Amino Acids Why Essential Amino Acids Matter Proteins are built from amino acids, but not all amino acids are created equal. Your body can produce many of them on its own. However, nine amino acids must come from food  — these are called essential amino acids (EAAs) . Without adequate intake, key biological systems begin to suffer: Muscle repair slows Hormone production shifts Neurotransmitter balance changes Immune resilience declines Let’s break them down. 🔹 1. Histidine S