L-phenylalanine

Phenylalanine, often sold as L-phenylalanine or DL-phenylalanine, is an essential amino acid that is normally converted to tyrosine.

Theory
McGregor (2019) found that in people with ME/CFS, the 7-day severity of post-exertional malaise (PEM) and the 12-month frequency of PEM scores correlated with blood glucose levels, and negatively correlated with hypoxanthine, phenylalanine, lactate and threonine.

Risks and safety
Phenylalanine is generally recognized as safe, except for people with PKU, a genetic disorder that prevents the metabolism of phenylalanine.

Costs and availability
Inexpensive and available over the counter as a nutritional supplement.

Notable studies

 * 2019, Post-exertional malaise is associated with hypermetabolism, hypoacetylation and purine metabolism deregulation in ME/CFS cases - (Full text)
 * 1977, DL-phenylalanine in depressed patients: An open study (Abstract)

Learn more

 * L-Phenylalanine - DrugBank Online
 * L-Phenylalanine - PubChem