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The Cochrane Database of Systematic... Mar 2016Dysmenorrhoea refers to painful menstrual cramps and is a common gynaecological complaint. Conventional treatments include non-steroidal anti-inflammatory drugs (NSAIDs)... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Dysmenorrhoea refers to painful menstrual cramps and is a common gynaecological complaint. Conventional treatments include non-steroidal anti-inflammatory drugs (NSAIDs) and oral contraceptive pills (OCPs), which both reduce myometrial activity (contractions of the uterus). A suggested alternative approach is dietary supplements. We used the term 'dietary supplement' to include herbs or other botanical, vitamins, minerals, enzymes, and amino acids. We excluded traditional Chinese medicines.
OBJECTIVES
To determine the efficacy and safety of dietary supplements for treating dysmenorrhoea.
SEARCH METHODS
We searched sources including the Cochrane Gynaecology and Fertility Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, AMED, PsycINFO (all from inception to 23 March 2015), trial registries, and the reference lists of relevant articles.
SELECTION CRITERIA
We included randomised controlled trials (RCTs) of dietary supplements for moderate or severe primary or secondary dysmenorrhoea. We excluded studies of women with an intrauterine device. Eligible comparators were other dietary supplements, placebo, no treatment, or conventional analgesia.
DATA COLLECTION AND ANALYSIS
Two review authors independently performed study selection, performed data extraction and assessed the risk of bias in the included trials. The primary outcomes were pain intensity and adverse effects. We used a fixed-effect model to calculate odds ratios (ORs) for dichotomous data, and mean differences (MDs) or standardised mean differences (SMDs) for continuous data, with 95% confidence intervals (CIs). We presented data that were unsuitable for analysis either descriptively or in additional tables. We assessed the quality of the evidence using Grading of Recommendations Assessment, Development and Evaluation (GRADE) methods.
MAIN RESULTS
We included 27 RCTs (3101 women). Most included studies were conducted amongst cohorts of students with primary dysmenorrhoea in their late teens or early twenties. Twenty-two studies were conducted in Iran and the rest were performed in other middle-income countries. Only one study addressed secondary dysmenorrhoea. Interventions included 12 different herbal medicines (German chamomile (Matricaria chamomilla, M recutita, Chamomilla recutita), cinnamon (Cinnamomum zeylanicum, C. verum), Damask rose (Rosa damascena), dill (Anethum graveolens), fennel (Foeniculum vulgare), fenugreek (Trigonella foenum-graecum), ginger (Zingiber officinale), guava (Psidium guajava), rhubarb (Rheum emodi), uzara (Xysmalobium undulatum), valerian (Valeriana officinalis), and zataria (Zataria multiflora)) and five non-herbal supplements (fish oil, melatonin, vitamins B1 and E, and zinc sulphate) in a variety of formulations and doses. Comparators included other supplements, placebo, no treatment, and NSAIDs.We judged all the evidence to be of low or very low quality. The main limitations were imprecision due to very small sample sizes, failure to report study methods, and inconsistency. For most comparisons there was only one included study, and very few studies reported adverse effects. Effectiveness of supplements for primary dysmenorrhoea We have presented pain scores (all on a visual analogue scale (VAS) 0 to 10 point scale) or rates of pain relief, or both, at the first post-treatment follow-up. Supplements versus placebo or no treatmentThere was no evidence of effectiveness for vitamin E (MD 0.00 points, 95% CI -0.34 to 0.34; two RCTs, 135 women).There was no consistent evidence of effectiveness for dill (MD -1.15 points, 95% CI -2.22 to -0.08, one RCT, 46 women), guava (MD 0.59, 95% CI -0.13 to 1.31; one RCT, 151 women); one RCT, 73 women), or fennel (MD -0.34 points, 95% CI -0.74 to 0.06; one RCT, 43 women).There was very limited evidence of effectiveness for fenugreek (MD -1.71 points, 95% CI -2.35 to -1.07; one RCT, 101 women), fish oil (MD 1.11 points, 95% CI 0.45 to 1.77; one RCT, 120 women), fish oil plus vitamin B1 (MD -1.21 points, 95% CI -1.79 to -0.63; one RCT, 120 women), ginger (MD -1.55 points, 95% CI -2.43 to -0.68; three RCTs, 266 women; OR 5.44, 95% CI 1.80 to 16.46; one RCT, 69 women), valerian (MD -0.76 points, 95% CI -1.44 to -0.08; one RCT, 100 women), vitamin B1 alone (MD -2.70 points, 95% CI -3.32 to -2.08; one RCT, 120 women), zataria (OR 6.66, 95% CI 2.66 to 16.72; one RCT, 99 women), and zinc sulphate (MD -0.95 points, 95% CI -1.54 to -0.36; one RCT, 99 women).Data on chamomile and cinnamon versus placebo were unsuitable for analysis. Supplements versus NSAIDSThere was no evidence of any difference between NSAIDs and dill (MD 0.13 points, 95% CI -1.01 to 1.27; one RCT, 47 women), fennel (MD -0.70 points, 95% CI -1.81 to 0.41; one RCT, 59 women), guava (MD 1.19, 95% CI 0.42 to 1.96; one RCT, 155 women), rhubarb (MD -0.20 points, 95% CI -0.44 to 0.04; one RCT, 45 women), or valerian (MD points 0.62 , 95% CI 0.03 to 1.21; one RCT, 99 women),There was no consistent evidence of a difference between Damask rose and NSAIDs (MD -0.15 points, 95% CI -0.55 to 0.25; one RCT, 92 women).There was very limited evidence that chamomile was more effective than NSAIDs (MD -1.42 points, 95% CI -1.69 to -1.15; one RCT, 160 women). Supplements versus other supplementsThere was no evidence of a difference in effectiveness between ginger and zinc sulphate (MD 0.02 points, 95% CI -0.58 to 0.62; one RCT, 101 women). Vitamin B1 may be more effective than fish oil (MD -1.59 points, 95% CI -2.25 to -0.93; one RCT, 120 women). Effectiveness of supplements for secondary dysmenorrhoea There was no strong evidence of benefit for melatonin compared to placebo for dysmenorrhoea secondary to endometriosis (data were unsuitable for analysis). Safety of supplements Only four of the 27 included studies reported adverse effects in both treatment groups. There was no evidence of a difference between the groups but data were too scanty to reach any conclusions about safety.
AUTHORS' CONCLUSIONS
There is no high quality evidence to support the effectiveness of any dietary supplement for dysmenorrhoea, and evidence of safety is lacking. However for several supplements there was some low quality evidence of effectiveness and more research is justified.
Topics: Anti-Inflammatory Agents, Non-Steroidal; Dietary Supplements; Dysmenorrhea; Female; Humans; Magnesium; Phytotherapy; Randomized Controlled Trials as Topic; Thiamine; Vitamin B 6; Vitamin E
PubMed: 27000311
DOI: 10.1002/14651858.CD002124.pub2 -
The American Journal of Gastroenterology Jun 2021Constipation is commonly treated with over-the-counter (OTC) products whose efficacy and safety remain unclear. We performed a systematic review of OTC therapies for...
INTRODUCTION
Constipation is commonly treated with over-the-counter (OTC) products whose efficacy and safety remain unclear. We performed a systematic review of OTC therapies for chronic constipation and provide evidence-based recommendations.
METHODS
We searched PubMed and Embase for randomized controlled trials of ≥4-week duration that evaluated OTC preparations between 2004 and 2020. Studies were scored using the US Preventive Services Task Force criteria (0-5 scale) including randomization, blinding, and withdrawals. The strengths of evidence were adjudicated within each therapeutic category, and recommendations were graded (A, B, C, D, and I) based on the level of evidence (level I, good; II, fair; or III, poor).
RESULTS
Of 1,297 studies identified, 41 met the inclusion criteria. There was good evidence (grade A recommendation) for the use of the osmotic laxative polyethylene glycol (PEG) and the stimulant senna; moderate evidence (grade B) for psyllium, SupraFiber, magnesium salts, stimulants (bisacodyl and sodium picosulfate), fruit-based laxatives (kiwi, mango, prunes, and ficus), and yogurt with galacto-oligosaccharide/prunes/linseed oil; and insufficient evidence (grade I) for polydextrose, inulin, and fructo-oligosaccharide. Diarrhea, nausea, bloating, and abdominal pain were common adverse events, but no serious adverse events were reported.
DISCUSSION
The spectrum of OTC products has increased and quality of evidence has improved, but methodological issues including variability in study design, primary outcome measures, trial duration, and small sample sizes remain. We found good evidence to recommend polyethylene glycol or senna as first-line laxatives and moderate evidence supporting fiber supplements, fruits, stimulant laxatives, and magnesium-based products. For others, further validation with more rigorously designed studies is warranted.
Topics: Bisacodyl; Cathartics; Chronic Disease; Citrates; Constipation; Defecation; Fruit; Gastrointestinal Agents; Glucans; Humans; Inulin; Laxatives; Magnesium; Nonprescription Drugs; Oligosaccharides; Organometallic Compounds; Picolines; Polyethylene Glycols; Psyllium; Senna Extract; Yogurt
PubMed: 33767108
DOI: 10.14309/ajg.0000000000001222 -
The Cochrane Database of Systematic... Sep 2015Nausea, retching and vomiting are very commonly experienced by women in early pregnancy. There are considerable physical, social and psychological effects on women who... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Nausea, retching and vomiting are very commonly experienced by women in early pregnancy. There are considerable physical, social and psychological effects on women who experience these symptoms. This is an update of a review of interventions for nausea and vomiting in early pregnancy last published in 2014.
OBJECTIVES
To assess the effectiveness and safety of all interventions for nausea, vomiting and retching in early pregnancy, up to 20 weeks' gestation.
SEARCH METHODS
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register, the Cochrane Complementary Medicine Field's Trials Register (19 January 2015) and reference lists of retrieved studies.
SELECTION CRITERIA
All randomised controlled trials of any intervention for nausea, vomiting and retching in early pregnancy. We excluded trials of interventions for hyperemesis gravidarum, which are covered by another Cochrane review. We also excluded quasi-randomised trials and trials using a cross-over design.
DATA COLLECTION AND ANALYSIS
Four review authors, in pairs, reviewed the eligibility of trials and independently evaluated the risk of bias and extracted the data for included trials.
MAIN RESULTS
Forty-one trials involving 5449 women, met the inclusion criteria. These trials covered many interventions, including acupressure, acustimulation, acupuncture, ginger, chamomile, lemon oil, mint oil, vitamin B6 and several antiemetic drugs. There were no included studies of dietary and other lifestyle interventions. Evidence regarding the effectiveness of P6 acupressure, auricular (ear) acupressure and acustimulation of the P6 point was limited. Acupuncture (P6 or traditional) showed no significant benefit to women in pregnancy. The use of ginger products may be helpful to women, but the evidence of effectiveness was limited and not consistent, though three recent studies support ginger over placebo. There was only limited evidence from trials to support the use of pharmacological agents including vitamin B6, Doxylamine-pyridoxoine and other anti-emetic drugs to relieve mild or moderate nausea and vomiting. There was little information on maternal and fetal adverse outcomes and on psychological, social or economic outcomes.We were unable to pool findings from studies for most outcomes due to heterogeneity in study participants, interventions, comparison groups, and outcomes measured or reported. The methodological quality of the included studies was mixed. Risk of bias was low related to performance bias, detection bias and attrition bias for most studies. Selection bias risk was unclear for many studies and almost half of the studies did not fully or clearly report all pre-specified outcomes.
AUTHORS' CONCLUSIONS
Given the high prevalence of nausea and vomiting in early pregnancy, women and health professionals need clear guidance about effective and safe interventions, based on systematically reviewed evidence. There is a lack of high-quality evidence to support any particular intervention. This is not the same as saying that the interventions studied are ineffective, but that there is insufficient strong evidence for any one intervention. The difficulties in interpreting and pooling the results of the studies included in this review highlight the need for specific, consistent and clearly justified outcomes and approaches to measurement in research studies.
Topics: Acupuncture Therapy; Antiemetics; Female; Zingiber officinale; Humans; Morning Sickness; Nausea; Phytotherapy; Pregnancy; Pregnancy Complications; Randomized Controlled Trials as Topic; Treatment Outcome; Vitamin B 6; Vitamin B Complex; Vomiting
PubMed: 26348534
DOI: 10.1002/14651858.CD007575.pub4 -
Journal of Inherited Metabolic Disease Jan 2017Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to... (Review)
Review
Cystathionine beta-synthase (CBS) deficiency is a rare inherited disorder in the methionine catabolic pathway, in which the impaired synthesis of cystathionine leads to accumulation of homocysteine. Patients can present to many different specialists and diagnosis is often delayed. Severely affected patients usually present in childhood with ectopia lentis, learning difficulties and skeletal abnormalities. These patients generally require treatment with a low-methionine diet and/or betaine. In contrast, mildly affected patients are likely to present as adults with thromboembolism and to respond to treatment with pyridoxine. In this article, we present recommendations for the diagnosis and management of CBS deficiency, based on a systematic review of the literature. Unfortunately, the quality of the evidence is poor, as it often is for rare diseases. We strongly recommend measuring the plasma total homocysteine concentrations in any patient whose clinical features suggest the diagnosis. Our recommendations may help to standardise testing for pyridoxine responsiveness. Current evidence suggests that patients are unlikely to develop complications if the plasma total homocysteine concentration is maintained below 120 μmol/L. Nevertheless, we recommend keeping the concentration below 100 μmol/L because levels fluctuate and the complications associated with high levels are so serious.
Topics: Betaine; Cystathionine beta-Synthase; Homocysteine; Homocystinuria; Humans; Methionine; Pyridoxine
PubMed: 27778219
DOI: 10.1007/s10545-016-9979-0 -
Nutrients Jun 2023Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and is accessible in many dietary supplements. The three natural forms are pyridoxine,... (Review)
Review
INTRODUCTION
Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and is accessible in many dietary supplements. The three natural forms are pyridoxine, pyridoxal, and pyridoxamine. Both vitamin B6 deficiency and high B6 intake have been described as risk factors for developing peripheral neuropathy (PN). The aim of this systematic review is to characterize and comprehensively describe B6-related PN.
METHOD
A systematic, computer-based search was conducted using the PubMed database. Twenty articles were included in this review.
RESULTS
Higher vitamin B6 levels, which usually occur following the taking of nutritional supplements, may lead to the development of a predominantly, if not exclusively, sensory neuropathy of the axonal type. After pyridoxine discontinuation, such patients subjectively report improved symptoms. However, although low vitamin B6 levels can be seen in patients suffering from peripheral neuropathy of various etiologies, there is no firm evidence that low B6 levels have a direct causal relationship with PN. Many studies suggest subjective improvement of neuropathy symptoms in patients suffering from PN of various etiologies after receiving B6 supplementation; however, no data about B6 administration as a monotherapy exist, only as part of a combination treatment, usually with other vitamins. Therefore, the potential therapeutic role of B6 cannot be confirmed to date. Supplementation with vitamin B6, even as part of a nutritional multivitamin supplement, has not been proven harmful at permitted daily doses in patients who already suffer from PN.
CONCLUSION
Current scientific evidence supports a neurotoxic role of B6 at high levels. Although some studies suggest that low B6 is also a potential risk factor, further studies in this area are needed.
Topics: Humans; Pyridoxine; Vitamin B 6; Pyridoxal; Pyridoxamine; Vitamins; Peripheral Nervous System Diseases
PubMed: 37447150
DOI: 10.3390/nu15132823 -
Gut Sep 2017To compare efficacy of pharmacotherapies for chronic idiopathic constipation (CIC) based on comparisons to placebo using Bayesian network meta-analysis. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To compare efficacy of pharmacotherapies for chronic idiopathic constipation (CIC) based on comparisons to placebo using Bayesian network meta-analysis.
DATA SOURCES
We conducted searches (inception to May 2015) of MEDLINE, EMBASE, Scopus and Cochrane Central, as well as original data from authors or drug companies for the medications used for CIC.
STUDY SELECTION
Phase IIB and phase III randomised, placebo-controlled trials (RCT) of ≥4 weeks' treatment for CIC in adults with Rome II or III criteria for functional constipation; trials included at least one of four end points.
DATA EXTRACTION AND SYNTHESIS
Two investigators independently evaluated all full-text articles that met inclusion criteria and extracted data for primary and secondary end points, risk of bias and quality of evidence.
OUTCOMES
Primary end points were ≥3 complete spontaneous bowel movements (CSBM)/week and increase over baseline by ≥1 CSBM/week. Secondary end points were change from baseline (Δ) in the number of SBM/week and Δ CSBM/week.
RESULTS
Twenty-one RCTs (9189 patients) met inclusion and end point criteria: 9 prucalopride, 3 lubiprostone, 3 linaclotide, 2 tegaserod, 1 each velusetrag, elobixibat, bisacodyl and sodium picosulphate (NaP). All prespecified end points were unavailable in four polyethylene glycol studies. Bisacodyl, NaP, prucalopride and velusetrag were superior to placebo for the ≥3 CSBM/week end point. No drug was superior at improving the primary end points on network meta-analysis. Bisacodyl appeared superior to the other drugs for the secondary end point, Δ in number of SBM/week.
CONCLUSIONS
Current drugs for CIC show similar efficacy. Bisacodyl may be superior to prescription medications for Δ in the number of SBM/week in CIC.
Topics: Azabicyclo Compounds; Benzofurans; Bisacodyl; Chronic Disease; Citrates; Constipation; Defecation; Drug Monitoring; Gastrointestinal Agents; Humans; Organometallic Compounds; Picolines; Randomized Controlled Trials as Topic; Treatment Outcome
PubMed: 27287486
DOI: 10.1136/gutjnl-2016-311835 -
Translational Psychiatry Jul 2022Antipsychotic-induced hyperprolactinemia (AP-induced HPRL) occurs overall in up to 70% of patients with schizophrenia, which is associated with hypogonadism and sexual... (Meta-Analysis)
Meta-Analysis
Antipsychotic-induced hyperprolactinemia (AP-induced HPRL) occurs overall in up to 70% of patients with schizophrenia, which is associated with hypogonadism and sexual dysfunction. We summarized the latest evidence for the benefits of prolactin-lowering drugs. We performed network meta-analyses to summarize the evidence and applied Grading of Recommendations Assessment, Development, and Evaluation frameworks (GRADE) to rate the certainty of evidence, categorize interventions, and present the findings. The search identified 3,022 citations, 31 studies of which with 1999 participants were included in network meta-analysis. All options were not significantly better than placebo among patients with prolactin (PRL) less than 50 ng/ml. However, adjunctive aripiprazole (ARI) (5 mg: MD = -64.26, 95% CI = -87.00 to -41.37; 10 mg: MD = -59.81, 95% CI = -90.10 to -29.76; more than 10 mg: MD = -68.01, 95% CI = -97.12 to -39.72), switching to ARI in titration (MD = -74.80, 95% CI = -134.22 to -15.99) and adjunctive vitamin B6 (MD = -91.84, 95% CI = -165.31 to -17.74) were associated with significant decrease in AP-induced PRL among patients with PRL more than 50 ng/ml with moderated (adjunctive vitamin B6) to high (adjunctive ARI) certainty of evidence. Pharmacological treatment strategies for AP-induced HPRL depends on initial PRL level. No effective strategy was found for patients with AP-induced HPRL less than 50 ng/ml, while adjunctive ARI, switching to ARI in titration and adjunctive high-dose vitamin B6 showed better PRL decrease effect on AP-induced HPRL more than 50 ng/ml.
Topics: Antipsychotic Agents; Aripiprazole; Humans; Hyperprolactinemia; Network Meta-Analysis; Prolactin; Vitamin B 6
PubMed: 35790713
DOI: 10.1038/s41398-022-02027-4 -
JAMA Network Open Mar 2024Antipsychotic-induced akathisia (AIA) occurs in 14% to 35% of patients treated with antipsychotics and is associated with increased suicide and decreased adherence in... (Meta-Analysis)
Meta-Analysis
IMPORTANCE
Antipsychotic-induced akathisia (AIA) occurs in 14% to 35% of patients treated with antipsychotics and is associated with increased suicide and decreased adherence in patients with schizophrenia. However, no comprehensive review and network meta-analysis has been conducted to compare the efficacy of treatments for AIA.
OBJECTIVE
To compare the efficacy associated with AIA treatments.
DATA SOURCES
Three databases (MEDLINE, Web of Science, and Google Scholar) were systematically searched by multiple researchers for double-blind randomized clinical trials (RCTs) comparing active drugs for the treatment of AIA with placebo or another treatment between May 30 and June 18, 2023.
STUDY SELECTION
Selected studies were RCTs that compared adjunctive drugs for AIA vs placebo or adjunctive treatment in patients treated with antipsychotics fulfilling the criteria for akathisia, RCTs with sample size of 10 patients or more, only trials in which no additional drugs were administered during the study, and RCTs that used a validated akathisia score. Trials with missing data for the main outcome (akathisia score at the end points) were excluded.
DATA EXTRACTION AND SYNTHESIS
Data extraction and synthesis were performed, estimating standardized mean differences (SMDs) through pairwise and network meta-analysis with a random-effects model. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed.
MAIN OUTCOMES AND MEASURES
The primary outcome was the severity of akathisia measured by a validated scale at the last available end point.
RESULTS
Fifteen trials involving 492 participants compared 10 treatments with placebo. Mirtazapine (15 mg/d for ≥5 days; SMD, -1.20; 95% CI, -1.83 to -0.58), biperiden (6 mg/d for ≥14 days; SMD, -1.01; 95% CI, -1.69 to -0.34), vitamin B6 (600-1200 mg/d for ≥5 days; SMD, -0.92; 95% CI, -1.57 to -0.26), trazodone (50 mg/d for ≥5 days; SMD, -0.84; 95% CI, -1.54 to -0.14), mianserin (15 mg/d for ≥5 days; SMD, -0.81; 95% CI, -1.44 to -0.19), and propranolol (20 mg/d for ≥6 days; SMD, -0.78; 95% CI, -1.35 to -0.22) were associated with greater efficacy than placebo, with low to moderate heterogeneity (I2 = 34.6%; 95% CI, 0.0%-71.1%). Cyproheptadine, clonazepam, zolmitriptan, and valproate did not yield significant effects. Eight trials were rated as having low risk of bias; 2, moderate risk; and 5, high risk. Sensitivity analyses generally confirmed the results for all drugs except for cyproheptadine and propranolol. No association between effect sizes and psychotic severity was found.
CONCLUSIONS AND RELEVANCE
In this systematic review and network meta-analysis, mirtazapine, biperiden, and vitamin B6 were associated with the greatest efficacy for AIA, with vitamin B6 having the best efficacy and tolerance profile. Trazodone, mianserin, and propranolol appeared as effective alternatives with slightly less favorable efficacy and tolerance profiles. These findings should assist prescribers in selecting an appropriate medication for treating AIA.
Topics: Humans; Antipsychotic Agents; Biperiden; Cyproheptadine; Gallopamil; Mianserin; Mirtazapine; Network Meta-Analysis; Propranolol; Randomized Controlled Trials as Topic; Trazodone; Vitamin B 6; Akathisia, Drug-Induced
PubMed: 38451521
DOI: 10.1001/jamanetworkopen.2024.1527 -
The Cochrane Database of Systematic... Nov 2018Vitamins and minerals have many functions in the nervous system which are important for brain health. It has been suggested that various different vitamin and mineral... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Vitamins and minerals have many functions in the nervous system which are important for brain health. It has been suggested that various different vitamin and mineral supplements might be useful in maintaining cognitive function and delaying the onset of dementia. In this review, we sought to examine the evidence for this in people who already had mild cognitive impairment (MCI).
OBJECTIVES
To evaluate the effects of vitamin and mineral supplementation on cognitive function and the incidence of dementia in people with mild cognitive impairment.
SEARCH METHODS
We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's (CDCIG) specialised register, as well as MEDLINE, Embase, PsycINFO, CENTRAL, CINAHL, LILACs, Web of Science Core Collection, ClinicalTrials.gov, and the WHO Portal/ICTRP, from inception to 25 January 2018.
SELECTION CRITERIA
We included randomised or quasi-randomised, placebo-controlled trials which evaluated orally administered vitamin or mineral supplements in participants with a diagnosis of mild cognitive impairment and which assessed the incidence of dementia or cognitive outcomes, or both. We were interested in studies applicable to the general population of older people and therefore excluded studies in which participants had severe vitamin or mineral deficiencies.
DATA COLLECTION AND ANALYSIS
We sought data on our primary outcomes of dementia incidence and overall cognitive function and on secondary outcomes of episodic memory, executive function, speed of processing, quality of life, functional performance, clinical global impression, adverse events, and mortality. We conducted data collection and analysis according to standard Cochrane systematic review methods. We assessed the risk of bias of included studies using the Cochrane 'Risk of bias' assessment tool. We grouped vitamins and minerals according to their putative mechanism of action and, where we considered it to be clinically appropriate, we pooled data using random-effects methods. We used GRADE methods to assess the overall quality of evidence for each comparison and outcome.
MAIN RESULTS
We included five trials with 879 participants which investigated B vitamin supplements. In four trials, the intervention was a combination of vitamins B6, B12, and folic acid; in one, it was folic acid only. Doses varied. We considered there to be some risks of performance and attrition bias and of selective outcome reporting among these trials. Our primary efficacy outcomes were the incidence of dementia and scores on measures of overall cognitive function. None of the trials reported the incidence of dementia and the evidence on overall cognitive function was of very low-quality. There was probably little or no effect of B vitamins taken for six to 24 months on episodic memory, executive function, speed of processing, or quality of life. The evidence on our other secondary clinical outcomes, including harms, was very sparse or very low-quality. There was evidence from one study that there may be a slower rate of brain atrophy over two years in participants taking B vitamins. The same study reported subgroup analyses based on the level of serum homocysteine (tHcy) at baseline and found evidence that B vitamins may improve episodic memory in those with tHcy above the median at baseline.We included one trial (n = 516) of vitamin E supplementation. Vitamin E was given as 1000 IU of alpha-tocopherol twice daily. We considered this trial to be at risk of attrition and selective reporting bias. There was probably no effect of vitamin E on the probability of progression from MCI to Alzheimer's dementia over three years (HR 1.02; 95% CI 0.74 to 1.41; n = 516; 1 study, moderate-quality evidence). There was also no evidence of an effect at intermediate time points. The available data did not allow us to conduct analyses, but the authors reported no significant effect of three years of supplementation with vitamin E on overall cognitive function, episodic memory, speed of processing, clinical global impression, functional performance, adverse events, or mortality (five deaths in each group). We considered this to be low-quality evidence.We included one trial (n = 256) of combined vitamin E and vitamin C supplementation and one trial (n = 26) of supplementation with chromium picolinate. In both cases, there was a single eligible cognitive outcome, but we considered the evidence to be very low-quality and so could not be sure of any effects.
AUTHORS' CONCLUSIONS
The evidence on vitamin and mineral supplements as treatments for MCI is very limited. Three years of treatment with high-dose vitamin E probably does not reduce the risk of progression to dementia, but we have no data on this outcome for other supplements. Only B vitamins have been assessed in more than one RCT. There is no evidence for beneficial effects on cognition of supplementation with B vitamins for six to 24 months. Evidence from a single study of a reduced rate of brain atrophy in participants taking vitamin B and a beneficial effect of vitamin B on episodic memory in those with higher tHcy at baseline warrants attempted replication.
Topics: Aged; Aged, 80 and over; Ascorbic Acid; Cognition; Cognition Disorders; Dementia; Dietary Supplements; Executive Function; Humans; Memory, Episodic; Middle Aged; Mortality; Picolinic Acids; Quality of Life; Randomized Controlled Trials as Topic; Trace Elements; Vitamin B Complex; Vitamins; alpha-Tocopherol
PubMed: 30383288
DOI: 10.1002/14651858.CD011905.pub2 -
The Cochrane Database of Systematic... Dec 2018Vitamins and minerals play multiple functions within the central nervous system which may help to maintain brain health and optimal cognitive functioning.... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Vitamins and minerals play multiple functions within the central nervous system which may help to maintain brain health and optimal cognitive functioning. Supplementation of the diet with various vitamins and minerals has been suggested as a means of maintaining cognitive function, or even of preventing dementia, in later life.
OBJECTIVES
To evaluate the effects of vitamin and mineral supplementation on cognitive function in cognitively healthy people aged 40 years or more.
SEARCH METHODS
We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group's (CDCIG) specialised register, as well as MEDLINE, Embase, PsycINFO, CINAHL, ClinicalTrials.gov and the WHO Portal/ICTRP from inception to 26th January 2018.
SELECTION CRITERIA
We included randomised controlled trials that evaluated the cognitive effects on people aged 40 years or more of any vitamin or mineral supplements taken by mouth for at least three months.
DATA COLLECTION AND ANALYSIS
Study selection, data extraction, and quality assessments were done in duplicate. Vitamins were considered broadly in the categories of B vitamins, antioxidant vitamins, and combinations of both. Minerals were considered separately, where possible. If interventions and outcomes were considered sufficiently similar, then data were pooled. In order to separate short-term cognitive effects from possible longer-term effects on the trajectory of cognitive decline, data were pooled for various treatment durations from 3 months to 12 months and up to 10 years or more.
MAIN RESULTS
In total, we included 28 studies with more than 83,000 participants. There were some general limitations of the evidence. Most participants were enrolled in studies which were not designed primarily to assess cognition. These studies often had no baseline cognitive assessment and used only brief cognitive assessments at follow-up. Very few studies assessed the incidence of dementia. Most study reports did not mention adverse events or made only very general statements about them. Only 10 studies had a mean follow-up > 5 years. Only two studies had participants whose mean age was < 60 years at baseline. The risk of bias in the included studies was generally low, other than a risk of attrition bias for longer-term outcomes. We considered the certainty of the evidence behind almost all results to be moderate or low.We included 14 studies with 27,882 participants which compared folic acid, vitamin B12, vitamin B6, or a combination of these to placebo. The majority of participants were aged over 60 years and had a history of cardio- or cerebrovascular disease. We found that giving B vitamin supplements to cognitively healthy adults, mainly in their 60s and 70s, probably has little or no effect on global cognitive function at any time point up to 5 years (SMD values from -0.03 to 0.06) and may also have no effect at 5-10 years (SMD -0.01). There were very sparse data on adverse effects or on incidence of cognitive impairment or dementia.We included 8 studies with 47,840 participants in which the active intervention was one or more of the antioxidant vitamins: ß-carotene, vitamin C or vitamin E. Results were mixed. For overall cognitive function, there was low-certainty evidence of benefit associated with ß-carotene after a mean of 18 years of treatment (MD 0.18 TICS points, 95% CI 0.01 to 0.35) and of vitamin C after 5 years to 10 years (MD 0.46 TICS points, 95% CI 0.14 to 0.78), but not at earlier time points. From two studies which reported on dementia incidence, there was low-certainty evidence of no effect of an antioxidant vitamin combination or of vitamin E, either alone or combined with selenium. One of the included studies had been designed to look for effects on the incidence of prostate cancer; it found a statistically significant increase in prostate cancer diagnoses among men taking vitamin E.One trial with 4143 participants compared vitamin D3 (400 IU/day) and calcium supplements to placebo. We found low- to moderate-certainty evidence of no effect of vitamin D3 and calcium supplements at any time-point up to 10 years on overall cognitive function (MD after a mean of 7.8 years -0.1 MMSE points, 95% CI -0.81 to 0.61) or the incidence of dementia (HR 0.94, 95% CI 0.72 to 1.24). A pilot study with 60 participants used a higher dose of vitamin D3 (4000 IU on alternate days) and found preliminary evidence that this dose probably has no effect on cognitive function over six months.We included data from one trial of zinc and copper supplementation with 1072 participants. There was moderate-certainty evidence of little or no effect on overall cognitive function (MD 0.6 MMSE points, 95% CI -0.19 to 1.39) or on the incidence of cognitive impairment after 5 years to 10 years. A second smaller trial provided no usable data, but reported no cognitive effects of six months of supplementation with zinc gluconate.From one study with 3711 participants, there was low-certainty evidence of no effect of approximately five years of selenium supplementation on the incidence of dementia (HR 0.83, 95% CI 0.61 to 1.13).Finally, we included three trials of complex supplements (combinations of B vitamins, antioxidant vitamins, and minerals) with 6306 participants. From the one trial which assessed overall cognitive function, there was low-certainty evidence of little or no effect on the TICS (MD after a mean of 8.5 years 0.12, 95% CI -0.14 to 0.38).
AUTHORS' CONCLUSIONS
We did not find evidence that any vitamin or mineral supplementation strategy for cognitively healthy adults in mid or late life has a meaningful effect on cognitive decline or dementia, although the evidence does not permit definitive conclusions. There were very few data on supplementation starting in midlife (< 60 years); studies designed to assess cognitive outcomes tended to be too short to assess maintenance of cognitive function; longer studies often had other primary outcomes and used cognitive measures which may have lacked sensitivity. The only positive signals of effect came from studies of long-term supplementation with antioxidant vitamins. These may be the most promising for further research.
Topics: Adult; Aged; Antioxidants; Ascorbic Acid; Calcium; Cholecalciferol; Cognition; Cognitive Dysfunction; Copper; Dementia; Dietary Supplements; Folic Acid; Humans; Middle Aged; Minerals; Randomized Controlled Trials as Topic; Selenium; Vitamin A; Vitamin B 12; Vitamin B 6; Vitamin E; Vitamins; Zinc; beta Carotene
PubMed: 30556597
DOI: 10.1002/14651858.CD011906.pub2