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 very hard to set a standard dose.
Can you get phenylalanine naturally from foods?
Phenylalanine is found in many foods, including:
Products containing aspartame
What are the risks of taking phenylalanine?
Side effects. Phenylalanine can trigger allergic reactions, with symptoms such as:
Keep drugs for high blood pressure from working properly
Interfere with the drug levodopa in people with Parkinson's disease
Increase the effect of sedatives
It may also affect how your body breaks down other drugs and supplements. And use with caution if you are taking a monoamine oxidase inhibitor (MAOI) drug.
Supplements are not regulated by the FDA. Tell your doctor about any supplements you're taking, even if they're natural. That way, your doctor can check on any potential side effects or interactions with any medications.