Which clinical doses of Bacopa, Ginkgo, citicoline and phosphatidylserine are supported by human studies for memory and focus?
Executive summary
Human trials support specific, repeatable dosing ranges for the four compounds: Bacopa monnieri shows benefit in the roughly 150–300 mg/day range taken for weeks to months (effects typically emerge after 6–12 weeks) [1] [2] [3], Ginkgo biloba has been studied acutely at 120 mg and chronically in standard extract ranges used in randomized trials [4] [5], citicoline (CDP‑choline) is supported in trials at about 250 mg daily and in some clinical work up to 1,000 mg daily for attention and memory outcomes [3] [6], and phosphatidylserine has clinical backing at roughly 100–300 mg/day with many trials using ~100 mg [7] [8]. These dose windows reflect what appears repeatedly in human research, but strength of evidence and consistency differ across compounds and populations [9] [5].
1. Bacopa monnieri — chronic dosing, modest memory gains over weeks
Randomized human trials that reported reliable memory benefits typically used standardized Bacopa extracts in the ballpark of 150–300 mg per day, with some popular formulations and reviewers recommending 300 mg and others showing positive effects at 150 mg; benefits usually manifest after continuous use for 6–12 weeks rather than immediately [1] [3] [2]. Clinical reviews found consistent improvements across several trials in healthy adults and those with age‑related decline but also flagged gastrointestinal side effects in some subjects and methodological bias risk in parts of the literature [9] [5].
2. Ginkgo biloba — acute and chronic study doses, mixed signals
Human research includes both single‑dose cognitive modulation studies (for example, 120 mg single doses have been used to test acute performance) and longer randomized trials with standardized Ginkgo extracts for older adults and those with subjective cognitive complaints; the Cochrane‑style and systematic sources document the 120 mg acute paradigm and multiple chronic trial formats but also emphasize variable outcomes across studies [4] [5]. Systematic reviewers note apparent benefits in some memory/executive measures but caution about heterogeneity and methodological limitations [5].
3. Citicoline (CDP‑choline) — attention and memory across a broad clinical range
Clinical trials and practical guides frequently cite citicoline doses starting at 250 mg/day with many studies and commercial products using 250 mg as a standard clinical dose; other clinical reviews and guides extend the studied range up toward 1,000 mg/day for memory and attention benefits in middle‑aged and older adults [3] [6]. Citicoline has been trialed specifically in controlled designs for attention and memory and is often paired with other phosphatide precursors in combination studies [10] [3].
4. Phosphatidylserine — commonly 100–300 mg/day, evidence in older adults
The conventional clinical range recommended in medical summaries and used in many trials is approximately 100–300 mg daily, with much of the human work showing effects at or near 100 mg/day and some combination formulas containing smaller per‑capsule amounts [7] [8]. Randomized studies in older adults with mild cognitive complaints report short‑term memory improvements with PS‑containing supplements, but reviewers note that earlier trials sometimes used bovine‑derived PS (now largely replaced by soy/plant sources) and that results across populations are inconsistent [8] [7] [9].
5. Evidence strength, safety, and commercial context
Across all four agents the signal is modest: repeatable effects in some cognitive domains (memory, parts of executive function, attention) but not universal, with the clearest requirements being standardized extracts, adequate dose, and sufficient duration (notably Bacopa’s 6–12 week window) [2] [5] [9]. Adverse events are generally mild (gastrointestinal upset, occasional headaches or insomnia at higher doses) and interactions exist — for example phosphatidylserine can influence certain labs and citicoline engages cholinergic pathways relevant to some medications — so clinical oversight is prudent [7] [6]. Finally, much of the public guidance and product labeling comes from supplement marketers and review sites that echo clinical dose ranges (e.g., 150–300 mg Bacopa, 250 mg citicoline, 100 mg PS) but may understate uncertainty; readers should weigh academic systematic reviews and randomized trials more heavily than promotional content [3] [1] [11].
Limitations: the reporting assembled here summarizes dosing ranges that are supported in published human work cited above but does not exhaustively list every trial or subgroup; where the literature is mixed (notably Ginkgo and cholinergic precursors) that inconsistency is documented by systematic reviews in the supplied sources [9] [5].