Carnosine

Carnosine (β-alanyl-L-histidine) is a naturally occurring dipeptide composed of the amino acids beta-alanine and L-histidine. It is highly concentrated in muscle and brain tissues.

Occurrence and Distribution:

Carnosine is found in relatively high concentrations in skeletal muscle, heart, brain, and other excitable tissues. Its concentration varies depending on factors such as diet, age, muscle fiber type (higher in fast-twitch fibers), and training status. Carnosine is more abundant in animal tissues, particularly red meat, than in plant-based foods.

Synthesis and Metabolism:

Carnosine is synthesized in vivo by the enzyme carnosine synthetase (ATP:L-histidine beta-alanine ligase). The dipeptide is broken down by the enzyme carnosinase (CN1), with CN1 present in blood serum and various tissues except for muscle. Muscle tissue possesses a different carnosinase isoform (CN2) that is relatively insensitive to inhibition.

Physiological Functions:

Carnosine possesses a range of biological activities, including:

• Buffering capacity: Carnosine acts as a buffer in muscle tissue, helping to neutralize acidity produced during intense exercise. This buffering effect can delay muscle fatigue and improve performance.

• Antioxidant activity: Carnosine exhibits antioxidant properties, scavenging free radicals and protecting cells from oxidative stress.

• Metal chelation: Carnosine can bind to metal ions, such as copper and zinc, which may contribute to its antioxidant and neuroprotective effects.

• Anti-glycation activity: Carnosine can inhibit the formation of advanced glycation end-products (AGEs), which are implicated in aging and various diseases.

• Neuroprotective effects: Carnosine has shown potential neuroprotective properties in experimental models, possibly by reducing oxidative stress, excitotoxicity, and protein aggregation.

Dietary Supplementation:

Carnosine is available as a dietary supplement, often marketed to athletes and individuals seeking anti-aging benefits. Oral carnosine supplementation can increase carnosine levels in muscle tissue, although bioavailability can be variable. Beta-alanine supplementation is also used to increase muscle carnosine levels, as beta-alanine is the rate-limiting precursor for carnosine synthesis.

Research Areas:

Ongoing research is investigating the potential therapeutic applications of carnosine in various conditions, including:

• Neurodegenerative diseases (e.g., Alzheimer's disease, Parkinson's disease)
• Cardiovascular disease
• Diabetes and its complications
• Autism spectrum disorder
• Wound healing

Safety and Side Effects:

Carnosine is generally considered safe when taken as a dietary supplement at recommended doses. However, high doses may cause mild gastrointestinal discomfort in some individuals. There are no known significant drug interactions.