Phosphatidylserine
Phosphatidylserine (PS) is a phospholipid found in cell membranes, sold as a supplement (soy- or sunflower-derived) marketed to blunt exercise-induced cortisol and support cognition. Small studies suggest high doses can attenuate the cortisol response to intense exercise and overtraining, but effects on performance and body composition are modest and inconsistent. Well tolerated; a genuine supplement rather than a drug.
01 Overview
PS is a component of the inner leaflet of cell membranes and is involved in cell signalling. Early cognition research used bovine-cortex PS; modern supplements use plant-derived PS. In exercise studies, doses around 600 mg/day have blunted the rise in cortisol after intense or prolonged exercise and reduced perceived soreness in some small trials, which underpins its marketing to lifters and endurance athletes managing training stress.
The evidence is limited and mixed: cortisol attenuation is the most reproducible finding, but downstream benefits for strength, recovery or body composition are not well established. It is inexpensive, generally very well tolerated, and not prohibited in sport, but expectations should be modest.
02 Mechanism
Membrane phospholipid proposed to modulate the hypothalamic-pituitary-adrenal response, blunting ACTH-driven cortisol release after physical stress; exact mechanism not fully defined.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Cognitive support | 100–300 mg/day | Oral | Lower doses used in cognition research. |
| Cortisol/exercise stress | 300–800 mg/day | Oral | ~600 mg/day used in exercise-cortisol studies. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Blunted exercise cortisolHigh doses reduced the cortisol rise after intense exercise in some small trials. | modest attenuation | Observational | |
| Reduced perceived soreness/stressSome users and small studies report less soreness and lower perceived stress in overreaching. | small | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Mild GI upsetOccasional nausea or stomach upset, mostly at higher doses. | Mild | Uncommon | Observational | |
| Insomnia if taken lateSome report difficulty sleeping when dosed late in the day. | Mild | Rare | Anecdotal |