Metabolic and endocrine effects of long-chain versus essential omega-3 polyunsaturated fatty acids in polycystic ovary syndrome

The Effect of Plant-Derived Low-Ratio Linoleic Acid/α-Linolenic Acid on Markers of Glucose Controls: A Systematic Review and Meta-Analysis

The objective of this meta-analysis was to examine the impact of a low-ratio linoleic acid/α-linolenic acid (LA/ALA) diet on the glycemic profile of adults. A comprehensive search was performed across four databases (Web of Science, Scopus, Embase, and PubMed) to evaluate the influence of the low-ratio LA/ALA. Relevant references were screened up until February 2023. Intervention effects were analyzed by calculating change values as weighted mean differences (WMD) and 95% confidence intervals (CI) using fixed-effects models. Additionally, subgroup analysis and meta-regression were employed to investigate potential sources of heterogeneity. Twenty-one randomized controlled trials (RCTs) were included, and the low-ratio LA/ALA diet had no significant effect on fasting blood sugar (FBS, WMD: 0.00 mmol/L, 95% CI: -0.06, 0.06, p = 0.989, I2 = 0.0%), insulin levels (WMD: 0.20 μIU/mL, 95% CI: -0.23, 0.63, p = 0.360, I2 = 3.2%), homeostatic model assessment insulin resistance (HOMA-IR, WMD: 0.09, 95% CI: -0.06, 0.23, p = 0.243, I2 = 0.0%), and hemoglobin A1c (HbA1c, WMD: -0.01%, 95% CI: -0.07, 0.06, p = 0.836, I2 = 0.0%). Based on subgroup analyses, it was observed that the impact of a low-ratio LA/ALA diet on elevated plasma insulin (WMD: 1.31 μIU/mL, 95% CI: 0.08, 2.54, p = 0.037, I2 = 32.0%) and HOMA-IR (WMD: 0.47, 95% CI: 0.10, 0.84, p = 0.012, I2 = 0.0%) levels exhibited greater prominence in North America compared to Asian and European countries. Publication bias was not detected for FBS, insulin, HOMA-IR, and HbA1c levels according to the Begg and Egger tests. Furthermore, the conducted sensitivity analyses indicated stability, as the effects of the low-ratio LA/ALA diet on various glycemic and related metrics remained unchanged even after removing individual studies. Overall, based on the available studies, it can be concluded that the low-ratio LA/ALA diet has limited impact on blood glucose-related biomarker levels.

Can flaxseed supplementation affect circulating adipokines in adults? An updated systematic review and meta-analysis of randomized controlled trials

Introduction

The findings of randomized controlled trials (RCTs) regarding the effect of flaxseed on adipokine concentrations are conflicting. Therefore, the present meta-analysis was conducted to provide definite and conclusive results.

Methods

Systematically, Scopus, Embase, PubMed, Web of Science databases, and Google Scholar were searched for relevant literature published up to December 2022. Based on random-effect models, standard mean differences (SMDs) were calculated for net changes in adipokine concentrations.

Results

Overall, 13 RCTs (15 arms) were eligible to be included. The results indicated that leptin was significantly reduced after the intervention with flaxseed supplement (SMD = -0.69, 95% CI: -1.37, -0.01; p = 0.048; I2 = 92.0%, p < 0.001). In addition, flaxseed supplements had no considerable effect on plasma adiponectin (SMD = 0.52, 95% CI: -0.20, 1.25, p = 0.159; I2 = 92.0%, p < 0.001).

Discussion

Flaxseed significantly improves leptin but does not affect adiponectin concentrations. Additional future well-designed trials are required to further assess the potential benefits of flaxseed on adipokines in humans.

Effects of Dietary Linoleic Acid on Blood Lipid Profiles: A Systematic Review and Meta-Analysis of 40 Randomized Controlled Trials

Th aim of this meta-analysis was to elucidate whether dietary linoleic acid (LA) supplementation affected blood lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), compared with other fatty acids. Embase, PubMed, Web of Science and the Cochrane Library databases, updated to December 2022, were searched. The present study employed weighted mean difference (WMD) and a 95% confidence interval (CI) to examine the efficacy of the intervention. Out of the 3700 studies identified, a total of 40 randomized controlled trials (RCTs), comprising 2175 participants, met the eligibility criteria. Compared with the control group, the dietary intake of LA significantly decreased the concentrations of LDL-C (WMD: -3.26 mg/dL, 95% CI: -5.78, -0.74, I² = 68.8%, p = 0.01), and HDL-C (WMD: -0.64 mg/dL, 95% CI: -1.23, -0.06, I² = 30.3%, p = 0.03). There was no significant change in the TG and TC concentrations. Subgroup analysis showed that the LA intake was significantly reduced in blood lipid profiles compared with saturated fatty acids. The effect of LA on lipids was not found to be dependent on the timing of supplementation. LA supplementation in an excess of 20 g/d could be an effective dose for lowering lipid profiles. The research results provide further evidence that LA intake may play a role in reducing LDL-C and HDL-C, but not TG and TC.

The effects of flaxseed or its oil supplementations on polycystic ovary syndrome: A systematic review of clinical trials

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders around the world that can endanger reproductive, metabolic, and psychological health in women. Flaxseed is considered as a functional food which provides remarkable amounts of α-linolenic acid (ALA), phytosterogenic lignans, and dietary fibers. This study aimed to investigate the effectiveness of flaxseed or its oil supplementation on PCOS patients. We systematically searched all published randomized clinical trials indexed in PubMed, Scopus, and Google Scholar databases from inception up to May 2022. Intended exposure and outcome were flaxseed or its oil and metabolic, anthropometric, and hormonal status of women with PCOS, respectively. Initial search via related keywords revealed 69 articles. After excluding duplicates, title and abstract of 55 remaining papers were screened. Fourteen papers were obtained for full text screening. Finally, nine clinical trials published between 2011 and 2021 were included in qualitative synthesis. Based on the results of the present systematic review, we suggest that flaxseed supplementation has the potential to improve metabolic, hormonal, and anthropometric parameters in women with PCOS. However, we also deduce that due to the scarcity of high-quality studies, additional studies need to be conducted in order to derive a solid conclusion.

Omega-3 fatty acids in the management of dry eye disease-An updated systematic review and meta-analysis

PURPOSE

The purpose of this study was to examine the effectiveness of omega-3 fatty acids in comparison to a placebo in the management of dry eye disease.

METHODS

A systematic literature search was performed including randomised controlled trials (RCTs) comparing omega-3 versus placebo in the management of dry eye disease in human subjects. There were no language or time restrictions. Eligible trials were assessed for bias and assigned a risk-of-bias score. Data extraction was carried out using a standardised data extraction form, and meta-analysis was performed using a random effects model for continuous data. The outcome measures were Ocular Surface Disease Index (OSDI) scores, tear breakup time (TBUT) measurements, corneal staining and Schirmer's score. Statistical heterogeneity was defined as substantial if the I2 test achieved a value >60%.

RESULTS

Eight parallel RCTs including 1107 subjects met eligibility criteria. None of the included studies achieved low risk of bias. Data synthesis demonstrated an improvement in the mean change in OSDI score from baseline to final assessment. Omega-3 supplementation conferred no evident improvement in corneal staining, TBUT or Schirmer's score. There was considerable statistical heterogeneity in all four outcome measures.

CONCLUSIONS

This updated systematic review and meta-analysis indicates that omega-3 supplementation improves subjective symptoms in patients with dry eye disease.

Omega-3 supplementation in the treatment of polycystic ovary syndrome (PCOS) - a review of clinical trials and cohort

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women associated with cardiovascular disease and obesity. The possible benefits of omega-3 supplementation in this syndrome have been discussed much. This study is aimed to verify, based on the scientific data published, if there are any benefits in the omega-3 supplementation in the treatment of PCOS and to indicate its possible dosages for the treatment of polycystic ovary. The work consists of a systematic review of clinical trials and cohort of the MEDLINE/PubMed database from 2009 to October 2019. All studies that analyzed the omega-3 supplementation in women with PCOS were included. Cross-sectional studies, review articles, systematic reviews, meta-analysis, duplicates, studies in animals or cell culture, studies with omega-3 supplementation via food or associated with other supplementations were not included, except those involving vitamin E. In total, 21 articles were selected. Despite the heterogeneity of the studies selected, indirect benefits were observed mainly regarding the glycemic profile, such as insulin resistance reduction, lipid profile modulation (i.e. decrease in total cholesterol, triglycerides, and elevation of high-density lipoprotein), and the regulation of the androgenic profile. As for the anthropometric profile, the studies were scarce and most of them had no significant meaning. Regarding the antioxidant profile and inflammatory biomarkers, the findings differ among studies, but promising results were observed with different doses over 12 weeks of use, such as C-reactive protein (CRP) reduction. Thus, omega-3 fatty acids promote indirect benefits in the treating of women with PCOS. However, to reveal well-defined standards for dosage and supplementation time, further studies are needed.

A Pilot Trial: Fish Oil and Metformin Effects on ApoB-Remnants and Triglycerides in Women With Polycystic Ovary Syndrome

CONTEXT

Women with polycystic ovary syndrome (PCOS) have increased incidence of atherogenic dyslipidemia and cardiovascular disease (CVD). Interventions targeting atherogenic dyslipidemia to reduce CVD risk are limited in women with PCOS.

OBJECTIVE

This pilot study was conducted to determine the effect of 12 weeks of high dose fish oil (FO), metformin, and FO as an adjunct to metformin (FO-metformin) therapy on fasting and nonfasting plasma lipids and ApoB-remnants in young women with the metabolic syndrome (MetS) and PCOS.

METHODS

In this open-label parallel pilot trial, women with MetS and PCOS (18-30 years of age) were randomized into 1 of 3 interventions: (1) FO; (2) metformin; and (3) FO-metformin. Plasma lipids and ApoB (48 and 100)-lipoproteins and triglycerides (TG) were measured in the fasted and postprandial state following a high-fat meal at baseline and postintervention.

RESULTS

FO-metformin significantly lowered fasting plasma TG by >40% compared with FO and metformin treatments. Fasting plasma apoB48 was lowered 40% in FO-metformin and 15% in the FO groups from baseline to postintervention. ApoB48 area under the curve (ApoB48AUC), ApoB48 incremental AUC (ApoB48iAUC), ApoB100AUC, and ApoB100iAUC decreased in all groups from baseline to postintervention; however, these findings did not reach statistical significance.

CONCLUSION

The findings of this pilot trial show that high dose FO and FO-metformin combination therapy tend to lower fasting and postprandial plasma TG and ApoB-lipoprotein remnants compared with metformin; however, the study is limited by small sample size. These results may be clinically significant in individuals with PCOS for management of atherogenic dyslipidemia.

Secondary data analysis investigating effects of marine omega-3 fatty acids on circulating levels of leptin and adiponectin in older adults

BACKGROUND

Higher leptin and lower adiponectin levels have been linked to progressing systemic inflammation and diseases of aging. Among older adults with obesity and an inflammatory conditions, we quantified effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on leptin, adiponectin, and the leptin-to-adiponectin ratio (LAR). We also examined associations among adipokine and cytokine levels.

METHODS

Using a randomized, double-blind, placebo-controlled design, participants (mean age 61.3 ± 2.1) received 1.5 g EPA + 1.0 g DHA (n = 14) or mineral oil (n = 18) daily. Plasma adipokine and cytokine levels were quantified by electrochemiluminescence at all study intervals.

RESULTS

While no between-group differences were detected, there was a reduction in the LAR (by 23%, p=.065) between weeks 4 and 8 among the EPA+DHA group. Adiponectin levels were negatively associated with IL-1β levels at week 4 (p=.02) and TNF-α levels at week 8 (p=.03).

CONCLUSION

Potential benefits of EPA+DHA supplementation among aging populations warrant further study.

The effects of low-ratio n-6/n-3 PUFA on biomarkers of inflammation: a systematic review and meta-analysis

OBJECTIVE

The purpose of the systematic review and meta-analysis was to determine if low-ratio n-6/n-3 long-chain polyunsaturated fatty acid (PUFA) supplementation affects serum inflammation markers based on the current studies.

METHODS

PubMed, Embase and The Cochrane library databases were systematically searched to find randomized controlled trials (RCTs) on the effect of low-ratio n-6/n-3 PUFA intervention on inflammation markers up to July 2020. Data were pooled using standardized mean difference (SMD) and 95% confidence intervals (95% CI), with P value ≦ 0.05 as statistical significance.

RESULTS

Thirty-one RCTs were included in the meta-analysis. The analysis indicated that increasing low-ratio n-6/n-3 PUFA supplementation decreased the level of tumor necrosis factor-α (TNF-α) (SMD = -0.270; 95% CI: -0.433, -0.106; P = 0.001) and interleukin 6 (IL-6) (SMD = -0.153; 95% CI: -0.260, -0.045; P = 0.005). There were no significant effects on C-reactive protein (CRP) (SMD = -0.027; 95% CI: -0.189: 0.135; P = 0.741). Subgroup analysis indicated that there was a significant reduction in TNF-α serum concentration in subjects from Asia (SMD: -0.367; 95% CI: -0.579, -0.155; P = 0.001) and in subjects with diseases (SMD: -0.281; 95% CI: -0.436, -0.127; P < 0.001). In the subgroup of the n-6/n-3 ratio ≦5, low-ratio n-6/n-3 PUFA supplementation could decrease the level of TNF-α (SMD: -0.335; 95% CI: -0.552, -0.119; P = 0.002). Serum IL-6 decreased significantly in patients from the Europe subgroup (SMD: -0.451; 95% CI: -0.688, -0.214; P < 0.001), but not in Asia (SMD: -0.034; 95% CI: -0.226, 0.157; P = 0.724), North America (SMD: -0.115; 95% CI: -0.274, 0.044; P = 0.157) and Oceania (SMD: 0.142; 95% CI: -0.557, 0.842; P = 0.690).

CONCLUSION

Low-ratio n-6/n-3 PUFA supplementation could decrease significantly the concentration of serum TNF-α and IL-6, but not decrease CRP concentration.

Systematic review of marine-derived omega-3 fatty acid supplementation effects on leptin, adiponectin, and the leptin-to-adiponectin ratio

Increasing evidence suggests that adipokines, leptin and adiponectin, produced and secreted by adipocytes, are involved in regulating systemic inflammation and may be important targets for interventions to reduce the chronic systemic inflammation linked to some conditions common in aging (e.g., atherosclerosis). Lower leptin levels and higher adiponectin levels in peripheral circulation have been associated with less systemic inflammation. While some studies have shown that marine-derived omega-3 fatty acids (eicosapentaenoic acid [EPA] and/or docosahexaenoic acid [DHA]) have effects on leptin and adiponectin in the context of inflammation, the extent of their effects remain unclear. The purpose of this systematic review was to summarize findings from randomized, controlled trials that measured effects of EPA+DHA supplementation on circulating levels of leptin and adiponectin to determine the state of the science. PubMed, CINAHL, Web of Science, Scopus, and Cochrane Trials were searched up to June 2018 for studies meeting inclusion criteria. Thirty-one studies included in this review were conducted in 16 countries. Eighteen studies reported lower leptin and/or higher adiponectin levels with EPA+DHA supplementation versus placebo at study end point (9 reported statistically significant differences), but doses, supplementation duration, and population characteristics varied across studies. In 9 studies reporting significantly lower leptin and/or higher adiponectin levels the EPA+DHA dose was 0.52 to 4.2 g/day for 4 to 24 weeks. Additional studies are warranted which assess dose parameters and patient populations similar to studies reporting significant effects of EPA+DHA on leptin or adiponectin in order to evaluate the extent of reproducibility before recommending EPA+DHA as a therapy to target these adipokines.

Polycystic Ovary Syndrome: A Brain Disorder Characterized by Eating Problems Originating during Puberty and Adolescence

Polycystic ovary syndrome (PCOS) is an endocrine condition associated with reproductive and psychiatric disorders, and with obesity. Eating disorders, such as bulimia and recurrent dieting, are also linked to PCOS. They can lead to the epigenetic dysregulation of the hypothalamic-pituitary-gonadal (HPG) axis, thereby impacting on ovarian folliculogenesis. We postulate that PCOS is induced by psychological distress and episodes of overeating and/or dieting during puberty and adolescence, when body dissatisfaction and emotional distress are often present. We propose that upregulated activation of the central HPG axis during this period can be epigenetically altered by psychological stressors and by bulimia/recurrent dieting, which are common during adolescence and which can lead to PCOS. This hypothesis is based on events that occur during a largely neglected stage of female reproductive development. To date, most research into the origins of PCOS has focused on the prenatal induction of this disorder, particularly in utero androgenization and the role of anti-Müllerian hormone. Establishing causality in our peripubertal model requires prospective cohort studies from infancy. Mechanistic studies should consider the role of the gut microbiota in addition to the epigenetic regulation of (neuro) hormones. Finally, clinicians should consider the importance of underlying chronic psychological distress and eating disorders in PCOS.

Antioxidants for female subfertility

BACKGROUND

A couple may be considered to have fertility problems if they have been trying to conceive for over a year with no success. This may affect up to a quarter of all couples planning a child. It is estimated that for 40% to 50% of couples, subfertility may result from factors affecting women. Antioxidants are thought to reduce the oxidative stress brought on by these conditions. Currently, limited evidence suggests that antioxidants improve fertility, and trials have explored this area with varied results. This review assesses the evidence for the effectiveness of different antioxidants in female subfertility.

OBJECTIVES

To determine whether supplementary oral antioxidants compared with placebo, no treatment/standard treatment or another antioxidant improve fertility outcomes for subfertile women.

SEARCH METHODS

We searched the following databases (from their inception to September 2019), with no language or date restriction: Cochrane Gynaecology and Fertility Group (CGFG) specialised register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL and AMED. We checked reference lists of relevant studies and searched the trial registers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any type, dose or combination of oral antioxidant supplement with placebo, no treatment or treatment with another antioxidant, among women attending a reproductive clinic. We excluded trials comparing antioxidants with fertility drugs alone and trials that only included fertile women attending a fertility clinic because of male partner infertility.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. The primary review outcome was live birth; secondary outcomes included clinical pregnancy rates and adverse events.

MAIN RESULTS

We included 63 trials involving 7760 women. Investigators compared oral antioxidants, including: combinations of antioxidants, N-acetylcysteine, melatonin, L-arginine, myo-inositol, carnitine, selenium, vitamin E, vitamin B complex, vitamin C, vitamin D+calcium, CoQ10, and omega-3-polyunsaturated fatty acids versus placebo, no treatment/standard treatment or another antioxidant. Only 27 of the 63 included trials reported funding sources. Due to the very low-quality of the evidence we are uncertain whether antioxidants improve live birth rate compared with placebo or no treatment/standard treatment (odds ratio (OR) 1.81, 95% confidence interval (CI) 1.36 to 2.43; P < 0.001, I² = 29%; 13 RCTs, 1227 women). This suggests that among subfertile women with an expected live birth rate of 19%, the rate among women using antioxidants would be between 24% and 36%. Low-quality evidence suggests that antioxidants may improve clinical pregnancy rate compared with placebo or no treatment/standard treatment (OR 1.65, 95% CI 1.43 to 1.89; P < 0.001, I² = 63%; 35 RCTs, 5165 women). This suggests that among subfertile women with an expected clinical pregnancy rate of 19%, the rate among women using antioxidants would be between 25% and 30%. Heterogeneity was moderately high. Overall 28 trials reported on various adverse events in the meta-analysis. The evidence suggests that the use of antioxidants makes no difference between the groups in rates of miscarriage (OR 1.13, 95% CI 0.82 to 1.55; P = 0.46, I² = 0%; 24 RCTs, 3229 women; low-quality evidence). There was also no evidence of a difference between the groups in rates of multiple pregnancy (OR 1.00, 95% CI 0.63 to 1.56; P = 0.99, I² = 0%; 9 RCTs, 1886 women; low-quality evidence). There was also no evidence of a difference between the groups in rates of gastrointestinal disturbances (OR 1.55, 95% CI 0.47 to 5.10; P = 0.47, I² = 0%; 3 RCTs, 343 women; low-quality evidence). Low-quality evidence showed that there was also no difference between the groups in rates of ectopic pregnancy (OR 1.40, 95% CI 0.27 to 7.20; P = 0.69, I² = 0%; 4 RCTs, 404 women). In the antioxidant versus antioxidant comparison, low-quality evidence shows no difference in a lower dose of melatonin being associated with an increased live-birth rate compared with higher-dose melatonin (OR 0.94, 95% CI 0.41 to 2.15; P = 0.89, I² = 0%; 2 RCTs, 140 women). This suggests that among subfertile women with an expected live-birth rate of 24%, the rate among women using a lower dose of melatonin compared to a higher dose would be between 12% and 40%. Similarly with clinical pregnancy, there was no evidence of a difference between the groups in rates between a lower and a higher dose of melatonin (OR 0.94, 95% CI 0.41 to 2.15; P = 0.89, I² = 0%; 2 RCTs, 140 women). Three trials reported on miscarriage in the antioxidant versus antioxidant comparison (two used doses of melatonin and one compared N-acetylcysteine versus L-carnitine). There were no miscarriages in either melatonin trial. Multiple pregnancy and gastrointestinal disturbances were not reported, and ectopic pregnancy was reported by only one trial, with no events. The study comparing N-acetylcysteine with L-carnitine did not report live birth rate. Very low-quality evidence shows no evidence of a difference in clinical pregnancy (OR 0.81, 95% CI 0.33 to 2.00; 1 RCT, 164 women; low-quality evidence). Low quality evidence shows no difference in miscarriage (OR 1.54, 95% CI 0.42 to 5.67; 1 RCT, 164 women; low-quality evidence). The study did not report multiple pregnancy, gastrointestinal disturbances or ectopic pregnancy. The overall quality of evidence was limited by serious risk of bias associated with poor reporting of methods, imprecision and inconsistency.

AUTHORS' CONCLUSIONS

In this review, there was low- to very low-quality evidence to show that taking an antioxidant may benefit subfertile women. Overall, there is no evidence of increased risk of miscarriage, multiple births, gastrointestinal effects or ectopic pregnancies, but evidence was of very low quality. At this time, there is limited evidence in support of supplemental oral antioxidants for subfertile women.

Influence of n-3 fatty acid supplementation on inflammatory and oxidative stress markers in patients with polycystic ovary syndrome: a systematic review and meta-analysis

Polycystic ovary syndrome (PCOS) is defined as a reproductive endocrine disease that results in a low-grade inflammatory and pro-oxidant state. Dietary factors, including n-3 fatty acids, may have a key role in improving metabolic disorders in PCOS patients. The present study aimed to investigate the influence of n-3 fatty acid supplementation on inflammatory and oxidative stress (OS) markers in patients with PCOS. A systematic literature search of Medline/PubMed, Cochrane Central Register of Controlled Trials, Scopus and Lilacs, until November 2019, was conducted. Randomised clinical trials that reported inflammatory and OS markers as endpoints in women with PCOS receiving n-3 fatty acid supplementation were included. The pooled estimates of the weighted mean differences (WMD) and the standard mean differences (SMD) were calculated. Random effects models were adopted to measure the pooled outcomes. Among the 323 studies retrieved, ten fulfilled the inclusion criteria for a meta-analysis. We founded a significant decrease in high-sensitivity C-reactive protein (hs-CRP) (SMD -0·29 (95 % CI -0·56, -0·02) mg/l) and an increase in adiponectin (WMD 1·42 (95 % CI 1·09, 1·76) ng/ml) concentrations in the intervention group when compared with the placebo group. No statistically significant results were found in the meta-analysis for visfatin, nitric oxide, GSH or malondialdehyde levels or total antioxidant capacity. The data suggest that supplementation of n-3 fatty acids could reduce the inflammatory state in women with PCOS, through a decrease in hs-CRP and an increase in adiponectin levels.

Flaxseed for Health and Disease: Review of Clinical Trials

BACKGROUND

Flaxseed (Linum usitatissimum) is an oil-based seed that contains high amounts of alpha-linolenic acid, linoleic acid, lignans, fiber and many other bioactive components which is suggested for a healthier life. Nowadays, flaxseed is known as a remarkable functional food with different health benefits for humans and protects against cardiovascular disease, diabetes, dyslipidemia, obesity and altogether metabolic syndrome.

METHODS

To review the bioactive components of flaxseed and their potential health effects, PubMed and Scopus were searched from commencement to July 2019. Keywords including: "flaxseed", "Linum usitatissimum", "metabolic syndrome", "obesity", "inflammation", "insulin resistance", "diabetes", "hyperlipidemia" and "menopause" were searched in the databases with varying combinations.

CONCLUSION

Consumption of flaxseed in different forms has valuable effects and protects against cardiovascular disease, hypertension, diabetes, dyslipidemia, inflammation and some other complications. Flaxseed can serve as a promising candidate for the management of metabolic syndrome to control blood lipid levels, fasting blood sugar, insulin resistance, body weight, waist circumference, body mass and blood pressure.

Dietary α-Linolenic Acid-Rich Flaxseed Oil Exerts Beneficial Effects on Polycystic Ovary Syndrome Through Sex Steroid Hormones-Microbiota-Inflammation Axis in Rats

Polycystic ovary syndrome (PCOS) represents a common endocrine-metabolic disorder disease with chronic low-grade inflammation and alteration of intestinal flora. Serving as functional food, flaxseed oil (FO), which is rich in plant-derived α-linolenic acid of omega-3 polyunsaturated fatty acids, has been proven to benefit for chronic metabolic diseases. However, the exact role of dietary FO on PCOS remains largely unclear. In the present study, 6-week-old female Sprague-Dawley rats were randomly divided into four groups (eight rats/group), including (a) pair-fed (PF) control (CON) group (PF/CON), (b) FO-fed CON group (FO/CON), (c) PF with letrozole-induced PCOS model (MOD) group (PF/MOD), and (d) FO-fed MOD group (FO/MOD). All rats were fed a standard diet. After 3 weeks of modeling and subsequent 8 weeks of treatment, the rats in diverse groups were euthanized and associated indications were investigated. The results showed that dietary FO ameliorated the disorder of estrous cycle and ovarian morphology. In parallel, dietary FO improved the sex steroid hormone disturbance (luteinizing hormone/follicle-stimulating hormone, estrogen, testosterone, and progesterone), body weights, dyslipidemia, and insulin resistance. Moreover, FO treatment improved plasma and ovary inflammatory interleukin (IL)-1β, IL-6, IL-10, and IL-17A, tumor necrosis factor-α, and monocyte chemoattractant protein-1. Additionally, FO intervention significantly modulated the composition of gut microbiota and vaginal microbiota by increasing the abundances of Allobaculum, Lactobacillus, Butyrivibrio, Desulfovibrio, Bifidobacterium, Faecalibacterium, Parabacteroides as well as decreasing the abundances of Actinobacteria, Bacteroides, Proteobacteria, and Streptococcus, the ratio of Firmicutes/Bacteroidetes. A decrease in plasma lipopolysaccharide level and an increase in short-chain fatty acids, including acetic acid, propionic acid, butyric acid and pentanoic acid, were determined after dietary FO supplementation. Correlation analysis revealed close relationships among sex steroid hormones, inflammation, and gut/vaginal microbiota. Collectively, this study demonstrated that dietary FO ameliorated PCOS through the sex steroid hormones-microbiota-inflammation axis in rats, which may contribute to the understanding of pathogenesis and potentially serve as an inexpensive intervention in the control of PCOS.

Low-Dose Omega-3 Fatty Acid and Vitamin D for Anthropometric, Biochemical Blood Indices and Respiratory Function. Does it work?

Abstract. Omega-3 fatty acids and vitamin D3 have beneficial effects on different blood, cardiovascular parameters and physical performance. However, the effect of low-dose omega-3 fatty acid supplementation remains unclear. 84 office workers aged 40–60 years, participated in a 16-week open, randomized, placebo-controlled, parallel-group study. The experimental group received 330 mg of omega-3 fatty acid and 0.005 mg (200 IU) of vitamin D3 per day and the control group received placebo. Anthropometric, biochemical blood and respiratory indices were measured at 12 and 16 weeks. Body mass (BM) and body mass index (BMI) significantly reduced in both the experimental (BM from 74.4 ± 13.04 to 73.2 ± 13.02 kg, p < 0.001; BMI from 25.8 ± 4.1 to 25.4 ± 4.3 kg/m2, p < 0.001) and the placebo groups (BM from 69.5 ± 11. to 68.7 ± 11.4 kg, p < 0.05; BMI from 24.1 ± 4.0 to 23.8 ± 4.2 kg/m2, p < 0.05). Omega-3 fatty acid supplementation significantly improved glucose (from 5.12 ± 0.55 to 4.97 ± 0.62 mmol/l; p = 0.05), total cholesterol (from 5.86 ± 1.0 to 5.32 ± 1.55 mmol/l; p = 0.003), and vitamin D levels (from 35.07 ± 21.65 to 68.63 ± 25.94 nmol/l; p = 0.000). Maximal oxygen consumption (from 33.7 ± 2.4 to 36.6 ± 3.2 ml/kg/min, p = 0.035), forced vital capacity (from 3.5 ± 0.6 to 3.9 ± 0.9 l, p = 0.044), forced expiratory volume (from 3.2 ± 0.6 to 3.5 ± 0.7 l, p = 0.014), and peak expiratory flow (from 6.7 ± 1.4 to 7.5 ± 1.6 l/s, p = 0.019) also slightly improved in the omega-3 fatty acid group. Daily supplementation of 330 mg of omega-3 fatty acids had a slight positive impact on total cholesterol and glucose level, while there was no effect on low and high density lipoproteins, and triglycerides levels. Therefore, dose of 330 mg per day seems as insufficient.

Effects of Flaxseed Interventions on Circulating Inflammatory Biomarkers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

There have been various clinical studies on the effect of flaxseed-derived products on circulating inflammatory biomarkers, but the findings from these are contradictory. The aim of the present study was to clarify any association. A comprehensive literature search was conducted from inception to May 2018. From the eligible trials, 32 articles describing studies conducted on adults aged 18-70 y were selected for the meta-analysis. Meta-analyses using the random-effects model were performed to investigate the data and results showed significant effects of flaxseed intake on circulating high-sensitivity CRP (hs-CRP) [weighted mean difference (WMD) = -0.75; 95% CI: -1.19, -0.30; P < 0.001] and TNFα (WMD = -0.38; 95% CI: -0.75,-0.01; P = 0.04). However, no significant changes were found in IL6 concentration (WMD = -0.24; 95% CI: -0.70, 0.21; P = 0.28) and C-reactive protein (CRP) (WMD = -0.34; 95% CI:-0.89, 0.20; P = 0.22). Moreover, by eliminating 1 of the studies from the sensitivity analysis, changes in IL6 concentration were significant (WMD = -0.44; 95% CI: -0.81, -0.08). The changes in inflammatory biomarkers were dependent on study design (parallel or crossover), supplement type (flaxseed, flaxseed oil, or lignan), study quality (high or low), and participants' age and BMI. According to this meta-analysis, flaxseed significantly reduced circulating concentrations of hs-CRP and TNFα, but did not affect IL6 and CRP. Further research is needed to examine the effect of different doses and long-term benefits of flaxseed and its derivatives on inflammatory factors.

Long-term vitamin D and high-dose n-3 fatty acids' supplementation improve markers of cardiometabolic risk in type 2 diabetic patients with CHD

This study was performed to evaluate the effects of vitamin D and n-3 fatty acids' co-supplementation on markers of cardiometabolic risk in diabetic patients with CHD. This randomised, double-blinded, placebo-controlled trial was conducted among sixty-one vitamin D-deficient diabetic patients with CHD. At baseline, the range of serum 25-hydroxyvitamin D levels in study participants was 6·3-19·9 ng/ml. Subjects were randomly assigned into two groups either taking 50 000 IU vitamin D supplements every 2 weeks plus 2× 1000 mg/d n-3 fatty acids from flaxseed oil (n 30) or placebo (n 31) for 6 months. Vitamin D and n-3 fatty acids' co-supplementation significantly reduced mean (P = 0·01) and maximum levels of left carotid intima-media thickness (CIMT) (P = 0·004), and mean (P = 0·02) and maximum levels of right CIMT (P = 0·003) compared with the placebo. In addition, co-supplementation led to a significant reduction in fasting plasma glucose (β -0·40 mmol/l; 95 % CI -0·77, -0·03; P = 0·03), insulin (β -1·66 μIU/ml; 95 % CI -2·43, -0·89; P < 0·001), insulin resistance (β -0·49; 95 % CI -0·72, -0·25; P < 0·001) and LDL-cholesterol (β -0·21 mmol/l; 95 % CI -0·41, -0·01; P = 0·04), and a significant increase in insulin sensitivity (β +0·008; 95 % CI 0·004, 0·01; P = 0·001) and HDL-cholesterol (β +0·09 mmol/l; 95 % CI 0·01, 0·17; P = 0·02) compared with the placebo. Additionally, high-sensitivity C-reactive protein (β -1·56 mg/l; 95 % CI -2·65, -0·48; P = 0·005) was reduced in the supplemented group compared with the placebo group. Overall, vitamin D and n-3 fatty acids' co-supplementation had beneficial effects on markers of cardiometabolic risk.

Multicenter Randomized Controlled Trial of Omega-3 Fatty Acids Versus Omega-6 Fatty Acids for the Control of Cancer-Related Fatigue Among Breast Cancer Survivors

Background

Cancer-related fatigue (CRF) is a common side effect of adjuvant therapy and becomes a chronic problem for approximately one-third of survivors. Omega-3 polyunsaturated fatty acids (O3-PUFA) demonstrated preliminary antifatigue effects in previous research, but have not been investigated in fatigued cancer survivors.

Methods

Breast cancer survivors 4–36 months posttreatment with a CRF score of 4 or more of 10 using the symptom inventory (SI) were randomly assigned to O3-PUFA (fish oil, 6 g/d), omega-6 PUFA (O6-PUFA; soybean oil, 6 g/d), or a low-dose combination of O3-/O6-PUFA (3 g/d O3-PUFA and O6-PUFA) for 6 weeks. CRF was assessed by the SI (screening question), the Brief Fatigue Inventory, and the Multidimensional Fatigue Symptom Index. Protein and mRNA levels of inflammatory and antioxidant biomarkers, along with fatty acid and lipid levels, were assessed at baseline and week 6. Statistical tests were two-sided.

Results

A total of 108 breast cancer survivors consented; 97 subjects were randomly assigned and 81 completed the trial. The SI CRF score decreased by 2.51 points at week 6 with O6-PUFA and by 0.93 points with O3-PUFA, with statistically significant between-group difference (effect size = −0.86, P < .01). Similar changes were observed for the Brief Fatigue Inventory and Multidimensional Fatigue Symptom Index but were not statistically significant. Stratified analyses showed the largest benefit was observed in those with severe baseline CRF (≥7). Compared with O3-PUFA, O6-PUFA supplementation statistically significantly decreased proinflammatory markers in the TNF-α signaling pathway.

Conclusion

Contrary to our original hypothesis, O6-PUFA statistically significantly reduced CRF compared with O3-PUFA. Further research is needed to confirm these findings and to elucidate mechanisms of action.

Effects of omega-3 polyunsaturated fatty acids on steroidogenesis and cellular development in PCOS rats

Polycystic ovary syndrome (PCOS) is a common endocrine disorder, which is characterized by hyperandrogenism.

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.

The effects of fish oil omega-3 fatty acid supplementation on mental health parameters and metabolic status of patients with polycystic ovary syndrome: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

This study was conducted to evaluate the effects of fish oil omega-3 fatty acid supplementation on mental health parameters and metabolic status of women with polycystic ovary syndrome (PCOS).

METHODS

This randomized double-blind, placebo-controlled trial was conducted on 60 women with PCOS, aged 18-40 years old. Participants were randomly assigned into two groups to receive either 2 × 1000 mg/day fish oil omega-3 fatty acid (n = 30) or placebo (n = 30) after lunch for 12 weeks. Metabolic profiles were quantified at baseline and after the 12-week intervention.

RESULTS

Compared with the placebo, omega-3 fatty acid intake led to a significant improvement in Beck Depression Inventory [β (difference in the mean outcomes measures between treatment groups after intervention) -1.05; 95% CI: -1.84, -0.26; p = .01], general health questionnaire (β -1.68; 95% CI: -3.12, -0.24; p = .02) and depression anxiety and stress scale (β -2.03; 95% CI: -3.60, -0.46; p = .01). Omega-3 fatty acid supplementation significantly decreased serum insulin levels (β -2.09 µIU/mL; 95% CI: -3.77, -0.41; p = .01), homeostasis model of assessment-insulin resistance (β -0.74; 95% CI: -1.13, -0.34; p < .001), total testosterone (β -0.23 ng/mL; 95% CI: -0.39, -0.06; p = .03) and hirsutism (β -0.75; 95% CI: -1.17, -0.33; p = .001), and significantly increased the quantitative insulin sensitivity check index (β 0.01; 95% CI: 0.003, 0.02; p = .008) compared with the placebo. Additionally, omega-3 fatty acid intake resulted in a significant decrease in high sensitivity C-reactive protein (β -1.46 mg/L; 95% CI: -2.16, -0.75; p < .001) and malondialdehyde (β -0.28 µmol/L; 95% CI: -0.52, -0.05; p = .03); also significant rises in plasma total glutathione (β 59.09 µmol/L; 95% CI: 7.07, 111.11; p = .02) was observed compared with the placebo. Omega-3 fatty acid supplementation did not change other metabolic parameters.

CONCLUSION

Overall, omega-3 fatty acid supplementation for 12 weeks to patients with PCOS had beneficial effects on mental health parameters, insulin metabolism, total testosterone, hirsutism and few inflammatory markers and oxidative stress.

Supplementation with omega-3 fatty acids and plasma adiponectin in women with polycystic ovary syndrome

OBJECTIVE

To study plasma adiponectin levels in women diagnosed with polycystic ovary syndrome given omega-3 fatty acid supplements.

PATIENTS AND METHODS

A study was conducted in 195 women diagnosed with polycystic ovary syndrome treated with omega-3 fatty acids for 12weeks (n=97; groupA) and control women given placebo (n=98, groupB). General characteristics, metabolism, lipid profile, and hormone and adiponectin levels were compared.

RESULTS

There were no significant differences between the two groups in general characteristics. No significant differences were also found in hormone, blood glucose, and HOMA levels between the groups. Women in study groupsA andB showed no statistically significant differences in total calorie, carbohydrate, protein, and total fat intake between the baseline and final values. Decreased total cholesterol, low-density lipoprotein, and triglyceride levels were found in groupA women (P<.0001). Mean of adiponectin levels also showed a statistically significant increase after treatment (P<.0001). There were no statistically significant differences in the mean values of the different variables in groupB women.

CONCLUSION

Omega-3 fatty acid supplementation for 12weeks caused a significant increase in plasma adiponectin levels in women with polycystic ovary syndrome.

Nutritional supplements and herbal medicines for women with polycystic ovary syndrome; a systematic review and meta-analysis

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common, reproductive endocrinopathy associated with serious short and long term health risks. Many women with PCOS use ingestible complementary medicines. This systematic review examined the effect on menstrual regulation and adverse effects from randomised controlled trials.

METHODS

Randomised controlled trials (RCTs) that compared herbal or nutritional supplements to placebo or active controls in women with PCOS were eligible for inclusion. Electronic databases were searched to July 2017. Study selection and assessment of quality were conducted independently by two review authors.

RESULTS

Twenty four studies (1406 women) investigating seven nutritional supplements and four herbal medicines were included. No one study was assessed as having a low risk of bias. Four trials reported on the primary endpoint menstrual regulation. There was no evidence on improved menstrual regularity for calcium plus vitamin D compared to Metformin (RR: 0.66, 95% CI 0.35 to 1.23, p = 0.19), reduced amenorrhoea for Camellia sinensis compared to placebo (RR: 0.17, 95% CI 0.02 to 1.72, p = 0.13) and no difference in the number of menses per month for Cinnamomum sp. against placebo (MD 0.05, 95% CI -0.36 to 1.36, p = 0.26). Adverse effects were investigated in seven studies (164 women). Mild adverse effects were found for Cinnamomum sp. compared to placebo (17 women, RR: 0.36, 95% CI 0.03 to 0.70, p = 0.03). No difference was found for adverse effects between inositol, B complex vitamins, vitamin D, chromium and placebo. Improved reproduction, metabolic hormones and hyperandrogenism was found for inositol and improved cholesterol for omega three fish oils.

CONCLUSION

There is no high quality evidence to support the effectiveness of nutritional supplements and herbal medicine for women with PCOS and evidence of safety is lacking. High quality trials of nutritional supplements and herbal medicines examining menstrual regulation and adverse effects in women with PCOS are needed.

The Effects of Flaxseed Oil Omega-3 Fatty Acids Supplementation on Metabolic Status of Patients with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial

Objective This study was conducted to evaluate the effects of flaxseed oil omega-3 fatty acids supplementation on metabolic status of patients with polycystic ovary syndrome (PCOS).

Methods This randomized double-blind, placebo-controlled trial was conducted on 60 women with PCOS according to the Rotterdam criteria aged 18–40 years old. Participants were randomly assigned into two groups to receive either 1,000 mg flaxseed oil omega-3 fatty acids (n=30) or placebo (n=30) twice a day for 12 weeks. Metabolic, endocrine, inflammatory factors were quantified at baseline and after the 12-week intervention.

Results After the 12-week intervention, compared to the placebo, flaxseed oil omega-3 supplementation significantly decreased insulin values (−2.6±7.7 vs.+1.3±3.9 µIU/mL, P=0.01), homeostasis model of assessment-estimated insulin resistance (−0.7±1.7 vs.+0.3±0.9, P=0.01), mF-G scores (−1.2±1.7 vs. -0.1±0.4, P=0.001), and increased quantitative insulin sensitivity check index (+0.01±0.02 vs. −0.01±0.02, P=0.01). In addition, supplementation with flaxseed oil omega-3 resulted in significant decreases in serum triglycerides (−5.1±20.9 vs.+9.7±26.1 mg/dL, P=0.01), VLDL-cholesterol (−1.0±4.2 vs.+1.9±5.2 mg/dL, P=0.01) and high-sensitivity C-reactive protein (hs-CRP) (−1.6±3.1 vs.+0.2±1.5 mg/L, P=0.004) compared to the placebo. We did not see any significant effect of flaxseed oil omega-3 supplementation on hormonal and other lipid profiles, and plasma nitric oxide levels.

Conclusions Overall, flaxseed oil omega-3 supplementation for 12 weeks in women with PCOS had beneficial effects on insulin metabolism, mF-G scores, serum triglycerides, VLDL-cholesterol and hs-CRP levels, but did not affect hormonal and other lipid profiles, and plasma nitric oxide levels.

The effect of flaxseed supplementation on body weight and body composition: a systematic review and meta-analysis of 45 randomized placebo-controlled trials

Flaxseed consumption may be inversely associated with obesity; however, findings of available randomized controlled trials (RCTs) are conflicting. The present study aimed to systematically review and analyse RCTs assessing the effects of flaxseed consumption on body weight and body composition. PubMed, Medline via Ovid, SCOPUS, EMBASE and ISI Web of Sciences databases were searched up to November 2016. Mean changes in body composition indices including body weight, body mass index (BMI) and waist circumference were extracted. Effect sizes were expressed as weighted mean difference (WMD) and 95% confidence intervals (CI). Heterogeneity between studies was assessed with the I² test. Publication bias and subgroup analyses were also performed. The quality of articles was assessed via the Jadad scale. A total of 45 RCTs were included. Meta-analyses suggested a significant reduction in body weight (WMD: -0.99 kg, 95% CI: -1.67, -0.31, p = 0.004), BMI (WMD: -0.30 kg m^-2 , 95% CI: -0.53, -0.08, p = 0.008) and waist circumference (WMD: -0.80 cm, 95% CI: -1.40, -0.20, p = 0.008) following flaxseed supplementation. Subgroup analyses showed that using whole flaxseed in doses ≥30 g d^-1 , longer-term interventions (≥12 weeks) and studies including participants with higher BMI (≥ 27 kg m^-2 ) had positive effects on body composition. Whole flaxseed is a good choice for weight management particularly for weight reduction in overweight and obese participants.

Antioxidants for female subfertility

BACKGROUND

A couple may be considered to have fertility problems if they have been trying to conceive for over a year with no success. This may affect up to a quarter of all couples planning a child. It is estimated that for 40% to 50% of couples, subfertility may result from factors affecting women. Antioxidants are thought to reduce the oxidative stress brought on by these conditions. Currently, limited evidence suggests that antioxidants improve fertility, and trials have explored this area with varied results. This review assesses the evidence for the effectiveness of different antioxidants in female subfertility.

OBJECTIVES

To determine whether supplementary oral antioxidants compared with placebo, no treatment/standard treatment or another antioxidant improve fertility outcomes for subfertile women.

SEARCH METHODS

We searched the following databases (from their inception to September 2016) with no language or date restriction: Cochrane Gynaecology and Fertility Group (CGFG) specialised register, the Cochrane Central Register of Studies (CENTRAL CRSO), MEDLINE, Embase, PsycINFO, CINAHL and AMED. We checked reference lists of appropriate studies and searched for ongoing trials in the clinical trials registers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any type, dose or combination of oral antioxidant supplement with placebo, no treatment or treatment with another antioxidant, among women attending a reproductive clinic. We excluded trials comparing antioxidants with fertility drugs alone and trials that only included fertile women attending a fertility clinic because of male partner infertility.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected eligible studies, extracted the data and assessed the risk of bias of the included studies. The primary review outcome was live birth; secondary outcomes included clinical pregnancy rates and adverse events. We pooled studies using a fixed-effect model, and calculated odds ratios (ORs) with 95% confidence intervals (CIs) for the dichotomous outcomes of live birth, clinical pregnancy and adverse events. We assessed the overall quality of the evidence by applying GRADE criteria.

MAIN RESULTS

We included 50 trials involving 6510 women. Investigators compared oral antioxidants, including combinations of antioxidants, N-acetyl-cysteine, melatonin, L-arginine, myo-inositol, D-chiro-inositol, carnitine, selenium, vitamin E, vitamin B complex, vitamin C, vitamin D+calcium, CoQ10, pentoxifylline and omega-3-polyunsaturated fatty acids versus placebo, no treatment/standard treatment or another antioxidant.Very low-quality evidence suggests that antioxidants may be associated with an increased live birth rate compared with placebo or no treatment/standard treatment (OR 2.13, 95% CI 1.45 to 3.12, P > 0.001, 8 RCTs, 651 women, I2 = 47%). This suggests that among subfertile women with an expected live birth rate of 20%, the rate among women using antioxidants would be between 26% and 43%.Very low-quality evidence suggests that antioxidants may be associated with an increased clinical pregnancy rate compared with placebo or no treatment/standard treatment (OR 1.52, 95% CI 1.31 to 1.76, P < 0.001, 26 RCTs, 4271 women, I2 = 66%). This suggests that among subfertile women with an expected clinical pregnancy rate of 22%, the rate among women using antioxidants would be between 27% and 33%. Heterogeneity was moderately high.There was insufficient evidence to determine whether there was a difference between the groups in rates of miscarriage (OR 0.79, 95% CI 0.58 to 1.08, P = 0.14, 18 RCTs, 2834 women, I2 = 23%, very low quality evidence). This suggests that, among subfertile women with an expected miscarriage rate of 7%, use of antioxidants would be expected to result in a miscarriage rate of between 4% and 7%. There was also insufficient evidence to determine whether there was a difference between the groups in rates of multiple pregnancy (OR 1.00, 95% CI 0.73 to 1.38, P = 0.98, 8 RCTs, 2163 women, I2 = 4%, very low quality evidence). This suggests that among subfertile women with an expected multiple pregnancy rate of 8%, use of antioxidants would be expected to result in a multiple pregnancy rate between 6% and 11%. Likewise, there was insufficient evidence to determine whether there was a difference between the groups in rates of gastrointestinal disturbances (OR 1.55, 95% CI 0.47 to 5.10, P = 0.47, 3 RCTs, 343 women, I2 = 0%, very low quality evidence). This suggests that among subfertile women with an expected gastrointestinal disturbance rate of 2%, use of antioxidants would be expected to result in a rate between 1% and 11%. Overall adverse events were reported by 35 trials in the meta-analysis, but there was insufficient evidence to draw any conclusions.Only one trial reported on live birth, clinical pregnancy or adverse effects in the antioxidant versus antioxidant comparison, and no conclusions could be drawn.Very low-quality evidence suggests that pentoxifylline may be associated with an increased clinical pregnancy rate compared with placebo or no treatment (OR 2.07, 95% CI 1.20 to 3.56, P = 0.009, 3 RCTs, 276 women, I2 = 0%). This suggests that among subfertile women with an expected clinical pregnancy rate of 25%, the rate among women using pentoxifylline would be between 28% and 53%.There was insufficient evidence to determine whether there was a difference between the groups in rates of miscarriage (OR 1.34, 95% CI 0.46 to 3.90, P = 0.58, 3 RCTs, 276 women, I2 = 0%) or multiple pregnancy (OR 0.78, 95% CI 0.20 to 3.09, one RCT, 112 women, very low quality evidence). This suggests that among subfertile women with an expected miscarriage rate of 4%, the rate among women using pentoxifylline would be between 2% and 15%. For multiple pregnancy, the data suggest that among subfertile women with an expected multiple pregnancy rate of 9%, the rate among women using pentoxifylline would be between 2% and 23%.The overall quality of evidence was limited by serious risk of bias associated with poor reporting of methods, imprecision and inconsistency.

AUTHORS' CONCLUSIONS

In this review, there was very low-quality evidence to show that taking an antioxidant may provide benefit for subfertile women, but insufficient evidence to draw any conclusions about adverse events. At this time, there is limited evidence in support of supplemental oral antioxidants for subfertile women.

Effect of n-3 Polyunsaturated Fatty Acid Supplementation on Metabolic and Inflammatory Biomarkers in Type 2 Diabetes Mellitus Patients

BACKGROUND

Type 2 diabetes mellitus (T2DM) is accompanied by chronic low-grade inflammation, with an imbalance in the secretion of adipokines and, worsening insulin resistance. Supplementation with n-3 PUFA in T2DM decreases inflammatory markers, the purpose of the study was to investigate the effect of n-3 PUFA supplementation on adipokines, metabolic control, and lipid profile in T2DM Mexican adults.

METHODS

In a randomized, single-blind, placebo-controlled pilot study, 54 patients with T2DM received 520 mg of DHA + EPA-enriched fish-oil (FOG) or a placebo (PG) daily. Baseline and 24-week anthropometric and biochemical measurements included glucose, insulin, glycosylated hemoglobin (Hb1Ac), leptin, adiponectin, resistin, and lipid profile; n-3 PUFA intake was calculated in g/day.

RESULTS

Waist circumference and blood glucose showed significant reductions in the FOG group (p = 0.001 and p = 0.011, respectively). Hb1Ac (p = 0.009 and p = 0.004), leptin (p < 0.000 and p < 0.000), and leptin/adiponectin ratio (p < 0.000 and p < 0.000) decreased significantly in both groups after 24 weeks (FOG and PG respectively). Serum resistin (FOG p < 0.000 and PG p = 0.001), insulin (FOG p < 0.000 and PG p < 0.000), and HOMA-IR (FOG p = 0.000 and PG p < 0.000) increased significantly in both groups. FOG had an overall improvement in the lipid profile with a significant decrease in triacylgycerols (p = 0.002) and atherogenic index (p = 0.031); in contrast, the PG group had increased total cholesterol (p < 0.000), non-HDL cholesterol (p < 0.000), and atherogenic index (p = 0.017).

CONCLUSIONS

We found a beneficial effect of n-3 PUFA supplementation on waist circumference, glucose, Hb1Ac, leptin, leptin/adiponectin ratio, and lipid profile, without significant changes in adiponectin, and increases in resistin, insulin, and HOMA-IR in both groups.

Omega-3 supplementation effects on polycystic ovary syndrome symptoms and metabolic syndrome

Background:

Polycystic ovary syndrome (PCOS) is the most common female endocrine disorder with unknown etiology and with different complications. The aim of this study was to evaluate the effect of omega-3 supplementation on PCOS symptoms and metabolic syndrome.

Materials and Methods:

This double-blind clinical trial was performed in 2015 in Alzahra and Shahid Beheshti Hospitals, Isfahan, Iran, on 88 patients with PCOS. Intervention group took omega-3 supplements with dose of 2 g/day for 6 months (two capsules), but control group received two olive oil capsules. Finally, ultrasound and laboratory findings and the recovery rate of menstrual disorders in both groups were compared.

Results:

After 6 months’ intervention, waist circumference (WC) was significantly lower in omega-3 as compared to control (81.18 ± 2.87 vs. 84.22 ± 2.61 cm, respectively, P < 0.0001). High-density lipoprotein was increased (47.2 ± 1.37 vs. 41.56 ± 1.34 mg/dl, respectively, P < 0.0001) while low-density lipoprotein (107.79 ± 1.68 vs. 117.4 ± 1.57 mg/dl, respectively), triglyceride (116.02 ± 3.13 vs. 125.06 ± 2.91 mg/dl, respectively), and cholesterol (180.34 ± 6.34 vs. 189.56 ± 5.93 mg/dl, respectively) in omega-3 were significantly lower than control (P < 0.0001). The interval between periods in omega-3 was significantly shorter than control (29.83 ± 4.68 vs. 47.11 ± 8.72 days, respectively, P < 0.001).

Conclusion:

Omega-3 decrease lipid profiles, WC, and interval between periods while weight, hip circumference, fasting blood sugar, number of ovarian follicle, size of ovary, bleeding volume, menstrual bleeding, and hirsutism score did not change by administration of omega-3.

Effect of omega-3 fatty acids supplementation on insulin resistance in women with polycystic ovary syndrome: Meta-analysis of randomized controlled trials

BACKGROUND

Several studies have shown that omega-3 polyunsaturated fatty acids (PUFA) may improve insulin resistance in various diseases. However, the possible effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on insulin resistance in PCOS still remains unclear. We evaluated the effect of omega-3 PUFA supplementation on insulin resistance in women with PCOS in a meta-analysis.

METHODS

Literature searches of MEDLINE, PubMed Central and EMBASE for publications in English were conducted up to December 2015. We included all randomized controlled trials (RCTs) that investigated effects of omega-3 fatty acids supplements on insulin resistance in women with PCOS. Results are summarized as mean differences (MD) with 95% confidence intervals (CI). Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). We assessed the potential sources of heterogeneity using the standard χ2 test.

RESULTS

Of 1202 papers, three RCTs were eligible for inclusion which involved 72 cases and 73 controls. The dose range for omega3 supplement was 1.2g to 3.6g and the duration of follow-up was from 6 to 8 weeks. There was no significant effect of omega-3 fatty acids supplements compared to placebo on insulin resistance (MD: 6.18; CI; -3.347, 15.382; p=0.208) and HOMA -IR (MD: 0.276; 95% CI=-1.428, 1.981; p=0.751) in women with PCOS.

CONCLUSION

The results provide an evidence that supplementation with omega-3 fatty acids may not have a beneficial effect on improving insulin resistance in women with PCOS.

Dietary patterns and the phenotype of polycystic ovary syndrome: the chance of ongoing pregnancy

Polycystic ovary syndrome (PCOS) is generally considered a complex disorder caused by interactions between genetic and environmental factors. In a sub-cohort of women with PCOS visiting the preconception outpatient clinic of a tertiary hospital with follow-up in a periconception cohort, we identified specific dietary patterns and adherence in patients with PCOS with and without hyperandrogenism and the chance of ongoing pregnancy. Food frequency questionnaires were available from 55 patients diagnosed with PCOS during follow-up in routine clinical practice, including 25 with hyperandrogenism and 30 without hyperandrogenism. Strong adherence to the healthy dietary pattern was inversely associated with the hyperandrogenic PCOS phenotype (Adjusted OR 0.27; 95% CI 0.07 to 0.99). In women with PCOS overall, a strong adherence to the healthy dietary pattern showed a three-fold higher chance of ongoing pregnancy (adjusted OR 3.38; 95% CI 1.01 to 11.36) and an association with anti-Müllerian hormone concentration (β -0.569 µg/L; 95% CI -0.97 to -0.17). The effect of this dietary pattern on the chance of ongoing pregnancy and AMH suggests causality, which needs further investigation in prospective studies in the general population.

The effects of omega-3 fatty acids and vitamin E co-supplementation on gene expression of lipoprotein(a) and oxidized low-density lipoprotein, lipid profiles and biomarkers of oxidative stress in patients with polycystic ovary syndrome

This study was conducted to determine the effects of omega-3 fatty acids and vitamin E co-supplementation on gene expression of lipoprotein(a) (Lp[a]) and oxidized low-density lipoprotein (Ox-LDL), lipid profiles and biomarkers of oxidative stress in women with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was done on 68 women diagnosed with PCOS according to the Rotterdam criteria aged 18-40 years old. Participants were randomly assigned into two groups to receive either 1000 mg omega-3 fatty acids from flaxseed oil containing 400 mg α-Linolenic acid plus 400 IU vitamin E supplements (n = 34) or placebo (n = 34) for 12 weeks. Lp(a) and Ox-LDL mRNA levels were quantified in peripheral blood mononuclear cells of PCOS women with RT-PCR method. Lipid profiles and biomarkers of oxidative stress were quantified at the beginning of the study and after 12-week intervention. Quantitative results of RT-PCR demonstrated that compared with the placebo, omega-3 fatty acids and vitamin E co-supplementation downregulated expressed levels of Lp(a) mRNA (P < 0.001) and Ox-LDL mRNA (P < 0.001) in peripheral blood mononuclear cells of women with PCOS. In addition, compared to the placebo group, omega-3 fatty acids and vitamin E co-supplementation resulted in a significant decrease in serum triglycerides (-22.1 ± 22.3 vs. +7.7 ± 23.6 mg/dL, P < 0.001), VLDL- (-4.4 ± 4.5 vs. +1.5 ± 4.7 mg/dL, P < 0.001), total- (-20.3 ± 16.6 vs. +12.2 ± 26.1 mg/dL, P < 0.001), LDL- (-16.7 ± 15.3 vs. +11.9 ± 26.1 mg/dL, P < 0.001) and total-/HDL-cholesterol (-0.5 ± 0.6 vs. +0.4 ± 0.8, P < 0.001). There were a significant increase in plasma total antioxidant capacity (+89.4 ± 108.9 vs. +5.9 ± 116.2 mmol/L, P = 0.003) and a significant decrease in malondialdehyde levels (-0.3 ± 0.4 vs. -0.008 ± 0.6 μmol/L, P = 0.01) by combined omega-3 fatty acids and vitamin E intake compared with the placebo group. Overall, omega-3 fatty acids and vitamin E co-supplementation for 12 weeks in PCOS women significantly improved gene expression of Lp(a) and Ox-LDL, lipid profiles and biomarkers of oxidative stress.

Nutrients as novel therapeutic approaches for metabolic disturbances in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women. This disease is characterized by infertility, menstrual dysfunction, and hyperandrogenism. Also, PCOS is often associated with hyperlipidemia and impaired glucose tolerance, conditions that are associated with cardiovascular disorder, type 2 diabetes, cancer and hypertension. Evidence supports that some nutrients may affect the hormonal and metabolic disturbances of PCOS. Here in this study, we aimed to review the available literature that assessed the nutrients such as inostol, isoflavonids, resveratrol, vitamin D, and PUFA (polyunsaturated fatty acids), known to influence the hormonal and metabolic disturbances of PCOS, along with the strategies and future directions of nutrient supplementations in such patients.

Changes in plasma metabolites and glucose homeostasis during omega-3 polyunsaturated fatty acid supplementation in women with polycystic ovary syndrome

Background

Both fish (FO) and flaxseed oils (FLX) are n-3 polyunsaturated fatty acids (PUFA). Fish oil contains long chain while FLX contains essential n-3 PUFA. We demonstrated that FO altered insulin secretion and resistance in polycystic ovary syndrome (PCOS) women but FLX did not. Surprisingly, the effects of FO were similar to those of the n-6 PUFA-rich soybean oil (SBO). Since increased branched chain (BCAA) and aromatic amino acids (AA) affect insulin secretion and resistance, we investigated whether FO, FLX and /or SBO affect plasma metabolites, especially AA.

Methods and findings

In this six-week, randomized, 3-parallel arm, double-blinded study, 54 women received 3.5 g/day FO, FLX or SBO. In 51 completers (17 from each arm), fasting plasma metabolites were measured at the beginning and at the end.

As compared to FLX, FO and SBO increased insulin response and resistance as well as several BCAA and aromatic AA. Pathway analysis indicated that FO exerted the largest biochemical impact, affecting AA degradation and biosynthesis, amine, polyamine degradation and alanine, glycine, l-carnitine biosynthesis and TCA cycle, while FLX had minimal impact affecting only alanine biosynthesis and l-cysteine degradation.

Conclusion

Effects of FO and SBO on plasma AA were similar and differed significantly from those of the FLX. The primary target of dietary PUFA is not known. Dietary PUFA may influence insulin secretion and resistance directly and alter plasma AA indirectly. Alternatively, as a novel concept, dietary PUFA may directly affect AA metabolism and the changes in insulin secretion and resistance may be secondary.

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Increased serum branched chain amino acids (BCAA) and aromatic amino acids are associated with insulin resistance and type 2 diabetes.

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Although both fish oil (FO) and flaxseed oil (FLX) are n-3 PUFA, FO contains the long chain, while FLX contains the essential n-3 PUFA.

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We compared the effects of different PUFAs on plasma metabolites in women with insulin resistance.

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Fish oil, but not FLX, increased plasma BCAA, and insulin resistance and secretion, indicating differential effects of essential vs. long chain n-3 PUFA.

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It is possible that effects of FO on insulin resistance and secretion may have been indirect, through its actions on BCAA metabolism.

Effect of Flaxseed Intervention on Inflammatory Marker C-Reactive Protein: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Functional food-flaxseed and its derivatives (flaxseed oil or lignans) are beneficial for human health, possibly because of their anti-inflammatory effects. C-reactive protein (CRP), a sensitive marker of inflammation was chosen to evaluate the anti-inflammatory effects of flaxseed. We searched randomized controlled trials from PubMed and the Cochrane Library in October 2015 and conducted a meta-analysis to evaluate the effectiveness of flaxseed and its derivatives on CRP. The mean differences (net change) in CRP (mg/L) concentrations were pooled with a random- or a fixed-effects model depending on the results of heterogeneity tests. Overall, flaxseed interventions had no effects on reduction of CRP (p = 0.428). The null effects were consistent in the subgroup analysis with multiple studies and population characteristics. Significant heterogeneity was observed in most of the analyses. Meta-regression identified baseline body mass index (BMI) as a significant source of heterogeneity (P-interaction = 0.032), with a significant reduction in CRP of 0.83 mg/L (95% confidence interval −1.34 to −0.31; p = 0.002) among subjects with a BMI of ≥30 kg/m². In conclusion, our meta-analysis did not find sufficient evidence that flaxseed and its derivatives have a beneficial effect on reducing circulating CRP. However, they may significantly reduce CRP in obese populations.

Does Fish Oil Have an Anti-Obesity Effect in Overweight/Obese Adults? A Meta-Analysis of Randomized Controlled Trials

Context

Accumulating evidence has suggested favorable effects of fish oil on weight loss in animal experiments; however, findings remain inconsistent in humans.

Objects

The meta-analysis was performed to investigate the influence of fish oil on some parameters of body composition in overweight/obese adults.

Design

Human randomized, placebo-controlled trials were identified by a systematic search of Embase, PubMed, the Cochrane Library, web of science and reference lists of related reviews and articles. The random-effects model was used to estimate the calculated results.

Results

In total, 21 studies with 30 study arms were included in this analysis. Calculated results of the meta-analysis demonstrated that fish oil had no effect on reducing body weight (overall SMD = -0.07, 95% CI -0.21 to 0.07, P = 0.31) and BMI (overall SMD = -0.09, 95% CI -0.22 to 0.03, P = 0.14) whether alone or combined with life modification intervention in overweight/obese subjects. However, waist circumference was significantly reduced (SMD = -0.23, 95% CI -0.40 to -0.06, P = 0.008) in those with fish oil supplementation combined with life modification intervention. Waist hip ratio (WHR) was significantly reduced (overall SMD = -0.52 95% CI -0.76 to -0.27, P < 0.0005) in fish oil supplemented individuals with or without combination life modification intervention.

Conclusion

Current evidence cannot support an exact anti-obesity role of n-3 polyunsaturated fatty acids (PUFAs) in overweight/obese subjects. However, these subjects may benefit from reducing abdominal fat with fish oil supplementation especially when combined with life modification intervention. Further large-scale and long-term clinical trials are needed to gain definite conclusions.

Does omega-3 fatty acids supplementation affect circulating leptin levels? A systematic review and meta-analysis on randomized controlled clinical trials

BACKGROUND

Omega-3 fatty acids have attracted researchers for their effect on circulatory hormone-like peptides affecting weight control.

OBJECTIVE

Our objective was to conduct a systematic review and meta-analysis on randomized controlled trials (RCTs) assessed the effects of omega-3 supplementation on serum leptin concentration and to find the possible sources of heterogeneity in their results.

METHODS

We searched PubMed/Medline, Google Scholar, Ovid, SCOPUS and ISI web of science up to April 2014. RCTs conducted among human adults, examined the effect of omega-3 fatty acid supplements on serum leptin concentrations as an outcome variable were included. The mean difference and standard deviation (SD) of changes in serum leptin levels were used as effect size for the meta-analysis. Summary mean estimates with their corresponding SDs were derived using random effects model.

RESULTS

Totally 14 RCTs were eligible to be included in the systematic review, and the meta-analysis was performed on 13 articles. Our analysis showed that omega-3 supplementation significantly reduces leptin levels (mean difference (MD) = -1·71 ng/ml 95% confidence interval (CI): -3·17 to -0·24, P = 0·022). Subgroup analysis based on BMI status showed that the omega-3 supplementation reduces leptin when used for nonobese subjects (MD = -3·60 ng/ml; 95% CI -6·23 to -0·90; P = 0·011); however, this was not true for obese participants (MD = -0·86 ng/ml; 95% CI: -2·63 to -0·90; P = 0·296). Subgroup analysis based on omega-3 source also showed that omega-3 from marine sources may significantly reduce leptin levels (MD = -1·73 ng/ml; 95% CI -3·25 to -0·2; P = 0·026), but plant sources do not significantly affect serum leptin levels (MD = -1·48 ng/ml; 95% CI -6·78 to 3·23; P = 0·585). Our results were highly sensitive to one study.

CONCLUSIONS

Omega-3 supplementation might moderately decrease circulatory leptin levels only among nonobese adults. RCTs with longer follow-up period, using higher doses for obese adults and exploring the effect in different genders, are needed to replicate our results.

Effect of Omega-3 Supplementation on Visfatin, Adiponectin, and Anthropometric Indices in Women with Polycystic Ovarian Syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a multifactorial, metabolic disorder. Characteristics are chronic anovulation, polycystic ovaries and hyperandrogenism. The aim of this study was to determine the effect of omega-3 supplementation on visfatin, adiponectin, and anthropometric indices in PCOS women.

METHODS

The study was a randomized double blind placebo-controlled clinical trial. It was conducted on 84 women with polycystic ovary syndrome (26.92±5.05 years, BMI=31.69 Kg/m (2)) who referred to the fertility and infertility research center and Shahid Sadoughi hospital in Yazd. After the examination, evaluation and para-medical assessment by obstetrician, they were recruited. They took 3 capsules of omega-3 (each one contained 180 mg EPA and 120 mg DHA) or placebo (each contained 1 g paraffin) daily for 8 weeks. Statistical analysis was paired T-test and student T-test, and a p<0.05 was considered statistically significant.

RESULTS

After the intervention, visfatin concentration did not change in neither groups. But, at the end of the study, the mean of adiponectin concentration increased (p<0.001) in omega-3 group. Moreover, the mean of changes in this factor was significantly different between groups (p<0.005). FSH did not change in two groups of the study. However, the mean of LH decreased about 1.74 mlU/ml in omega-3 group (p<0.005). The mean of change of LH/FSH ratio between groups was significant (p<0.05). After the intervention, prolactin did not meaningfully change in both groups.

CONCLUSION

Our results showed that 8 weeks of supplementation of omega-3 may have some beneficial effects on PCOS biochemical characteristics such as LH, LH/FSH, and adiponectin.

Effect of dietary lipids on circulating adiponectin: a systematic review with meta-analysis of randomised controlled trials

Different dietary interventions have been identified as potential modifiers of adiponectin concentrations, and they may be influenced by lipid intake. We identified studies investigating the effect of dietary lipids (type/amount) on adiponectin concentrations in a systematic review with meta-analysis. A literature search was conducted until July 2013 using databases such as Medline, Embase and Scopus (MeSH terms: ‘adiponectin’, ‘dietary lipid’, ‘randomized controlled trials (RCT)’). Inclusion criteria were RCT in adults analysing adiponectin concentrations with modification of dietary lipids. Among the 4930 studies retrieved, fifty-three fulfilled the inclusion criteria and were grouped as follows: (1) total dietary lipid intake; (2) dietary/supplementary n-3 PUFA; (3) conjugated linoleic acid (CLA) supplementation; (4) other dietary lipid interventions. Diets with a low fat content in comparison to diets with a high-fat content were not associated with positive changes in adiponectin concentrations (twelve studies; pooled estimate of the difference in means: − 0·04 (95 % CI − 0·82, 0·74) μg/ml). A modest increase in adiponectin concentrations with n-3 PUFA supplementation was observed (thirteen studies; 0·27 (95 % CI 0·07, 0·47) μg/ml). Publication bias was found by using Egger's test (P= 0·01) and funnel plot asymmetry. In contrast, CLA supplementation reduced the circulating concentrations of adiponectin compared with unsaturated fat supplementation (seven studies; − 0·74 (95 % CI − 1·38, − 0·10) μg/ml). However, important sources of heterogeneity were found as revealed by the meta-regression analyses of both n-3 PUFA and CLA supplementation. Results of new RCT would be necessary to confirm these findings.

Adiponectin and lipoprotein metabolism

Adiponectin is secreted by the adipose tissue and it has been shown to be down-regulated in states of insulin resistance and in cardiovascular disease. It has also been found to be correlated with various parameters of lipoprotein metabolism, and in particular, it is associated with the metabolism of high-density lipoprotein (HDL) and triglycerides; adiponectin appears to induce an increase in serum HDL, and conversely, HDL can up-regulate adiponectin levels, and in addition, adiponectin lowers serum triglycerides through enhancement of the catabolism of triglyceride-rich lipoproteins. Studies investigating whether adiponectin is causally linked with lipoprotein metabolism have yielded conflicting data, and the mechanisms underlying the interplay between adiponectin and lipoproteins remain to be elucidated. The adiponectin-HDL relationship can explain at least in part the presumed protective role of adiponectin in cardiovascular disease and the adiponectin changes observed after dieting, exercise and lipid-lowering treatment. Statins, fibrates, niacin and n-3 fatty acids may influence circulating adiponectin levels, indicating that adiponectin may mediate some of the metabolic effects of these agents. Further studies to investigate more thoroughly the role of adiponectin in lipoprotein metabolism in the human setting should be carefully planned, focusing on causality and the possible impact of adiponectin on the pathogenesis of cardiovascular disease.

Antioxidants for female subfertility

BACKGROUND

A couple may be considered to have fertility problems if they have been trying to conceive for over a year with no success. This difficulty with conception may affect up to a quarter of all couples planning a child. The reported prevalence of subfertility has increased significantly over the past twenty years. It is estimated that for 40% to 50% of couples, subfertility may be a result of female problems, including ovulatory disorders, poor egg quality, fallopian tube damage and endometriosis. Antioxidants are thought to reduce the oxidative stress brought on by these conditions. Currently, limited evidence suggests that antioxidants improve fertility, and trials have explored this area with varied results. This review assessed the evidence for the effectiveness of different antioxidants in female subfertility.

OBJECTIVES

To determine whether supplementary oral antioxidants compared with placebo, no treatment/standard treatment or another antioxidant improve fertility outcomes for subfertile women.

SEARCH METHODS

We searched the following databases (from inception to April 2013) with no language restrictions applied: Cochrane Menstrual Disorders and Subfertility Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS and OpenSIGLE. We also searched conference abstracts and citation lists in the ISI Web of Knowledge. Ongoing trials were searched in the Trials Registers. Reference lists were checked, and a search on Google was performed.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any type, dose or combination of oral antioxidant supplement with placebo, no treatment or treatment with another antioxidant, among women attending a reproductive clinic. Trials comparing antioxidants with fertility drugs alone and trials that exclusively included fertile women attending a fertility clinic because of male partner infertility were excluded.

DATA COLLECTION AND ANALYSIS

Three review authors independently screened 2127 titles and abstracts, and 67 of these potentially eligible trials were appraised for inclusion and quality through review of full texts and contact with authors. Three review authors were involved in data extraction and assessment of risk of bias. Review authors also collected data on adverse events as reported from the trials. Studies were pooled using fixed-effect models; however, if high heterogeneity was found, a random-effects model was used. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for the dichotomous outcomes of live birth, clinical pregnancy and adverse events. Analyses were stratified by type of antioxidant, by indications for subfertility and by those women also undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection techniques (ICSIs). The overall quality of the evidence was assessed by applying GRADE criteria.

MAIN RESULTS

A total of 28 trials involving 3548 women were included in this review. Investigators compared oral antioxidants, including combinations of antioxidants, pentoxifylline, N-acetyl-cysteine, melatonin, L-arginine, vitamin E, myo-inositol, vitamin C, vitamin D+calcium and omega-3-polyunsaturated fatty acids with placebo, with no treatment/standard treatment or another antioxidant.Antioxidants were not associated with an increased live birth rate compared with placebo or no treatment/standard treatment (OR 1.25, 95% CI 0.19 to 8.26, P = 0.82, 2 RCTs, 97 women, I(2) = 75%, very low-quality evidence). This suggests that among subfertile women with an expected live birth rate of 37%, the rate among women taking antioxidants would be between 10% and 83%.Antioxidants were not associated with an increased clinical pregnancy rate compared with placebo or no treatment/standard treatment (OR 1.30, 95% CI 0.92 to 1.85, P = 0.14, 13 RCTs, 2441 women, I(2)= 55%, very low-quality evidence). This suggests that among subfertile women with an expected clinical pregnancy rate of 23%, the rate among women taking antioxidants would be between 22% and 36%.Only one trial reported on live birth in the antioxidant versus antioxidant comparison, and two trials reported on clinical pregnancy in this comparison. Only subtotals were used in this analysis, and meta-analysis was not possible as each trial used a different antioxidant.Pentoxifylline was associated with an increased clinical pregnancy rate compared with placebo or no treatment (OR 2.03, 95% CI 1.19 to 3.44, P = 0.009, 3 RCTs, 276 women, I(2) = 0%).Adverse events were reported by 14 trials in the meta-analysis and included miscarriage, multiple pregnancy, ectopic pregnancy and gastrointestinal effects. No evidence revealed a difference in adverse effects between antioxidant groups and control groups, but these data were limited.The overall quality of evidence was 'very low' to 'low' because of poor reporting of outcomes, the number of small studies included, high risk of bias within studies and heterogeneity in the primary analysis.

AUTHORS' CONCLUSIONS

The quality of the evidence in the 'antioxidant versus placebo/no treatment' and in the 'antioxidant versus antioxidant' comparisons was assessed to be 'very low'. Antioxidants were not associated with an increased live birth rate or clinical pregnancy rate. There was some evidence of an association of pentoxifylline with an increased clinical pregnancy rate; however, there were only three trials included in this comparison. Future trials may change this result. Variation in the types of antioxidants given meant that we could not assess whether one antioxidant was better than another. There did not appear to be any association of antioxidants with adverse effects for women, but data for these outcomes were limited.