L-Carnosine — The Anti-Glycation Dipeptide
L-carnosine is a naturally occurring dipeptide composed of beta-alanine and L-histidine, highly concentrated in muscle and brain tissue. It is valued in longevity for its ability to inhibit the formation of advanced glycation end-products (AGEs) and protect cellular proteins from oxidative damage.
Mechanism of Action
L-carnosine acts as a potent scavenger of reactive oxygen species (ROS) and a sacrificial peptide that binds to reactive aldehydes, preventing them from cross-linking with structural proteins to form advanced glycation end-products (AGEs). By buffering intracellular pH and chelating transition metals like copper and zinc, it mitigates oxidative stress. Furthermore, carnosine has been shown to upregulate the Keap1/Nrf2 signaling pathway, enhancing endogenous antioxidant defenses, and may modulate mTOR activity to promote cellular homeostasis.
Human Trial Evidence
Human evidence for L-carnosine primarily focuses on age-related metabolic and cognitive decline rather than lifespan extension. Clinical trials have demonstrated that oral supplementation can improve glycemic control, reduce markers of oxidative stress, and support cognitive function in older adults. No published human longevity trials exist; direct lifespan evidence is limited to animal and in-vitro models.
Dosing Protocol
500–1,000 mg/day is the standard oral dose used in clinical studies, typically divided into two doses to counteract rapid degradation by the serum enzyme carnosinase. Some protocols combine it with beta-alanine to further boost intracellular carnosine levels.
Safety & Contraindications
L-carnosine is generally recognized as safe and well-tolerated at standard doses. Mild side effects can include gastrointestinal discomfort or overstimulation if taken late in the day. It has no major known contraindications, though its safety in pregnancy and breastfeeding remains unestablished.