Effect of carnosine supplementation on lipid profile, fasting blood glucose, HbA1C and insulin resistance: A systematic review and meta-analysis of long-term randomized controlled trials

Probiotics, prebiotics, and synbiotics in type 1 diabetes mellitus: A systematic review and meta-analysis of clinical trials

Dysbiosis or imbalance of microbes in the gut has been associated with susceptibility and progression of type 1 diabetes mellitus (T1DM). The present systematic review and meta-analysis examined the effects of probiotics, prebiotics, and synbiotics on fasting blood glucose (FBG), haemoglobin A1c (HbA1c), C-peptide, and insulin requirements in T1DM patients. A systematic search for trials published up to October 2022 was conducted in PubMed, EMBASE, Scopus, Google Scholar, ScienceDirect, Web of Science, and the Central Cochrane Library. Random effect models were used to synthesise quantitative data by STATA14 . After the evaluation of 258 identified entries, five randomised controlled trials (n = 356; mean age = 11.7 years old) were included. The pooled effect size showed that FBG decreased following probiotic supplementation (weighted mean difference = -31.24 mg/dL; 95% confidence interval = -45.65, -16.83; p < 0.001), however, there was no significant improvement in serum HbA1c, C-peptide, and insulin requirements. Probiotic supplementation could be a complementary therapeutic strategy in T1DM. The evidence is limited; therefore, it is crucial to conduct more trials.

Dual effects of dietary carnosine during in vitro digestion of a Western meal model with added ascorbic acid

The beneficial role of carnosine during in vitro digestion of meat was previously demonstrated, and it was hypothesized that such benefits could also be obtained in a meal system. The current study, therefore, assessed carnosine effects on markers of lipid and protein oxidation and of advanced glycation end products (AGEs) during gastric and duodenal in vitro digestion of a burger meal model. The model included intrinsic (low) and enhanced (medium and high) carnosine levels in a mix of pork mince and bread, with or without ascorbic acid (AA) and/or fructose as anti- and prooxidants, respectively. In the presence of either AA or fructose, a carnosine prooxidative potential during digestion was observed at the medium carnosine level depending on markers and digestive phases. However, free carnosine found at the high carnosine level exerted a protective effect reducing the formation of 4-hydroxynonenal in the gastric phase and glyoxal in both the gastric and duodenal phases. Dual effects of carnosine are likely concentration related, whereby at the medium level, free radical production increases through carnosine's ferric-reducing capacity, but there is insufficient quantity to reduce the resulting oxidation, while at the higher carnosine level some decreases in oxidation are observed. In order to obtain carnosine benefits during meal digestion, these findings demonstrate that consideration must be given to the amount and nature of other anti- and prooxidants present and any potential interactions. PRACTICAL APPLICATION: Carnosine, a natural compound in meat, is a multifunctional and beneficial molecule for health. However, both pro- and antioxidative effects of carnosine were observed during digestion of a model burger meal when ascorbic acid was included at a supplemental level. Therefore, to obtain benefits of dietary carnosine during digestion of a meal, consideration needs to be given to the amount and nature of all anti- and prooxidants present and any potential interactions.

Carnosine Did Not Affect Vascular and Metabolic Outcomes in Patients with Prediabetes and Type 2 Diabetes: A 14-Week Randomized Controlled Trial

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality in patients with prediabetes and type 2 diabetes mellitus (T2DM). Carnosine has been suggested as a potential approach to reduce ASCVD risk factors. However, there is a paucity of human data. Hence, we performed a 14-week double-blind randomized placebo-controlled trial to determine whether carnosine compared with placebo improves vascular and metabolic outcomes in individuals with prediabetes and T2DM. In total, 49 patients with prediabetes and T2DM with good glycemic control were randomly assigned either to receive 2 g/day carnosine or matching placebo. We evaluated endothelial dysfunction, arterial stiffness, lipid parameters, blood pressure, heart rate, hepatic and renal outcomes before and after the intervention. Carnosine supplementation had no effect on heart rate, peripheral and central blood pressure, endothelial function (logarithm of reactive hyperemia (LnRHI)), arterial stiffness (carotid femoral pulse wave velocity (CF PWV)), lipid parameters, liver fibroscan indicators, liver transient elastography, liver function tests, and renal outcomes compared to placebo. In conclusion, carnosine supplementation did not improve cardiovascular and cardiometabolic risk factors in adults with prediabetes and T2DM with good glycemic control. Therefore, it is improbable that carnosine supplementation would be a viable approach to mitigating the ASCVD risk in these populations. The trial was registered at clinicaltrials.gov (NCT02917928).

Ionophore Ability of Carnosine and Its Trehalose Conjugate Assists Copper Signal in Triggering Brain-Derived Neurotrophic Factor and Vascular Endothelial Growth Factor Activation In Vitro

l-carnosine (β-alanyl-l-histidine) (Car hereafter) is a natural dipeptide widely distributed in mammalian tissues and reaching high concentrations (0.7-2.0 mM) in the brain. The molecular features of the dipeptide underlie the antioxidant, anti-aggregating and metal chelating ability showed in a large number of physiological effects, while the biological mechanisms involved in the protective role found against several diseases cannot be explained on the basis of the above-mentioned properties alone, requiring further research efforts. It has been reported that l-carnosine increases the secretion and expression of various neurotrophic factors and affects copper homeostasis in nervous cells inducing Cu cellular uptake in keeping with the key metal-sensing system. Having in mind this l-carnosine ability, here we report the copper-binding and ionophore ability of l-carnosine to activate tyrosine kinase cascade pathways in PC12 cells and stimulate the expression of BDNF. Furthermore, the study was extended to verify the ability of the dipeptide to favor copper signaling inducing the expression of VEGF. Being aware that the potential protective action of l-carnosine is drastically hampered by its hydrolysis, we also report on the behavior of a conjugate of l-carnosine with trehalose that blocks the carnosinase degradative activity. Overall, our findings describe a copper tuning effect on the ability of l-carnosine and, particularly its conjugate, to activate tyrosine kinase cascade pathways.

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

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.

Effect of probiotics supplementation on disease progression, depression, general health, and anthropometric measurements in relapsing-remitting multiple sclerosis patients: A systematic review and meta-analysis of clinical trials

BACKGROUND

Probiotics may have a promising role in chronic autoinflammatory diseases. The current systematic review and meta-analysis investigated the effects of probiotics on disease progression, depression, general health, and anthropometric measurements in Relapsing-Remitting Multiple Sclerosis (RRMS) patients.

METHODS

The English literature search was performed using PubMed, Scopus, Web of Science, and the Central Cochrane Library through January 2021. Random effect models were used to synthesise quantitative data by STATA₁₄ .

RESULTS

From a total of 152 identified entries, four trials were included in quantitative synthesis (n = 213; 106 as intervention, 107 as control). An additional six studies with the same structure and different markers were also systematically reviewed. The pooled effect size showed that Expanded Disability Status Scale (EDSS) (WMD = -0.43; 95% CI = -0.65, -0.20; P < .001), Beck Depression Inventory-Ⅱ (BDI-Ⅱ) (WMD = -3.22; 95% CI = -4.38, -2.06; P < .001) and General Health Questionnaire (GHQ) (WMD = -4.37; 95% CI = -6.43, -2.31; P < .001) were improved following probiotics supplementation. However, body weight and body mass index did not statistically change.

CONCLUSION

Our findings revealed that probiotics supplementation can improve disease progression, suppress depression, and general health in MS patients; although, further investigations may be needed.

Study on the Effects of Chinese Materia Medica Processing on the Hypoglycemic Activity and Chemical Composition of Anemarrhenae Rhizoma

PURPOSE

To compare the hypoglycemic effects of different extracts of Anemarrhenae Rhizoma (AR) before and after being stir-baked with salt water on the diabetic mice and to detect the contents of 8 components in the corresponding active parts simultaneously using the UPLC-MS method, in order to screen the better extracts for diabetes and to clear the material basis for enhancing hypoglycemic activity of Anemarrhenae Rhizoma stir-baked with salt water (SAR).

METHODS

Taking spontaneous type II diabetic db/db mice as models and fasting blood glucose (FBG), oral glucose tolerance test (OGTT), glycated hemoglobin or glycosylated hemoglobin (HbAlc), serum resistin (RESISTEIN), fasting insulin (FINS), superoxide dismutase (SOD), malondialdehyde (MDA), and nitric oxide (NO) as indicators, the hypoglycemic effects of different active parts of Anemarrhenae Rhizoma were evaluated. The chromatographic separation was performed on a Waters BEH C18 (2.1 mm × 50 mm, 1.7 μm) column using acetonitrile (B) and 0.1% formic acid in water (A) as mobile phases, and the flow rate was 0.3 ml/min. The column temperature was set as 28°C, and the injection volume was 10 μL. A mass spectrometer was connected to the UPLC system via an electrospray ionization (ESI) interface. Full-scan data acquisition was performed in the negative ion mode.

RESULT

In the study of pharmacodynamics, the hypoglycemic effect of Anemarrhenae Rhizoma stir-baked with salt water is better than that of Anemarrhenae Rhizoma and the hypoglycemic effect of ethanol extract of Anemarrhenae Rhizoma is more remarkable than that of the decoction. The measured components all have a good linear relationship within their respective linear ranges (r ≥ 0.9990); the average recovery rates are 98.86%-100.69%, RSD <2.90%. Compared with the raw Anemarrhenae Rhizoma, the contents of Timosaponin AIII, Timosaponin BII, Timosaponin BIII, Anemarrhenasaponin I, Anemarrhenasaponin Ia, and Mangiferin of Anemarrhenae Rhizoma stir-baked with salt water are all higher, the changes of Timosaponin AI and Anemarrhenasaponin AII are not obvious, and all the contents of chemical composition in the ethanol extract of Anemarrhenae Rhizoma and Anemarrhenae Rhizoma stir-baked with salt water were obviously higher compared with the water decoction.

CONCLUSION

The processing method, stir-baking with salt water, can increase the contents of active compositions in Anemarrhenae Rhizoma and strengthen the hypoglycemic effect. The ethanol extract of Anemarrhenae Rhizoma stir-baked with salt water is the better active site.

Carnosine, Small but Mighty-Prospect of Use as Functional Ingredient for Functional Food Formulation

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine's biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

The effect of probiotics on lipid profile & anthropometric indices in diabetic nephropathy; a systematic review and meta-analysis of clinical trials

Purpose

Recent trials have demonstrated the possible improvements in lipid profile & anthropometric indices after probiotics supplementation. We aimed to reanalyze the related literature to explore the efficacy of probiotics in Diabetic Nephropathy (DN) patients.

Methods

PubMed, Embase, Web of science, google scholar, Scopus, and Cochrane Library databases were systematically searched to find the related data on diabetic nephropathy population. All Randomized controlled trials (RCTs) that investigated the effect of probiotics on serum lipid markers (High-Density Lipoprotein [HDL], Triglyceride, Total Cholesterol, TC-to-HDL ratio, Low-Density Lipoprotein, Very Low-Density Lipoprotein) and anthropometric indices (Body Weight, Body Mass Index, waist-to-hip ratio) were included (PROSPERO No.CRD42020186189). Meta-analysis was performed using the random-effect model.

Results

Of 156 studies, seven were eligible for inclusion. Lipid biomarkers had a marginal reduction (except for HDL; WMD = 2.59 mg/dl; 95% CI = -0.28, 5.47; P = 0.077); whereas anthropometric indices increased in a non-significant manner.

Conclusion

There is limited evidence to support the efficacy of probiotics for the modulation of lipid profile and anthropometric indices in DN patients.

Graphical abstract

Probiotics did not beneficial effect on lipid profile & anthropometric markers in Diabetic Nephropathy; anyway, more trials should be conducted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00765-8.