Glycine is a conditionally essential amino acid that serves as both an inhibitory and excitatory neurotransmitter. It is the chemically simplest and most omnipresent of all the amino acids. It combines with many toxic substances, converting them to harmless forms which are then excreted.This amino acid has a calming effect on the brain and is also involved in growth.6-15 Research suggests that glycine may help promote deeper sleep. Glycine also has a positive impact on attention and memory in adults. Glycine may also help boost the immune defense system and has oxidative stress regulating effects.Most people need to take between one to three grams of glycine to be effective even though studies show high doses are safe. However, most glycine products are only available in 500 mg capsules. That makes taking higher doses cumbersome and costly. However, Life Extension's glycine comes in easy-to-swallow 1000-mg capsules.