Healthwise L-Tyrosine Powder 300g is 100% pure L-Tyrosine Powder packed without fillers or flowing agents. Tyrosine is a natural amino acid - one of the building blocks of protein. It plays an important role as a precursor to various neurotransmitters and hormones found in the human brain. These neurotransmitters are required for concentration, alertness, memory and a happy, stable mood. Tyrosine is required for the manufacture of thyroid hormones.