D-Alanine
Alanine is basically a non-essential amino acid sometimes found in high levels in its free state in human plasma. This amino acid is synthesized by reductive amination of pyruvate, and participates in sugar and acid metabolism. It is also known for increasing immunity and providing energy for brain and central nervous system, let alone the muscle tissue. In addition, Alanine plays a central role in glucose-Alanine cycle taking place between tissues and liver.