Background: The burden of obesity and type 2 diabetes is rapidly increasing. Carnosine (β alanyl L-histidine), a dipeptide with anti-inflammatory, anti-glycating, and anti-oxidative properties, may be a potential strategy to mitigate cardiometabolic risk factors. However, studies examining the effects of carnosine and related histidine-containing dipeptides (HCDs; e.g., beta-alanine) on cardiometabolic risk have been inconsistent.
Objective: We conducted a systematic review and meta-analysis examining the effects of all HCDs on cardiometabolic risk factors in all population groups.
Methods: MEDLINE, CINAHL, EMBASE, and EBM were searched for randomized controlled trials investigating the effects of carnosine and/or HCDs on cardiometabolic risk factors, compared with placebo, usual care, or other interventions. Meta-analyses using random-effects models were used to calculate the mean difference (MD) and 95% confidence interval (CI) for each outcome.
Results: Forty- nine RCTs totaling 1709 participants were included. Carnosine and/or HCD supplementation lowered waist circumference (n= 162, MD [95% CI]= -3.53 cm [-5.65,1.41], p=0.001); post-prandial glucose (PPG) (n=230, MD [95% CI]= -0.79 mmol/L [-1.23,-0.35], p=0.0004), HbA1c (n=283, MD [95% CI]= -0.37% [-0.64,-0.10], p=0.006) and C-reactive protein (CRP) (n=272, MD [95% CI]= -0.43 mg/L [-0.64,-0.22], p< 0.0001) compared with control. In sensitivity analyses of RCTs using carnosine only, PPG, HbA1c, and CRP remained significantly lower with carnosine supplementation (all p<0.05), and fasting glucose and triglycerides became significantly lower with carnosine versus control (n=309 for both, MD [95% CI]= -0.58 mmol/L [-1.12,-0.05], p=0.03; and -0.2 mmol/L [-0.27,-0.13], p<0.0001, respectively).
Conclusion: Our findings provide level 1 evidence that carnosine and HCDs have potential benefits for prevention and treatment of diabetes.
K. Aravind Menon: None. A. Mousa: None. C. Marquina: None. B. de Courten: None.