < 0.001), interleukin-6 (IL-6) (p = 0.001), tumor necrosis factor-α (TNF-α) (p = 0.002), malondialdehyde (MDA) (p = 0.001), total antioxidant capacity (TAC) (p = 0.029), alanine transaminase (ALT) (p < 0.001), and aspartate transaminase (AST) (p < 0.001) in intervention, compared to the placebo group. Subgroup analyses showed that L-carnitine supplementation had a lowering effect on CRP and TNF-α in trial duration ≥ 12 weeks in type 2 diabetes and BMI ≥ 25 kg/m2. L-carnitine supplementation reduced ALT levels in overweight and normal BMI subjects at any trial dose and trial duration ≥ 12 weeks and reduced AST levels in overweight subjects and trial dose ≥ 2 g/day. This meta-analysis revealed that L-carnitine supplementation effectively reduces the inflammatory state by increasing the level of TAC and decreasing the levels of CRP, IL-6, TNF-α and MDA in the serum.

Effects of L-carnitine supplementation on glucolipid metabolism: a systematic review and meta-analysis

Background: L-carnitine supplementation has been utilized against glucolipid metabolism disruption. However, to the best of our knowledge, no meta-analysis process has analyzed the effects of L-carnitine supplementation on insulin resistance, fasting blood glucose, lipid metabolism, and liver enzyme levels in adults. Methods: Through the analysis and screening of 12 221 studies, 15 studies were selected from eligible trials for meta-analysis. Meta-analysis was performed in a random effect model with heterogeneity determined by I², and subgroup analyses were used to further identify the source of heterogeneity. Result: The results showed significant effects of L-carnitine on FBG (MD = -4.94 mg dL^-1, 95% CI: -7.07 to -2.82), insulin (MD = -0.99 μU mL^-1, 95% CI: -1.41 to -0.56), HOMA-IR (MD = -0.58, 95% CI: -0.77 to -0.38), TG (MD = -11.22 mg dL^-1, 95% CI: -19.21 to -3.22), TC (MD = -6.45 mg dL^-1, 95% CI: -9.95 to -2.95, LDLc (MD = -8.28 mg dL^-1, 95% CI: -11.08 to -5.47), and ALT (MD = -19.71 IU L^-1, 95% CI: -36.45 to -2.96). However, no significant effect of L-carnitine supplementation was observed in HDLc (MD = -0.77 mg dL^-1, 95% CI: -0.10 to -1.63) or AST (MD = -11.05 IU L^-1, 95% CI: -23.08 to 0.99). The duration of carnitine supplementation was negatively associated with mean differences in FBG, as assessed by meta-regression. Conclusion: The current meta-analysis revealed that L-carnitine may have favorable effects on glucolipid profile, especially insulin, FBG, HOMA-IR, TG, TC, LDLc, and ALT levels.

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.

Lifestyle management in polycystic ovary syndrome - beyond diet and physical activity

Polycystic ovary syndrome (PCOS) is a common condition affecting reproductive-aged women with reproductive, metabolic and psychological consequences. Weight and lifestyle (diet, physical activity and behavioural) management are first-line therapy in international evidence-based guidelines for PCOS. While these recommend following population-level diet and physical activity guidelines, there is ongoing interest and research in the potential benefit of including psychological and sleep interventions, as well as a range of traditional, complimentary and integrative medicine (TCIM) approaches, for optimal management of PCOS. There is limited evidence to recommend a specific diet composition for PCOS with approaches including modifying protein, carbohydrate or fat quality or quantity generally having similar effects on the presentations of PCOS. With regards to physical activity, promising evidence supports the provision of vigorous aerobic exercise, which has been shown to improve body composition, cardiorespiratory fitness and insulin resistance. Psychological and sleep interventions are also important considerations, with women displaying poor emotional wellbeing and higher rates of clinical and subclinical sleep disturbance, potentially limiting their ability to make positive lifestyle change. While optimising sleep and emotional wellbeing may aid symptom management in PCOS, research exploring the efficacy of clinical interventions is lacking. Uptake of TCIM approaches, in particular supplement and herbal medicine use, by women with PCOS is growing. However, there is currently insufficient evidence to support integration into routine clinical practice. Research investigating inositol supplementation have produced the most promising findings, showing improved metabolic profiles and reduced hyperandrogenism. Findings for other supplements, herbal medicines, acupuncture and yoga is so far inconsistent, and to reduce heterogeneity more research in specific PCOS populations, (e.g. defined age and BMI ranges) and consistent approaches to intervention delivery, duration and comparators are needed. While there are a range of lifestyle components in addition to population-recommendations for diet and physical activity of potential benefit in PCOS, robust clinical trials are warranted to expand the relatively limited evidence-base regarding holistic lifestyle management. With consumer interest in holistic healthcare rising, healthcare providers will be required to broaden their knowledge pertaining to how these therapies can be safely and appropriately utilised as adjuncts to conventional medical management.

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.

Dietary Supplementations and Depression

Depression is a mood disturbance condition that occurs for more than two weeks in a row, leading to suicide. Due to adverse effects of depression, antidepressants and adjunctive therapies, such as dietary supplementation, are used for treatment. Therefore, this review explored and summarized dietary supplements’ types, dosages, and effectiveness in preventing and treating depression. A literature search of the PubMed database was conducted in August 2021 to identify studies assessing depression, after which scale measurements based on dietary supplements were identified. From the obtained 221 studies, we selected 63 papers. Results showed PUFA (EPA and DHA combination), vitamin D, and probiotics as the most common supplementation used in clinical studies to reduce depressive symptoms. We also observed that although the total daily PUFA dosage that exhibited beneficial effects was in the range of 0.7–2 g EPA and 0.4–0.8 g DHA daily, with an administration period of three weeks to four months, positive vitamin D-based supplementation effects were observed after administering doses of 2000 IU/day or 50,000 IU/week between 8 weeks and 24 months. Alternatively, microbes from the genus Lactobacillus and Bifidobacterium in the probiotic group with a minimum dose of 10⁸ CFU in various dose forms effectively treated depression. Besides, a depression scale was helpful to assess the effect of an intervention on depression. Hence, PUFA, vitamin D, and probiotics were proposed as adjunctive therapies for depression treatment based on the results from this study.

Clinical and Biochemical Potential of Antioxidants in Treating Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common cause of infertility in reproductive-age women. Increased reactive oxygen species levels and decreased antioxidant capacity in PCOS patients can lead to metabolic disorders and damage the ovarian tissues, resulting in the occurrence of related symptoms. Antioxidants have been used in the treatment of PCOS and have yielded satisfactory outcomes due to their ability to counter oxidative stress. Many experiments on PCOS patients have proved that antioxidants can not only improve the ovarian environment, promote follicular maturation, and elevate oocyte quantities but can also regulate lipid and glucose metabolism as well as vascular endothelial cell function in PCOS patients, thereby attenuating adiposity and reducing the occurrence rate of chronic complications to ensure that patients can obtain long-term benefits. This review describes the use of antioxidants in PCOS, which have been used in the treatment.

Carnitine and Depression

Depression has become one of the most common mental diseases in the world, but the understanding of its pathogenesis, diagnosis and treatments remains insufficient. Carnitine is a natural substance that exists in organisms, which can be synthesized in vivo or supplemented by intake. Relationships of carnitine with depression, bipolar disorder and other mental diseases have been reported in different studies. Several studies show that the level of acylcarnitines (ACs) changes significantly in patients with depression compared with healthy controls while the supplementation of acetyl-L-carnitine is beneficial to the treatment of depression. In this review, we aimed to clarify the effects of ACs in depressive patients and to explore whether ACs might be the biomarkers for the diagnosis of depression and provide new ideas to treat depression.

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.

Mitigating the pro-oxidant state and melanogenesis of Retinitis pigmentosa: by counteracting mitochondrial dysfunction

Retinitis pigmentosa (RP) is a group of mitochondrial diseases characterized by progressive degeneration of rods and cones leading to retinal loss of light sensitivity and, consequently, to blindness. To date, no cure is available according to the clinical literature. As a disease associated with pigmentation-related, pro-oxidant state, and mitochondrial dysfunction, RP may be viewed at the crossroads of different pathogenetic pathways involved in adverse health outcomes, where mitochondria play a preeminent role. RP has been investigated in a number of experimental and clinical studies aimed at delaying retinal hyperpigmentation by means of a number of natural and synthetic antioxidants, as well as mitochondrial cofactors, also termed mitochondrial nutrients (MNs), such as alpha-lipoic acid, coenzyme Q10 and carnitine. One should consider that each MN plays distinct-and indispensable-roles in mitochondrial function. Thus, a logical choice would imply the administration of MN combinations, instead of individual MNs, as performed in previous studies, and with limited, if any, positive outcomes. A rational study design aimed at comparing the protective effects of MNs, separately or in combinations, and in association with other antioxidants, might foresee the utilization of animal RP models. The results should verify a comparative optimization in preventing or effectively contrasting retinal oxidative stress in mouse RP models and, in prospect, in human RP cases.

Nutritional Supplements and Complementary Therapies in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) affects 1 in 5 women of reproductive age, and is characterized by menstrual irregularities, clinical or biochemical hyperandrogenism, and the presence of polycystic ovary morphology. One of the recommended treatment strategies in the international evidence-based guidelines is lifestyle modification, which includes diet and exercise, with the aim of improving a range of health outcomes. The incurable nature of PCOS reinforces the importance of developing novel and innovative symptomatic relief strategies, which are currently the only available approaches for improving quality of life for these women. Women with PCOS tend to be nutrient deficient in many common vitamins and minerals, thought to be associated with the psychological (depression, anxiety, etc.) and physiological (insulin resistance, diabetes, infertility, etc.) sequelae of the condition. Nutrient supplementation and the integration of complementary medicine as adjuncts to traditional lifestyle-based therapies in PCOS could therefore provide additional benefits to these women. In this review, we synthesize the evidence regarding nutrient supplementation and complementary therapies in PCOS, predominantly from randomized controlled trials, systematic reviews, and meta-analyses, to provide an overview of the state of knowledge in this field. The evidence to date suggests that specific vitamins (B-12, inositols, folate, vitamins D, E, and K), vitamin-like nutrients (bioflavonoids and α-lipoic acid), minerals (calcium, zinc, selenium, and chromium picolinate), and other formulations (melatonin, ω-3 fatty acids, probiotics, and cinnamon), as well as some complementary approaches such as acupuncture and yoga may be beneficial in PCOS. However, there remain areas of uncertainty and key limitations in the literature that must be overcome before these therapies can be integrated into routine clinical practice.

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.

Role of Carnitine in Non-alcoholic Fatty Liver Disease and Other Related Diseases: An Update

Carnitine is an amino acid-derived substance that coordinates a wide range of biological processes. Such functions include transport of long-chain fatty acids from the cytoplasm to the mitochondrial matrix, regulation of acetyl-CoA/CoA, control of inter-organellar acyl traffic, and protection against oxidative stress. Recent studies have found that carnitine plays an important role in several diseases, including non-alcoholic fatty liver disease (NAFLD). However, its effect is still controversial, and its mechanism is not clear. Herein, this review provides current knowledge on the biological functions of carnitine, the “multiple hit” impact of carnitine on the NAFLD progression, and the downstream mechanisms. Based on the “multiple hit” hypothesis, carnitine inhibits β-oxidation, improves mitochondrial dysfunction, and reduces insulin resistance to ameliorate NAFLD. L-carnitine may have therapeutic role in liver diseases including non-alcoholic steatohepatitis, cirrhosis, hepatocellular carcinoma, alcoholic fatty liver disease, and viral hepatitis. We also discuss the prospects of L-carnitine supplementation as a therapeutic strategy in NAFLD and related diseases, and the factors limiting its widespread use.

Effect of Nutritional Supplementation on Oxidative Stress and Hormonal and Lipid Profiles in PCOS-Affected Females

Polycystic ovary syndrome (PCOS) affects several reproductive and endocrine features in females and has a poorly understood etiology. Treatment strategies for PCOS are limited and are based primarily on diet and nutrient supplementation. Recent studies have recommended some nutrients such as vitamins, minerals and vitamin-like nutrients for the therapy for PCOS. Therefore, it is claimed that the cause of PCOS could be vitamin or mineral deficiency. This review provides a narrative on the effect of nutritional supplementation on oxidative stress induced in PCOS. Oxidative stress plays a formative role in PCOS pathophysiology. This article reviews oxidative stress, its markers, nutritional supplementation and clinical studies. We also aim to show the effect of nutritional supplementation on genes affecting hormonal and glucose-mediated pathways.

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.

Metabolomics in endometriosis: challenges and perspectives for future studies

Endometriosis is a complex disease characterized by inflammation and the growth of endometrial- like glands and stroma outside the uterine cavity. The pathophysiology of endometriosis is not entirely understood, however, with a prevalence of ~10% of women in their reproductive years, the disease symptoms significantly affect the quality of life of millions of women globally. Metabolomic studies have previously identified specific metabolites that could be a signature of endometriosis. This approach could potentially be used as a non-invasive tool for early diagnosis and provide a better understanding of endometriosis pathophysiology. This review aims to provide insight as to how endometriosis affects the metabolome by reviewing different studies that have used this approach to design follow-up studies. The search query included the term 'endometriosis' in combination with 'metabolomics', 'lipidomics', or 'sphingolipidomics' published between 2012 and 2020. We included studies in humans and animal models. Most studies reported differences in the metabolome of subjects with endometriosis in comparison to healthy controls and used samples taken from serum, endometrial tissue, follicular fluid, urine, peritoneal fluid, or endometrial fluid. Statistically significant metabolites contributed to group separation between patients and healthy controls. Reported metabolites included amino acids, lipids, organic acids, and other organic compounds. Differences in methods, analytical techniques, and the presence of confounding factors can interfere with results and interpretation of data. Metabolomics seems to be a promising tool for identifying significant metabolites in patients with endometriosis. Nonetheless, more investigation is needed in order to understand the significance of the study results.

Lay summary

Endometriosis is a chronic disease affecting the quality of life in one out of every ten women during their reproductive years, causing pain and infertility. It is characterized by inflammation and growth of tissue like the endometrium (uterus lining) outside the uterine cavity. Studies have searched for a predictor of endometriosis-associated changes by observing small molecules necessary for metabolism on a large scale (metabolomics). Metabolomics could serve to resolve one of the biggest challenges that patients with endometriosis face: a delay in diagnosis. In this review, the authors summarize identified potential biomarkers from various bodily fluids and tissues that are characteristic of metabolic processes observed in endometriosis. Biomarkers include cell growth, cell survival, high energy demand, oxidative stress, and fatty acid levels. A metabolomics approach offers promise as a non-invasive tool to identify significant metabolite changes in patients with endometriosis, potentially leading to earlier diagnoses and new opportunities for back-translational strategies.

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.

Serum Metabolomic Profiling Based on Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry: Do the Dysfunctions of Metabolic Pathways Reveal a Universal Risk of Oxidative Stress in Schizophrenia?

Schizophrenia is a chronic, disabling, and complex mental illness, of which the pathogenesis remains elusive. To provide clues for the pathogenesis and etiology of schizophrenia, we performed serum metabolic profiling in 54 patients with schizophrenia and 54 matched healthy controls using Fourier transform-ion cyclotron resonance-mass spectrometry. Based on 94 differential metabolites identified, we discovered two dysregulated metabolic pathways in schizophrenia, including the upregulated arachidonic acid-related pathway and the downregulated aromatic amino acid-related pathway. Moreover, carnitine was identified as a promising diagnostic biomarker for schizophrenia with an area under the curve of 0.997. Given the antioxidant and pro-oxidant properties of these altered metabolites, these results pointed to an imbalance of the redox homeostasis in schizophrenia, which was further confirmed by a remarkable elevation of 8-hydroxydeoxyguanosine (8-OHdG), a reactive oxidative stress marker. Furthermore, correlation analyses demonstrated that 8-OHdG was negatively correlated with antioxidant biliverdin and positively related to oxidation products, 9-hydroxylinoleic acid and o-tyrosine, and that total antioxidant capacity was positively associated with antioxidant acetylcarnitine in schizophrenia. Our results lead to the hypothesis that the disturbed metabolic characteristics reveal enhanced oxidative stress, which in turn results in the damage of lipids, proteins, and DNA and ultimately promotes the development of schizophrenia.

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.

The effects of L-carnitine supplementation on indicators of inflammation and oxidative stress: a systematic review and meta-analysis of randomized controlled trials

Objective

Several trials investigated the efficacy of L-carnitine administration on markers of inflammation and indicators of oxidative stress; however, their findings are controversial. The aim of this study was to conduct a comprehensive meta-analysis and a critical review, which would analyze all randomized controlled trials (RCTs) in order to determine the effects of L-carnitine supplementation on inflammatory markers and oxidative stress.

Methods

An electronic search was performed using Scopus, Cochrane Library, PubMed, Google scholar and Web of Science databases on publications from 1990 up to May 2020. Human RCTs conducted in healthy subjects or participants with certain disorders which investigating the efficacy of L-carnitine supplementation compared to control (placebo, usual treatment or no intervention) on inflammation and oxidative markers were included. Data were pooled applying a random-effects model and as the overall effect size, weighted mean difference (WMD) was presented. Between heterogeneity among studies was computed using Cochran's Q test and I-square (I²). Quality of studies assessed using the Jadad scale. Dose-response analysis was measured using meta-regression. The funnel plot, as well as the Egger's regression test was applied to determine the publication bias.

Results

44 trials (reported 49 effect sizes for different outcomes of interest) met the inclusion criteria for this meta-analysis. According to the findings, L-carnitine supplementation resulted in a significant reduction in C-reactive protein (CRP) (WMD: -0.10; 95% CI: -0.14, -0.06), interleukin 6 (IL-6) (WMD: -1.87; 95% CI: -2.80, -0.95), tumor necrosis factor-α (TNF-α) levels (WMD: -1.43; 95% CI: -2.03, -0.84), and malondialdehyde (MDA) (WMD: -0.47; 95% CI: -0.76, -0.18) levels, while there was a significant increase in superoxide dismutase (SOD) (WMD: 2.14; 95% CI: 1.02, 3.25). However, no significant effects of L-carnitine on glutathione peroxidase (GPx) (WMD: 0.02; 95% CI: -0.01, 0.05) and total antioxidant capacity (TAC) (WMD: 0.14; 95% CI: -0.05, 0.33) were found.

Conclusions

L-carnitine supplementation was associated with lowering of CRP, IL-6, TNF-α, and MDA, and increasing SOD levels, but did not affect other inflammatory and oxidative stress biomarkers.

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.

Metabolic profiling for water-soluble metabolites in patients with schizophrenia and healthy controls in a Chinese population: A case-control study

Objectives: Objective measures integrated with clinical symptoms may improve early prevention and detection of schizophrenia. Herein we aim to evaluate potential water-soluble metabolic biomarkers in schizophrenia.Methods: We recruited adults with schizophrenia (n = 113) who had not received pharmacological treatment for at least 1 month prior to enrollment and 111 age- and sex-matched healthy subjects from Weifang, Shandong province, China. All serum samples were analysed using liquid chromatography-tandem mass spectrometry coupled with a hydrophilic interaction liquid chromatography column.Results: Eleven metabolites, namely carnitines (oleoylcarnitine, l-palmitoylcarnitine, 9-decenoylcarnitine and 2-trans,4-cis-decadienoylcarnitine), polar lipids (lysophosphatidylcholine (LPC)(P-16:0), LPC (16:0), LPC (15:0) and LPC(14:0)), amino acids (taurine and l-arginine), and organic acid (2,5-dichloro-4-oxohex-2-enedioate), separated the patients and healthy controls. Compared with healthy controls, taurine, l-palmitoylcarnitine and oleoylcarnitine levels were higher, whereas the remaining eight metabolites were lower in patients with schizophrenia. A combination of four metabolites, i.e., oleoylcarnitine, 9-decenoylcarnitine, LPC (15:0) and LPC (14:0), provided the most robust between-group separation.Conclusions: This study appears to distinguish between groups of patients and controls, which should be considered as a contribution to putative potential biomarkers. The water-soluble metabolites were determined to be significantly different between the groups in the current study, and were primarily related to cellular bioenergetics, notably oxidative stress.

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.

Does L-carnitine supplementation affect serum levels of enzymes mainly produced by liver? A systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND AND AIMS

L-carnitine supplementation is proposed to reduce liver enzymes levels; however, previous findings were equivocal. The current systematic review and meta-analysis of randomized controlled clinical trials (RCTs) were performed to assess the effect of L-carnitine supplementation on serum levels of enzymes mainly produced by liver [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transpeptidase (GGTP)].

METHODS

Online databases as well as the reference lists of relevant studies were searched from inception up to June 2019. The risk of bias in individual studies was assessed using Cochrane Collaboration's tool. Data were pooled using the random-effects model and expressed as mean differences (MDs) with 95% confidence intervals (CIs).

RESULTS

In total, 18 RCTs (1161 participants) met the eligibility criteria. L-carnitine supplementation dose ranged from 500 to 4000 mg/day. L-carnitine supplementation significantly reduced serum ALT (MD = - 8.65 IU/L, 95% CI - 13.40, - 3.90), AST (MD = - 8.52 IU/L, 95% CI - 12.16, - 4.89), and GGTP (MD = - 8.80 IU/L, 95% CI - 13.67, - 3.92) levels. The subgroup analysis showed that L-carnitine might be more effective in reducing the enzymes when supplemented in higher doses (≥ 2000 mg/day), for longer durations (> 12 weeks), and among patients with liver diseases. The meta-evidence was graded as "moderate" for ALT and AST, and "low" for GGTP according to NutriGrade scoring system.

CONCLUSION

L-carnitine supplementation significantly improves circulating ALT, AST and GGTP levels; therefore, it might positively affect liver function, especially among patients with liver diseases. Further high-quality RCTs are recommended to confirm our results.

l-Carnitine plus metformin in clomiphene-resistant obese PCOS women, reproductive and metabolic effects: a randomized clinical trial

To evaluate the reproductive and metabolic effects of L-carnitine plus metformin in clomiphene citrate (CC) resistant obese polycystic ovary syndrome (PCOS) women. A double-blinded randomized controlled clinical trial, clomiphene-citrate resistant obese women were allocated randomly to receive CC plus metformin and L-carnitine (n = 138) or CC plus metformin and placebo (n = 136). The primary outcome was clinical pregnancy rate. The secondary outcomes were hormonal and metabolic profile changes in addition to ovulation and first trimester (13 weeks) miscarriage rates. Clomiphene-citrate, L-carnitine, and metformin group showed significant improvement in the menstrual regularity, ovulation rate, and pregnancy rate compared to CC plus metformin and placebo group (29% vs. 9%, 34.7% vs.11%, and 28.2% vs. 6.6%, respectively). No statistically significant difference in the miscarriage rate between the two groups (p = .08). After three months of treatment, the reduction in body mass index (BMI) was non-significant (p = .061) between both groups. The hormonal and metabolic parameters were more significantly improved in the L-carnitine group compared with the placebo group. l-Carnitine may act synergistically with metformin for improvement of reproductive performance, insulin resistance, and lipid profile in clomiphene-resistant obese PCOS women.

Randomized controlled trial of N-acetylcysteine versus l-carnitine among women with clomiphene-citrate-resistant polycystic ovary syndrome

OBJECTIVE

To compare clinical and metabolic profiles between N-acetylcysteine and l-carnitine among women with clomiphene citrate (CC)-resistant polycystic ovary syndrome (PCOS).

METHODS

A randomized trial at Zagazig University between January 2017 and March 2018. Women with CC-resistant PCOS were allocated randomly to receive CC plus N-acetylcysteine or CC plus l-carnitine. The primary outcome was clinical pregnancy rate; secondary outcomes were ovulation rate and metabolic changes.

RESULTS

Overall, 162 women completed the study (N-acetylcysteine group, n=82; l-carnitine group, n=80). After 3 months, there was no difference in pregnancy (P=0.15), ovulation (P=0.21), or spontaneous abortion (P=0.11) rates between the two groups. There was no significant decrease in BMI in either group (both P>0.05). There were improvements in menstrual pattern, follicle-stimulating hormone, luteinizing hormone, free testosterone, and insulin resistance markers in both groups (all P<0.05). An improvement in lipid profile was observed only in the l-carnitine group (P<0.001). N-Acetylcysteine treatment led to significantly greater improvement in free testosterone and insulin resistance parameters as compared with l-carnitine (all P<0.05).

CONCLUSIONS

Both N-acetylcysteine and l-carnitine were equally effective in improving pregnancy and ovulation rates among women with CC-resistant PCOS. However, N-acetylcysteine was superior in ameliorating insulin resistance and only l-carnitine improved lipid profile.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03164421.

Potential roles of carnitine in patients with polycystic ovary syndrome: a systematic review

Polycystic ovary syndrome (PCOS) is recognized as the most prevalent endocrinopathy in reproductive-aged women. This systematic review was performed with focus on the current knowledge on carnitine concerning metabolic variables in PCOS. PubMed, Scopus, Embase, ClinicalTrials.gov and Google Scholar databases were searched from inception until May 2018. All clinical trials and observational studies published in English-language journals were eligible. Studies that provided insufficient outcomes, animal and in vitro studies were excluded. Out of 451 articles identified in our search, only six articles were eligible for analysis. Two observational studies evaluated the association of serum carnitine levels with metabolic variables, and four clinical trials examined the effect of carnitine supplementation in patients with PCOS. Serum carnitine levels had inverse relationship with glycemic status, body mass index (BMI) and waist circumference. Also, carnitine supplementation resulted in improved weight loss, glycemic status, oxidative stress, follicles and size of ovarian cells; no significant effects were reported on sex hormones and lipid profile. According to the current evidence, carnitine might improve weight loss, glycemic status and oxidative stress. However, to explore the exact mechanisms of carnitine role in patients with PCOS, further studies are recommended.

Carnitine and chromium co-supplementation affects mental health, hormonal, inflammatory, genetic, and oxidative stress parameters in women with polycystic ovary syndrome

OBJECTIVE

The aim of this study was to evaluate the effect of the co-administration of carnitine and chromium on mental health, hormonal, inflammatory and genetic parameters in women with PCOS.

METHODS

This randomized, double-blinded, placebo-controlled clinical trial was conducted on 54 subjects, aged 18-40 years old. Subjects were randomly allocated to take either 1000 mg/d carnitine plus 200 µg/d chromium as chromium picolinate (n = 26) or placebo (n = 27) for 12 weeks.

RESULTS

Carnitine and chromium co-supplementation, compared with the placebo, significantly improved beck depression inventory (β - 0.84; 95% CI, -1.51, -0.17; p = 0.01), general health questionnaire scores (β - 1.13; 95% CI, -2.13, -0.14; p = 0.02) and depression anxiety and stress scale scores (β - 0.96; 95% CI, -0.78, -0.14; p = 0.02). Participants who received carnitine plus chromium supplements had significantly lower total testosterone (β - 0.15 ng/mL; 95% CI, -0.24, -0.06; p = 0.002), hirsutism (β - 0.48; 95% CI, -0.91, -0.06; p = 0.02), high-sensitivity C-reactive protein (hs-CRP) (β - 1.02 mg/L; 95% CI, -1.79, -0.25; p = 0.01), and malondialdehyde (MDA) levels (β - 0.38 µmol/L; 95% CI, -0.56, -0.20; p < 0.001), and higher total antioxidant capacity (TAC) levels (β 107.18 mmol/L; 95% CI, 44.24, 170.12; p = 0.001) compared with the placebo. Moreover, carnitine and chromium co-supplementation upregulated gene expression of interleukin-6 (IL-6) (p = 0.02) and tumor necrosis factor alpha (TNF-α) (p = 0.02) compared with the placebo.

CONCLUSION

Overall, the co-administration of carnitine and chromium for 12 weeks to women with PCOS had beneficial effects on mental health parameters, serum total testosterone, mF-G scores, hs-CRP, TAC and MDA levels, and gene expression of IL-6 and TNF-α.

The effect of l-carnitine supplementation on lipid profile and glycaemic control in adults with cardiovascular risk factors: A systematic review and meta-analysis of randomized controlled clinical trials

BACKGROUND & AIMS

Several randomized clinical trials (RCTs) have investigated the effect of l-carnitine supplementation on lipid profile and glycaemic control in adults with cardiovascular risk factors; however, the results were conflicting. Therefore, a meta-analysis was performed to assess the effect of l-carnitine on lipid profile and glycaemic control in adults with cardiovascular risk factors.

METHODS

We searched PubMed, Scopus, Cochrane Databases, Google Scholar, ProQuest, Web of Science and Embase for randomized, placebo-controlled human trials that investigated the effect of l-carnitine supplementation on lipid profile and glycaemic control up to April 2017. From the eligible trials, 24 articles were selected for the meta-analysis. The meta-analysis was performed in a random-effects model. Heterogeneity was determined by I² statistics and Cochrane Q test.

RESULTS

The result showed significant effect of l-carnitine on TC (WMD: -13.73 [95% CI: -22.28, -5.17] mg/dL; P < 0.001), LDL-C (WMD = - 7.70 [95% CI: - 11.80, -3.61]mg/dL; p < 0.001), HDL-C (WMD = 0.82 [95% CI: 0.44, 1.21] mg/dL; P > 0.001), Lp(a) (WMD = - 7.13 [95% CI: -9.82,- 4.43]mg/dL; P < 0.001), FPG (WMD = -6.25 [95% CI: -10.35, -2.16] mg/dL; P < 0.001), HbA1C (WMD (%) = - 0.35 [95% CI: -0.65,- 0.05]; p = 0.02) and HOMA-IR (WMD (%) = - 0.94 [95% CI: -1.89, -0.00]; P = 0.05). No effect of l-carnitine was detected in TG, Apo A-I and Apo B 100 on pooled effect size. Additionally, sensitivity analysis showed l-carnitine supplementation could improve glycaemic control, particularly along with hypocaloric diet.

CONCLUSION

This meta-analysis showed that l-carnitine supplementation could improve lipid profile levels, particularly in doses more than 1500 mg/day. More RCTs with large sample sizes, focusing on gut microbiome profiles and dietary patterns are needed to better understand the effect of l-carnitine on patients with cardiovascular risk factors.

Characterizing acyl-carnitine biosignatures for schizophrenia: a longitudinal pre- and post-treatment study

Subjects with schizophrenia have high risks of metabolic abnormalities and bioenergetic dysfunction. Acyl-carnitines involved in bioenergetic pathways provide potential biomarker targets for identifying early changes and onset characteristics in subjects with schizophrenia. We measured 29 acyl-carnitine levels within well-characterized plasma samples of adults with schizophrenia and healthy controls using liquid chromatography-mass spectrometry (LC-MS). Subjects with schizophrenia were measured at baseline and after 8 weeks of treatment. A total of 225 subjects with schizophrenia and 175 age- and gender-matched healthy controls were enrolled and 156 subjects completed the 8-week follow-up. With respect to plasma acyl-carnitines, the individuals with schizophrenia at baseline showed significantly higher levels of C4-OH (C3-DC) and C16:1, but lower concentrations of C3, C8, C10, C10:1, C10:2, C12, C14:1-OH, C14:2, and C14:2-OH when compared with healthy controls after controlling for age, sex, body mass index (BMI), smoking, and drinking. For the comparison between pretreatment and posttreatment subjects, all detected acyl-carnitines were significantly different between the two groups. Only the concentration of C3 and C4 were increased after selection by variable importance in projection (VIP) value >1.0 and false discovery rate (FDR) q value <0.05. A panel of acyl-carnitines were selected for the ability to differentiate subjects of schizophrenia at baseline from controls, pre- from post-treatment, and posttreatment from controls. Our data implicated acyl-carnitines with abnormalities in cellular bioenergetics of schizophrenia. Therefore, acyl-carnitines can be potential targets for future investigations into their roles in the pathoetiology of schizophrenia.

The effect of nutrient supplementation in the management of polycystic ovary syndrome-associated metabolic dysfunctions: A critical review

Polycystic ovary syndrome (PCOS) is complex heterogeneous disorder that has several aspects in terms of pathology such as metabolic, endocrine, reproductive, and psychological. However, the etiology of PCOS remains poorly understood. Several studies suggest that insulin resistance and hyperandrogenism play a central role in the progression of PCOS pathophysiology. Therefore, common treatment strategies of PCOS are based on lifestyle modification, which include exercise, diet, and nutrient supplementation therapy. Recent studies have recommended some nutrients such as vitamins, minerals, and vitamin-like nutrients for the therapy of PCOS because each has at least one functional property in PCOS-induced pathways. Therefore, it is claimed that the cause of PCOS could be vitamin or mineral deficiency. This review aims to provide a critical literature survey on nutritional supplementation for the treatment of PCOS-associated endocrine and metabolic dysfunctions and discuss the role of nutrients in the management of PCOS in view of the clinical trials and experimental studies.

Mitochondrial regulation of [Ca2+]i oscillations during cell cycle resumption of the second meiosis of oocyte

Oocyte is arrested at metaphase of the second meiosis until fertilization switching on [Ca²⁺]i oscillations. Oocyte activation inefficiency is the most challenging problem for failed fertilization and embryonic development. Mitochondrial function and intracellular [Ca²⁺]i oscillations are two critical factors for the oocyte's developmental potential. We aimed to understand the possible correlation between mitochondrial function and [Ca²⁺]i oscillations in oocytes. To this end, mitochondrial uncoupler CCCP which damages mitochondrial function and two small molecule mitochondrial agonists, L-carnitine (LC) and BGP-15, were used to examine the regulation of [Ca²⁺]i by mitochondrial functions. With increasing CCCP concentrations, [Ca²⁺]i oscillations were gradually diminished and high concentrations of CCCP led to oocyte death. LC enhanced mitochondrial membrane potential and [Ca²⁺]i oscillations and even improved the damage induced by CCCP, however, BGP-15 had no beneficial effect on oocyte activation. We have found that mitochondrial function plays a vital role in the generation of [Ca²⁺]i oscillations in oocytes, and thus mitochondria may interact with the ER to generate [Ca²⁺]i oscillations during oocyte activation. Improvement of mitochondrial functions with small molecules can be expected to improve oocyte activation and embryonic development in infertile patients without invasive micromanipulation.

Role of L-carnitine in female infertility

BACKGROUND

L-carnitine (LC), and its acetylated form, acetyl L-carnitine (ALC), have immense functional capabilities to regulate the oxidative and metabolic status of the female reproductive system. The vulnerability of this system to free radicals demand for advanced strategies to combat them. For this purpose, the 'quasi vitamins' LC and ALC can be used either individually, or in combination with each other or with other antioxidants.

MAIN BODY

This review (a) summarizes the effects of carnitines on female fertility along with the findings from various in vivo and in vitro studies involving human, animal and assisted reproductive technology, and (b) proposes their mechanism of actions in improving female fertility through their integrated actions on reducing cellular stress, maintaining hormonal balance and enhancing energy production. They reportedly aid β-oxidation in oocytes, maintain its cell membrane stability by acetylation of phospholipids and amphiphilic actions, prevent free radical-induced DNA damage and also stabilize acetyl Co-A/Co-A ratio for adequate acetyl storage as energy supply to maintain the robustness of reproductive cells.

CONCLUSION

While both LC and ALC have their applications in improving female fertility, ALC is preferred for its better antioxidant properties and LC for amelioration of energy supply to the cells. These beneficial effects show great promise in its application as a treatment option for women facing infertility disorders.