Effect of L-Carnosine in Patients with Age-Related Diseases: A Systematic Review and Meta-Analysis

Abstract

Introduction: L-carnosine has been found to have multimodal activity. Aim: The aim of this review was to find out the efficacy of Lcarnosine in patients with age-related diseases. Methods: Clinical studies evaluated the effect of L-carnosine on cancer, cardiovascular disease, diabetes, and neurodegenerative disorders were searched in electronic bibliographic databases. The protocol has been registered with PROSPERO (CRD42022314033). The revised Cochrane risk of bias tool for randomized trials was used to assess all of the reports for risk of bias. RevMan 5.4 was used to conduct the meta-analysis. Results: Following the screening process, 14 papers were selected for systematic review, with 9 of them being qualified for meta-analysis. Many of the included studies showed that L-carnosine has potential therapeutic activity in age related diseases. Results from the meta-analysis showed that in diabetes mellitus, HbA1c [mean difference (MD) 95% CI = -1.25 (-2.49, -0.022); p = 0.05; p = 0.001; I 2 = 85%] and fasting blood sugar (FBS) [MD 95% CI = -12.44 (-22.44, -2.44); p = 0.01; p = 0.40; I 2 = 0%] and in neurodegenerative disorder, Wechsler Memory Scale Logical Memory 2 (WMS-LM2) [MD 95% CI = 1.34 (0.83, 1.85); p < 0.00001; p = 0.43; I 2 = 0%], showed statistically significant difference, favoring the L-carnosine group over the control group. While in neurodegenerative disorder, Alzheimer 's Disease Assessment Scale (ADAS) [MD 95% CI = 0.98 (-1.55, -0.42); p = 0.0007; p = 0.86; I 2 = 0%] and Back Depression Inventory (BDI) [MD 95% CI = -1.12 (-1.87, -0.37); p = 0.003; p = 0.73; I 2 = 0%] showed statistically significant difference, favoring the control group over L-carnosine group. Conclusions: Clinical studies were conducted to manage chemotherapy induced toxicities and there are no clinical studies available for its anti-cancer use, and the current evidence does not support its use in the treatment of cardiovascular disease.

Carnosine and Beta-Alanine Supplementation in Human Medicine: Narrative Review and Critical Assessment

“…Slowing the progression and improving the symptoms of certain neurodegenerative diseases, specifically AD and PD, has been confirmed sporadically in clinical trials in specific patient groups [ 59 , 60 , 61 , 64 ]. A meta-analysis of randomized trials confirmed the positive effect of carnosine supplementation (in doses of up to 1.5 g per day) in the Alzheimer’s Disease Assessment Scale and the Beck’s Depression Inventory [ 46 ]. Unfortunately, the number of clinical trials is very small.…”

“…A meta-analysis showed that supplementation with carnosine and beta-alanine led to reductions in fasting glycaemia, a decrease in HbA1c levels and insulin resistance [ 45 ]. Another meta-analysis including only randomized trials confirmed the effect of carnosine supplementation on DM patients, specifically on their HbA1c and fasting glucose levels [ 46 ]. This is supported by the results of yet another meta-analysis on 30 clinical trials of the effect of carnosine and related dipeptides in obese subjects, which showed reductions in fasting glycaemia and HbA1c, as well as reductions in obesity (waist circumference) [ 47 ].…”

“…Findings from clinical trials show that supplementation with carnosine (ranging from 500 mg to 2 g per day) and beta-alanine (4 g per day) is important in preventing and slowing the progression of T2DM. At the same time, it reduces complications associated with obesity, T1DM and T2DM, including oxidative stress, and improves carbohydrate metabolism [ 45 , 46 , 47 ].…”

“…The beneficial properties of carnosine and its components (beta-alanine and histidine) have been described in the additional literature [ 53 , 56 , 57 ]. A meta-analysis of randomized trials confirmed the effects of carnosine supplementation on the Wechsler memory scale-revised logical memory delayed recall (WMS-LM2), specifically in doses of around 300 mg of carnosine per day [ 46 ].…”

“…In some experimental studies, mostly performed in vitro, the added value of carnosine supplementation is suggested [ 98 , 99 ]. The results of very few human clinical trials are available [ 100 , 101 ] and the effect was not confirmed in the published meta-analysis [ 46 ]. High-quality clinical trials confirming these mechanisms are still lacking.…”