Acute balenine supplementation in humans as a natural carnosinase-resistant alternative to carnosine.

Balenine possesses some of carnosine's and anserine's functions, yet it appears more resistant to the hydrolysing CN1 enzyme. The aim of this study was to elucidate the stability of balenine in the systemic circulation and its bioavailability in humans following acute supplementation. Two experiments were conducted in which (in vitro) carnosine, anserine and balenine were added to plasma to compare degradation profiles and (in vivo) three increasing doses (1-4-10 mg/kg) of balenine were acutely administered to 6 human volunteers. Half-life of balenine (34.9 ± 14.6 min) was respectively 29.1 and 16.3 times longer than that of carnosine (1.20 ± 0.36 min, p = 0.0044) and anserine (2.14 ± 0.58 min, p = 0.0044). In vivo, 10 mg/kg of balenine elicited a peak plasma concentration (Cmax) of 28 µM, which was 4 and 18 times higher than with 4 (p = 0.0034) and 1 mg/kg (p = 0.0017), respectively. CN1 activity showed strong negative correlations with half-life (ρ = - 0.829; p = 0.0583), Cmax (r = - 0.938; p = 0.0372) and incremental area under the curve (r = - 0.825; p = 0.0433). Overall, balenine seems more resistant to CN1 hydrolysis resulting in better in vivo bioavailability, yet its degradation remains dependent on enzyme activity. Although a similar functionality as carnosine and anserine remains to be demonstrated, opportunities arise for balenine as nutraceutical or ergogenic aid.

Effects of dietary ß-alanine supplementation on growth performance, meat quality, carnosine content, amino acid composition and muscular antioxidant capacity in Chinese indigenous Ningxiang pig.

ß-alanine has been demonstrated to improve carcass traits and meat quality of animals. However, no research has been found on the effects of dietary ß-alanine in the meat quality control of finishing pigs, which are among the research focus. Therefore, this study aimed to evaluate the effects of dietary ß-alanine supplementation on growth performance, meat quality, carnosine content, amino acid composition and muscular antioxidant capacity of Chinese indigenous Ningxiang pigs. The treatments contained a basal diet (control, CON) and a basal diet supplemented with 600 mg/kg ß-alanine. Each treatment group consisted of five pens, with five pigs per pen. Results showed that compared with CON, supplemental ß-alanine did not affect the final body weight, average daily gain, average daily feed intake and the feed-to-gain ratio of pigs. Dietary ß-alanine supplementation tended to increase the pH45 min (p = 0.071) while decreasing the shear force (p = 0.085) and the drip loss (p = 0.091). Moreover, it improved (p < 0.05) the activities of glutathione peroxidase and catalase and lessened (p < 0.05) malondialdehyde concentration. Added ß-alanine in diets of finishing pigs could enhance the concentrations of arginine, alanine, and glutamate (p < 0.05) in the longissimus dorsi muscle and tended to raise the levels of cysteine, glycine and anserine (p = 0.060, p = 0.098 and p = 0.091 respectively). Taken together, our results showed that dietary ß-alanine supplementation contributed to the improvement of the carcass traits, meat quality and anserine content, the amelioration of muscle antioxidant capacity and the regulation of amino acid composition in Chinese indigenous Ningxiang pigs.

A metabolomics comparison of plant-based meat and grass-fed meat indicates large nutritional differences despite comparable Nutrition Facts panels.

A new generation of plant-based meat alternatives-formulated to mimic the taste and nutritional composition of red meat-have attracted considerable consumer interest, research attention, and media coverage. This has raised questions of whether plant-based meat alternatives represent proper nutritional replacements to animal meat. The goal of our study was to use untargeted metabolomics to provide an in-depth comparison of the metabolite profiles a popular plant-based meat alternative (n = 18) and grass-fed ground beef (n = 18) matched for serving size (113 g) and fat content (14 g). Despite apparent similarities based on Nutrition Facts panels, our metabolomics analysis found that metabolite abundances between the plant-based meat alternative and grass-fed ground beef differed by 90% (171 out of 190 profiled metabolites; false discovery rate adjusted p < 0.05). Several metabolites were found either exclusively (22 metabolites) or in greater quantities in beef (51 metabolites) (all, p < 0.05). Nutrients such as docosahexaenoic acid (ω-3), niacinamide (vitamin B3), glucosamine, hydroxyproline and the anti-oxidants allantoin, anserine, cysteamine, spermine, and squalene were amongst those only found in beef. Several other metabolites were found exclusively (31 metabolites) or in greater quantities (67 metabolites) in the plant-based meat alternative (all, p < 0.05). Ascorbate (vitamin C), phytosterols, and several phenolic anti-oxidants such as loganin, sulfurol, syringic acid, tyrosol, and vanillic acid were amongst those only found in the plant-based meat alternative. Large differences in metabolites within various nutrient classes (e.g., amino acids, dipeptides, vitamins, phenols, tocopherols, and fatty acids) with physiological, anti-inflammatory, and/or immunomodulatory roles indicate that these products should not be viewed as truly nutritionally interchangeable, but could be viewed as complementary in terms of provided nutrients. The new information we provide is important for making informed decisions by consumers and health professionals. It cannot be determined from our data if either source is healthier to consume.

Carnosine and anserine homeostasis in skeletal muscle and heart is controlled by ß-alanine transamination.

KEY POINTS: Using recombinant DNA technology, the present study provides the first strong and direct evidence indicating that ß-alanine is an efficient substrate for the mammalian transaminating enzymes 4-aminobutyrate-2-oxoglutarate transaminase and alanine-glyoxylate transaminase. The concentration of carnosine and anserine in murine skeletal and heart muscle depends on circulating availability of ß-alanine, which is in turn controlled by degradation of ß-alanine in liver and kidney. Chronic oral ß-alanine supplementation is a popular ergogenic strategy in sports because it can increase the intracellular carnosine concentration and subsequently improve the performance of high-intensity exercises. The present study can partly explain why the ß-alanine supplementation protocol is so inefficient, by demonstrating that exogenous ß-alanine can be effectively routed toward oxidation. ABSTRACT: The metabolic fate of orally ingested ß-alanine is largely unknown. Chronic ß-alanine supplementation is becoming increasingly popular for improving high-intensity exercise performance because it is the rate-limiting precursor of the dipeptide carnosine (ß-alanyl-l-histidine) in muscle. However, only a small fraction (3-6%) of the ingested ß-alanine is used for carnosine synthesis. Thus, the present study aimed to investigate the putative contribution of two ß-alanine transamination enzymes, namely 4-aminobutyrate-2-oxoglutarate transaminase (GABA-T) and alanine-glyoxylate transaminase (AGXT2), to the homeostasis of carnosine and its methylated analogue anserine. We found that, when transfected into HEK293T cells, recombinant mouse and human GABA-T and AGXT2 are able to transaminate ß-alanine efficiently. The reaction catalysed by GABA-T is inhibited by vigabatrin, whereas both GABA-T and AGXT2 activity is inhibited by aminooxyacetic acid (AOA). Both GABA-T and AGXT2 are highly expressed in the mouse liver and kidney and the administration of the inhibitors effectively reduced their enzyme activity in liver (GABA-T for vigabatrin; GABA-T and AGXT2 for AOA). In vivo, injection of AOA in C57BL/6 mice placed on ß-alanine (0.1% w/v in drinking water) for 2 weeks lead to a 3-fold increase in circulating ß-alanine levels and to significantly higher levels of carnosine and anserine in skeletal muscle and heart. By contrast, specific inhibition of GABA-T by vigabatrin did not affect carnosine and anserine levels in either tissue. Collectively, these data demonstrate that homeostasis of carnosine and anserine in mammalian skeletal muscle and heart is controlled by circulating ß-alanine levels, which are suppressed by hepatic and renal ß-alanine transamination upon oral ß-alanine intake.

Antioxidant status of turkey breast meat and blood after feeding a diet enriched with histidine.

The objective of this study was to investigate the effects of 1) spray dried blood cells rich in histidine and 2) pure histidine added to feed on the antioxidant status and concentration of carnosine related components in the blood and breast meat of female turkeys. The experiment was performed on 168 Big7 turkey females randomly assigned to 3 dietary treatments: control; control with the addition of 0.18% L-histidine (His); and control with the addition of spray dried blood cells (SDBC). Birds were raised for 103 d on a floor with sawdust litter, with drinking water and feed ad libitum. The antioxidant status of blood plasma and breast muscle was analyzed by ferric reducing ability (FRAP) and by 2,2-Azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging ability. The activity of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) was analyzed in the blood and breast meat, with the content of carnosine and anserine quantified by HPLC. Proximate analysis as well as amino acid profiling were carried out for the feed and breast muscles. Growth performance parameters also were calculated. Histidine supplementation of the turkey diet resulted in increased DPPH radical scavenging capacity in the breast muscles and blood, but did not result in higher histidine dipeptide concentrations. The enzymatic antioxidant system of turkey blood was affected by the diet with SDBC. In the plasma, the SDBC addition increased both SOD and GPx activity, and decreased GPx activity in the erythrocytes. Feeding turkeys with an SDBC containing diet increased BW and the content of isoleucine and valine in breast muscles.

ß-Alanine as a factor influencing the content of bioactive dipeptides in muscles of Hubbard Flex chickens.

BACKGROUND: The aim of this study was to determine the effect of various doses of ß-alanine administered in feed mixtures and of heat treatment on changes in the contents of dipeptides anserine and carnosine in meat of fast-growing Hubbard Flex chickens. RESULTS: The study demonstrated a significant effect of dietary administration of ß-alanine on anserine content in breast muscles and on carnosine content in leg muscles of the chickens. A successive increase in dipeptide content was observed with increasing ß-alanine content in the feed mixture. As a result of heat treatment, a significant (P ≤ 0.01) increase was observed in the anserine content of both breast and leg muscles: over twofold higher anserine content was detected in heat-treated muscles compared with raw muscles. The study showed that interesting effects might occur during ß-alanine administration to feed mixtures for chickens, especially including increased contents of anserine and carnosine in skeletal muscles of the birds. CONCLUSION: Taking into account the well-documented health-promoting effect of histidine dipeptides and possibilities of increasing their contents in the body by supplementation with ß-alanine, anserine and carnosine might be considered as potential components of functional foods.

Effect of dietary histidine on contents of carnosine and anserine in muscles of broilers.

Carnosine (ß-alanyl-L-histidine) and anserine (ß-alanyl-1-methyl-L-histidine) are dipeptides mainly found in skeletal muscle and brain of many vertebrates, and particularly high concentrations are observed in chicken pectoral muscles. It was reported that these peptides have many functions, such as antioxidant activity. In this study, we examined the effect of different levels of dietary histidine on carnosine and anserine contents in broiler muscles. The 14-days-old female Chunky strain broilers were given feeds containing three different levels of histidine; 67% (Low-His), 100% (Control) and 200% (High-His) of histidine requirement according to the NRC (1994). Chicks were fed experimental diets for 10 days. Both dipeptides in muscle were significantly decreased. In particular, carnosine was not detected at all in the Low-His group and was significantly increased in the High-His group. Both dipeptides were not detected in plasma. These results indicated the possibility to produce chicken meat with enhanced amount of these dipeptides by high histidine feeding.

Effect of beta-alanine and carnosine supplementation on muscle contractility in mice.

PURPOSE: Enhanced carnosine levels have been shown to be ergogenic for high-intensity exercise performances, although the role of carnosine in the control of muscle function is poorly understood. Therefore, the aim of this study was to investigate the effect of long-term supplementation with increasing doses of carnosine and beta-alanine on muscle carnosine, anserine, and taurine levels and on in vitro contractility and fatigue in mice. METHODS: Male Naval Medical Research Institute mice (n = 66) were control fed or supplemented with either carnosine (0.1%, 0.5%, or 1.8%) or beta-alanine (0.6 or 1.2%) in their drinking water for 8-12 wk. Soleus and extensor digitorum longus (EDL) were tested for in vitro contractile properties, and carnosine, anserine, and taurine content were measured in EDL and tibialis anterior by high-performance liquid chromatography. RESULTS: Only supplementation with 1.8% carnosine and 1.2% beta-alanine resulted in markedly higher carnosine (up to +160%) and anserine levels (up to +46%) compared with control mice. Beta-alanine supplementation (1.2%) resulted in increased fatigue resistance in the beginning of the fatigue protocol in soleus (+2%-4%) and a marked leftward shift of the force-frequency relation in EDL (10%-31% higher relative forces). CONCLUSION: Comparable with humans, beta-alanine availability seems to be the rate-limiting step for synthesis of muscle histidine-containing dipeptides in mice. Moreover, muscle histidine-containing dipeptides loading in mice moderately and muscle dependently affects excitation-contraction coupling and fatigue.

Oral administration of chicken breast extract increases brain carnosine and anserine concentrations in rats.

Carnosine (beta-alanyl-L-histidine) and its derivative anserine (beta-alanyl-1-methyl-L-histidine) are antioxidants and putative neurotransmitters in the brain. These dipeptides are rich in the commercially available supplement chicken breast extract (CBEX). To clarify the effects of CBEX on the brain, we examined whether single oral administration of CBEX (20 ml/kg) affects brain dipeptide and free amino acid concentrations in male Wistar rats. CBEX significantly and time-dependently increased carnosine and anserine levels in the plasma (at 120 min after injection, increase rates were 2976 and 4142%, respectively), hippocampus (64 and 78%), and hypothalamus (188 and 120%), but not in cerebral cortex. Significant and time-dependent increases in citrulline in the hippocampus (49%) and hypothalamus (41%) demonstrated generation of nitric oxide due to the increased carnosine and/or anserine levels in these brain regions. These findings suggest that CBEX modifies brain functions by increasing levels of these dipeptides.

Histidine nutrition and genotype affect cataract development in Atlantic salmon, Salmo salar L.

The aim of this study was to investigate effects of dietary levels of histidine (His) and iron (Fe) on cataract development in two strains of Atlantic salmon monitored through parr-smolt transformation. Three experimental diets were fed: (i) a control diet (CD) with 110 mg kg(-1) Fe and 11.7 g kg(-1) His; (ii) CD supplemented with crystalline His to a level of 18 g kg(-1) (HD); and (iii) HD with added iron up to 220 mg kg(-1) (HID). A cross-over design, with two feeding periods was used. A 6-week freshwater (FW) period was followed by a 20-week period, of which the first three were in FW and the following 17 weeks in sea water (SW). Fish were sampled for weighing, cataract assessment and tissue analysis at five time points. Cataracts developed in all groups in SW, but scores were lower in those fed high His diets (P < 0.05). This effect was most pronounced when HD or HID was given in SW, but was also observed when these diets were given in FW only. Histidine supplementation had a positive effect on growth performance and feed conversion ratio (P < 0.05), whereas this did not occur when iron was added. Groups fed HD or HID had higher lens levels of His and N-acetyl histidine (NAH), the latter showing a marked increase post-smoltification (P < 0.05). The HD or HID groups also showed higher muscle concentrations of the His dipeptide anserine (P < 0.05). There was a strong genetic influence on cataract development in the CD groups (P < 0.001), not associated with tissue levels of His or NAH. The role of His and His-related compounds in cataractogenesis is discussed in relation to tissue buffering, osmoregulation and antioxidation.