Action and Occurrence of Carnosine

From a biochemical standpoint, carnosine is categorized as a non-proteinogenic dipeptide whose molecular framework is composed of two essential amino acids: β-alanine and L-histidine. Its systematic chemical designation—β-alanyl-L-histidine dipeptide—precisely reflects the constituent elements of this compound. Within the human body, carnosine fulfills a critical metabolic role, with its serum concentration subject to modulation based on dietary patterns and overall nutritional status. It ranks among the predominant endogenous dipeptides while simultaneously serving as the primary non-protein nitrogenous compound localized in skeletal muscle tissue. Quantitative estimates suggest that carnosine constitutes approximately 0.2% to 0.5% of the total mass of skeletal musculature. Notably, the distribution of carnosine extends beyond the muscular system, as this compound is also present in structures of the central nervous system, where elevated concentrations are particularly observed in glial cells (which form a vital supportive component of the brain) and in olfactory neurons responsible for processing scent stimuli. It is important to emphasize, however, that advancing age is associated with a physiological decline in carnosine levels across tissues, a phenomenon that may carry implications for organismal function.

The β-alanyl-L-histidine dipeptide known as carnosine exhibits a multifaceted array of health-promoting biological activities, substantiated through both *in vitro* cell culture models and human *in vivo* investigations. While its antioxidant capacity is modest compared to that of vitamin C or α-tocopherol (vitamin E), carnosine effectively neutralizes a spectrum of reactive oxygen and nitrogen species—including hydroxyl radicals, superoxide anions, singlet oxygen, and chloramines—thereby safeguarding cellular membrane lipids from peroxidative damage. Beyond its direct antioxidant role, carnosine acts as a "scavenger" of oxidative stress byproducts that, upon adduct formation with DNA, proteins, and lipoproteins, disrupt their structural integrity and induce cellular toxicity. Given its dual capacity to mitigate carbonyl and oxidative stress, carnosine is under scrutiny as a prospective therapeutic agent for neurodegenerative disorders (e.g., Alzheimer’s disease, Parkinson’s disease, autism spectrum conditions), metabolic dysregulations (diabetic complications), and cardiovascular pathologies (atherosclerosis, hypertension, myocardial infarction). In sports science, carnosine facilitates the repair of exercise-induced muscle fiber microtrauma, enhances contractile strength and endurance in skeletal muscles—as demonstrated in amphibian muscle stimulation experiments—and may attenuate cellular senescence via telomere-lengthening mechanisms, as suggested by research conducted by Shao and colleagues.

Carnosine, a non-protein dipeptide with a broad spectrum of health-promoting properties, is predominantly found in animal tissues—both in mammalian muscle and in fish, particularly fatty species rich in omega-3 fatty acids such as salmon, mackerel, and herring. Its endogenous synthesis within the human body is directly dependent on the availability of two key amino acids: histidine, which is present in high concentrations in foods such as oily marine fish (e.g., salmon, tuna), aged hard cheeses (e.g., cheddar, gouda), legumes (lentils, beans, peas), and red beef and pork; and beta-alanine, primarily sourced from high-protein foods, including lean and fatty poultry, chicken eggs, cow’s milk and its derivatives (yogurt, kefir, cottage cheese), as well as oilseeds (sunflower seeds, flaxseeds) and legumes. It is critical to note that while carnosine can be synthesized internally, its levels in tissues and bodily fluids (e.g., skeletal muscle, brain, blood plasma) increase substantially with the consumption of foods containing these precursors. Plant-based sources of histidine and beta-alanine—such as sesame, poppy seeds, peanuts, almonds, and pumpkin seeds—not only provide these essential amino acids but also supply unsaturated fatty acids, B vitamins, and trace minerals (magnesium, zinc, selenium), further enhancing antioxidant defenses. Due to its ability to chelate transition metal ions, scavenge reactive oxygen species, and inhibit the formation of advanced glycation end-products (AGEs), carnosine plays a pivotal role in preventing diseases associated with oxidative and carbonyl stress, including neurodegenerative disorders (e.g., Alzheimer’s disease), metabolic conditions (e.g., type 2 diabetes), and cardiovascular diseases. Therefore, a balanced diet incorporating both animal and plant-based sources of these amino acids may serve as a vital component of preventive healthcare strategies.