Phosphatidylserine Dosage: 300mg for Memory, 600-800mg Cortisol
Educational summary — not medical advice. PS has no established RDA or upper limit, and no long-term (6-month+) human safety data at any dose. This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.
The honest answer
300 mg/day (100 mg three times daily) is the classic memory-trial dose — used by both the bovine-cortex-PS trials (Crook 1991, Crook 1992, positive) and the direct soy-PS replication (Jorissen 2001, null). Cortisol/exercise trials used 600–800 mg/day — well above what most single retail servings provide. ADHD trials used 200 mg/day in children only, under clinical supervision — not a general or adult recommendation. There's no RDA or upper limit because PS isn't an essential nutrient.
The dose depends on which trial's evidence you're chasing — and which ingredient
PS doesn't have one settled dose, and unlike most supplements, the bigger honesty gap here is which ingredient the dose was tested in, not just the number. Four of the trials in this evidence base used exactly 300 mg/day: Crook 1991 (bovine-cortex PS, n=149, positive), Crook 1992 (bovine-cortex PS, n=51, positive, Alzheimer's population), and Jorissen 2001 (soy-derived PS, n=120, the direct replication of the Crook design at the same dose — and it found no significant difference from placebo on any outcome). Same number, different ingredient, opposite result. The cortisol/exercise-stress trials used higher doses: Starks 2008 (two of its authors are sports-supplement-industry researchers) tested 600 mg/day for 10 days in 10 healthy men (blunting the peak cortisol response to an exercise-stress test by ~39%), and Monteleone 1992 tested 800 mg/day orally for 10 days in 9 healthy men (blunted ACTH and cortisol response to exercise). A third, older Monteleone trial (Monteleone 1990) used PS intravenously at 50-75 mg — not comparable to any oral dose, cited here only for mechanistic plausibility. The newest trial on the actual sunflower ingredient sold today (Friling 2025) tested only 100 mg/day — a third of the classic cognition dose — in children, and found no significant effect on primary or secondary outcomes across the full cohort. No trial establishes that 100 mg sunflower PS is dose-equivalent to 300 mg soy or bovine PS.
| Use case | Dose studied | Result |
|---|---|---|
| Classic memory dose | 300 mg/day, 12wk | Bovine-cortex PS positive (Crook 1991/1992); direct soy-PS replication at the same dose NULL (Jorissen 2001) |
| Soy-PS + omega-3, combination | 300 mg PS/day (active), 100 mg maintenance, 15wk | Significant improvement in a higher-baseline-performance subgroup only, not the full sample (Vakhapova 2010); combination product, can't isolate PS alone |
| Cortisol/exercise stress | 600–800 mg/day, 10 days | Blunted cortisol/ACTH response to exercise (Starks 2008, Monteleone 1992); no measured performance outcome in these trials |
| Modern sunflower trial | 100 mg/day, 12wk, children | NULL on primary/secondary outcomes across full cohort; benefit only in a below-median-baseline subgroup (Friling 2025, industry-funded) |
| Pediatric ADHD | 200 mg/day, 8wk, children 4-14y | Symptom improvement in individual trials (Hirayama 2014, Manor 2012); pooled meta-analysis found most outcomes NOT significant (Bruton 2021) |
Dose checker: how much PS are you actually taking?
Enter the phosphatidylserine milligrams per serving from your label (look for "Phosphatidylserine ___ mg" on the Supplement Facts panel) and how many servings you take per day.
How to think about dose, honestly
- 300 mg/day is the reference point for the memory claim — but remember the positive version of that trial used an ingredient (bovine-cortex PS) that no longer exists on any shelf.
- Most 100 mg retail servings require 3 capsules/day to reach the classic cognition dose — check your label's serving size before assuming one capsule is "the trial dose."
- Cortisol/exercise-motivated buyers are likely under-dosing at a typical 100-300 mg single serving; the trials that actually blunted cortisol used 600-800 mg/day, meaningfully higher.
- Don't treat 100 mg sunflower PS (the Friling 2025 dose) as equivalent to 300 mg soy or bovine PS. No trial has tested that equivalence, and the 100 mg sunflower trial was null on its primary outcome anyway.
- 200 mg/day ADHD dosing is pediatric-specific and clinically supervised (medication-naive children, ages 4-14) in the source trials — not a general adult or self-directed "focus" dose.
Picks by dose
Full ranking, including source and branding tiers (the primary axis for PS), is on best PS.
Discloses 300 mg per serving — the exact classic memory-trial dose, no multi-capsule math needed.
As an Amazon Associate we earn from qualifying purchases. Of 6 products tracked; ranked by disclosed mg, never commissions.
Frequently asked questions
How much phosphatidylserine should I take per day?
300 mg/day is the classic memory-trial dose. Cortisol/exercise trials used 600-800 mg/day, higher than most retail servings. No RDA or upper limit exists.
Is 300mg the "right" dose for memory?
It's the most-replicated number, but the ingredient matters more: bovine-PS at 300mg was positive (now discontinued); soy-PS at the same 300mg dose was null (Jorissen 2001).
Why do cortisol trials use higher doses than retail servings?
Starks 2008 and Monteleone 1992 used 600-800 mg/day, 2-2.7x the 300mg memory dose and above most single retail servings — a real supply-vs-evidence gap.
Is phosphatidylserine safe at these doses?
No serious adverse events reported from 100-800 mg/day for up to 30 weeks (the longest human data). No trial has tested longer, so no long-term safety data exists.
Related
- Phosphatidylserine: what it is & who it's for
- Best PS — ranked by source/branding disclosure, then cost per mg
- PS for age-related memory
- The FDA "qualified" claim, explained
Sources
- Crook TH, Tinklenberg J, Yesavage J, et al. "Effects of phosphatidylserine in age-associated memory impairment." Neurology. 1991. PMID: 2027477 (300 mg/day, bovine-cortex PS)
- Crook TH, Petrie W, Wells C, Massari DC. "Effects of phosphatidylserine in Alzheimer's disease." Psychopharmacol Bull. 1992. PMID: 1609044 (300 mg/day, bovine-cortex PS)
- Jorissen BL, et al. "The influence of soy-derived phosphatidylserine on cognition." Nutr Neurosci. 2001. PMID: 11842880 (300/600 mg/day soy-PS, NULL)
- Starks MA, et al. "The effects of phosphatidylserine on endocrine response to moderate intensity exercise." J Int Soc Sports Nutr. 2008. PMID: 18662395 (600 mg/day)
- Monteleone P, et al. "Blunting by chronic phosphatidylserine administration of the stress-induced activation of the hypothalamo-pituitary-adrenal axis in healthy men." Eur J Clin Pharmacol. 1992. PMID: 1325348 (800 mg/day oral)
- Friling R, et al. Sunflower-derived phosphatidylserine (Sharp-PS® Green) in healthy children. Nutr J. 2025. PMID: 41318468 (100 mg/day, NULL primary)
- Full product dataset: /phosphatidylserine/cost-by-brand.json (CC BY 4.0).