Beta-Alanine vs Glycine

Mechanism

Beta-alanine is the rate-limiting precursor for carnosine (beta-alanyl-L-histidine) synthesis in skeletal muscle. Carnosine functions as an intracellular pH buffer, neutralizing hydrogen ions (H+) produced during high-intensity exercise, delaying the onset of muscular fatigue from acidosis. Carnosine also acts as an antioxidant (scavenges reactive oxygen and nitrogen species), an anti-glycation agent (prevents AGE formation), and a metal ion chelator. Chronic supplementation increases muscle carnosine content by 40-80%, with greater accumulation in Type II (fast-twitch) muscle fibers.

Standard Dosing

3.2-6.4g daily

Timing

Timing relative to exercise does NOT matter — beta-alanine works by chronic muscle carnosine loading, not acute effects. Split into 800mg-1600mg doses throughout the day to reduce paresthesia. Sustained-release form allows larger single doses.

Cycle Duration

ongoing (carnosine washout occurs over 6-15 weeks after cessation)

Side Effects

• Paresthesia (tingling/itching of skin, especially face, neck, hands — caused by activation of MrgprD receptors on sensory neurons; dose-dependent, harmless, resolves in 60-90 min)
• Mild flushing
• GI upset at high single doses

Contraindications

• Very few. Paresthesia is a nuisance, not a safety concern.

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Mechanism

Glycine is the simplest amino acid with profound neurological and metabolic roles. It is an inhibitory neurotransmitter acting at glycine receptors (strychnine-sensitive) in the brainstem and spinal cord, inducing a drop in core body temperature that facilitates sleep onset. It is also an obligatory co-agonist at the NMDA receptor glycine binding site, modulating excitatory neurotransmission. Metabolically, glycine is the rate-limiting amino acid for glutathione synthesis (glutathione = glycine + cysteine + glutamate), a key substrate for collagen synthesis (every 3rd amino acid), essential for creatine synthesis, bile acid conjugation, heme synthesis, and one-carbon metabolism.

Standard Dosing

3-5g daily

Timing

3g before bed for sleep (core body temperature reduction). Divided doses during day for glutathione support. Powder in water has a mildly sweet taste.

Cycle Duration

ongoing

Side Effects

• Mild drowsiness
• Soft stools at high doses
• Nausea (rare)
• Generally extremely well-tolerated

Contraindications

• Very few absolute contraindications. Caution in severe renal disease.

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