Plain language summary
L-carnosine is naturally produced in the body and is found in high concentrations in the brain, muscles and gut. It has many roles including acting as an anti-inflammatory and antioxidant. As such, it may have a role in the prevention and management of many different chronic diseases such as cancer, heart disease, diabetes and brain degenerative disorders. This systematic review and meta-analysis aimed to determine the clinical usage of L-carnosine in these chronic diseases. The study included 14 different studies and showed that L-carnosine supplementation may be a potential therapy for age related diseases such as diabetes and brain degenerative diseases. No studies were found for its use in individuals with cancer and the current evidence does not support its use in heart disease. It was concluded that L-carnosine is of benefit to individuals with diabetes and cognitive impairment, but not heart disease. This study could be used by health care professionals to understand that L-carnosine supplementation may be of benefit to indivduals with diabetes and neurodegenerative disorders.
Abstract
INTRODUCTION L-carnosine has been found to have multimodal activity. AIM: The aim of this review was to find out the efficacy of L-carnosine 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; I2 = 85%] and fasting blood sugar (FBS) [MD 95% CI = -12.44 (-22.44, -2.44); p = 0.01; p = 0.40; I2 = 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; I2 = 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; I2 = 0%] and Back Depression Inventory (BDI) [MD 95% CI = -1.12 (-1.87, -0.37); p = 0.003; p = 0.73; I2 = 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.
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