Effects of whole grain intake on glycemic traits: A systematic review and meta-analysis of randomized controlled trials

Abstract

Whole grains (WGs) may have various health benefits, including lowering blood glucose and improving insulin sensitivity. To conduct a meta-analysis of the effects of WGs compared with non-WGs on changes in fasting glucose, fasting insulin, glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR). A systematic literature search was performed for all published randomized controlled trials on the effects of WG intake on fasting glucose, fasting insulin, HbA1c and HOMA-IR response up to February 2021. Weighted mean differences (WMD) were calculated. Pre-specified subgroup and univariate meta-regression analyses were explored to identify the sources of heterogeneity. Sensitivity analysis and bias analysis were conducted to appraise study quality. Among 12,435 articles screened for eligibility, data were extracted from 48 articles. Meta-analysis of 4,118 participants showed that WG consumption resulted in a significant reduction in fasting glucose by −0.15 mmol/L, fasting insulin by −2.71 pmol/L, HbA1c by −0.44%, and HOMA-IR by −0.28, respectively. Compared with mixed grains, brown rice, and wheat, oats were significantly lower on marker of glycemic. Besides, multiple interventions per day consolidated effectiveness of WGs. WG consumption decreased the levels of fasting glucose, fasting insulin, HbA1c, and HOMA-IR compared with non-WG consumption.

Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.2001429 .

Keywords:

• Glucose
• HbA1c
• HOMA-IR
• insulin
• whole grains

Acknowledgements

I would like to thank all teaching staff at Institute of Agro-Food Science and Technology, Shandong Academy of Agricultural Sciencesfor their helpful suggestions on my paper. I am also grateful to all the other graduate students for their help.

Disclosure statement

No potential conflict of interest was reported by the authors.

The authors’ responsibilities were as follows-TX and DL: Designed the research. FD led development of the search strategy and conducted the searches of the different databases. AZ, ZX, and LL: Conducted the research. WL, and JW: Analyzed the data. SL, RA, HW, JL, and XG: Wrote the paper. TX supervised the conduct of the research and had primary responsibility for the final content. All authors contributed to interpretation of the results, reviewed the manuscript for important intellectual content, and read and approved the final manuscript.

Register

We were registering at this website (https://www.crd.york.ac.uk/PROSPERO/#record, ID:CRD42020190129, Date: July 5, 2020).

Additional information

Funding

This work was supported by the Beijing Advanced Innovation Center for Food Nutrition and Human Health under Grant 20171030; the Open Project Program of China-Canada Joint Lab of Food Nutrition and Health, Beijing Technology and Business University under Grant ZJ-2020-08; and the National Key R & D Project under Grant 2019YFD1002704.