Phenylalanine is an essential amino acid that cannot be synthesized by the body , so it must be obtained through our diet as it is converted into another amino acid, Tyrosine, which in turn is used by the body to produce a class of neurotransmitters called catecholamines, which include adrenaline, noradrenaline and dopamine. Phenylalanine exists in two forms, L-Phenylalanine , which is a natural amino acid found in proteins, and D-Phenylalanine, which can be produced in a laboratory without being an essential nutrient for our body. Finally, it is a precursor to the neurotransmitters – adrenaline, noradrenaline and dopamine, which are important for alertness, memory retention and coordination of muscle movements. LambertsL-Phenylalanine is presented in its free form to achieve optimal absorption.