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Drugs for preventing lung cancer in healthy people.
Cortés-Jofré, M, Rueda, JR, Asenjo-Lobos, C, Madrid, E, Bonfill Cosp, X
The Cochrane database of systematic reviews. 2020;(3):CD002141
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Abstract
BACKGROUND This is the second update of this Cochrane Review. Some studies have suggested a protective effect of antioxidant nutrients and higher dietary levels of fruits and vegetables on lung cancer. OBJECTIVES To determine whether vitamins and minerals and other potential agents, alone or in combination, reduce lung cancer incidence and lung cancer mortality in healthy populations. SEARCH METHODS We searched CENTRAL, MEDLINE and Embase from 1974 to May 2019 and screened references included in published studies and reviews. SELECTION CRITERIA We included randomised controlled trials (RCTs) comparing vitamins or mineral supplements with placebo, administered to healthy people with the aim of preventing lung cancer. DATA COLLECTION AND ANALYSIS Four review authors independently selected the trials to be included in the review, assessed their methodological quality and extracted data. For dichotomous outcomes we calculated risk ratios (RRs) and 95% confidence intervals (CIs) and pooled results using the random-effects model. We assessed the risk of bias using Cochrane's 'Risk of bias' assessment tool and certainty of evidence using the GRADE approach. MAIN RESULTS In this update, we identified three new trials for a total of 12 studies. Six analysed vitamin A, three vitamin C, three combined vitamin D3 + calcium, four vitamin E combined with other products, one selenium supplements and nine studied combinations of two or more products. Four studies included only men and five only women. Vitamin A results in little to no difference in lung cancer incidence (RR 1.09, 95% CI 1.00 to 1.19; 5 RCTs, 212314 participants; high-certainty evidence) and lung cancer mortality (RR 1.06, 95% CI 0.81 to 1.38; 3 RCTs, 190118 participants; high-certainty evidence). But in smokers or asbestos workers vitamin A increases the risk of lung cancer incidence (RR 1.10, 95% CI 1.01 to 1.20; 3 RCTs, 43995 participants; high-certainty evidence), lung cancer mortality (RR 1.18, 95% CI 1.01 to 1.38; 2 RCTs, 29426 participants; high-certainty evidence) and all-cause mortality (RR 1.09, 95% CI 1.05 to 1.13; 2 RCTs, 32883 participants; high-certainty evidence). Vitamin A increases the risk of minor side effects, such as yellowing of the skin and minor gastrointestinal symptoms (high-certainty evidence). Vitamin C likely results in little to no difference in lung cancer incidence (RR 1.29, 95% CI 0.67 to 2.49; 2 RCTs, 14953 participants; moderate-certainty evidence). In women, vitamin C increases the risk of lung cancer incidence (RR 1.84, 95% CI 1.14 to 2.95; 1 RCT, 7627 participants; high-certainty evidence). In men, vitamin C results in little to no difference in mortality for lung cancer (RR 0.81, 95% CI 0.53 to 1.23; 1 RCT, 7326 participants; high-certainty evidence). Vitamin D + calcium may result in little to no difference in lung cancer incidence in postmenopausal women (RR 0.90, 95% CI 0.39 to 2.08; 3 RCTs, 37601 women; low-certainty evidence). Vitamin E results in little to no difference in lung cancer incidence (RR 1.01, 95% CI 0.90 to 1.14; 3 RCTs, 36841 participants; high-certainty evidence) or to lung cancer mortality (RR 0.96, 95% CI 0.77 to 1.18; 2 RCTs, 29214 participants; high-certainty evidence), but increases the risk of haemorrhagic strokes (hazard ratio (HR), 1.74, 95% CI 1.04 to 2.91; 1 RCT, 14641 participants; high-certainty evidence). Calcium results in little to no difference in lung cancer incidence in postmenopausal women (RR 0.65, 95% CI 0.13 to 3.18; 1 RCT, 733 participants) or in risk of renal calculi (RR 1.94, 95% CI 0.20 to 18.57; 1 RCT, 733 participants; low-certainty evidence). Selenium in men results in little to no difference in lung cancer incidence (RR 1.11, 95% CI 0.80 to 1.54; 1 RCT, 17448 participants; high-certainty evidence) and lung cancer mortality (RR 1.09, 95% CI 0.72 to 1.66; 1 RCT, 17448 participants; high-certainty evidence) and increases the risk for grade 1 to 2 dermatitis (RR 1.16, 95% CI 1.04 to 1.31; 1 RCT, 17448 participants; high-certainty evidence) and for alopecia (RR 1.28, 95% CI 1.07 to 1.53; 1 RCT, 17448 participants; high-certainty evidence). The combination of vitamins A, C, E + selenium + zinc results in little to no difference in lung cancer incidence (RR 0.64, 95% CI 0.28 to 1.48; 1 RCT, 12741 participants; high-certainty evidence). AUTHORS' CONCLUSIONS Well-designed RCTs have shown no beneficial effect of supplements for the prevention of lung cancer and lung cancer mortality in healthy people. Vitamin A supplements increase lung cancer incidence and mortality in smokers or persons exposed to asbestos. Vitamin C increases lung cancer incidence in women. Vitamin E increases the risk of haemorrhagic strokes.
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Vitamins and Minerals for Migraine Prophylaxis: A Systematic Review and Meta-analysis.
Okoli, GN, Rabbani, R, Kashani, HH, Wierzbowski, AK, Neilson, C, Mansouri, B, Zarychanski, R, Abou-Setta, AM
The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques. 2019;(2):224-233
Abstract
OBJECTIVE To summarize the findings of randomized controlled trials (RCTs) on the efficacy and safety of vitamins and minerals for migraine prophylaxis. METHODS We systematically searched bibliographic databases and relevant websites for parallel and crossover RCTs reporting efficacy and/or safety of vitamins and/or minerals for migraine prophylaxis. Our primary outcomes were migraine frequency (number of attacks) and duration (hours). Secondary outcomes were severity (intensity), days with migraine, and adverse events. Meta-analysis was conducted when analyzable data were available from at least two trials. RESULTS Eighteen placebo-controlled trials met our eligibility criteria. Only coenzyme Q10 and magnesium contributed to meta-analyses. In adults, compared with placebo, coenzyme Q10 did not significantly decrease migraine frequency (mean difference (MD) -0.44 (-2.14 to 1.26); I2 53%; 2 trials; 97 participants; moderate strength of the evidence), duration (MD -1.97 (-4.82 to 0.87); I2 0%; 2 trials; 97 participants; moderate strength of the evidence), or severity (ratio of means (RoM) -0.05 (-0.20 to 0.11); I2 0%; 2 trials; 97 participants). In adults, compared with placebo, magnesium did not significantly decrease migraine severity (RoM -0.17 (-0.36 to 0.02); I2 48%; 3 trials; 226 participants; low strength of the evidence). Meta-analysis of other vitamins and minerals, and other outcomes were not feasible due to a lack of sufficiently reported data. CONCLUSIONS Based on insufficient evidence, it is unknown if coenzyme Q10 and magnesium are effective for migraine prophylaxis in adults. High-quality, adequately powered RCTs are needed to fully evaluate the efficacy and safety of vitamins and minerals for migraine prophylaxis.
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Effect of Ascorbic Acid on Mineral and Bone Disorders in Hemodialysis Patients: a Systematic Review and Meta-Analysis.
Ke, G, Huang, J, Zhu, Y, Yang, J, Zhang, Y, Chen, L, Hu, J, Tao, S, Hu, Y, Yang, D, et al
Kidney & blood pressure research. 2018;(5):1459-1471
Abstract
BACKGROUND/AIMS: Hemodialysis (HD) patients often have inadequate nutrition, especially with respect to ascorbic acid (AA). It is reported that every HD session may cause a 50%- 75% decrease in plasma AA levels. Some studies have shown that supplementation of AA can change the outcome of chronic kidney disease-mineral bone disorders (CKD-MBD), but the effect of AA on HD patients with CKD-MBD remains controversial. Consequently, we decided to perform a meta-analysis to evaluate the efficacy of AA supplementation in CKD-MBD patients requiring dialysis. METHODS A search was conducted using Pubmed, EMBASE, Cochrane Central Register of Controlled Trials, Chinese National Knowledge Infrastructure (CNKI), Wanfang database and VIP information database up to April 2018 for all English and Chinese language publications. The main indicators of our study were changes in serum phosphate (P), calcium (Ca) and parathyroid hormone (PTH) levels after AA treatment. The efficacy of AA was evaluated by weighted mean difference (WMD) and confidence intervals (CI). Cardiovascular events, mortality and adverse events reported during the experiment were also noted. RESULTS In total, 371 patients in six studies were involved in this meta-analysis. Compared to placebo, AA treatment had no positive effect on serum P (353 patients; WMD = -0.05; 95% CI, -0.3 to 0.2; I2 = 28%) or PTH levels (275 patients; WMD = -17.04; 95%CI, -63.79 to 29.72; I2 = 75%). The pooled mean difference of the change of Ca levels from baseline was higher in the AA therapy group versus placebo (353 patients; WMD = 0.15; 95% CI, 0.01 to 0.3; I2 = 0%). No side effects were observed. CONCLUSION Our systematic review and meta-analysis does not support prescription of AA to HD patients with CKD-MBD. AA had no positive effect on CKD-MBD patients as it couldn't influence the serum P or PTH levels but did raise serum Ca levels in the short-term.
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Vitamin and mineral supplementation for maintaining cognitive function in cognitively healthy people in mid and late life.
Rutjes, AW, Denton, DA, Di Nisio, M, Chong, LY, Abraham, RP, Al-Assaf, AS, Anderson, JL, Malik, MA, Vernooij, RW, Martínez, G, et al
The Cochrane database of systematic reviews. 2018;(12):CD011906
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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.
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Vitamin and mineral status in chronic fatigue syndrome and fibromyalgia syndrome: A systematic review and meta-analysis.
Joustra, ML, Minovic, I, Janssens, KAM, Bakker, SJL, Rosmalen, JGM
PloS one. 2017;(4):e0176631
Abstract
BACKGROUND Many chronic fatigue syndrome (CFS) and fibromyalgia syndrome (FMS) patients (35-68%) use nutritional supplements, while it is unclear whether deficiencies in vitamins and minerals contribute to symptoms in these patients. Objectives were (1) to determine vitamin and mineral status in CFS and FMS patients as compared to healthy controls; (2) to investigate the association between vitamin and mineral status and clinical parameters, including symptom severity and quality of life; and (3) to determine the effect of supplementation on clinical parameters. METHODS The databases PubMed, EMBASE, Web of Knowledge, and PsycINFO were searched for eligible studies. Articles published from January 1st 1994 for CFS patients and 1990 for FMS patients till March 1st 2017 were included. Articles were included if the status of one or more vitamins or minerals were reported, or an intervention concerning vitamins or minerals was performed. Two reviewers independently extracted data and assessed the risk of bias. RESULTS A total of 5 RCTs and 40 observational studies were included in the qualitative synthesis, of which 27 studies were included in the meta-analyses. Circulating concentrations of vitamin E were lower in patients compared to controls (pooled standardized mean difference (SMD): -1.57, 95%CI: -3.09, -0.05; p = .042). However, this difference was not present when restricting the analyses to the subgroup of studies with high quality scores. Poor study quality and a substantial heterogeneity in most studies was found. No vitamins or minerals have been repeatedly or consistently linked to clinical parameters. In addition, RCTs testing supplements containing these vitamins and/or minerals did not result in clinical improvements. DISCUSSION Little evidence was found to support the hypothesis that vitamin and mineral deficiencies play a role in the pathophysiology of CFS and FMS, and that the use of supplements is effective in these patients. REGISTRATION Study methods were documented in an international prospective register of systematic reviews (PROSPERO) protocol, registration number: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015032528.
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Histological outcomes of sinus augmentation for dental implants with calcium phosphate or deproteinized bovine bone: a systematic review and meta-analysis.
Wu, J, Li, B, Lin, X
International journal of oral and maxillofacial surgery. 2016;(11):1471-1477
Abstract
This study compared the histological outcomes of deproteinized bovine bone (DBB) and technically derived calcium phosphate for sinus floor augmentation. MEDLINE, PubMed, Cochrane, EMBASE, and Google Scholar databases were searched until April 2015 with the following key words: dental implants, augmentation/augmented, calcium phosphate/ceramic/tricalcium phosphate, bovine bone/Bio-Oss, deproteinized/anorganic. Randomized controlled trials (RCTs) and two-arm prospective/retrospective studies that used DBB or biphasic calcium phosphate/tricalcium phosphate (BCP/TCP) for sinus augmentation with quantitative results were included. Outcomes were the percentage of new bone formed and percentage of surface contact between the graft material and new bone (bone-to-graft contact). Four RCTs and one prospective study were included, with a total of 110 patients and 145 implants. All studies reported the percentage of new vital bone; however, large heterogeneity was present (Q=15.23, P=0.004, I2=73.8%). BCP/TCP was associated with a higher percentage of new bone, but the pooled results did not reach significance (pooled standardized mean difference (SMD)=0.145, 95% confidence interval (CI) -0.488 to 0.778, P=0.654). Only two studies reported bone-to-graft contact, and BCP/TCP was associated with significantly lower bone-to-graft contact (pooled SMD=-0.807, 95% CI -1.276 to -0.337, P=0.001). This meta-analysis does not allow us to conclude superiority of one particular material with respect to histological outcomes.
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Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration.
Evans, JR, Lawrenson, JG
The Cochrane database of systematic reviews. 2012;:CD000254
Abstract
BACKGROUND It has been proposed that antioxidants may prevent cellular damage in the retina by reacting with free radicals that are produced in the process of light absorption. Higher dietary levels of antioxidant vitamins and minerals may reduce the risk of progression of age-related macular degeneration (AMD). OBJECTIVES The objective of this review was to assess the effects of antioxidant vitamin or mineral supplementation on the progression of AMD in people with AMD. SEARCH METHODS We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 8), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2012), EMBASE (January 1980 to August 2012), Allied and Complementary Medicine Database (AMED) (January 1985 to August 2012), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 20 August 2012. We searched the reference lists of identified reports and the Science Citation Index. We contacted investigators and experts in the field for details of unpublished studies. We also searched for systematic reviews of harms of vitamin supplements. SELECTION CRITERIA We included randomised trials comparing antioxidant vitamin or mineral supplementation (alone or in combination) to placebo or no intervention in people with AMD. DATA COLLECTION AND ANALYSIS Two authors assessed risk of bias and extracted data from the included trials. Where appropriate, we pooled data using a random-effects model unless three or fewer trials were available in which case we used a fixed-effect model. MAIN RESULTS Thirteen trials (6150 participants) were included in this review. Over half the participants (3640) were randomised in one trial (AREDS in the USA), which found a beneficial effect of antioxidant (beta-carotene, vitamin C and vitamin E) and zinc supplementation on progression to advanced AMD (adjusted odds ratio (OR) 0.68, 95% confidence interval (CI) 0.53 to 0.87) over an average of 6.3 years. People taking supplements were less likely to lose 15 or more letters of visual acuity (adjusted OR 0.77, 95% CI 0.62 to 0.96). The other trials, in general, had shorter follow-up (less than two years). No evidence for an effect of supplementation was seen in these smaller trials of shorter duration. Overall we considered the strength of the evidence to be moderate. We did not consider included trials, in general, to be at risk of bias, although we found it difficult to assess reporting biases. The main reason for downgrading the strength of the evidence was because, for several analyses, only one trial was included and therefore consistency of the findings could not be assessed. The included trials reported the following adverse effects: hospitalisation for genito-urinary problems was more common in people taking zinc and yellowing of skin was more common in people taking antioxidants. Systematic searching of the literature identified other potential harms of vitamin supplementation, in particular an increased risk of lung cancer in smokers associated with beta-carotene supplements, but we were unable to identify a good systematic review of the evidence for harms of nutritional supplementation. AUTHORS' CONCLUSIONS People with AMD may experience delay in progression of the disease with antioxidant vitamin and mineral supplementation. This finding is drawn from one large trial conducted in a relatively well-nourished American population. The generalisability of these findings to other populations is not known. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed.
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Drugs for preventing lung cancer in healthy people.
Cortés-Jofré, M, Rueda, JR, Corsini-Muñoz, G, Fonseca-Cortés, C, Caraballoso, M, Bonfill Cosp, X
The Cochrane database of systematic reviews. 2012;:CD002141
Abstract
BACKGROUND This is an updated version of the original review published in Issue 2, 2003. Some studies have suggested a protective effect of antioxidant nutrients on lung cancer. Observational epidemiological studies suggest an association between higher dietary levels of fruits and vegetables containing beta-carotene and a lower risk of lung cancer. OBJECTIVES To determine whether vitamins, minerals and other potential agents, alone or in combination, reduce incidence and mortality from lung cancer in healthy people. SEARCH METHODS For this update we have used a search strategy adapted from the design in the original review. The following electronic databases have been searched up to December 2011: MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials (CENTRAL). References included in published studies and reviews were also screened. SELECTION CRITERIA Included studies were randomised controlled clinical trials comparing different vitamins, mineral supplements or supplements with placebo, administered to healthy people with the aim of preventing lung cancer. DATA COLLECTION AND ANALYSIS Two authors independently selected the trials to be included in the review, assessed the methodological quality of each trial and extracted data using a standardised form. For each study, relative risk and 95% confidence limits were calculated for dichotomous outcomes and pooled results were calculated using the random-effect model. MAIN RESULTS In the first version of this review four studies were included; in this review update, an additional five studies have been included. Four studies included only males and two only females; two studies included only participants considered at high risk, namely smokers or exposed to asbestos, and one study included people deficient in many micronutrients. Six studies analysed vitamin A, three vitamin C, four vitamin E, one selenium supplements, and six studied combinations of two or more products. All the RCTs included in this review were classified as being of low risk of bias.For people not at high risk of lung cancer and compared to placebo, none of the supplements of vitamins or minerals or their combinations resulted in a statistically significant difference in lung cancer incidence or mortality, except for a single study that included 7627 women and found a higher risk of lung cancer incidence for those taking vitamin C but not for total cancer incidence, but that effect was not seen in males or when the results for males and females were pooled.For people at high risk of lung cancer, such as smokers and those exposed to asbestos and compared to placebo, beta-carotene intake showed a small but statistically significant higher risk of lung cancer incidence, lung cancer mortality and for all-causes mortality. AUTHORS' CONCLUSIONS There is no evidence for recommending supplements of vitamins A, C, E, selenium, either alone or in different combinations, for the prevention of lung cancer and lung cancer mortality in healthy people. There is some evidence that the use of beta-carotene supplements could be associated with a small increase in lung cancer incidence and mortality in smokers or persons exposed to asbestos.
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The effect of supplemental vitamins and minerals on the development of prostate cancer: a systematic review and meta-analysis.
Stratton, J, Godwin, M
Family practice. 2011;(3):243-52
Abstract
BACKGROUND Vitamin supplementation is used for many purposes with mainly alleged benefits. One of these is the use of various vitamins for the prevention of prostate cancer. METHODS We conducted a systematic review and meta-analysis on this topic. Pubmed, Embase and the Cochrane Database were searched; as well, we hand searched the references in key articles. Randomized controlled trials (RCTs), cohort studies and case-control studies were included. The review assessed the effect of supplemental vitamins on the risk of prostate cancer and on disease severity and death in men with prostate cancer. RESULTS Fourteen articles were included in the final assessment. Individually, a few of these studies showed a relationship between the ingestion of supplemental vitamins or minerals and the incidence or severity of prostate cancer, especially in smokers. However, neither the use of multivitamin supplementation nor the use of individual vitamin/mineral supplementation affected the overall occurrence of prostate cancer or the occurrence of advanced/metastatic prostate cancer or death from prostate cancer when the results of the studies were combined in a meta-analysis. We also conducted several sensitivity analyses by running meta-analysis using just the higher quality studies and just the RCTs. There were still no associations found. CONCLUSIONS There is no convincing evidence that the use of supplemental multivitamins or any specific vitamin affects the occurrence or severity of prostate cancer. There was high heterogeneity among the studies so it is possible that unidentified subgroups may benefit or be harmed by the use of vitamins.
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Does taking vitamin, mineral and fatty acid supplements prevent cognitive decline? A systematic review of randomized controlled trials.
Jia, X, McNeill, G, Avenell, A
Journal of human nutrition and dietetics : the official journal of the British Dietetic Association. 2008;(4):317-36
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BACKGROUND Observational studies have shown associations between nutritional status and cognition in later life but evidence from intervention studies is unclear. The present study systematically reviewed the evidence on the effect of nutrient supplementation on cognitive function in people aged >or=65 years. METHODS Databases including MEDLINE and EMBASE were searched up to 1 September 2006. Randomized controlled trials using at least one kind of vitamin, mineral or omega-3 fatty acid, evaluating standardized neuropsychological test(s), were included. There were no restrictions on participants' baseline nutritional status or cognitive function. Quality assessment and data abstraction were conducted by one author and checked by another. RESULTS Of 4229 articles retrieved, 22 trials (3442 participants) were identified. Many were small, short duration and of poor methodology. Only 16 out of 122 cognitive tests were significantly different between groups. A meta-analysis showed no significant effect of taking B vitamins or antioxidant vitamins on global cognitive function. There was insufficient evidence to evaluate the effect of omega-3 fatty acids on any cognitive domains. CONCLUSION There was little evidence of a beneficial effect from taking B vitamins or antioxidant supplements on global cognitive function in later life. Larger-scale randomized controlled trials of longer duration in selected age groups are needed.