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Cited by 137Nuts composition and effectsNutritional Studies and DietCardiovascular Health and Risk Factors

Nut consumption in relation to cardiovascular disease risk and type 2 diabetes: a systematic review and meta-analysis of prospective studies

Open access
Zhou, Donghao, Yu, Haibing, He, Fang, Reilly, Kathleen Heather, Zhang, Jingling, Li, Shuangshuang, Zhang, Tao, Wang, Baozhen +2 more·2014·The American Journal of Clinical Nutrition
DOI 10.3945/ajcn.113.079152
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Abstract

Background Many prospective cohort studies have investigated the association between nut consumption and risk of coronary artery disease (CAD), stroke, hypertension, and type 2 diabetes (T2D). However, results have been inconsistent.Objective We aimed to investigate the association between nut consumption and risk of CAD, stroke, hypertension, and T2D.Design PubMed and EMBASE databases were searched up to October 2013. All prospective cohort studies of nut consumption and risk of CAD, stroke, hypertension, and T2D were included. Summary RRs with 95% CIs were estimated by using a fixed- or random-effects model.Results A total of 23 prospective studies (9 studies for CAD, 4 studies for stroke, 4 studies for hypertension, and 6 studies for T2D) from 19 publications were included in the meta-analysis. There were 179,885 participants and 7236 CAD cases, 182,730 participants and 5669 stroke cases, 40,102 participants and 12,814 hypertension cases, and 342,213 participants and 14,400 T2D cases. The consumption of each 1 serving of nuts/d was significantly associated with incident CAD (RR: 0.81; 95% CI: 0.72, 0.91; P < 0.001) and hypertension (RR: 0.66; 95% CI: 0.44, 1.00; P = 0.049). However, there was no association between the consumption of each 1 serving of nuts/d and risk of stroke (RR: 0.90; 95% CI: 0.71, 1.14) or T2D (RR: 0.80; 95% CI: 0.57, 1.14).Conclusions A higher consumption of nuts was associated with reduced risk of CAD and hypertension but not stroke or T2D. Large randomized controlled trials are warranted to confirm the observed associations.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review and meta-analysis of 23 prospective studies found that higher nut consumption was associated with lower risk of coronary artery disease and hypertension, but not stroke or type 2 diabetes. The authors conclude that large randomized controlled trials are needed to confirm these observational associations.

Key findings

  • For each 1-serving/d increment in nut consumption, pooled RRs were 0.81 (95% CI: 0.72, 0.91; P < 0.001) for CAD and 0.66 (95% CI: 0.44, 1.00; P = 0.049) for hypertension; no significant associations were found for stroke (RR: 0.90; 95% CI: 0.71, 1.14) or T2D (RR: 0.80; 95% CI: 0.57, 1.14).
  • Highest compared with lowest nut intake was inversely associated with CAD (RR: 0.83; 95% CI: 0.74, 0.93) and hypertension (RR: 0.85; 95% CI: 0.79, 0.92), but not stroke (RR: 0.87; 95% CI: 0.74, 1.03) or T2D (RR: 0.92; 95% CI: 0.78, 1.09).
  • The meta-analysis included 179,885 participants and 7,236 CAD cases; 182,730 participants and 5,669 stroke cases; 40,102 participants and 12,814 hypertension cases; and 342,213 participants and 14,400 T2D cases.

Methods

  • Systematic review and meta-analysis of prospective cohort studies identified from PubMed and EMBASE up to 10 October 2013, including 23 prospective studies from 19 publications.
  • Pooled RRs with 95% CIs were estimated using fixed- or random-effects models; dose-response analyses used Greenland et al. and Orsini et al. methods, with restricted cubic splines to test nonlinearity.
  • Heterogeneity was assessed with the Q test and I² statistic; meta-regression, sensitivity analyses, and Begg’s and Egger’s tests were used to explore heterogeneity and publication bias; study quality was assessed with the Newcastle-Ottawa scale.

Limitations

  • The paper states that observational cohort design cannot rule out unmeasured or residual confounding; most included studies did not provide data on nut types or preparation methods; and most used baseline nut consumption, so dietary changes during follow-up could misclassify exposure.
  • The paper also states there was between-study heterogeneity for CAD, stroke, and T2D that meta-regression could not explain, and not all studies adjusted for all covariates such as energy intake, BMI, and age.
  • Evident from the text: stroke and hypertension analyses included only 4 cohort studies each, and the authors did not perform stroke subtype subgroup analyses because there were only a few stroke studies; hypertension dose-response analysis had high heterogeneity (I² = 75.9%) and a sensitivity range that included the null (0.67; 95% CI: 0.38, 1.17 to 0.55; 95% CI: 0.38, 0.82).

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3945/ajcn.113.079152

Cites

42 of 42 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 11 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Each 1 serving/d increment in nut consumption is associated with a lower risk of hypertension (RR 0.66; 95% CI 0.44, 1.00; P = 0.049).

    “The consumption of each 1 serving of nuts/d was significantly associated with incident CAD (RR: 0.81; 95% CI: 0.72, 0.91; P , 0.001) and hypertension (RR: 0.66; 95% CI: 0.44, 1.00; P = 0.049).”
    • Also stated in: § Dose-response analysis · plain
      “The summary RR for each 1-serving/d intake was 0.66 (95% CI: 0.44, 1.00; P = 0.049; Figure 4)”
    Quote in the paperSubstantial claim
  • Findingown data

    Each 1 serving/d increment in nut consumption is not associated with risk of stroke (RR 0.90; 95% CI 0.71, 1.14).

    “However, there was no association between the consumption of each 1 serving of nuts/d and risk of stroke (RR: 0.90; 95% CI: 0.71, 1.14)”
    • Also stated in: § Dose-response analysis · plain
      “There was no significant association between higher nut consumption and risk of stroke [RR: 0.90 (95% CI: 0.71, 1.14) for each 1-serving/d consumption, Figure 3)”
    Quote in the paperSubstantial claim
  • Findingown data

    Each 1 serving/d increment in nut consumption is not associated with risk of type 2 diabetes (T2D) (RR 0.80; 95% CI 0.57, 1.14).

    “or T2D (RR: 0.80; 95% CI: 0.57, 1.14)”
    • Also stated in: § Dose-response analysis · plain
      “There was no significant association between higher nut consumption and risk of T2D (for each 1-serving/d consumption: RR: 0.80 (95% CI: 0.57, 1.14); P = 0.217; Figure 5)”
    Quote in the paperSubstantial claim
  • Findingown data

    There is no curvilinear association between nut consumption and risk of T2D (P-nonlinearity > 0.05).

    “We showed no evidence of a curvelinear association between nut consumption and risk of T2D (P-nonlinearity .0.05).”
    Quote in the paperNot a substantial claim
  • Findingown data

    There is no curvilinear association between nut consumption and risk of CAD (P-nonlinearity > 0.05).

    “We did not find a curvelinear association between nut consumption and risk of CAD (P-nonlinearity .0.05).”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. 5
  • May combine two claims. 6
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    The quality of each included study was assessed using the Newcastle-Ottawa quality scale, a validated scale for nonrandomized studies in meta-analysis.

    “The quality of each study was assessed by using the Newcastle-Ottawa quality scale (24), which is a validated scale for nonrandomized studies in a meta-analysis.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [24] Wells GA, Shea B, O’connell D, Peterson J, Welch V, Losos M, Tugwell P. The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Available from: http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp (cited 14 October 2013).

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Two authors independently assessed articles for compliance with inclusion and exclusion criteria and resolved disagreements through discussion.

    “Two authors (BX and SL) independently assessed the articles for compliance with the inclusion and exclusion criteria and resolved disagreements through discussion.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    Not all included studies adjusted for all important covariates (e.g., energy intake, BMI, age), so the combined results should be interpreted with caution.

    “Fifth, included studies adjusted for important covariates (see Table S1 under”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductreasoning

    Because most studies used baseline nut consumption as the exposure and some individuals might have changed diet habits during follow-up, misclassification of exposure might have biased the results.

    “Third, the majority of studies used the nut consumption at baseline as the dietary exposure.However, during the follow-up period, some individuals might have changed their diet habits.Thus, the misclassification of exposure might have biased the results.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Study design and conductown data

    Meta-regression did not identify publication year, subtype endpoint, sex, duration of follow-up, or quality score as the source of heterogeneity for any of the 4 outcomes.

    “However, none of these variables were identified as the source of heterogeneity for all 4 outcomes (all P .0.05).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    None of the authors had a conflict of interest.

    “None of the authors had a conflict of interest.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    Most included studies did not provide data on types of nuts consumed and their preparation, so the influence of types of nuts or preparation methods on outcomes could not be examined.

    “Second, most in-cluded studies did not provide data on types of nuts consumed and their preparation including salted, spiced, roasted, or raw nuts.Thus, we are unable to examine the influence of types of nuts or preparation methods on outcomes.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    Funders had no role in the study design, implementation, analysis, and interpretation of data.

    “Funders had no role in the study design, implementation, analysis, and interpretation of data.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    A previous meta-analysis of 4 cohort studies suggested an average risk reduction of CAD death by 37% for the highest compared with lowest amounts of nut consumption and a reduction of 8.3% in risk of CAD death for each weekly serving of nuts.

    “A previous metaanalysis of 4 cohort studies suggested an average risk reduction of CAD death by 37% for the highest compared with lowest amounts of nut consumption and a reduction of 8.3% in risk of CAD death for each weekly serving of nuts (10).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [10] Kelly, 2006, Nuts and coronary heart disease: an epidemiological perspective, Br J Nutr source

      Not checked in the free run.

9 of 9

Claims other papers make about this one

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Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Steffen study has conflicting publication years

    Minor

    Table 1 lists the Steffen study as published in 2006, but reference 14 gives its publication year as 2005.

1 of 1

Cites

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Related

Authors
Zhou, D., Yu, H., He, F., Reilly, K. H., Zhang, J., Li, S., Zhang, T., Wang, B., Ding, Y., & Xi, B.
Affiliations
Shandong University (CN)
ORCID
Venue
The American Journal of Clinical Nutrition
Publisher
Elsevier BV
Published
2014-07
Volume
100
Issue
1
Pages
270-277
ISSN
0002-9165 (ISSN-L)
DOI
10.3945/ajcn.113.079152
OpenAlex
W2163875227
Semantic Scholar
a6f11859e0273e0faba029754dffd6e6096be49c
Cited by
137
References
42
Citations by year
2026: 1 · 2025: 2 · 2024: 8 · 2023: 10 · 2022: 16 · 2021: 11 · 2020: 9 · 2019: 10 · 2018: 21 · 2017: 14 · 2016: 7 · 2015: 19 · 2014: 9
FWCI
1.87
Type
journal article
Language
en
Open access
Licence
Locations
  • American Journal of Clinical Nutrition (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Natural Science Foundation of China (81273166)
  • Key Projects of Science and Technology Plan Medical and Scientific Research Units of Dongguan (2012105102010)
  • Science and Technology Innovation Team Project in Doctor Granting of Guangdong Medical College (STIF201121)
  • Science and Technology Innovation Project of Guangdong Province (2013KJCX0089)
  • Key Disciplines of Guangdong Medical College Project (GDMCKSF201105)
  • NIH (psychoceramics-1152342)
Topics
  • Health Sciences › Nursing › Nutrition and Dietetics › Nuts composition and effects
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Nutritional Studies and Diet
  • Health Sciences › Medicine › Cardiology and Cardiovascular Medicine › Cardiovascular Health and Risk Factors
Keywords
nut consumption, cardiovascular risk, coronary artery disease, stroke, hypertension, type 2 diabetes, dietary fat, prospective cohort
MeSH terms
Cardiovascular Diseases, Diabetes Mellitus, Type 2, Diet, Humans, Nuts, Risk Factors, Databases, Factual, Risk Reduction Behavior

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