Are you in need of a naturally occurring non-essential amino acid which is not used in protein synthesis, It seems like there's a product on which you haven't tried out yet. The product is L-Citrulline by Now Foods. L-Citrulline is useful in the formation of urea in the liver. The synthesis and elimination of urea are essential for removing toxic protein metabolites from the body. This also facilitates protein synthesis for muscle tissue retention and helps to maintain healthy protein balance. Natural color variation may occur in this product.