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Fertility and Sterility Aug 2014To report an update on the role of vitamin D (VD) in ovarian physiology with a focus on genes involved in steroidogenesis, follicular development, and ovarian reserve,... (Review)
Review
OBJECTIVE
To report an update on the role of vitamin D (VD) in ovarian physiology with a focus on genes involved in steroidogenesis, follicular development, and ovarian reserve, as well as ovulatory dysfunction associated with polycystic ovary syndrome (PCOS), and ovarian response to assisted reproductive technology (ART).
DESIGN
Systematic review.
SETTING
Not applicable.
PATIENT(S)
Human, animal, and cell culture models.
INTERVENTION(S)
Pubmed literature search.
MAIN OUTCOME MEASURE(S)
Granulosa cell function, serum antimüllerian hormone (AMH), AMH and its receptor gene expression, soluble receptor for advanced glycation end-products (sRAGE), PCOS parameters, and ART outcome.
RESULT(S)
In human granulosa cells, VD alters AMH signaling, FSH sensitivity, and progesterone production and release, indicating a possible physiologic role for VD in ovarian follicular development and luteinization. In the serum, 25-hydroxyvitamin D (25OH-D) is positively correlated with AMH, and appropriate VD supplementation in VD-depleted women can suppress the seasonal changes that occur in serum AMH. In VD-deficient women with PCOS, VD supplementation lowers the abnormally elevated serum AMH levels, possibly indicating a mechanism by which VD improves folliculogenesis. The antiinflammatory sRAGE serum levels significantly increase in women with PCOS after VD replacement. Although follicular fluid 25OH-D correlates with IVF outcomes, there is a lack of data pertaining to the impact of VD supplementation on pregnancy rates following IVF.
CONCLUSION(S)
This review underscores the need for understanding the mechanistic actions of VD in ovarian physiology and the critical need for randomized trials to elucidate the impact of VD supplementation on controlled ovarian hyperstimulation/IVF outcome and ovulatory dysfunction associated with PCOS.
Topics: Animals; Dietary Supplements; Female; Fertility; Humans; Infertility, Female; Male; Ovarian Follicle; Ovary; Polycystic Ovary Syndrome; Pregnancy; Reproductive Techniques, Assisted; Signal Transduction; Treatment Outcome; Vitamin D; Vitamin D Deficiency
PubMed: 24933120
DOI: 10.1016/j.fertnstert.2014.04.046 -
Ciencia & Saude Coletiva Mar 2019To evaluate the effect of vitamin A supplementation in postpartum infants and women on serum retinol levels and breast milk. The databases Medline, PubMed, Lilacs and...
To evaluate the effect of vitamin A supplementation in postpartum infants and women on serum retinol levels and breast milk. The databases Medline, PubMed, Lilacs and SciELO were consulted. The descriptors used were vitamin A, dietary supplement, child, postpartum period, infant and nutrition programs policies. Search found 7432 articles. After elimination of duplicity and application of eligibility criteria, 8 studies remained. All evaluated the effect of vitamin A supplementation on immediate postpartum, five studies used retinyl palmitate supplementation, one with retinyl palmitate and two did not specify the form of supplementation. Six studies evaluated colostrum and two included supplementation of children. It was found that supplementation in the puerperium increases the concentrations of serum retinol and breast milk, however, this result was in the short term and was relevant when the previous concentrations of the mother were low. When maternal serum concentrations are adequate, the retinol content in milk does not change, with little relevance for children. Further studies should be performed to evaluate the effect of megadoses supplementation on serum concentrations of children.
Topics: Colostrum; Dietary Supplements; Diterpenes; Female; Humans; Infant, Newborn; Milk, Human; Postpartum Period; Pregnancy; Retinyl Esters; Time Factors; Vitamin A; Vitamin A Deficiency
PubMed: 30892504
DOI: 10.1590/1413-81232018243.07112017 -
Nutrients Mar 2018Observational studies have indicated an inverse association between vitamin D levels and the risk of diabetes, yet evidence from population interventions remains... (Meta-Analysis)
Meta-Analysis Review
Observational studies have indicated an inverse association between vitamin D levels and the risk of diabetes, yet evidence from population interventions remains inconsistent. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched up to September 2017. Data from studies regarding serum 25(OH)D, fasting blood glucose (FBG), hemoglobin A1c (HbA1c), fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were pooled. Twenty studies ( = 2703) were included in the meta-analysis. Vitamin D supplementation resulted in a significant improvement in serum 25(OH)D levels (weighted mean difference (WMD) = 33.98; 95%CI: 24.60-43.37) and HOMA-IR (standardized mean difference (SMD) = -0.57; 95%CI: -1.09~-0.04), but not in other outcomes. However, preferred changes were observed in subgroups as follows: short-term (WMD = -8.44; 95%CI: -12.72~-4.15), high dose (WMD = -8.70; 95%CI: -12.96~-4.44), non-obese (SMD = -1.80; 95%CI: -2.66~-0.95), Middle Easterners (WMD = -10.43; 95%CI: -14.80~-6.06), baseline vitamin D deficient individuals (WMD = -5.77; 95%CI: -10.48~-1.05) and well-controlled HbA1c individuals (WMD = -4.09; 95%CI: -15.44~7.27). Vitamin D supplementation was shown to increase serum 25(OH)D and reduce insulin resistance effectively. This effect was especially prominent when vitamin D was given in large doses and for a short period of time, and to patients who were non-obese, Middle Eastern, vitamin D deficient, or with optimal glycemic control at baseline.
Topics: Adult; Aged; Biomarkers; Blood Glucose; Diabetes Mellitus, Type 2; Dietary Supplements; Female; Glycated Hemoglobin; Humans; Insulin Resistance; Male; Middle Aged; Treatment Outcome; Vitamin D; Vitamin D Deficiency
PubMed: 29562681
DOI: 10.3390/nu10030375 -
Pharmacological Research Jan 2023Meta-analyses of interventional and observational studies investigating the efficacy and the relationship between vitamin D and depression provided inconsistent results.... (Meta-Analysis)
Meta-Analysis Review
Meta-analyses of interventional and observational studies investigating the efficacy and the relationship between vitamin D and depression provided inconsistent results. The current umbrella meta-analysis was conducted to assess the available evidence and provide a conclusive outcome in this regard. The following international databases were systematically searched till March 2022: PubMed, Scopus, Embase, Web of Science, and Google Scholar. Random-effects model was carried out to calculate the pooled point estimates and their respective 95 % confidence intervals (CI). Ten meta-analyses of randomised controlled trials (RCTs) revealed significant reduction in depression symptoms comparing participants on vitmain D supplements to those on placebo (Pooled standardised mean difference: - 0.40; 95 % CI: - 0.60, - 0.21, p < 0.01: I = 89.1 %, p < 0.01). Four meta-analyses of cohort studies (with one having two subgroups) revealed that participants with lower levels of serum vitamin D were at increased odds of depression than those with higher levels of serum vitamin D (Pooled odds ratio: 1.60; 95 % CI: 1.08, 2.36, p < 0.01; I = 91.3 %, p < 0.01). The present umbrella meta-analysis confirms the potential benefits of vitamin D supplementation and higher serum vitamin D levels in reducing the development and symptoms of depression.
Topics: Humans; Vitamin D; Depression; Vitamins; Dietary Supplements; Vitamin D Deficiency
PubMed: 36509315
DOI: 10.1016/j.phrs.2022.106605 -
Nutrients Jun 2022Iron-deficiency anemia is the most frequent nutritional deficiency, with women of reproductive age being particularly at risk of its development. The aim of the... (Review)
Review
Iron-deficiency anemia is the most frequent nutritional deficiency, with women of reproductive age being particularly at risk of its development. The aim of the systematic review was to assess the effectiveness of dietary interventions to treat iron-deficiency anemia in women based on the randomized controlled trials. The systematic review was conducted according to the PRISMA guidelines and registered in the PROSPERO database (CRD42021261235). The searching procedure was based on PubMed and Web of Science databases, while it covered records published until June 2021. It included all randomized controlled trials assessing effectiveness of various dietary interventions on treatment of iron-deficiency anemia in women of childbearing age. The total number of 7825 records were screened, while 14 of them were finally included in the systematic review. The studies were screened, included, and reported, and the risk of bias was assessed using the revised Cochrane risk-of-bias tool for randomized trials by two independent researchers. The included studies compared the effectiveness of various dietary interventions with supplementation, placebo, control, or any other dietary intervention, while the assessed dietary interventions were based either on increasing iron supply and/or on increasing its absorption (by increasing vitamin C or vitamin D or decreasing phytate intake). The duration of applied intervention was diversified from 3 months or less, through 4 or 5 months, to half of a year or more. Among the assessed biochemical measures, the following were analyzed in majority of studies: hemoglobin, ferritin, transferrin receptor, hematocrit, and transferrin. The majority of included studies supported the influence of dietary interventions on the treatment of iron-deficiency anemia, as the applied dietary intervention was not effective in only three studies. The majority of included studies were assessed as characterized by medium risk of bias, while the overall risk was high for only four studies, which resulted from the randomization process, deviations from the intended interventions, and selection of the reported result. The majority of included studies were conducted for increasing iron supply and/or increasing vitamin C supply; however, only for the interventions including increasing iron supply and simultaneously increasing its absorption by vitamin C supply were all results confirmed effective. Vitamin D also seems to be an effective dietary treatment, but further studies are necessary to confirm the observations. Considering this fact, dietary interventions recommended for anemic female patients should include increased intake of iron and vitamin C.
Topics: Anemia, Iron-Deficiency; Ascorbic Acid; Dietary Supplements; Female; Humans; Iron; Randomized Controlled Trials as Topic; Vitamin D; Vitamins
PubMed: 35807904
DOI: 10.3390/nu14132724 -
Nutrients Mar 2021A potential role of vitamin D in some components of mental health is currently suggested, but the analyses are conducted mainly for adults, while for young individuals...
A potential role of vitamin D in some components of mental health is currently suggested, but the analyses are conducted mainly for adults, while for young individuals mental health is especially important, due to its lifelong effects. The aim of the study was to analyze the association between vitamin D intake or status and mental health in children within a systematic review of literature, including both intervention and observational studies. The literature search was conducted according to the PRISMA guidelines and it covered peer-reviewed studies included in databases of PubMed and Web of Science until October 2019. The studies presenting either vitamin D intake, or vitamin D status in human subjects were allowed (excluding subjects with intellectual disabilities, eating disorders and neurological disorders), while for mental health the various methods of assessment and wide scope of factors were included. The bias was assessed using the Newcastle-Ottawa Scale (NOS). The review was registered in the PROSPERO database (CRD42020155779). A number of 7613 studies after duplicate removing were extracted by two independent researchers, followed by screening and assessment for eligibility, conducted by two independent researchers in two steps (based on title and abstract). Afterwards, the full texts were obtained and after reviewing, a number of 24 studies were included. The synthetic description of the results was prepared, structured around exposure (vitamin D supplementation/status) and outcome (components of mental health). The included studies were conducted either in groups of healthy individuals, or individuals with mental health problems, and they assessed following issues: behavior problems, violence behaviors, anxiety, depressive symptoms/depression, aggressive disorder, psychotic features, bipolar disorder, obsessive compulsive disorder, suicidal incident, as well as general patterns, as follows: mental health, level of distress, quality of life, well-being, mood, sleep patterns. The vast majority of assessed studies, including the most prominent ones (based on the NOS score) supported potential positive influence of vitamin D on mental health in children. As a limitation of the analysis, it should be indicated that studies conducted so far presented various studied groups, outcomes and psychological measures, so more studies are necessary to facilitate comparisons and deepen the observations. Nevertheless, vitamin D intake within a properly balanced diet or as a supplementation, except for a safe sun exposure, should be indicated as an element supporting mental health in children, so it should be recommended to meet the required 25(OH)cholecalciferol blood level in order to prevent or alleviate mental health problems.
Topics: Child; Dietary Supplements; Humans; Mental Disorders; Mental Health; Vitamin D; Vitamin D Deficiency
PubMed: 33809478
DOI: 10.3390/nu13030952 -
Nutrients Sep 2019A systematic review and meta-analysis was undertaken to examine and quantify the effects of B vitamin supplementation on mood in both healthy and 'at-risk' populations.... (Meta-Analysis)
Meta-Analysis
A systematic review and meta-analysis was undertaken to examine and quantify the effects of B vitamin supplementation on mood in both healthy and 'at-risk' populations. A systematic search identified all available randomised controlled trials (RCTs) of daily supplementation with ≥3 B group vitamins with an intervention period of at least four weeks. Random effects models for a standardized mean difference were used to test for overall effect. Heterogeneity was tested using the I statistic. Eighteen articles (16 trials, 2015 participants) were included, of which 12 were eligible for meta-analysis. Eleven of the 18 articles reported a positive effect for B vitamins over a placebo for overall mood or a facet of mood. Of the eight studies in 'at-risk' cohorts, five found a significant benefit to mood. Regarding individual facets of mood, B vitamin supplementation benefited stress ( = 958, SMD = 0.23, 95% CI = 0.02, 0.45, = 0.03). A benefit to depressive symptoms did not reach significance ( = 568, SMD = 0.15, 95% CI = -0.01, 0.32, = 0.07), and there was no effect on anxiety ( = 562, SMD = 0.03, 95% CI = -0.13, 0.20, = 0.71). The review provides evidence for the benefit of B vitamin supplementation in healthy and at-risk populations for stress, but not for depressive symptoms or anxiety. B vitamin supplementation may particularly benefit populations who are at risk due to (1) poor nutrient status or (2) poor mood status.
Topics: Adolescent; Adult; Affect; Aged; Aged, 80 and over; Anxiety; Depression; Dietary Supplements; Female; Humans; Male; Middle Aged; Nutritional Status; Randomized Controlled Trials as Topic; Risk Assessment; Risk Factors; Stress, Psychological; Treatment Outcome; Vitamin B Complex; Vitamin B Deficiency; Young Adult
PubMed: 31527485
DOI: 10.3390/nu11092232 -
American Journal of Physiology. Renal... Dec 2016Insulin resistance (IR) is an early metabolic alteration in chronic kidney disease (CKD) patients, being apparent when the glomerular filtration rate is still within the... (Review)
Review
Insulin resistance (IR) is an early metabolic alteration in chronic kidney disease (CKD) patients, being apparent when the glomerular filtration rate is still within the normal range and becoming almost universal in those who reach the end stage of kidney failure. The skeletal muscle represents the primary site of IR in CKD, and alterations at sites beyond the insulin receptor are recognized as the main defect underlying IR in this condition. Estimates of IR based on fasting insulin concentration are easier and faster but may not be adequate in patients with CKD because renal insufficiency reduces insulin catabolism. The hyperinsulinemic euglycemic clamp is the gold standard for the assessment of insulin sensitivity because this technique allows a direct measure of skeletal muscle sensitivity to insulin. The etiology of IR in CKD is multifactorial in nature and may be secondary to disturbances that are prominent in renal diseases, including physical inactivity, chronic inflammation, oxidative stress, vitamin D deficiency, metabolic acidosis, anemia, adipokine derangement, and altered gut microbiome. IR contributes to the progression of renal disease by worsening renal hemodynamics by various mechanisms, including activation of the sympathetic nervous system, sodium retention, and downregulation of the natriuretic peptide system. IR has been solidly associated with intermediate mechanisms leading to cardiovascular (CV) disease in CKD including left ventricular hypertrophy, vascular dysfunction, and atherosclerosis. However, it remains unclear whether IR is an independent predictor of mortality and CV complications in CKD. Because IR is a modifiable risk factor and its reduction may lower CV morbidity and mortality, unveiling the molecular mechanisms responsible for the pathogenesis of CKD-related insulin resistance is of importance for the identification of novel therapeutic targets aimed at reducing the high CV risk of this condition.
Topics: Disease Progression; Glucose Clamp Technique; Humans; Inflammation; Insulin Resistance; Oxidative Stress; Renal Insufficiency, Chronic; Vitamin D Deficiency
PubMed: 27707707
DOI: 10.1152/ajprenal.00340.2016 -
Nutrients Aug 2019Research has investigated 25-hydroxyvitamin D (25(OH)D) levels in the Atopic Dermatitis (AD) population, as well as changes in AD severity after vitamin D (VitD)... (Meta-Analysis)
Meta-Analysis
Vitamin D Deficiency and Effects of Vitamin D Supplementation on Disease Severity in Patients with Atopic Dermatitis: A Systematic Review and Meta-Analysis in Adults and Children.
Research has investigated 25-hydroxyvitamin D (25(OH)D) levels in the Atopic Dermatitis (AD) population, as well as changes in AD severity after vitamin D (VitD) supplementation. We performed an up-to-date systematic review and meta-analysis of these findings. Electronic searches of MEDLINE, EMBASE and COCHRANE up to February 2018 were performed. Observational studies comparing 25(OH)D between AD patients and controls, as well as trials documenting baseline serum 25(OH)D levels and clinical severity by either SCORAD/EASI scores, were included. Of the 1085 articles retrieved, sixteen were included. A meta-analysis of eleven studies of AD patients vs. healthy controls (HC) found a mean difference of -14 nmol/L (95% CI -25 to -2) for all studies and -16 nmol/L (95% CI -31 to -1) for the paediatric studies alone. A meta-analysis of three VitD supplementation trials found lower SCORAD by -11 points (95% CI -13 to -9, < 0.00001). This surpasses the Minimal Clinical Important Difference for AD of 9.0 points (by 22%). There were greater improvements in trials lasting three months and the mean weighted dose of all trials was 1500-1600 IU/daily. Overall, the AD population, especially the paediatric subset, may be at high-risk for lower serum 25(OH)D. Supplementation with around 1600 IU/daily results in a clinically meaningful AD severity reduction.
Topics: Adolescent; Biomarkers; Child; Child, Preschool; Dermatitis, Atopic; Dietary Supplements; Female; Humans; Incidence; Infant; Male; Risk Factors; Severity of Illness Index; Treatment Outcome; Vitamin D; Vitamin D Deficiency
PubMed: 31405041
DOI: 10.3390/nu11081854 -
The Cochrane Database of Systematic... Mar 2022Vitamin A deficiency (VAD) is a major public health problem in low- and middle-income countries, affecting 190 million children under five years of age and leading to... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Vitamin A deficiency (VAD) is a major public health problem in low- and middle-income countries, affecting 190 million children under five years of age and leading to many adverse health consequences, including death. Based on prior evidence and a previous version of this review, the World Health Organization has continued to recommend vitamin A supplementation (VAS) for children aged 6 to 59 months. The last version of this review was published in 2017, and this is an updated version of that review.
OBJECTIVES
To assess the effects of vitamin A supplementation (VAS) for preventing morbidity and mortality in children aged six months to five years.
SEARCH METHODS
We searched CENTRAL, MEDLINE, Embase, six other databases, and two trials registers up to March 2021. We also checked reference lists and contacted relevant organisations and researchers to identify additional studies.
SELECTION CRITERIA
Randomised controlled trials (RCTs) and cluster-RCTs evaluating the effect of synthetic VAS in children aged six months to five years living in the community. We excluded studies involving children in hospital and children with disease or infection. We also excluded studies evaluating the effects of food fortification, consumption of vitamin A rich foods, or beta-carotene supplementation.
DATA COLLECTION AND ANALYSIS
For this update, two review authors independently assessed studies for inclusion resolving discrepancies by discussion. We performed meta-analyses for outcomes, including all-cause and cause-specific mortality, disease, vision, and side effects. We used the GRADE approach to assess the quality of the evidence.
MAIN RESULTS
The updated search identified no new RCTs. We identified 47 studies, involving approximately 1,223,856 children. Studies were set in 19 countries: 30 (63%) in Asia, 16 of these in India; 8 (17%) in Africa; 7 (15%) in Latin America, and 2 (4%) in Australia. About one-third of the studies were in urban/periurban settings, and half were in rural settings; the remaining studies did not clearly report settings. Most studies included equal numbers of girls and boys and lasted about one year. The mean age of the children was about 33 months. The included studies were at variable overall risk of bias; however, evidence for the primary outcome was at low risk of bias. A meta-analysis for all-cause mortality included 19 trials (1,202,382 children). At longest follow-up, there was a 12% observed reduction in the risk of all-cause mortality for VAS compared with control using a fixed-effect model (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.83 to 0.93; high-certainty evidence). Nine trials reported mortality due to diarrhoea and showed a 12% overall reduction for VAS (RR 0.88, 95% CI 0.79 to 0.98; 1,098,538 children; high-certainty evidence). There was no evidence of a difference for VAS on mortality due to measles (RR 0.88, 95% CI 0.69 to 1.11; 6 studies, 1,088,261 children; low-certainty evidence), respiratory disease (RR 0.98, 95% CI 0.86 to 1.12; 9 studies, 1,098,538 children; low-certainty evidence), and meningitis. VAS reduced the incidence of diarrhoea (RR 0.85, 95% CI 0.82 to 0.87; 15 studies, 77,946 children; low-certainty evidence), measles (RR 0.50, 95% CI 0.37 to 0.67; 6 studies, 19,566 children; moderate-certainty evidence), Bitot's spots (RR 0.42, 95% CI 0.33 to 0.53; 5 studies, 1,063,278 children; moderate-certainty evidence), night blindness (RR 0.32, 95% CI 0.21 to 0.50; 2 studies, 22,972 children; moderate-certainty evidence), and VAD (RR 0.71, 95% CI 0.65 to 0.78; 4 studies, 2262 children, moderate-certainty evidence). However, there was no evidence of a difference on incidence of respiratory disease (RR 0.99, 95% CI 0.92 to 1.06; 11 studies, 27,540 children; low-certainty evidence) or hospitalisations due to diarrhoea or pneumonia. There was an increased risk of vomiting within the first 48 hours of VAS (RR 1.97, 95% CI 1.44 to 2.69; 4 studies, 10,541 children; moderate-certainty evidence).
AUTHORS' CONCLUSIONS
This update identified no new eligible studies and the conclusions remain the same. VAS is associated with a clinically meaningful reduction in morbidity and mortality in children. Further placebo-controlled trials of VAS in children between six months and five years of age would not change the conclusions of this review, although studies that compare different doses and delivery mechanisms are needed. In populations with documented VAD, it would be unethical to conduct placebo-controlled trials.
Topics: Child; Child, Preschool; Diarrhea; Dietary Supplements; Female; Humans; Male; Measles; Morbidity; Respiration Disorders; Vitamin A; Vitamin A Deficiency
PubMed: 35294044
DOI: 10.1002/14651858.CD008524.pub4