L-tryptophan is an essential amino acid that helps the body make proteins and certain brain-signaling chemicals.
Your body changes L-tryptophan into a brain chemical called serotonin. Serotonin helps control your mood and sleep.
Some research, mainly from the 1970s and 1980s, offers some support for using it for depression. Several studies also showed that L-phenylalanine plus ultraviolet A light may be helpful for people with vitiligo.
There is less evidence to support its use for other conditions.
Optimal doses of phenylalanine have not been set for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it difficult to set a standard dose. However, commonly used dosages, depending on the condition, range from 150 mg to 5,000 mg daily.
Can you get phenylalanine naturally from foods?
Phenylalanine is found in many foods, including:
Products containing aspartame
What are the risks of taking phenylalanine?
Phenylalanine can trigger allergic reactions, with symptoms such as: