A2
Agmatine sulfate
- Product declaration
- Agmatine Sulfate: 500 mg
- Selected studied range
- No dose range selected
- Protocol and duration
- Not recorded in the selected comparison
- Studied context
- Human data is comparatively sparse. A randomized double-blind placebo-controlled trial studied oral agmatine sulfate (1,335-3,560 mg/day for up to 3 weeks) for lumbar disc-associated radiculopathy (a clinical/pain context, not sports performance). A 2019 Scientific Reports paper examined safety and neurochemical profiles of acute and sub-chronic oral agmatine sulfate treatment.
- Limitations
- Sports-performance-specific human efficacy data for agmatine sulfate (e.g., a dedicated ISSN position stand) was not located in this research pass. Evidence located centers on safety/tolerability and non-sports clinical contexts rather than an authoritative performance-outcome verdict. Long-term safety in larger populations remains an open gap per the safety literature reviewed.
Selected evidence: Safety and neurochemical profiles of oral agmatine sulfate, 2019 · Open source
A2
Alpha-GPC
- Product declaration
- Alpha-GPC (Alpha-Glyceryl Phosphoryl Choline 99%): 150 mg
- Selected studied range
- 300 to 600 mg
- Protocol and duration
- single dose, 30 to 90 minutes before testing or training
- Studied context
- Studied for acute cognitive performance (e.g., Stroop-test measures) and for acute power output/strength in resistance exercise. A 2024 study found both 300 mg and 600 mg doses improved Stroop-test performance in healthy young men. Separate studies cited 600 mg dosed 90 minutes pre-exercise increasing post-exercise growth hormone and peak bench-press force, and 600 mg/day over 6 days increasing lower-body isometric strength by over 3%.
- Limitations
- NIH ODS's Choline Health Professional fact sheet does not mention alpha-GPC at all, and states no studies have compared relative bioavailability across the choline supplement forms it does cover (choline bitartrate, phosphatidylcholine, lecithin). Alpha-GPC's comparative bioavailability is outside what NIH has assessed in that document. A large 2021 observational study (JAMA Network Open, South Korean national-insurance cohort, n=12,008,977 adults 50+) found an association between alpha-GPC use and 10-year stroke risk (adjusted HR 1.46, 95% CI 1.43-1.48 for total stroke) in a dose- and duration-response pattern, but the authors explicitly flag confounding limitations: alpha-GPC users were older with more comorbidities at baseline, and the study is observational (association, not proven causation).
Selected evidence: Acute alpha-GPC supplementation and cognitive performance, 2024
