L-phenylalanine is an essential amino acid. It’s also found in protein in the foods we eat.
People have tried to treat a number of conditions with phenylalanine, including:
- Chronic pain
- Depression
- ADHD
- Vitiligo (light-colored patches on the skin)
Several studies showed that L-phenylalanine plus ultraviolet A light may be helpful for people with vitiligo.