L-Phenylalanine L-phenylalanine is an essential amino acid, meaning the body cannot produce it on its own and must obtain it through diet. It plays a foundational role in neurotransmitter production, mood balance, and cognitive performance. Because it directly influences brain chemistry, L-phenylalanine is often discussed in the context of mental clarity, stress resilience, and emotional regulation. How L-Phenylalanine Works in the Body L-phenylalanine acts as a precursor to
