Effects of Saturated Fat, Polyunsaturated Fat, Monounsaturated Fat, and Carbohydrate on Glucose-Insulin Homeostasis: A Systematic Review and Meta-analysis of Randomised Controlled Feeding Trials
- PMID: 27434027
- PMCID: PMC4951141
- DOI: 10.1371/journal.pmed.1002087
Effects of Saturated Fat, Polyunsaturated Fat, Monounsaturated Fat, and Carbohydrate on Glucose-Insulin Homeostasis: A Systematic Review and Meta-analysis of Randomised Controlled Feeding Trials
Abstract
Background: Effects of major dietary macronutrients on glucose-insulin homeostasis remain controversial and may vary by the clinical measures examined. We aimed to assess how saturated fat (SFA), monounsaturated fat (MUFA), polyunsaturated fat (PUFA), and carbohydrate affect key metrics of glucose-insulin homeostasis.
Methods and findings: We systematically searched multiple databases (PubMed, EMBASE, OVID, BIOSIS, Web-of-Knowledge, CAB, CINAHL, Cochrane Library, SIGLE, Faculty1000) for randomised controlled feeding trials published by 26 Nov 2015 that tested effects of macronutrient intake on blood glucose, insulin, HbA1c, insulin sensitivity, and insulin secretion in adults aged ≥18 years. We excluded trials with non-isocaloric comparisons and trials providing dietary advice or supplements rather than meals. Studies were reviewed and data extracted independently in duplicate. Among 6,124 abstracts, 102 trials, including 239 diet arms and 4,220 adults, met eligibility requirements. Using multiple-treatment meta-regression, we estimated dose-response effects of isocaloric replacements between SFA, MUFA, PUFA, and carbohydrate, adjusted for protein, trans fat, and dietary fibre. Replacing 5% energy from carbohydrate with SFA had no significant effect on fasting glucose (+0.02 mmol/L, 95% CI = -0.01, +0.04; n trials = 99), but lowered fasting insulin (-1.1 pmol/L; -1.7, -0.5; n = 90). Replacing carbohydrate with MUFA lowered HbA1c (-0.09%; -0.12, -0.05; n = 23), 2 h post-challenge insulin (-20.3 pmol/L; -32.2, -8.4; n = 11), and homeostasis model assessment for insulin resistance (HOMA-IR) (-2.4%; -4.6, -0.3; n = 30). Replacing carbohydrate with PUFA significantly lowered HbA1c (-0.11%; -0.17, -0.05) and fasting insulin (-1.6 pmol/L; -2.8, -0.4). Replacing SFA with PUFA significantly lowered glucose, HbA1c, C-peptide, and HOMA. Based on gold-standard acute insulin response in ten trials, PUFA significantly improved insulin secretion capacity (+0.5 pmol/L/min; 0.2, 0.8) whether replacing carbohydrate, SFA, or even MUFA. No significant effects of any macronutrient replacements were observed for 2 h post-challenge glucose or insulin sensitivity (minimal-model index). Limitations included a small number of trials for some outcomes and potential issues of blinding, compliance, generalisability, heterogeneity due to unmeasured factors, and publication bias.
Conclusions: This meta-analysis of randomised controlled feeding trials provides evidence that dietary macronutrients have diverse effects on glucose-insulin homeostasis. In comparison to carbohydrate, SFA, or MUFA, most consistent favourable effects were seen with PUFA, which was linked to improved glycaemia, insulin resistance, and insulin secretion capacity.
Conflict of interest statement
I have read the journal's policy and the authors of this manuscript have the following competing interests: DM reports ad hoc honoraria or consulting from Boston Heart Diagnostics, Haas Avocado Board, Astra Zeneca, GOED, DSM, and Life Sciences Research Organization; chapter royalties from UpToDate; and scientific advisory board, Elysium Health. Harvard University has been assigned patent US8889739 B2, listing DM as one of three co-inventors, for use of trans-palmitoleic acid in identifying and treating metabolic disease. RM and JHYW received research support from Unilever R&D (project reference number MA-2015-01161) for work on fatty acid biomarkers and incident cardiometabolic diseases.
Figures
Similar articles
-
Impact of saturated compared with unsaturated dietary fat on insulin sensitivity, pancreatic β-cell function and glucose tolerance: a systematic review and meta-analysis of randomized, controlled trials.Am J Clin Nutr. 2023 Oct;118(4):739-753. doi: 10.1016/j.ajcnut.2023.07.018. Epub 2023 Jul 25. Am J Clin Nutr. 2023. PMID: 37500058
-
Omega-3, omega-6, and total dietary polyunsaturated fat for prevention and treatment of type 2 diabetes mellitus: systematic review and meta-analysis of randomised controlled trials.BMJ. 2019 Aug 21;366:l4697. doi: 10.1136/bmj.l4697. BMJ. 2019. PMID: 31434641 Free PMC article.
-
Plant-derived polyunsaturated fatty acids and markers of glucose metabolism and insulin resistance: a meta-analysis of randomized controlled feeding trials.BMJ Open Diabetes Res Care. 2019 Feb 8;7(1):e000585. doi: 10.1136/bmjdrc-2018-000585. eCollection 2019. BMJ Open Diabetes Res Care. 2019. PMID: 30899527 Free PMC article. Review.
-
Metabolic Effects of Monounsaturated Fatty Acid-Enriched Diets Compared With Carbohydrate or Polyunsaturated Fatty Acid-Enriched Diets in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials.Diabetes Care. 2016 Aug;39(8):1448-57. doi: 10.2337/dc16-0513. Diabetes Care. 2016. PMID: 27457635 Free PMC article. Review.
-
Reduction in saturated fat intake for cardiovascular disease.Cochrane Database Syst Rev. 2015 Jun 10;(6):CD011737. doi: 10.1002/14651858.CD011737. Cochrane Database Syst Rev. 2015. Update in: Cochrane Database Syst Rev. 2020 May 19;5:CD011737. doi: 10.1002/14651858.CD011737.pub2. PMID: 26068959 Updated. Review.
Cited by
-
Saturated fatty acids inhibit unsaturated fatty acid induced glucose uptake involving GLUT10 and aerobic glycolysis in bovine granulosa cells.Sci Rep. 2024 Apr 30;14(1):9888. doi: 10.1038/s41598-024-59883-x. Sci Rep. 2024. PMID: 38688953 Free PMC article.
-
Association of birth weight with type 2 diabetes mellitus and the mediating role of fatty acids traits: a two-step mendelian randomization study.Lipids Health Dis. 2024 Apr 2;23(1):97. doi: 10.1186/s12944-024-02087-z. Lipids Health Dis. 2024. PMID: 38566047 Free PMC article.
-
Substitution of dietary monounsaturated fatty acids from olive oil for saturated fatty acids from lard increases low-density lipoprotein apolipoprotein B-100 fractional catabolic rate in subjects with dyslipidemia associated with insulin resistance: a randomized controlled trial.Am J Clin Nutr. 2024 May;119(5):1270-1279. doi: 10.1016/j.ajcnut.2024.03.015. Epub 2024 Mar 20. Am J Clin Nutr. 2024. PMID: 38518848 Clinical Trial.
-
Association Between Dietary Habits and Type 2 Diabetes Mellitus in Thai Adults: A Case-Control Study.Diabetes Metab Syndr Obes. 2024 Mar 6;17:1143-1155. doi: 10.2147/DMSO.S445015. eCollection 2024. Diabetes Metab Syndr Obes. 2024. PMID: 38465346 Free PMC article.
-
Dietary assessment of type 2 diabetic patients using healthful plant-based diet score in the Eastern Province of Saudi Arabia.BMC Nutr. 2024 Feb 28;10(1):37. doi: 10.1186/s40795-024-00843-z. BMC Nutr. 2024. PMID: 38419128 Free PMC article.
References
-
- International Diabetes Federatoin. The Global Burden In: IDF Diabetes Atlas. 6th ed. Brussels, Belgium: International Diabetes Federation; 2013. p. 29–49.
-
- Deakin T, Duncan A, Dyson P, Frost G, Harrison Z, Kelly T, et al. Evidence-based nutrition guidelines for the prevention and management of diabetes. Kelly T, Dyson P, editors. 2011. Available:https://www.diabetes.org.uk/About_us/What-we-say/Food-nutrition-lifestyl... (accessed 2016 Apr 29) - PubMed
-
- Fats and fatty acids in human nutrition Roma, Italy: Food and Agriculture Organization; 2010.
Publication types
MeSH terms
Substances
Grants and funding
LinkOut - more resources
Full Text Sources
Other Literature Sources
Medical
Miscellaneous