Phosphatidylserine
A phospholipid with cognitive trials in older adults and cortisol-attenuation trials in athletes. Strongest historical trials used bovine PS (withdrawn post-BSE); modern soy/sunflower PS evidence is thinner.
Why this matters
Phosphatidylserine (PS) is a structural phospholipid that makes up roughly 10% of the inner-leaflet membrane of every cell in the brain. The supplemental form is sourced from soy or sunflower lecithin via enzymatic conversion; both yield biochemically identical PS. PS sits in an unusual regulatory category: the FDA grants a qualified health claim for cognitive function in older adults but pairs it with an explicit 'limited and inconclusive scientific evidence' disclaimer, which is closer to the truth than most adjacent supplement claims. The clinical dossier is real but uneven. Older trials in cognitively-intact older adults at 100-300mg/day for 6-12 weeks show small but consistent gains on memory and attention endpoints; acute-stress trials at 600mg single-dose show measurable cortisol attenuation in exercised subjects (Starks 2008 and replications). The compound is well-tolerated and has a benign side-effect profile, with one major historical caveat: pre-2000 trials were largely run on bovine-cortex-derived PS, which became a regulatory dead-end after BSE concerns and is no longer the supply line. All current consumer products are plant-derived, so the older trial data should be treated as suggestive rather than directly transferable. Use PS as a low-risk add-on with modest expected effect size, not as a load-bearing nootropic.
What it does
Phosphatidylserine (PS) at 100 to 300 mg/day shows modest cognitive improvement in older adults with memory complaints. 600 mg/day blunts exercise-induced cortisol in trained men. The bovine-vs-soy/sunflower distinction is critical for evidence interpretation.
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Cognitive function in older adults Moderate evidence
100 to 300 mg/day shows memory and attention improvement over 12 weeks in older adults with age-associated memory impairment. Strongest historical trials used bovine-cortex PS, withdrawn post-BSE; modern soy/sunflower PS evidence is smaller and less consistent.
Sources: PMID 25933483 · PMID 20523044
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Exercise-induced cortisol attenuation Preliminary evidence
600 mg/day blunted cortisol elevation following intense resistance / endurance exercise and reduced perceived muscle soreness.
Sources: PMID 18662395
What works
- 100-300mg/day plant-derived PS for 6-12 weeks for cognitive-aging endpoints (memory, attention).
- 600mg single-dose ~60 minutes pre-stress for cortisol attenuation (acute use, sport/competition contexts).
- Consistent daily dosing rather than as-needed. The mechanism is membrane composition, which turns over slowly.
- Pairing with omega-3. PS shares the same membrane-phospholipid story; deficient EPA/DHA limits the upside.
What doesn't
- Bovine-cortex-derived PS. Off the market for 20+ years for BSE reasons; if you find it, do not buy.
- Sub-100mg daily doses. Below the trial baseline; the signal washes out.
- Expecting acute single-dose cognitive effects. The cortisol-attenuation use case at 600mg is real; the cognitive endpoint is structural over weeks.
- Treating PS as a stand-alone solution to age-related memory concerns. Effect size in trials is small; baseline cardiovascular and sleep optimization matters more.
Top picks
- 1 Check on Amazon
Jarrow Formulas
PS-100 (Sharp-PS, soy)
Sharp-PS branded; the most-studied modern soy/sunflower form.
- 2 Check on Amazon
Doctor's Best
Best Phosphatidyl Serine 100
100 mg per cap, easy to titrate. Soy-lecithin-derived extract; verify the COA if a specific Sharp-PS or SerinAid sourcing claim matters for your protocol.
- 3 Check price
NOW Foods
Phosphatidyl Serine 100 mg (sunflower-derived)
Sunflower source; soy-free.
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How to use it
- Dosage
- 100 to 300 mg/day for cognitive support; 600 mg/day for cortisol/exercise stress.
- Timing
- Split AM/PM for cognitive; pre-training for athletic protocols.
- With food
- Yes
- Onset
- 6 to 12 weeks for cognitive endpoints; ~10 days for cortisol blunting.
What to look for
FAQ
- Soy or sunflower?
- Sunflower if you avoid soy. Both are lab-equivalent; the source affects allergens, not efficacy.
Suggested protocol
Daily plant-derived PS for membrane support
100-300mg/day of soy- or sunflower-derived PS, taken with food, for at least 12 weeks. The acute-stress 600mg single-dose is a separate use case, not a daily protocol.
- Phosphatidylserine (plant-derived) 100-300mg daily
Timing: With breakfast or dinner
Confirm 'soy-derived' or 'sunflower-derived' on the label. Avoid anything bovine-derived.
- Optional acute-stress dose 600mg single-dose, only on stress-test or competition days
Timing: 60 minutes before the stressor
Do not stack with the daily 100-300mg unless on the stress day specifically.