Taurine vs Glycine: The Winner Surprised Me!

The video introduces a comparison between Taurine and Glycine, two amino acids with thousands of studies supporting their safety and effectiveness. Taurine is a sulfonic acid, not a true amino acid, accumulating in the heart, brain, retina, and muscles, acting as an osmolite, calcium buffer, mitochondrial cofactor, and antioxidant. Glycine, the simplest amino acid, is crucial for protein synthesis (especially collagen), glutathione, creatine, heme, purines, and bile acids, and functions as a neurotransmitter.

Taurine shows a significant advantage in cardiovascular health, having been approved in Japan since 1985 for treating congestive heart failure. Meta-analyses demonstrate taurine's ability to reduce heart rate and blood pressure, improve left ventricular ejection fraction, and enhance heart failure patient classification. Glycine also offers cardiovascular benefits by modulating inflammation and supporting nitric oxide synthesis, but its evidence base is smaller compared to taurine.

Glycine outperforms taurine in improving sleep. Studies show that glycine taken before bed can shorten sleep onset latency, improve subjective sleep quality, reduce daytime sleepiness, and enhance memory performance the next day. Glycine achieves this by acting on NMDA receptors in the superchiasmatic nucleus, triggering vasodilation and a core body temperature drop, which signals the brain to initiate sleep. While taurine has calming effects, human trials indicate glycine is a stronger fit for sleep improvement.

Both amino acids support mitochondrial function but through different pathways. Taurine works directly within the mitochondria, while glycine supports glutathione synthesis, the body's master antioxidant. The GLYAC (glycine and N-acetylcysteine) trial showed that supplementation in older adults restored intracellular glutathione, reduced oxidative stress and inflammation, improved mitochondrial function, insulin resistance, endothelial function, muscular strength, and cognition.

Taurine has a stronger evidence base for acute exercise performance, with meta-analyses showing improvements in aerobic endurance, strength, power, and agility. Glycine has an emerging role in enhancing peak power output, reducing lactic acid, supporting muscle protein synthesis, and improving recovery, particularly through its role in collagen synthesis for connective tissue support. The combination of collagen/gelatin (rich in glycine) with vitamin C significantly boosts collagen synthesis in tendons and ligaments.

Both play distinct roles. Glycine acts as a direct neurotransmitter and co-agonist at the NMDA receptor, explaining its effect on memory consolidation and potential in schizophrenia treatment. Taurine modulates the brain, acting as gabaurgic and glycinERGIC, protecting against glutamate excitotoxicity, and smoothing out caffeine's jittery effects. The verdict is an even split, with glycine for sleep-related cognition and NMDA function, and taurine for daytime nervous system modulation and stress.

Glycine's longevity case is arguably stronger. While taurine's impact on human longevity biomarkers is now uncertain, glycine's benefits include mimicking methionine restriction, improving multiple hallmarks of aging in the GLYAC trial, and supporting collagen synthesis, which declines with age. Glycine is a rate-limiting step for collagen production, making it crucial for age-related tissue health.

The speaker advises that both amino acids are beneficial. Taurine is generally preferred during the daytime, while glycine is better before sleep, though some may find glycine keeps them awake due to conversion to glutamate. Recommended dosages are 5-6g of taurine daily and 3-6g of glycine daily, with suggestions to split doses to avoid GI side effects.