Effect of Carnosine or β-Alanine Supplementation on Markers of Glycemic Control and Insulin Resistance in Humans and Animals: A Systematic Review and Meta-analysis

Matthews, Joseph J. and Dolan, Eimear and Swinton, Paul A. and Santos, Livia and Artioli, Guilherme G. and Turner, Mark D. and Elliott-Sale, Kirsty J. and Sale, Craig (2021) Effect of Carnosine or β-Alanine Supplementation on Markers of Glycemic Control and Insulin Resistance in Humans and Animals: A Systematic Review and Meta-analysis. Advances in Nutrition: An International Review Journal. ISSN 2156-5376

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There is growing evidence that supplementation with carnosine, or its rate-limiting precursor β-alanine, can ameliorate aspects of metabolic dysregulation that occur in diabetes and its related conditions. The purpose of this systematic review and meta-analysis was to evaluate the effect of carnosine or β-alanine supplementation on markers of glycemic control and insulin resistance in humans and animals. We performed a systematic search of 6 electronic databases up to 31 December 2020. Primary outcomes were changes in 1) fasting glucose, 2) glycated hemoglobin (HbA1c), and 3) 2-h glucose following a glucose-tolerance test. A set of additional outcomes included fasting insulin and homeostatic model assessment of β-cell function (HOMA-β) and insulin resistance (HOMA-IR).We assessed risk of bias using the Cochrane risk of bias (RoB) 2.0 (human studies) and the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) RoB (animal studies) tools; and used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess certainty. We used Bayesian hierarchical random-effects models, with informative priors for human data and noninformative priors for animal data. Inferences were made on posterior samples generated by Hamiltonian Markov Chain Monte Carlo using 90% credible intervals (90% CrI) and calculated probabilities. Twenty studies (n= 4 human, n= 16 rodent) were included, providing data for 2 primary outcomes (fasting glucose and HbA1c) and 3 additional outcomes (fasting insulin, HOMA-β, and HOMA-IR). The model provides evidence that supplementation decreases fasting glucose [humans: mean difference (MD)0.5 =–0.95 mmol · L–1 (90% CrI: –2.1, 0.08); rodent: MD0.5 = –2.26 mmol · L–1 (90% CrI: –4.03, –0.44)], HbA1c [humans: MD0.5 = –0.91% (90% CrI: –1.46, –0.39); rodents: MD0.5 = –1.05% (90% CrI: –1.64, –0.52)], HOMA-IR [humans: standardized mean difference (SMD)0.5 = –0.41 (90% CrI: –0.82, –0.07); rodents: SMD0.5 = –0.63 (90% CrI: –1.98, 0.65)], and fasting insulin [humans: SMD0.5 = –0.41 (90% CrI: –0.77, –0.07)]. GRADE assessment showed our certainty in the effect estimate of each outcome to be moderate (human outcomes) or very low (rodent outcomes). Supplementation with carnosine or β-alanine may reduce fasting glucose, HbA1c, and HOMA-IR in humans and rodents, and fasting insulin in humans; both compounds show potential as therapeutics to improve glycemic control and insulin resistance. This review was registered at PROSPERO as CRD42020191588.

Item Type: Article
Identification Number: https://doi.org/10.1093/advances/nmab087
17 June 2021Accepted
31 July 2021Published Online
Uncontrolled Keywords: endocrinology, histidine, metabolic health, metabolism, nutrition, obesity
Subjects: CAH01 - medicine and dentistry > CAH01-01 - medicine and dentistry > CAH01-01-01 - medical sciences (non-specific)
CAH02 - subjects allied to medicine > CAH02-06 - allied health > CAH02-06-02 - nutrition and dietetics
Divisions: Faculty of Health, Education and Life Sciences > Centre for Life and Sport Sciences (C-LASS)
Depositing User: Joseph Matthews
Date Deposited: 03 Nov 2021 10:22
Last Modified: 03 Nov 2021 10:22
URI: https://www.open-access.bcu.ac.uk/id/eprint/12366

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