The order of toxicity is

The order of toxicity is Methionine > Tyrosine > Threonine.
Too much methionine can cause brain damage and death. Methionine can increase blood levels of homocysteine, a chemical that may cause heart disease, and might also promote the growth of some Tumors.
Tyrosine is possibly safe when taken as a medicine, short-term. It seems to be safe when taken in doses of up to 150 mg/kg daily for up to 3 months. Some people experience side effects such as nausea, headache, fatigue, and heartburn.
Threonine is an essential amino acid not known to cause any adverse health effects.