Labdoor tested 45 best-selling pre-workout supplements in the United States for active and inactive ingredient content and heavy metal (arsenic, cadmium, lead, mercury) contamination.
Tested products often cited “proprietary blends” without specified quantities of active ingredients. Key active ingredients tested in this batch include creatine, beta-alanine, tyrosine (as L-tyrosine and N-acetyl-L-tyrosine (NALT)), arginine (as L-arginine HCl and arginine alpha-ketoglutarate (AAKG)), caffeine, and taurine. For products with specified quantities, actual active ingredient content ranged from being 81.2% less to 89.0% more than its respective label claim. Only 2 of 45 products tested had formulations in which all of their claimed active ingredients were measured to meet levels established in research to be effective. 41 products measured caffeine, but only 17 specified actual quantities. Of the 24 products that did not specify caffeine content, 5 exceeded 300 mg per serving, more than 3 times the caffeine content in an average cup of coffee. 1 product, Legion Pulse Pre-Workout, exceeded 400 mg per serving, the FDA-cited upper threshold for safe caffeine intake in one day for healthy adults.
Pre-workout supplements were generally heavy on potentially harmful ingredients. 39 of 45 products recorded some combination of flagged ingredients including artificial sweeteners, coloring agents (FD&C Blue 1, Blue 2, Red 40, Yellow 5, Yellow 6), and benzoate preservatives with cancer-causing potential. 1 product, Train CriticalFX (beverage), was found to contain BMPEA (beta-methylphenethylamine), an amphetamine analog classified as a doping agent.
Collective data for this batch analysis relied on analytical chemistry methods including HPLC (High Performance Liquid Chromatography) to quantify amounts of individual amino acids and caffeine, and ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) to determine heavy metal (arsenic, cadmium, lead, mercury) load. Products from manufacturers previously cited by the FDA for using illicit stimulants were also screened by HPLC for illicit stimulants.