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 phenylketonuria (PKU), a genetic disorder that prevents the metabolism of phenylalanine. Phenylalanine is found in many different foods.

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

Notable studies

 * 2016, Metabolic profiling indicates impaired pyruvate dehydrogenase function in myalgic encephalopathy/chronic fatigue syndrome (Full Text)
 * 1977, DL-phenylalanine in depressed patients: An open study (Abstract)
 * 2019, Post-exertional malaise is associated with hypermetabolism, hypoacetylation and purine metabolism deregulation in ME/CFS cases - (Full text)

Learn more

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