Carnosine is a performance-enhancing food supplement with a potential to modulate muscle energy metabolism and toxic metabolites disposal. In this study we explored interrelations between carnosine supplementation (2 g/day, 12 weeks) induced effects on carnosine muscle loading and parallel changes in (i) muscle energy metabolism, (ii) serum albumin glycation and (iii) reactive carbonyl species sequestering in twelve (M/F=10/2) sedentary, overweight-to-obese (BMI: 30.0+/-2.7 kg/m2) adults (40.1+/-6.2 years). Muscle carnosine concentration (Proton Magnetic Resonance Spectroscopy; 1H-MRS), dynamics of muscle energy metabolism (Phosphorus Magnetic Resonance Spectroscopy; 31P-MRS), body composition (Magnetic Resonance Imaging; MRI), resting energy expenditure (indirect calorimetry), glucose tolerance (oGTT), habitual physical activity (accelerometers), serum carnosine and carnosinase-1 content/activity (ELISA), albumin glycation, urinary carnosine and carnosine-propanal concentration (mass spectrometry) were measured. Supplementation-induced increase in muscle carnosine was paralleled by improved dynamics of muscle post-exercise phosphocreatine recovery, decreased serum albumin glycation and enhanced urinary carnosine-propanal excretion (all p<0.05). Magnitude of supplementation-induced muscle carnosine accumulation was higher in individuals with lower baseline muscle carnosine, who had lower BMI, higher physical activity level, lower resting intramuscular pH, but similar muscle mass and dietary protein preference. Level of supplementation-induced increase in muscle carnosine correlated with reduction of protein glycation, increase in reactive carbonyl species sequestering, and acceleration of muscle post-exercise phosphocreatine recovery.

• MeSH
• Adult MeSH
• Phosphocreatine metabolism   MeSH
• Carnosine * metabolism   pharmacology   MeSH
• Muscle, Skeletal metabolism   MeSH
• Humans MeSH
• Maillard Reaction MeSH
• Dietary Supplements MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phosphocreatine MeSH
• Carnosine * MeSH
• propionaldehyde MeSH Browser

L-serine plays an essential role in a broad range of cellular functions including protein synthesis, neurotransmission, and folate and methionine cycles and synthesis of sphingolipids, phospholipids, and sulphur containing amino acids. A hydroxyl side-chain of L-serine contributes to polarity of proteins, and serves as a primary site for binding a phosphate group to regulate protein function. D-serine, its D-isoform, has a unique role. Recent studies indicate increased requirements for L-serine and its potential therapeutic use in some diseases. L-serine deficiency is associated with impaired function of the nervous system, primarily due to abnormal metabolism of phospholipids and sphingolipids, particularly increased synthesis of deoxysphingolipids. Therapeutic benefits of L-serine have been reported in primary disorders of serine metabolism, diabetic neuropathy, hyperhomocysteinemia, and amyotrophic lateral sclerosis. Use of L-serine and its metabolic products, specifically D-serine and phosphatidylserine, has been investigated for the therapy of renal diseases, central nervous system injury, and in a wide range of neurological and psychiatric disorders. It is concluded that there are disorders in which humans cannot synthesize L-serine in sufficient quantities, that L-serine is effective in therapy of disorders associated with its deficiency, and that L-serine should be classified as a "conditionally essential" amino acid.

• Keywords
• deoxysphingolipids, diabetes, glycine, hyperhocysteinemia, neuropathy, serine supplementation,
• MeSH
• Amino Acids, Essential MeSH
• Phospholipids MeSH
• Humans MeSH
• Serine * MeSH
• Sphingolipids metabolism   MeSH
• Amino Acid Metabolism, Inborn Errors * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Amino Acids, Essential MeSH
• Phospholipids MeSH
• Serine * MeSH
• Sphingolipids MeSH

The aim of the article is to examine side effects of increased dietary intake of amino acids, which are commonly used as a dietary supplement. In addition to toxicity, mutagenicity and carcinogenicity, attention is focused on renal and gastrointestinal tract functions, ammonia production, and consequences of a competition with other amino acids for a carrier at the cell membranes and enzymes responsible for their degradation. In alphabetic order are examined arginine, beta-alanine, branched-chain amino acids, carnosine, citrulline, creatine, glutamine, histidine, beta -hydroxy- beta -methylbutyrate, leucine, and tryptophan. In the article is shown that enhanced intake of most amino acid supplements may not be risk-free and can cause a number of detrimental side effects. Further research is necessary to elucidate effects of high doses and long-term consumption of amino acid supplements on immune system, brain function, muscle protein balance, synthesis of toxic metabolites, and tumor growth and examine their suitability under certain circumstances. These include elderly, childhood, pregnancy, nursing a baby, and medical condition, such as diabetes and liver disease. Studies are also needed to examine adaptive response to a long-term intake of any substance and consequences of discontinuation of supplementation.

• MeSH
• Amino Acids adverse effects   metabolism   MeSH
• Arginine pharmacology   MeSH
• Child MeSH
• Glutamine * metabolism   pharmacology   MeSH
• Histidine metabolism   MeSH
• Muscle, Skeletal metabolism   MeSH
• Humans MeSH
• Dietary Supplements * adverse effects   MeSH
• Aged MeSH
• Pregnancy MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Aged MeSH
• Pregnancy MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Amino Acids MeSH
• Arginine MeSH
• Glutamine * MeSH
• Histidine MeSH

Histidine (HIS) is an essential amino acid investigated for therapy of various diseases, used for tissue protection in transplantation and cardiac surgery, and as a supplement to increase muscle performance. The data presented in the review show that HIS administration may increase ammonia and affect the level of several amino acids. The most common are increased levels of alanine, glutamine, and glutamate and decreased levels of glycine and branched-chain amino acids (BCAA, valine, leucine, and isoleucine). The suggested pathogenic mechanisms include increased flux of HIS through HIS degradation pathway (increases in ammonia and glutamate), increased ammonia detoxification to glutamine and exchange of the BCAA with glutamine via L-transporter system in muscles (increase in glutamine and decrease in BCAA), and tetrahydrofolate depletion (decrease in glycine). Increased alanine concentration is explained by enhanced synthesis in extrahepatic tissues and impaired transamination in the liver. Increased ammonia and glutamine and decreased BCAA levels in HIS-treated subjects indicate that HIS supplementation is inappropriate in patients with liver injury. The studies investigating the possibilities to elevate carnosine (beta-alanyl-L-histidine) content in muscles show positive effects of beta-alanine and inconsistent effects of HIS supplementation. Several studies demonstrate HIS depletion due to enhanced availability of methionine, glutamine, or beta-alanine.

• MeSH
• Amino Acids metabolism   MeSH
• Ammonia metabolism   MeSH
• Histidine pharmacology   MeSH
• Liver drug effects   metabolism   MeSH
• Muscle, Skeletal drug effects   metabolism   MeSH
• Humans MeSH
• Dietary Supplements MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Amino Acids MeSH
• Ammonia MeSH
• Histidine MeSH

L-histidine (HIS) is an essential amino acid with unique roles in proton buffering, metal ion chelation, scavenging of reactive oxygen and nitrogen species, erythropoiesis, and the histaminergic system. Several HIS-rich proteins (e.g., haemoproteins, HIS-rich glycoproteins, histatins, HIS-rich calcium-binding protein, and filaggrin), HIS-containing dipeptides (particularly carnosine), and methyl- and sulphur-containing derivatives of HIS (3-methylhistidine, 1-methylhistidine, and ergothioneine) have specific functions. The unique chemical properties and physiological functions are the basis of the theoretical rationale to suggest HIS supplementation in a wide range of conditions. Several decades of experience have confirmed the effectiveness of HIS as a component of solutions used for organ preservation and myocardial protection in cardiac surgery. Further studies are needed to elucidate the effects of HIS supplementation on neurological disorders, atopic dermatitis, metabolic syndrome, diabetes, uraemic anaemia, ulcers, inflammatory bowel diseases, malignancies, and muscle performance during strenuous exercise. Signs of toxicity, mutagenic activity, and allergic reactions or peptic ulcers have not been reported, although HIS is a histamine precursor. Of concern should be findings of hepatic enlargement and increases in ammonia and glutamine and of decrease in branched-chain amino acids (valine, leucine, and isoleucine) in blood plasma indicating that HIS supplementation is inappropriate in patients with liver disease.

• Keywords
• Bretschneider’s solution, HTK solution, ammonia, beta-alanine, branched-chain amino acids, carnosine, glutamine, histidine supplementation,
• MeSH
• Ammonia metabolism   MeSH
• Dermatitis, Atopic therapy   MeSH
• Chelating Agents MeSH
• Filaggrin Proteins MeSH
• Glutamine metabolism   MeSH
• Histamine MeSH
• Histidine * adverse effects   chemistry   physiology   therapeutic use   MeSH
• Hypertrophy etiology   MeSH
• Liver metabolism   pathology   MeSH
• Contraindications MeSH
• Humans MeSH
• Metabolic Syndrome therapy   MeSH
• Liver Diseases metabolism   MeSH
• Nervous System Diseases therapy   MeSH
• Dietary Supplements * MeSH
• Organ Preservation Solutions MeSH
• Free Radical Scavengers MeSH
• Amino Acids, Branched-Chain metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Ammonia MeSH
• Chelating Agents MeSH
• Filaggrin Proteins MeSH
• FLG protein, human MeSH Browser
• Glutamine MeSH
• Histamine MeSH
• Histidine * MeSH
• Organ Preservation Solutions MeSH
• Free Radical Scavengers MeSH
• Amino Acids, Branched-Chain MeSH