Wu et al. – Page 1
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The association between nut consumption and risk of developing cancer and type 2 diabetes: a systematic review and meta-analysis
Lang Wu, Zhen Wang, Jingjing Zhu, Angela L. Murad, Larry J. Prokop, Mohammad Hassan Murad
Center for Clinical and Translational Science (Wu); Division of Health Care Policy and Research (Wang); Mayo Clinic Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery (Wang, MH Murad); Dan Abraham Healthy Living Center (AL Murad); Mayo Clinic Libraries (Prokop); Division of
Preventive Medicine (MH Murad), Mayo Clinic, Rochester, Minnesota
Program of Quantitative Methods in Education (Zhu), University of Minnesota, Minneapolis, Minnesota
Corresponding Author :
Lang Wu
Address : Center for Clinical and Translational Science, Mayo Clinic, 200 First Street SW, Rochester, MN 55905
E-mail : Wu.Lang@mayo.edu
Phone : 507-293-1756
Criteria Brief description of how the criteria were handled in the metaanalysis
Reporting of background should include
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Problem definition To find appropriate food item which can decrease risk of cancer and type 2 diabetes is necessary in reducing health burden from them.
The current findings for benefits of nuts are inconsistent, thus a metaanalysis summarizing available evidence is necessary to clarify this
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Hypothesis statement
Description of study outcomes
 Type of exposure or intervention used problem (pages 3-4)
Nut consumption decreases risk of cancer and type 2 diabetes (page
4) specific cancer or type 2 diabetes (pages 3-4)
Nut consumption (page 4)
 Type of study designs used
 Study population
Reporting of search strategy should include
 Qualifications of searchers
Case-control, cohort studies, and clinical trials (page 5)
No restriction
The credentials of the investigators are indicated among the contents: experienced librarian, investigators of epidemiology, preventive medicine, statistics areas who have extensive experiences in

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Search strategy, including time period included in the synthesis and keywords
Databases and registries searched
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Search software used, name and version, including special features
 Use of hand searching
 List of citations located and those excluded, including justifications
 Method of addressing articles published in languages other than
English
 Method of handling abstracts and unpublished studies
 Description of any contact with authors
Reporting of methods should include
 Description of relevance or appropriateness of studies assembled for assessing the hypothesis to be tested
 Rationale for the selection and coding of data conducting meta-analysis (page 5) from each database’s earliest inception to December 2013; Controlled vocabulary supplemented with keywords was used to search, the actual strategy is within the supplementary material (page 5)
Medline In-Process & Other Non-Indexed Citations, MEDLINE,
EMBASE, Cochrane Central Register of Controlled Trials, Cochrane
Database of Systematic Reviews, and Scopus (page 5)
We did not employ search software. EndNote was used to merge retrieved citations and eliminate duplications
We hand-searched bibliographies of related review papers for additional references (page 5)
Details of the literature search process were outlined in Figure 1. The citation list is available upon request
We did not restrict on language (page 5)
We had contacted some authors for unpublished studies on the association (page 6)
We contacted authors whose articles did not provide detailed information for the risk estimation (page 6)
Detailed inclusion and exclusion criteria were described in the methods section (page 5)
Data extracted from each of the studies were relevant to the population characteristics, study design, exposure, outcome, and possible effect modifiers of the association (page 6)
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Assessment of confounding The majority of studies included present adjusted associations adjusting for important confounders in the studies (page 6)
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Assessment of study quality, including blinding of quality assessors; stratification or regression on possible predictors of study results
 Assessment of heterogeneity
Study quality was estimated based on the Newcastle-Ottawa Quality
Assessment Scale. Two investigators blindly evaluated the quality in an independent way (page 6)
Heterogeneity of the studies was explored using I 2 statistic that provides the relative amount of variance of the summary effect due to the between-study heterogeneity, where I 2> 50% suggests high heterogeneity (page 7)
 Description of statistical methods in Description of methods of meta-analyses was described in the
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 sufficient detail to be replicated
Provision of appropriate tables and graphics methods (pages 6 and 7)
We included 1 flow chart,1 study characteristic summary table, 2 tables for study quality assessment, 1 summary table of overall result,
1 summary table for subgroup analyses; combined with supplementary tables of search strategy (pages 23-37)
Table 4 and 5 (pages 33-35)
Reporting of results should include
 Graph summarizing individual study estimates and overall estimate
 Table giving descriptive information for each study included
 Results of sensitivity testing
Table 1 (pages 23-29)
None
 Indication of statistical uncertainty of findings
Reporting of discussion should include
 Quantitative assessment of bias
95% confidence intervals were presented with all summary estimates;
I 2 values were presented (pages 8-9)
We were unable to evaluate potential publication bias using visual inspection of symmetry of funnel plots and the Egger regression asymmetry test due to small number of studies included and high heterogeneity I 2> 50% in most analyses
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Justification for exclusion
 Assessment of quality of included studies
Our exclusion criteria were valid for maximizely utilizing all available evidence, and reducing bias from inappropriate studies
We discussed the potential reasons for the observed heterogeneity
(page 10)
Reporting of conclusions should include
 Consideration of alternative We compared our results with other studies with relevant context, and explanations for observed results
 Generalization of the conclusions provided discussions for the comparison (pages 10-11)
We generalized our conclusions to practical implication level. We discussed practice advices for nut consumption for health (pages 11-
12)
 Guidelines for future research Further studies are warranted to clarify associations between nut intake and risk of cancer detected in our study (page 11)
 Disclosure of funding source Page 13
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