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Linakis MW, Van Landingham C, Gasparini A, Longnecker MP. Re-expressing coefficients from regression models for inclusion in a meta-analysis. BMC Med Res Methodol 2024; 24:6. [PMID: 38191310 PMCID: PMC10773134 DOI: 10.1186/s12874-023-02132-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 12/19/2023] [Indexed: 01/10/2024] Open
Abstract
Meta-analysis poses a challenge when original study results have been expressed in a non-uniform manner, such as when regression results from some original studies were based on a log-transformed key independent variable while in others no transformation was used. Methods of re-expressing regression coefficients to generate comparable results across studies regardless of data transformation have recently been developed. We examined the relative bias of three re-expression methods using simulations and 15 real data examples where the independent variable had a skewed distribution. Regression coefficients from models with log-transformed independent variables were re-expressed as though they were based on an untransformed variable. We compared the re-expressed coefficients to those from a model fit to the untransformed variable. In the simulated and real data, all three re-expression methods usually gave biased results, and the skewness of the independent variable predicted the amount of bias. How best to synthesize the results of the log-transformed and absolute exposure evidence streams remains an open question and may depend on the scientific discipline, scale of the outcome, and other considerations.
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Affiliation(s)
- Matthew W Linakis
- Ramboll U.S. Consulting, Raleigh, NC, 27612, USA, 3214 Charles B Root Wynd #130.
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2
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Cooper SM, Fusar-Poli P, Uhlhaas PJ. Characteristics and clinical correlates of risk symptoms in individuals at clinical high-risk for psychosis: A systematic review and meta-analysis. Schizophr Res 2023; 254:54-61. [PMID: 36801514 DOI: 10.1016/j.schres.2023.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 01/19/2023] [Accepted: 02/05/2023] [Indexed: 02/17/2023]
Abstract
Emerging evidence suggests that the duration of risk symptoms (DUR) may have an impact on clinical outcomes in clinical high-risk for psychosis (CHRP) participants. To explore this hypothesis, we performed a meta-analysis on studies that examined DUR in CHR-P individuals in relation to their clinical outcomes. This review was conducted in accordance with the PRISMA guidelines and the protocol was registered with PROSPERO on 16th April 2021 (ID no. CRD42021249443). Literature searches were conducted using PsycINFO and Web of Science in March and November 2021, for studies reporting on DUR in CHR-P populations, in relation to transition to psychosis or symptomatic, functional, or cognitive outcomes. The primary outcome was transition to psychosis, while the secondary outcomes were remission from CHR-P status and functioning at baseline. Thirteen independent studies relating to 2506 CHR-P individuals were included in the meta-analysis. The mean age was 19.88 years (SD = 1.61) and 1194 individuals (47.65 %) were females. The mean length of DUR was 23.61 months (SD = 13.18). There was no meta-analytic effect of DUR on transition to psychosis at 12-month follow-up (OR = 1.000, 95%CI = 0.999-1.000, k = 8, p = .98), while DUR was related to remission (Hedge's g = 0.236, 95%CI = 0.014-0.458, k = 4, p = .037). DUR was not related to baseline GAF scores (beta = -0.004, 95%CI = -0.025-0.017, k = 3, p = .71). The current findings suggest that DUR is not associated with transition to psychosis at 12 months, but may impact remission. However, the database was small and further research in this area is required.
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Affiliation(s)
- Saskia M Cooper
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Paolo Fusar-Poli
- Early Psychosis: Interventions and Clinical-detection (EPIC) Lab, Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, United Kingdom; OASIS service, South London and Maudsley NHS Foundation Trust, London, United Kingdom; Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy; National Institute for Health Research Maudsley Biomedical Research Centre, South London and Maudsley NHS Foundation Trust, London, United Kingdom
| | - Peter J Uhlhaas
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom; Department of Child and Adolescent Psychiatry, Charité Universitätsmedizin, Berlin, Germany.
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3
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Howes OD, Whitehurst T, Shatalina E, Townsend L, Onwordi EC, Mak TLA, Arumuham A, O’Brien O, Lobo M, Vano L, Zahid U, Butler E, Osugo M. The clinical significance of duration of untreated psychosis: an umbrella review and random-effects meta-analysis. World Psychiatry 2021; 20:75-95. [PMID: 33432766 PMCID: PMC7801839 DOI: 10.1002/wps.20822] [Citation(s) in RCA: 98] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The idea that a longer duration of untreated psychosis (DUP) leads to poorer outcomes has contributed to extensive changes in mental health ser-vices worldwide and has attracted considerable research interest over the past 30 years. However, the strength of the evidence underlying this notion is unclear. To address this issue, we conducted an umbrella review of available meta-analyses and performed a random-effects meta-analysis of primary studies. MEDLINE, Web of Science, PsycINFO and EMBASE were searched from inception to September 3, 2020 to identify relevant meta-analyses of studies including patients with schizophrenia spectrum disorders, first-episode psychosis, or affective and non-affective psychosis. Thirteen meta-analyses were included, corresponding to 129 individual studies with a total sample size of 25,657 patients. We detected potential violations of statistical assumptions in some of these meta-analyses. We therefore conducted a new random-effects meta-analysis of primary studies. The association between DUP and each outcome was graded according to a standardized classification into convincing, highly suggestive, suggestive, weak, or non-significant. At first presentation, there was suggestive evidence for a relationship between longer DUP and more severe negative symptoms (beta=-0.07, p=3.6×10-5 ) and higher chance of previous self-harm (odds ratio, OR=1.89, p=1.1×10-5 ). At follow-up, there was highly suggestive evidence for a relationship between longer DUP and more severe positive symptoms (beta=-0.16, p=4.5×10-8 ), more severe negative symptoms (beta=-0.11, p=3.5×10-10 ) and lower chance of remission (OR=2.16, p=3.0×10-10 ), and suggestive evidence for a relationship between longer DUP and poorer overall functioning (beta=-0.11, p=2.2×10-6 ) and more severe global psychopathology (beta=-0.16, p=4.7×10-6 ). Results were unchanged when analysis was restricted to prospective studies. These effect sizes are clinically meaningful, with a DUP of four weeks predicting >20% more severe symptoms at follow-up relative to a DUP of one week. We conclude that DUP is an important prognostic factor at first presentation and predicts clinically relevant outcomes over the course of illness. We discuss conceptual issues in DUP research and methodological limitations of current evidence, and provide recommendations for future research.
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Affiliation(s)
- Oliver D. Howes
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK,MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK,South London and Maudsley Foundation NHS TrustMaudsley HospitalLondonUK
| | - Thomas Whitehurst
- MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK
| | - Ekaterina Shatalina
- MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK
| | - Leigh Townsend
- MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK
| | - Ellis Chika Onwordi
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK,MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK,South London and Maudsley Foundation NHS TrustMaudsley HospitalLondonUK
| | | | - Atheeshaan Arumuham
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK,MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK,South London and Maudsley Foundation NHS TrustMaudsley HospitalLondonUK
| | - Oisín O’Brien
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK
| | - Maria Lobo
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK
| | - Luke Vano
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK
| | - Uzma Zahid
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK
| | - Emma Butler
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK,South London and Maudsley Foundation NHS TrustMaudsley HospitalLondonUK
| | - Martin Osugo
- Institute of Psychiatry, Psychology and NeuroscienceKing’s College LondonLondonUK,MRC London Institute of Medical SciencesHammersmith HospitalLondonUK,Institute of Clinical Sciences, Faculty of MedicineImperial College LondonLondonUK
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4
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Ord TJ, Garcia-Porta J, Querejeta M, Collar DC. Gliding Dragons and Flying Squirrels: Diversifying versus Stabilizing Selection on Morphology following the Evolution of an Innovation. Am Nat 2020; 195:E51-E66. [DOI: 10.1086/706305] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Koureas M, Rousou X, Haftiki H, Mouchtouri VA, Rachiotis G, Rakitski V, Tsakalof A, Hadjichristodoulou C. Spatial and temporal distribution of p,p'-DDE (1‑dichloro‑2,2‑bis (p‑chlorophenyl) ethylene) blood levels across the globe. A systematic review and meta-analysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 686:440-451. [PMID: 31181528 DOI: 10.1016/j.scitotenv.2019.05.261] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/26/2019] [Accepted: 05/17/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND Although p,p'‑DDT (1,1,1‑trichloro-2,2‑bis (p‑chlorophenyl)‑ethane) has been banned for decades in most countries, its major metabolite p,p'-DDE (1‑dichloro‑2,2‑bis (p‑chlorophenyl) ethylene) is still detected in the vast majority of human blood samples. OBJECTIVES The purpose of this study was to quantitatively estimate the geographical distribution of DDE blood levels and record time-trends for specific countries and continents, exploiting available data from the scientific literature. METHODS A literature search was performed in SCOPUS and PUBMED databases. Studies were screened at 2 levels applying different sets of inclusion/exclusion criteria. Blood levels of DDE along with other variables of interest were extracted, and a meta-analysis of random effects was conducted, by using the package metafor within the statistical programming language R. Results were expressed as pooled geometric means (GM [95% confidence intervals, CIs]). RESULTS A total of 418 papers were included in the quantitative synthesis that contained data for 854 population subgroups, and analyzed a total of 195,595 samples. Overall global DDE concentrations dropped from 5207 (95% CI: 3616-7499) ng/g lipids during 1951-1969 to 207 (95% CI: 159-269) ng/g lipids for studies reporting sampling after 2000. Analyses for studies published from 2001 and onward revealed geographical differences regarding DDE burden. DISCUSSION The significant decline in DDE blood levels after its restriction is demonstrated in our results. Differences in decrease trends were observed in different parts of the globe, which can be explained by deferred implementation of environmental policies. In some countries DDE concentrations remain high, and systematic biomonitoring is proposed.
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Affiliation(s)
- M Koureas
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece
| | - X Rousou
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece
| | - H Haftiki
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece
| | - V A Mouchtouri
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece
| | - G Rachiotis
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece
| | - V Rakitski
- Russian Institute for Pesticides Hygiene, Toxicology and Chemical Safety, Russia
| | - A Tsakalof
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece; Department of Biochemistry, Faculty of Medicine, University of Thessaly, Larissa, Greece
| | - C Hadjichristodoulou
- Department of Hygiene and Epidemiology, Faculty of Medicine, University of Thessaly, 22 Papakyriazi Street, Larissa 41222, Greece.
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Crider KS, Devine O, Qi YP, Yeung LF, Sekkarie A, Zaganjor I, Wong E, Rose CE, Berry RJ. Systematic Review and Bayesian Meta-analysis of the Dose-response Relationship between Folic Acid Intake and Changes in Blood Folate Concentrations. Nutrients 2019; 11:nu11010071. [PMID: 30609688 PMCID: PMC6356991 DOI: 10.3390/nu11010071] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 12/22/2018] [Accepted: 12/28/2018] [Indexed: 11/25/2022] Open
Abstract
The threshold for population-level optimal red blood cell (RBC) folate concentration among women of reproductive age for the prevention of neural tube defects has been estimated at 906 nmol/L; however, the dose-response relationship between folic acid intake and blood folate concentrations is uncharacterized. To estimate the magnitude of blood folate concentration increase in response to specific dosages of folic acid under steady-state conditions (as could be achieved with food fortification), a systematic review of the literature and meta-analysis was conducted. Of the 14,002 records we identified, 533 were selected for full-text review, and data were extracted from 108 articles. The steady-state concentrations (homeostasis) of both serum/plasma and RBC folate concentrations were estimated using a Bayesian meta-analytic approach and one-compartment physiologically-based pharmacokinetic models. RBC folate concentrations increased 1.78 fold (95% credible interval (CI): 1.66, 1.93) from baseline to steady-state at 375–570 µg folic acid/day, and it took a median of 36 weeks of folic acid intake (95% CI: 27, 52) to achieve steady-state RBC folate concentrations. Based on regression analysis, we estimate that serum/plasma folate concentrations increased 11.6% (95% CI: 8.4, 14.9) for every 100 µg/day folic acid intake. These results will help programs plan and monitor folic acid fortification programs.
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Affiliation(s)
- Krista S Crider
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
| | - Owen Devine
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
- Karna, LLC, Atlanta, GA 30329, USA.
- G²S Corporation, San Antonio, TX 78216, USA.
| | - Yan Ping Qi
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
| | - Lorraine F Yeung
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
| | - Ahlia Sekkarie
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA.
- Doctoral Program in Nutrition Health Sciences, Laney Graduate School, Emory University, Atlanta, GA 30322, USA.
| | - Ibrahim Zaganjor
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA.
- Department of Epidemiology, Gilling's School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Eugene Wong
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA.
- Department of Epidemiology, Gilling's School of Global Public Health, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Charles E Rose
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
| | - Robert J Berry
- Centers for Disease Control and Prevention, National Center on Birth Defects and Developmental Disabilities, Division of Congenital and Developmental Disorders, Atlanta, GA 30341, USA.
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Tabrizi R, Saneei P, Lankarani KB, Akbari M, Kolahdooz F, Esmaillzadeh A, Nadi-Ravandi S, Mazoochi M, Asemi Z. The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials. Crit Rev Food Sci Nutr 2018; 59:2688-2696. [PMID: 30335479 DOI: 10.1080/10408398.2018.1507996] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Reza Tabrizi
- Health Policy Research Center, Institute of Health, Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Parvane Saneei
- Food Security Research Center, Department of Community Nutrition School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Kamran B Lankarani
- Health Policy Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Maryam Akbari
- Health Policy Research Center, Institute of Health, Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Fariba Kolahdooz
- Indigenous and Global Health Research, Department of Medicine, University of Alberta, Edmonton, Canada
| | - Ahmad Esmaillzadeh
- Food Security Research Center, Department of Community Nutrition School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
- Department of Community Nutrition School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayyeh Nadi-Ravandi
- Health Information Management Research Center, Kashan University of Medical Sciences, Kashan, Iran
| | - Majid Mazoochi
- Department of Cardiology School of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Zatollah Asemi
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Kashan University of Medical Sciences, Kashan, Iran
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Novaković R, Geelen A, Ristić-Medić D, Nikolić M, Souverein OW, McNulty H, Duffy M, Hoey L, Dullemeijer C, Renkema JMS, Gurinović M, Glibetić M, de Groot LCPGM, Van't Veer P. Systematic Review of Observational Studies with Dose-Response Meta-Analysis between Folate Intake and Status Biomarkers in Adults and the Elderly. ANNALS OF NUTRITION AND METABOLISM 2018; 73:30-43. [PMID: 29879709 DOI: 10.1159/000490003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 05/14/2018] [Indexed: 02/05/2023]
Abstract
BACKGROUND Dietary reference values for folate intake vary widely across Europe. METHODS MEDLINE and Embase through November 2016 were searched for data on the association between folate intake and biomarkers (serum/plasma folate, red blood cell [RBC] folate, plasma homocysteine) from observational studies in healthy adults and elderly. The regression coefficient of biomarkers on intake (β) was extracted from each study, and the overall and stratified pooled β and SE (β) were obtained by random effects meta-analysis on a double log scale. These dose-response estimates may be used to derive folate intake reference values. RESULTS For every doubling in folate intake, the changes in serum/plasma folate, RBC folate and plasma homocysteine were +22, +21, and -16% respectively. The overall pooled regression coefficients were β = 0.29 (95% CI 0.21-0.37) for serum/plasma folate (26 estimates from 17 studies), β = 0.28 (95% CI 0.21-0.36) for RBC (13 estimates from 11 studies), and β = -0.21 (95% CI -0.31 to -0.11) for plasma homocysteine (10 estimates from 6 studies). CONCLUSION These estimates along with those from randomized controlled trials can be used for underpinning dietary recommendations for folate in adults and elderly.
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Affiliation(s)
- Romana Novaković
- Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia
| | - Anouk Geelen
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Danijela Ristić-Medić
- Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia
| | - Marina Nikolić
- Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia
| | - Olga W Souverein
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Helene McNulty
- School of Biomedical Sciences, University of Ulster, Coleraine Campus, Londonderry, United Kingdom
| | - Maresa Duffy
- School of Biomedical Sciences, University of Ulster, Coleraine Campus, Londonderry, United Kingdom
| | - Leane Hoey
- School of Biomedical Sciences, University of Ulster, Coleraine Campus, Londonderry, United Kingdom
| | - Carla Dullemeijer
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Jacoba M S Renkema
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Mirjana Gurinović
- Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia
| | - Marija Glibetić
- Centre of Research Excellence in Nutrition and Metabolism, Institute for Medical Research, University of Belgrade, Belgrade, Serbia
| | - Lisette C P G M de Groot
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Pieter Van't Veer
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, the Netherlands
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Mueller M, D'Addario M, Egger M, Cevallos M, Dekkers O, Mugglin C, Scott P. Methods to systematically review and meta-analyse observational studies: a systematic scoping review of recommendations. BMC Med Res Methodol 2018; 18:44. [PMID: 29783954 PMCID: PMC5963098 DOI: 10.1186/s12874-018-0495-9] [Citation(s) in RCA: 239] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 04/24/2018] [Indexed: 12/16/2022] Open
Abstract
Background Systematic reviews and meta-analyses of observational studies are frequently performed, but no widely accepted guidance is available at present. We performed a systematic scoping review of published methodological recommendations on how to systematically review and meta-analyse observational studies. Methods We searched online databases and websites and contacted experts in the field to locate potentially eligible articles. We included articles that provided any type of recommendation on how to conduct systematic reviews and meta-analyses of observational studies. We extracted and summarised recommendations on pre-defined key items: protocol development, research question, search strategy, study eligibility, data extraction, dealing with different study designs, risk of bias assessment, publication bias, heterogeneity, statistical analysis. We summarised recommendations by key item, identifying areas of agreement and disagreement as well as areas where recommendations were missing or scarce. Results The searches identified 2461 articles of which 93 were eligible. Many recommendations for reviews and meta-analyses of observational studies were transferred from guidance developed for reviews and meta-analyses of RCTs. Although there was substantial agreement in some methodological areas there was also considerable disagreement on how evidence synthesis of observational studies should be conducted. Conflicting recommendations were seen on topics such as the inclusion of different study designs in systematic reviews and meta-analyses, the use of quality scales to assess the risk of bias, and the choice of model (e.g. fixed vs. random effects) for meta-analysis. Conclusion There is a need for sound methodological guidance on how to conduct systematic reviews and meta-analyses of observational studies, which critically considers areas in which there are conflicting recommendations. Electronic supplementary material The online version of this article (10.1186/s12874-018-0495-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Monika Mueller
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.,Translational Research Center, University Hospital of Psychiatry, University of Bern, Bern, Switzerland
| | - Maddalena D'Addario
- Translational Research Center, University Hospital of Psychiatry, University of Bern, Bern, Switzerland
| | - Matthias Egger
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Myriam Cevallos
- CTU Bern, Clinical Trials Unit Bern, Bern University Hospital and University of Bern, Bern, Switzerland
| | - Olaf Dekkers
- Department of Clinical Epidemiology, Leiden University Medical Centre, Leiden, The Netherlands.,Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
| | - Catrina Mugglin
- Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland
| | - Pippa Scott
- Department of Pathology and Biomedical Science, University of Otago, Christchurch, New Zealand.
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10
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Tsang BL, Devine OJ, Cordero AM, Marchetta CM, Mulinare J, Mersereau P, Guo J, Qi YP, Berry RJ, Rosenthal J, Crider KS, Hamner HC. Assessing the association between the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and blood folate concentrations: a systematic review and meta-analysis of trials and observational studies. Am J Clin Nutr 2015; 101:1286-94. [PMID: 25788000 DOI: 10.3945/ajcn.114.099994] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 02/09/2015] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND The methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism is a risk factor for neural tube defects. The T allele produces an enzyme with reduced folate-processing capacity, which has been associated with lower blood folate concentrations. OBJECTIVE We assessed the association between MTHFR C677T genotypes and blood folate concentrations among healthy women aged 12-49 y. DESIGN We conducted a systematic review of the literature published from January 1992 to March 2014 to identify trials and observational studies that reported serum, plasma, or red blood cell (RBC) folate concentrations and MTHFR C677T genotype. We conducted a meta-analysis for estimates of percentage differences in blood folate concentrations between genotypes. RESULTS Forty studies met the inclusion criteria. Of the 6 studies that used the microbiologic assay (MA) to measure serum or plasma (S/P) and RBC folate concentrations, the percentage difference between genotypes showed a clear pattern of CC > CT > TT. The percentage difference was greatest for CC > TT [S/P: 13%; 95% credible interval (CrI): 7%, 18%; RBC: 16%; 95% CrI: 12%, 20%] followed by CC > CT (S/P: 7%; 95% CrI: 1%, 12%; RBC: 8%; 95% CrI: 4%, 12%) and CT > TT (S/P: 6%; 95% CrI: 1%, 11%; RBC: 9%; 95% CrI: 5%, 13%). S/P folate concentrations measured by using protein-binding assays (PBAs) also showed this pattern but to a greater extent (e.g., CC > TT: 20%; 95% CrI: 17%, 22%). In contrast, RBC folate concentrations measured by using PBAs did not show the same pattern and are presented in the Supplemental Material only. CONCLUSIONS Meta-analysis results (limited to the MA, the recommended population assessment method) indicated a consistent percentage difference in S/P and RBC folate concentrations across MTHFR C677T genotypes. Lower blood folate concentrations associated with this polymorphism could have implications for a population-level risk of neural tube defects.
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Affiliation(s)
- Becky L Tsang
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Owen J Devine
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Amy M Cordero
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Claire M Marchetta
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Joseph Mulinare
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Patricia Mersereau
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Jing Guo
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Yan Ping Qi
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Robert J Berry
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Jorge Rosenthal
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Krista S Crider
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM)
| | - Heather C Hamner
- From the Division of Birth Defects and Developmental Disabilities, National Center for Birth Defects and Developmental Disabilities (NCBDDD), CDC, Atlanta, GA (AMC, RJB, JR, and KSC); the Division of Nutrition, Physical Activity, and Obesity, National Center on Chronic Disease Prevention and Health Promotion, CDC, Atlanta, GA (HCH); Acentia (contractor for CDC, NCBDDD), Falls Church, VA (JG); Carter Consulting Inc. (contractor for CDC, NCBDDD), Atlanta, GA (OJD, JM, and YPQ); the Oak Ridge Institute for Science and Education, Oak Ridge, TN (BLT, CMM, and YPQ); SciMetrika LLC (contractor for CDC, NCBDDD), Atlanta, GA (PM).
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11
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Marchetta CM, Devine OJ, Crider KS, Tsang BL, Cordero AM, Qi YP, Guo J, Berry RJ, Rosenthal J, Mulinare J, Mersereau P, Hamner HC. Assessing the association between natural food folate intake and blood folate concentrations: a systematic review and Bayesian meta-analysis of trials and observational studies. Nutrients 2015; 7:2663-86. [PMID: 25867949 PMCID: PMC4425166 DOI: 10.3390/nu7042663] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/06/2015] [Accepted: 03/09/2015] [Indexed: 12/25/2022] Open
Abstract
Folate is found naturally in foods or as synthetic folic acid in dietary supplements and fortified foods. Adequate periconceptional folic acid intake can prevent neural tube defects. Folate intake impacts blood folate concentration; however, the dose-response between natural food folate and blood folate concentrations has not been well described. We estimated this association among healthy females. A systematic literature review identified studies (1 1992-3 2014) with both natural food folate intake alone and blood folate concentration among females aged 12-49 years. Bayesian methods were used to estimate regression model parameters describing the association between natural food folate intake and subsequent blood folate concentration. Seven controlled trials and 29 observational studies met the inclusion criteria. For the six studies using microbiologic assay (MA) included in the meta-analysis, we estimate that a 6% (95% Credible Interval (CrI): 4%, 9%) increase in red blood cell (RBC) folate concentration and a 7% (95% CrI: 1%, 12%) increase in serum/plasma folate concentration can occur for every 10% increase in natural food folate intake. Using modeled results, we estimate that a natural food folate intake of ≥ 450 μg dietary folate equivalents (DFE)/day could achieve the lower bound of an RBC folate concentration (~ 1050 nmol/L) associated with the lowest risk of a neural tube defect. Natural food folate intake affects blood folate concentration and adequate intakes could help women achieve a RBC folate concentration associated with a risk of 6 neural tube defects/10,000 live births.
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Affiliation(s)
- Claire M Marchetta
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37831, USA.
| | | | - Krista S Crider
- Division of Birth Defects and Developmental Disabilities (DBDDD), National Center on Birth Defects and Developmental Disabilities (NCBDDD), Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | - Becky L Tsang
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37831, USA.
| | - Amy M Cordero
- Division of Birth Defects and Developmental Disabilities (DBDDD), National Center on Birth Defects and Developmental Disabilities (NCBDDD), Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | - Yan Ping Qi
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN 37831, USA.
| | - Jing Guo
- Acentia, Falls Church, VA 22042, USA.
| | - Robert J Berry
- Division of Birth Defects and Developmental Disabilities (DBDDD), National Center on Birth Defects and Developmental Disabilities (NCBDDD), Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | - Jorge Rosenthal
- Division of Birth Defects and Developmental Disabilities (DBDDD), National Center on Birth Defects and Developmental Disabilities (NCBDDD), Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
| | | | | | - Heather C Hamner
- Division of Nutrition, Physical Activity, and Obesity (DNPAO), National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP), Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
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12
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Ristić-Medić D, Dullemeijer C, Tepsić J, Petrović-Oggiano G, Popović T, Arsić A, Glibetić M, Souverein OW, Collings R, Cavelaars A, de Groot L, van't Veer P, Gurinović M. Systematic review using meta-analyses to estimate dose-response relationships between iodine intake and biomarkers of iodine status in different population groups. Nutr Rev 2014; 72:143-61. [PMID: 24697303 DOI: 10.1111/nure.12092] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The objective of this systematic review was to identify studies investigating iodine intake and biomarkers of iodine status, to assess the data of the selected studies, and to estimate dose-response relationships using meta-analysis. All randomized controlled trials, prospective cohort studies, nested case-control studies, and cross-sectional studies that supplied or measured dietary iodine and measured iodine biomarkers were included. The overall pooled regression coefficient (β) and the standard error of β were calculated by random-effects meta-analysis on a double-log scale, using the calculated intake-status regression coefficient (β) for each individual study. The results of pooled randomized controlled trials indicated that the doubling of dietary iodine intake increased urinary iodine concentrations by 14% in children and adolescents, by 57% in adults and the elderly, and by 81% in pregnant women. The dose-response relationship between iodine intake and biomarkers of iodine status indicated a 12% decrease in thyroid-stimulating hormone and a 31% decrease in thyroglobulin in pregnant women. The model of dose-response quantification used to describe the relationship between iodine intake and biomarkers of iodine status may be useful for providing complementary evidence to support recommendations for iodine intake in different population groups.
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13
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The relationship between zinc intake and growth in children aged 1-8 years: a systematic review and meta-analysis. Eur J Clin Nutr 2014; 69:147-53. [PMID: 25335444 DOI: 10.1038/ejcn.2014.204] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 08/21/2014] [Accepted: 08/26/2014] [Indexed: 11/09/2022]
Abstract
BACKGROUND/OBJECTIVES It is estimated that zinc deficiency affects 17% of the world's population, and because of periods of rapid growth children are at an increased risk of deficiency, which may lead to stunting. This paper presents a systematic review and meta-analysis of the randomised controlled trials (RCTs) that assess zinc intake and growth in children aged 1-8 years. This review is part of a larger systematic review by the European Micronutrient Recommendations Aligned Network of Excellence that aims to harmonise the approach to setting micronutrient requirements for optimal health in European populations (www.eurreca.org). SUBJECT/METHODS Searches were performed of literature published up to and including December 2013 using MEDLINE, Embase and the Cochrane Library databases. Included studies were RCTs in apparently healthy child populations aged from 1 to 8 years that supplied zinc supplements either as capsules or as part of a fortified meal. Pooled meta-analyses were performed when appropriate. RESULTS Nine studies met the inclusion criteria. We found no significant effect of zinc supplementation of between 2 weeks and 12 months duration on weight gain, height for age, weight for age, length for age, weight for height (WHZ) or WHZ scores in children aged 1-8 years. CONCLUSIONS Many of the children in the included studies were already stunted and may have been suffering from multiple micronutrient deficiencies, and therefore zinc supplementation alone may have only a limited effect on growth.
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14
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van der Velpen V, Hollman PC, van Nielen M, Schouten EG, Mensink M, Van't Veer P, Geelen A. Large inter-individual variation in isoflavone plasma concentration limits use of isoflavone intake data for risk assessment. Eur J Clin Nutr 2014; 68:1141-7. [PMID: 24939433 PMCID: PMC4197455 DOI: 10.1038/ejcn.2014.108] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 04/04/2014] [Accepted: 04/23/2014] [Indexed: 02/06/2023]
Abstract
Background/objectives: Isoflavones are present in soy foods and soy-based supplements. Despite low plasma isoflavone concentrations in the general Western population, concentrations in supplement users exceed those suggested to be beneficial for health in Asian populations, raising concerns for adverse effects. To aid risk assessment, quantification of the relation between isoflavone intake and plasma concentrations is essential. Subjects/methods: Plasma samples were collected from postmenopausal women in three placebo-controlled crossover studies with 8-week periods for supplements (two studies, ~100 mg isoflavones/day, n=88) or 4-week periods for soy foods (one study, ~48 mg isoflavones/day, n=15). Plasma isoflavone concentrations (daidzein, equol, genistein and glycitein) were quantified using high-performance liquid chromatography and electrochemical detection. The association between plasma concentrations and isoflavone intake, equol producer status, intake–producer interaction and background dietary intake was assessed based on the assumption of a log-linear relation. Results: Median plasma total isoflavone concentrations after the soy food and supplement interventions were respectively 2.16 and 3.47 μmol/l for equol producers and 1.30 and 2.39 μmol/l for non-producers. Regression analysis showed that doubling isoflavone intake increased plasma concentrations by 55–62% (±s.e. 1–2%, R2>0.87) for daidzein, genistein, equol (only for producers) and total isoflavones; for glycitein the association was weaker (15±1%, R2=0.48). Adjustments for energy, carbohydrate and fat intake did not affect these estimates. Inter-individual variation, estimated based on repeated measures in one of the studies, was 30–96%. Conclusions: Although the relation between isoflavone intake and plasma concentrations was adequately quantified, the use of isoflavone intake data for risk assessment needs caution due to large inter-individual variation in plasma concentrations.
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Affiliation(s)
- V van der Velpen
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - P C Hollman
- 1] Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands [2] RIKILT, Wageningen University & Research Centre, Wageningen, The Netherlands
| | - M van Nielen
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - E G Schouten
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - M Mensink
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - P Van't Veer
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
| | - A Geelen
- Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
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15
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van der Voet H, de Boer WJ, Souverein OW, Doets EL, van 't Veer P. A statistical method to base nutrient recommendations on meta-analysis of intake and health-related status biomarkers. PLoS One 2014; 9:e93171. [PMID: 24682145 PMCID: PMC3969369 DOI: 10.1371/journal.pone.0093171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 03/01/2014] [Indexed: 11/19/2022] Open
Abstract
Nutrient recommendations in use today are often derived from relatively old data of few studies with few individuals. However, for many nutrients, including vitamin B-12, extensive data have now become available from both observational studies and randomized controlled trials, addressing the relation between intake and health-related status biomarkers. The purpose of this article is to provide new methodology for dietary planning based on dose-response data and meta-analysis. The methodology builds on existing work, and is consistent with current methodology and measurement error models for dietary assessment. The detailed purposes of this paper are twofold. Firstly, to define a Population Nutrient Level (PNL) for dietary planning in groups. Secondly, to show how data from different sources can be combined in an extended meta-analysis of intake-status datasets for estimating PNL as well as other nutrient intake values, such as the Average Nutrient Requirement (ANR) and the Individual Nutrient Level (INL). For this, a computational method is presented for comparing a bivariate lognormal distribution to a health criterion value. Procedures to meta-analyse available data in different ways are described. Example calculations on vitamin B-12 requirements were made for four models, assuming different ways of estimating the dose-response relation, and different values of the health criterion. Resulting estimates of ANRs and less so for INLs were found to be sensitive to model assumptions, whereas estimates of PNLs were much less sensitive to these assumptions as they were closer to the average nutrient intake in the available data.
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Affiliation(s)
- Hilko van der Voet
- Biometris, Wageningen University and Research Centre, Wageningen, Netherlands,
- * E-mail:
| | - Waldo J. de Boer
- Biometris, Wageningen University and Research Centre, Wageningen, Netherlands,
| | - Olga W. Souverein
- Division of Human Nutrition, Wageningen University, Wageningen, Netherlands
| | - Esmée L. Doets
- Division of Human Nutrition, Wageningen University, Wageningen, Netherlands
| | - Pieter van 't Veer
- Division of Human Nutrition, Wageningen University, Wageningen, Netherlands
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16
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Lowe NM, Dykes FC, Skinner AL, Patel S, Warthon-Medina M, Decsi T, Fekete K, Souverein OW, Dullemeijer C, Cavelaars AE, Serra-Majem L, Nissensohn M, Bel S, Moreno LA, Hermoso M, Vollhardt C, Berti C, Cetin I, Gurinovic M, Novakovic R, Harvey LJ, Collings R, Hall-Moran V. EURRECA-Estimating zinc requirements for deriving dietary reference values. Crit Rev Food Sci Nutr 2014; 53:1110-23. [PMID: 23952091 DOI: 10.1080/10408398.2012.742863] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Zinc was selected as a priority micronutrient for EURRECA, because there is significant heterogeneity in the Dietary Reference Values (DRVs) across Europe. In addition, the prevalence of inadequate zinc intakes was thought to be high among all population groups worldwide, and the public health concern is considerable. In accordance with the EURRECA consortium principles and protocols, a series of literature reviews were undertaken in order to develop best practice guidelines for assessing dietary zinc intake and zinc status. These were incorporated into subsequent literature search strategies and protocols for studies investigating the relationships between zinc intake, status and health, as well as studies relating to the factorial approach (including bioavailability) for setting dietary recommendations. EMBASE (Ovid), Cochrane Library CENTRAL, and MEDLINE (Ovid) databases were searched for studies published up to February 2010 and collated into a series of Endnote databases that are available for the use of future DRV panels. Meta-analyses of data extracted from these publications were performed where possible in order to address specific questions relating to factors affecting dietary recommendations. This review has highlighted the need for more high quality studies to address gaps in current knowledge, in particular the continued search for a reliable biomarker of zinc status and the influence of genetic polymorphisms on individual dietary requirements. In addition, there is a need to further develop models of the effect of dietary inhibitors of zinc absorption and their impact on population dietary zinc requirements.
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Affiliation(s)
- Nicola M Lowe
- International Institute of Nutrition and Applied Food Safety Studies, University of Central Lancashire, Preston, United Kingdom.
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17
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Duffy ME, Hoey L, Hughes CF, Strain JJ, Rankin A, Souverein OW, Dullemeijer C, Collings R, Hooper L, McNulty H. Biomarker responses to folic acid intervention in healthy adults: a meta-analysis of randomized controlled trials. Am J Clin Nutr 2014; 99:96-106. [PMID: 24225357 DOI: 10.3945/ajcn.113.062752] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND The task of revising dietary folate recommendations for optimal health is complicated by a lack of data quantifying the biomarker response that reliably reflects a given folate intake. OBJECTIVE We conducted a dose-response meta-analysis in healthy adults to quantify the typical response of recognized folate biomarkers to a change in folic acid intake. DESIGN Electronic and bibliographic searches identified 19 randomized controlled trials that supplemented with folic acid and measured folate biomarkers before and after the intervention in apparently healthy adults aged ≥18 y. For each biomarker response, the regression coefficient (β) for individual studies and the overall pooled β were calculated by using random-effects meta-analysis. RESULTS Folate biomarkers (serum/plasma and red blood cell folate) increased in response to folic acid in a dose-response manner only up to an intake of 400 μg/d. Calculation of the overall pooled β for studies in the range of 50 to 400 μg/d indicated that a doubling of folic acid intake resulted in an increase in serum/plasma folate by 63% (71% for microbiological assay; 61% for nonmicrobiological assay) and red blood cell folate by 31% (irrespective of whether microbiological or other assay was used). Studies that used the microbiological assay indicated lower heterogeneity compared with studies using nonmicrobiological assays for determining serum/plasma (I(2) = 13.5% compared with I(2) = 77.2%) and red blood cell (I(2) = 45.9% compared with I(2) = 70.2%) folate. CONCLUSIONS Studies administering >400 μg folic acid/d show no dose-response relation and thus will not yield meaningful results for consideration when generating dietary folate recommendations. The calculated folate biomarker response to a given folic acid intake may be more robust with the use of a microbiological assay rather than alternative methods for blood folate measurement.
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Affiliation(s)
- Maresa E Duffy
- Northern Ireland Centre for Food and Health, University of Ulster, Coleraine, Northern Ireland (MED, L Hoey, CFH, JJS, AR, and HM); the Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, Netherlands (OWS and CD); and Norwich Medical School, University of East Anglia, Norfolk, United Kingdom (RC and L Hooper)
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18
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Vitamin B12, folate, homocysteine, and bone health in adults and elderly people: a systematic review with meta-analyses. J Nutr Metab 2013; 2013:486186. [PMID: 23509616 PMCID: PMC3590816 DOI: 10.1155/2013/486186] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 11/23/2012] [Indexed: 12/25/2022] Open
Abstract
Elevated homocysteine levels and low vitamin B12 and folate levels have been associated with deteriorated bone health. This systematic literature review with dose-response meta-analyses summarizes the available scientific evidence on associations of vitamin B12, folate, and homocysteine status with fractures and bone mineral density (BMD).
Twenty-seven eligible cross-sectional (n = 14) and prospective (n = 13) observational studies and one RCT were identified. Meta-analysis on four prospective studies including 7475 people showed a modest decrease in fracture risk of 4% per 50 pmol/L increase in vitamin B12 levels, which was borderline significant (RR = 0.96, 95% CI = 0.92 to 1.00). Meta-analysis of eight studies including 11511
people showed an increased fracture risk of 4% per μmol/L increase in homocysteine concentration (RR = 1.04, 95% CI = 1.02 to 1.07). We could not draw a conclusion regarding folate levels and fracture risk, as too few studies investigated this association. Meta-analyses regarding vitamin B12, folate and homocysteine levels, and BMD were possible in female populations only and showed no associations. Results from studies regarding BMD that could not be included in the meta-analyses were not univocal.
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19
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Dullemeijer C, Souverein OW, Doets EL, van der Voet H, van Wijngaarden JP, de Boer WJ, Plada M, Dhonukshe-Rutten RAM, In 't Veld PH, Cavelaars AEJM, de Groot LCPGM, van 't Veer P. Systematic review with dose-response meta-analyses between vitamin B-12 intake and European Micronutrient Recommendations Aligned's prioritized biomarkers of vitamin B-12 including randomized controlled trials and observational studies in adults and elderly persons. Am J Clin Nutr 2013; 97:390-402. [PMID: 23269815 DOI: 10.3945/ajcn.112.033951] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Many randomized controlled trials (RCTs) and observational studies have provided information on the association between vitamin B-12 intake and biomarkers. The use of these data to estimate dose-response relations provides a useful means to summarize the body of evidence. OBJECTIVE We systematically reviewed studies that investigated vitamin B-12 intake and biomarkers of vitamin B-12 status and estimated dose-response relations with the use of a meta-analysis. DESIGN This systematic review included all RCTs, prospective cohort studies, nested case-control studies, and cross-sectional studies in healthy adult populations published through January 2010 that supplied or measured dietary vitamin B-12 intake and measured vitamin B-12 status as serum or plasma vitamin B-12, methylmalonic acid (MMA), or holotranscobalamin. We calculated an intake-status regression coefficient ( ) for each individual study and calculated the overall pooled and SE ( ) by using random-effects meta-analysis on a double-log scale. RESULTS The meta-analysis of observational studies showed a weaker slope of dose-response relations than the meta-analysis of RCTs. The pooled dose-response relation of all studies between vitamin B-12 intake and status indicated that a doubling of the vitamin B-12 intake increased vitamin B-12 concentrations by 11% (95% CI: 9.4%, 12.5%). This increase was larger for studies in elderly persons (13%) than in studies in adults (8%). The dose-response relation between vitamin B-12 intake and MMA concentrations indicated a decrease in MMA of 7% (95% CI: -10%, -4%) for every doubling of the vitamin B-12 intake. The assessment of risk of bias within individual studies and across studies indicated risk that was unlikely to seriously alter these results. CONCLUSION The obtained dose-response estimate between vitamin B-12 intake and status provides complementary evidence to underpin recommendations for a vitamin B-12 intake of populations.
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Affiliation(s)
- Carla Dullemeijer
- Division of Human Nutrition, Wageningen University and Research Centre, Wageningen, Netherlands.
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The relationship between zinc intake and serum/plasma zinc concentration in adults: a systematic review and dose–response meta-analysis by the EURRECA Network. Br J Nutr 2012; 108:1962-71. [DOI: 10.1017/s0007114512004382] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Dietary Zn recommendations vary widely across Europe due to the heterogeneity of approaches used by expert panels. Under the EURopean micronutrient RECommendations Aligned (EURRECA) consortium a protocol was designed to systematically review and undertake meta-analyses of research data to create a database that includes ‘best practice’ guidelines which can be used as a resource by future panels when setting micronutrient recommendations. As part of this process, the objective of the present study was to undertake a systematic review and meta-analysis of previously published data describing the relationship between Zn intake and status in adults. Searches were performed of literature published up to February 2010 using MEDLINE, Embase and the Cochrane Library. Data extracted included population characteristics, dose of Zn, duration of study, dietary intake of Zn, and mean concentration of Zn in plasma or serum at the end of the intervention period. An intake–status regression coefficient ($\circ {>\beta }$) was estimated for each individual study, and pooled meta-analysis undertaken. The overall pooled $\circ {>\beta }$ for Zn supplementation on serum/plasma Zn concentrations from randomised controlled trials and observational studies was 0·08 (95 % CI 0·05, 0·11; P < 0·0001; I2 84·5 %). An overall $\circ {>\beta }$ of 0·08 means that for every doubling in Zn intake, the difference in Zn serum or plasma concentration is $2^{ \circ {>\beta }}$ (20·08 = 1·06), which is 6 %. Whether the dose–response relationship, as provided in the present paper, could be used as either qualitative or quantitative evidence to substantiate the daily Zn intake dose necessary to achieve normal or optimal levels of biomarkers for Zn status remains a matter of discussion.
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Casgrain A, Collings R, Harvey LJ, Hooper L, Fairweather-Tait SJ. Effect of iron intake on iron status: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr 2012; 96:768-80. [PMID: 22932280 DOI: 10.3945/ajcn.112.040626] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The response of status biomarkers to an increase in iron supply depends on several physiologic and environmental factors, which make it difficult to predict the outcome of an intervention. OBJECTIVE We assessed effects of baseline iron status, sex, menopausal status, duration of intervention, iron form, and daily dose on the change in iron status in response to iron supplementation. DESIGN A systematic review of randomized controlled trials (RCTs) of iron-supplementation and -fortification trials that assessed effects on hemoglobin, serum ferritin (SF), soluble transferrin receptor, or body iron was conducted. Subgrouping and straight-line and curved metaregression were used to describe the magnitude and dose-responsiveness of effect modifiers with respect to changes in status. RESULTS Forty-one RCTs were included; none of the RCTs were judged at low risk of bias. Random-effects meta-analyses showed that iron supplementation significantly improved iron status but with high levels of heterogeneity. Metaregression explained approximately one-quarter of between-study variance in effect size. There were clear effects on SF with study duration (increase in SF concentration/wk: 0.51 μg/L; 95% CI: 0.02, 1.00 μg/L; P = 0.04) and dose (increase in SF concentration/g Fe: 0.10 μg/L; 95% CI: 0.01, 0.20 μg/L; P = 0.036) and on hemoglobin concentrations with baseline iron status [-0.08 g/dL (95% CI: 0.15, 0.00 g/dL) per 10-μg/L increase in baseline SF concentration; P = 0.02]. Insufficient data were available to assess effects on body iron, sex, or menopausal status. CONCLUSION Quantitative relations between baseline iron status, study duration, and iron dose on changes in iron-status biomarkers, which were generated from the meta-analyses, can be used to predict effects of trials of iron supplementation and fortification and to design iron-intervention programs.
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Affiliation(s)
- Amelie Casgrain
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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Effect of folate intake on health outcomes in pregnancy: a systematic review and meta-analysis on birth weight, placental weight and length of gestation. Nutr J 2012; 11:75. [PMID: 22992251 PMCID: PMC3499376 DOI: 10.1186/1475-2891-11-75] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Accepted: 08/27/2012] [Indexed: 11/10/2022] Open
Abstract
The beneficial effect of folic acid supplementation before and shortly after conception is well recognized, whereas the effect of supplementation during the second and third trimesters is controversial and poorly documented. Our aims were to systematically review randomized controlled trials (RCTs) investigating the effect of folate supplementation on birth weight, placental weight and length of gestation and to assess the dose–response relationship between folate intake (folic acid plus dietary folate) and health outcomes. The MEDLINE, EMBASE and Cochrane Library CENTRAL databases were searched from inception to February 2010 for RCTs in which folate intake and health outcomes in pregnancy were investigated. We calculated the overall intake-health regression coefficient (
β^) by using random-effects meta-analysis on a loge-loge scale. Data of 10 studies from 8 RCTs were analyzed. We found significant dose–response relationship between folate intake and birth weight (P=0.001), the overall
β^ was 0.03 (95% confidence interval (CI): 0.01, 0.05). This relationship indicated 2% increase in birth weight for every two-fold increase in folate intake. In contrast, we did not find any beneficial effect of folate supplementation on placental weight or on length of gestation. There is a paucity of well-conducted RCTs investigating the effect of folate supplementation on health outcomes in pregnancy. The dose–response methodology outlined in the present systematic review may be useful for designing clinical studies on folate supplementation and for developing recommendations for pregnant women.
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Berti C, Fekete K, Dullemeijer C, Trovato M, Souverein OW, Cavelaars A, Dhonukshe-Rutten R, Massari M, Decsi T, van't Veer P, Cetin I. Folate intake and markers of folate status in women of reproductive age, pregnant and lactating women: a meta-analysis. J Nutr Metab 2012; 2012:470656. [PMID: 23024859 PMCID: PMC3449134 DOI: 10.1155/2012/470656] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 05/24/2012] [Indexed: 11/17/2022] Open
Abstract
Background. Pregnant and breastfeeding women are at risk for folate deficiency. Folate supplementation has been shown to be associated with enhanced markers of folate status. However, dose-response analyses for adult women are still lacking. Objective. To assess the dose-response relationship between total folate intake (folic acid plus dietary folate) and markers of folate status (plasma/serum folate, red blood cell folate, and plasma homocysteine); to evaluate potential differences between women in childbearing age, pregnant and lactating women. Methods. Electronic literature searches were carried out on three databases until February 2010. The overall pooled regression coefficient (β) and SE(β) were calculated using meta-analysis on a double-log scale. Results. The majority of data was based on nonpregnant, nonlactating women in childbearingage. The pooled estimate of the relationship between folate intake and serum/plasma folate was 0.56 (95% CI = 0.40-0.72, P < 0.00001); that is, the doubling of folate intake increases the folate level in serum/plasma by 47%. For red blood cell folate, the pooled-effect estimate was 0.30 (95% CI = 0.22-0.38, P < 0.00001), that is, +23% for doubling intake. For plasma-homocysteine it was -0.10 (95% = -0.17 to -0.04, P = 0.001), that is, -7% for doubling the intake. Associations tended to be weaker in pregnant and lactating women. Conclusion. Significant relationships between folate intake and serum/plasma folate, red blood cell folate, and plasma homocysteine were quantified. This dose-response methodology may be applied for setting requirements for women in childbearing age, as well as for pregnant and lactating women.
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Affiliation(s)
- Cristiana Berti
- Unit of Obstetrics and Gynecology, Department of Clinical Sciences Hospital ‘L. Sacco' and Center for Fetal Research Giorgio Pardi, University of Milan, 20157 Milan, Italy
| | | | - Carla Dullemeijer
- Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Monica Trovato
- Unit of Obstetrics and Gynecology, Department of Clinical Sciences Hospital ‘L. Sacco' and Center for Fetal Research Giorgio Pardi, University of Milan, 20157 Milan, Italy
| | - Olga W. Souverein
- Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Adriënne Cavelaars
- Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Rosalie Dhonukshe-Rutten
- Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Maddalena Massari
- Unit of Obstetrics and Gynecology, Department of Clinical Sciences Hospital ‘L. Sacco' and Center for Fetal Research Giorgio Pardi, University of Milan, 20157 Milan, Italy
| | | | - Pieter van't Veer
- Division of Human Nutrition, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Irene Cetin
- Unit of Obstetrics and Gynecology, Department of Clinical Sciences Hospital ‘L. Sacco' and Center for Fetal Research Giorgio Pardi, University of Milan, 20157 Milan, Italy
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Moran VH, Stammers AL, Medina MW, Patel S, Dykes F, Souverein OW, Dullemeijer C, Pérez-Rodrigo C, Serra-Majem L, Nissensohn M, Lowe NM. The relationship between zinc intake and serum/plasma zinc concentration in children: a systematic review and dose-response meta-analysis. Nutrients 2012; 4:841-58. [PMID: 23016120 PMCID: PMC3448075 DOI: 10.3390/nu4080841] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 06/27/2012] [Accepted: 07/10/2012] [Indexed: 01/17/2023] Open
Abstract
Recommendations for zinc intake during childhood vary widely across Europe. The EURRECA project attempts to consolidate the basis for the definition of micronutrient requirements, taking into account relationships among intake, status and health outcomes, in order to harmonise these recommendations. Data on zinc intake and biomarkers of zinc status reported in randomised controlled trials (RCTs) can provide estimates of dose-response relationships which may be used for underpinning zinc reference values. This systematic review included all RCTs of apparently healthy children aged 1–17 years published by February 2010 which provided data on zinc intake and biomarkers of zinc status. An intake-status regression coefficient () was calculated for each individual study and calculated the overall pooled and SE () using random effects meta-analysis on a double log scale. The pooled dose-response relationship between zinc intake and zinc status indicated that a doubling of the zinc intake increased the serum/plasma zinc status by 9%. This evidence can be utilised, together with currently used balance studies and repletion/depletion studies, when setting zinc recommendations as a basis for nutrition policies.
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Affiliation(s)
- Victoria Hall Moran
- Maternal & Infant Nutrition & Nurture Unit, University of Central Lancashire, Preston PR1 2HE, UK;
- Author to whom correspondence should be addressed; ; Tel.: +44-1772-893830; Fax: +44-1772-892998
| | - Anna-Louise Stammers
- International Institute of Nutritional Sciences and Food Safety Studies, University of Central Lancashire, Preston PR1 2HE, UK; (A.-L.S.); (M.W.M.); (S.P.); (N.M.L.)
| | - Marisol Warthon Medina
- International Institute of Nutritional Sciences and Food Safety Studies, University of Central Lancashire, Preston PR1 2HE, UK; (A.-L.S.); (M.W.M.); (S.P.); (N.M.L.)
| | - Sujata Patel
- International Institute of Nutritional Sciences and Food Safety Studies, University of Central Lancashire, Preston PR1 2HE, UK; (A.-L.S.); (M.W.M.); (S.P.); (N.M.L.)
| | - Fiona Dykes
- Maternal & Infant Nutrition & Nurture Unit, University of Central Lancashire, Preston PR1 2HE, UK;
| | - Olga W. Souverein
- Division of Human Nutrition, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands; (O.W.S.); (C.D.)
| | - Carla Dullemeijer
- Division of Human Nutrition, Wageningen University, PO Box 8129, 6700 EV Wageningen, The Netherlands; (O.W.S.); (C.D.)
| | | | - Lluis Serra-Majem
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria 35016, Spain; (L.S.-M.); (M.N.)
| | - Mariela Nissensohn
- Department of Clinical Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria 35016, Spain; (L.S.-M.); (M.N.)
| | - Nicola M. Lowe
- International Institute of Nutritional Sciences and Food Safety Studies, University of Central Lancashire, Preston PR1 2HE, UK; (A.-L.S.); (M.W.M.); (S.P.); (N.M.L.)
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Moran VH, Skinner AL, Medina MW, Patel S, Dykes F, Souverein OW, Dullemeijer C, Lowe NM. The relationship between zinc intake and serum/plasma zinc concentration in pregnant and lactating women: a systematic review with dose-response meta-analyses. J Trace Elem Med Biol 2012; 26:74-9. [PMID: 22613060 DOI: 10.1016/j.jtemb.2012.04.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 04/02/2012] [Indexed: 02/05/2023]
Abstract
Recommendations for zinc intake during pregnancy and lactation vary widely across Europe. Using data on zinc intake and biomarkers of zinc status reported in randomized controlled trials (RCTs) and observational studies can provide estimates of dose-response relationships that may be used for underpinning zinc reference values. This systematic review included all RCTs, prospective cohort studies, nested case-control studies and cross-sectional studies in healthy pregnant and lactating populations published by February 2010 which provided data on zinc intake and biomarkers of zinc status. An intake-status regression coefficient (βˆ) was calculated for each individual study and calculated the overall pooled βˆ and SE (βˆ) using random effects meta-analysis on a double log scale. The pooled dose-response relationship between zinc intake and zinc status found that a doubling of zinc intake was associated with an increase in serum/plasma zinc status by 3% in pregnant women and by 1% in lactating women. These modest associations are likely to reflect the low-moderate zinc bioavailability dietary patterns and the widespread use of other micronutrients in the populations included in this review, physiologic adjustments of zinc homeostasis, insensitivity of serum/plasma zinc as a biomarker of zinc status, and wide heterogeneity between study results which reflect real uncertainty in the current evidence base. Although this review provides useful information for dietary zinc requirements in populations vulnerable to zinc deficiency, it also highlights a need for further studies in pregnant and lactating women with different dietary patterns in order to provide useful complementary evidence that can be utilized when setting zinc recommendations as a basis for nutrition policies in Europe.
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Affiliation(s)
- Victoria Hall Moran
- Maternal & Infant Nutrition & Nurture Unit, University of Central Lancashire, Preston PR1 2HE, UK.
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