Phosphatidylserine

Updated June 29, 2026

Phosphatidylserine (PS) is a phospholipid that constitutes roughly 15 percent of the total phospholipid content of the brain, concentrated heavily in the inner leaflet of neuronal cell membranes. It plays structural and functional roles: it maintains membrane fluidity, facilitates the neurotransmitter release machinery at synapses, supports receptor function for dopamine and acetylcholine, and is required for neuronal apoptosis signalling. Dietary sources include soy, sunflower, egg yolk, and white beans, but the amounts from food are small — typically 100 to 200 mg per day even in a diet rich in these foods. Brain PS levels decline with age, correlating with reduced cognitive function.

The cognitive evidence is the most developed for any phospholipid supplement. Multiple double-blind trials in older adults with age-associated memory impairment show that 300 to 400 mg of PS per day improves memory consolidation, recall speed, and verbal fluency within 6 to 12 weeks. The FDA in 2003 reviewed the evidence and issued a qualified health claim: “consumption of phosphatidylserine may reduce the risk of dementia and cognitive dysfunction in the elderly.” That is an unusually direct regulatory acknowledgement for a supplement. Effects are most pronounced in people who begin with measurable cognitive deficits, but improvements in working memory and reaction time are also seen in younger, healthy populations.

The cortisol-blunting effect is a distinct and practically useful property. PS supplementation at 400 to 800 mg per day measurably reduces the cortisol and ACTH response to physical and psychological stress in multiple controlled trials. This makes it relevant for athletes managing overtraining, people under sustained work pressure, or anyone whose morning cortisol spike feels excessive. The mechanism appears to involve PS's modulation of HPA axis responsiveness rather than a direct cortisol-blocking action — it calibrates the stress response rather than suppressing it entirely.

Originally sourced from bovine brain cortex, modern supplements use soy or sunflower-derived PS to avoid BSE concerns. Sunflower PS is preferred by some due to soy's phytoestrogen content. Standard dosing is 100 mg three times daily (300 mg total), ideally with meals. Higher doses up to 600 to 800 mg are used for cortisol management and in some clinical trials. PS is well tolerated — the most common side effect at higher doses is mild insomnia if taken too late in the day, likely due to its dopaminergic stimulant properties. This is general information, not medical advice.