L-Phenylalanine is an amino acid that can be found in foods like cheese, poultry, fish and eggs. L-Phenylalanine is used as a dietary supplement to treat some medical conditions like depression and attention deficit hyperactivity disorder (ADHD).


L-Phenylalanine is a non-essential amino acid, which means that it can be synthesized by the body from other amino acids. L-Phenylalanine was discovered by William J. Jacobs in 1906 and its structure was determined in 1908 by Felix Ehrlich. L-Phenylalanine is an essential amino acid for humans and other mammals that cannot synthesize its own supply of phenylalanine. It is also an important precursor to the neurotransmitters norepinephrine (noradrenaline), dopamine, and tyrosine; these neurotransmitters are used in mood control and focus.


L-phenylalanine is the precursor to L-tyrosine, an amino acid that helps with cognitive function. It can also help with mood, sleep and weight loss by increasing your body's production of dopamine, norepinephrine, epinephrine and other neurotransmitters that regulate mood, energy levels and appetite. It's also been shown to reduce depression symptoms caused by low serotonin levels.

As a precursor to phenylalanine hydroxylase (the enzyme responsible for converting tyrosine into L-DOPA), it can also help treat ADHD symptoms such as inattention/concentration issues or hyperactivity/restlessness.


L-Phenylalanine helps the body produce other amino acids, which are the building blocks of proteins in the body. It's generally considered safe for healthy individuals, although it's important that those with phenylketonuria (PKU) keep their intake low to avoid potentially dangerous side effects.


L-phenylalanine has been shown to have many health benefits and may help improve some symptoms associated with depression and anxiety disorders, such as mood swings or lack of motivation.