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.; Dolan, Eimear; Swinton, Paul A.; Santos, L�via; Artioli, Guilherme G.; Turner, Mark D.; Elliott-Sale, Kirsty J.; Sale, Craig

Abstract

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.

Citation

MATTHEWS, J.J., DOLAN, E., SWINTON, P.A., SANTOS, L., ARTIOLI, G.G., TURNER, M.D., ELLIOTT-SALE, K.J. and SALE, C. 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 [online], 12(6), pages 2216-2231. Available from: https://doi.org/10.1093/advances/nmab087

• Journal Article Type: Review
• Acceptance Date: Jun 17, 2021
• Online Publication Date: Jul 31, 2021
• Publication Date: Nov 1, 2021
• Deposit Date: Aug 12, 2021
• Publicly Available Date: Aug 12, 2021
• Journal: Advances in nutrition
• Print ISSN: 2161-8313
• Electronic ISSN: 2156-5376
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 6
• Pages: 2216-2231
• DOI: https://doi.org/10.1093/advances/nmab087
• Keywords: Endocrinology; Histidine; Metabolic health; Metabolism; Nutrition; Obesity
• Public URL: https://rgu-repository.worktribe.com/output/1351910
• Related Public URLs: https://rgu-repository.worktribe.com/output/999672; https://rgu-repository.worktribe.com/output/1406147