Abstract
Background
Observational data have established a link between the consumption of whole grains
and reduced risk of cardiovascular disease (CVD); however, there is a need to review
interventional research.
Objective
Our aim was to determine whether interventions providing whole grain or whole pseudo-grain
for dietary consumption improved CVD-related outcomes compared with refined grain
or placebo in adults with or without chronic disease and/or associated risk factors.
Methods
A systematic review and meta-analysis of randomized controlled trials that compared
whole-grain vs refined-grain or placebo consumption by human adults was conducted.
PubMed, CINAHL, Embase, Web of Science, and Cochrane CENTRAL were searched for studies
of 12 weeks (or 2 weeks for inflammatory outcomes) duration until 21 February 2020.
Data were extracted for 14 types of CVD risk factors (40 outcomes in total). Risk
of bias was assessed using the Cochrane Risk-of-Bias tool. Meta-analysis was performed
using Comprehensive Meta-Analysis software. The Grading of Recommendations Assessment, Development and Evaluation method
was used to determine confidence in the pooled effects and to inform a clinical recommendation.
Results
Twenty-five randomized controlled trials were included and 22 were meta-analyzed.
Interventions ranged from 2 to 16 weeks; most samples were healthy (n = 13 studies)
and used mixed whole grains (n = 11 studies). Meta-analysis found that whole-grain
oats improved total cholesterol (standardized mean difference [SMD] = –0.54, 95% CI
–0.95 to –0.12) and low-density lipoprotein cholesterol (SMD = –0.57, 95% CI –0.84
to –0.31), whole-grain rice improved triglycerides (SMD = 0.22, 95% CI –0.44 to –0.01),
and whole grains (all types) improved hemoglobin A1c (SMD = –0.33, 95% CI –0.61 to
–0.04) and C-reactive protein (SMD = –0.22, 95% CI –0.44 to –0.00).
Conclusions
For adults with or without CVD risk factors, consuming whole grains as opposed to
refined grains can improve total cholesterol, low-density lipoprotein cholesterol,
hemoglobin A1c, and C-reactive protein. There is insufficient evidence to recommend
the whole grains as opposed to refined grains for the prevention and treatment of
CVD. Further interventional research is needed to better understand the preventive
and treatment potential of whole-grain and whole pseudo-grain dietary intake for cardiovascular
disease, particularly among those with existing CVD risk factors.
Keywords
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Biography
S. Marshall is an accredited practicing dietitian and scientific and education director, Nutrition Research Australia, Sydney, New South Wales, Australia, and a senior postdoctoral research fellow, Bond University Nutrition and Dietetics Research Group, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, Queensland, Australia.
Biography
P. Petocz is a statistician, Nutrition Research Australia, Sydney, New South Wales, Australia.
Biography
E. Duve is a research nutritionist, Nutrition Research Australia, Sydney, New South Wales, Australia.
Biography
T. Cassettari is a project director, Nutrition Research Australia, Sydney, New South Wales, Australia.
Biography
M. Blumfield is a research dietitian, Nutrition Research Australia, Sydney, New South Wales, Australia.
Biography
F. Fayet-Moore is chief executive officer, Nutrition Research Australia, Sydney, New South Wales, Australia.
Biography
K. Abbott is research dietitian, Nutrition Research Australia, Sydney, New South Wales, Australia, and research dietitian, Nutraceuticals Research Group, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, Australia.
Article info
Publication history
Published online: September 12, 2020
Accepted:
June 23,
2020
Received:
February 24,
2020
Footnotes
Supplementary materials: Figures 2 and 7 and Tables 2 and 5 are available at www.jandonline.org
STATEMENT OF POTENTIAL CONFLICT OF INTEREST Grains & Legumes Nutrition Council of Australia provided critical revision and feedback on the proposed review methodology; but had no contribution to the analysis or interpretation of results. All authors declare no existing or potential conflicts of interest.
FUNDING/SUPPORT This study received funding from Grains & Legumes Nutrition Council of Australia.
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© 2020 by the Academy of Nutrition and Dietetics.
