L-tryptophan is an essential amino acid that helps the body make proteins and certain brain-signaling chemicals. Your body changes L-tryptophan into a brain chemical called serotonin. Serotonin ...

L-glutamine is the supplement form of the amino acid glutamine. It can boost your gut health, aid wound healing, combat stress, and more, according to experts.

L-theanine is a natural compound that is present in green tea and black tea. It is considered generally safe and has some possible health benefits.

L-arginine is one form of arginine, an amino acid that is one of the building blocks of protein. Arginine is a non-essential amino acid because most humans can make it in their bodies.

Medicare Supplement Plan L is 1 of 10 Medigap plans. It helps cover many of the gaps in your Original Medicare coverage, and it caps your annual out-of-pocket costs related to Medicare.