Threonine is an essential amino acid.  Threonine is an amino acid that the body uses to build proteins. Foods high in threonine include poultry, fish, cottage cheese, meat, lentils, black turtle beans, and sesame seeds.  Threonine is used to treat various nervous system disorders including spinal spasticity, multiple sclerosis, familial spastic paraparesis, and amyotrophic lateral sclerosis  (ALS, Lou Gehrig’s disease).