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Showing all 19 ingredients

Nootropic Ingredients Guide 2026

19 evidence-backed nootropic compounds. Clinical doses, mechanisms of action, and which top-rated stacks contain each ingredient — graded on RCT evidence.

9 ingredients · Grade A
Multiple consistent RCTs
6 ingredients · Grade B
Smaller / fewer RCTs
4 ingredients · Grade C
Preliminary or mixed
Grade
Ingredient
Clinical dose
Trials
Our take
B
Lion's Mane
Lion's Mane (Hericium erinaceus) contains hericenones and erinacines that stimulate the synthesis of Nerve Growth Factor (NGF) in cell and animal studies.
1–1.8g/day in healthy-adult trials; 3g/day dry powder in the mild cognitive impairment trial
5
A 2009 double-blind, placebo-controlled trial (Mori et al., n=30) found higher cognitive function scores in adults with mild cognitive impairment after 16 weeks of 3g/day; scores fell again within 4 weeks of stopping. Its lead author works for Hokuto Corporation, a mushroom producer. A 2019 multicentre RCT improved MMSE scores but not the two other memory tests. In healthy adults, two small 2023 pilot RCTs found acute gains on Stroop, N-Back and reaction-time tasks at 1–1.8g, and only a non-significant trend toward lower stress after 28 days. The evidence is small-sample and short-term.
A
Bacopa Monnieri
Bacopa enhances synaptic communication by increasing dendritic branching and synaptic density.
300–450mg/day (standardised to 55% bacosides)
10
A meta-analysis of 9 RCTs (Kongkeaw et al., 2014, n=518) found Bacopa shortened Trail Making B and choice reaction times versus placebo, and two 12-week RCTs in healthy older adults (Calabrese 2008; Morgan & Stevens 2010) improved delayed word recall at 300mg/day. The newest 12-week RCT (Lopresti 2025, n=101, 300mg/day) found no effect on verbal learning, attention or working memory, though it did reduce self-reported stress. A 2026 network meta-analysis of 29 RCTs found ≥600mg/day beat 300–450mg/day for working memory. Best evidence is for delayed recall rather than acute effects.
B
Citicoline (CDP-Choline)
Citicoline (cytidine 5'-diphosphocholine) is a precursor to both acetylcholine and phosphatidylcholine.
250–500mg/day (the memory trials in older adults used 1000–2000mg/day)
5
An RCT in healthy older adults (Spiers et al., 1996) found 1000mg/day improved delayed verbal recall in people with relatively inefficient memory, with 2000mg/day improving immediate and delayed recall. A 2023 meta-analysis found a positive effect on cognitive status in MCI and dementia, but rated study quality poor with a high risk of bias. The 2005 Cochrane review found benefit on memory and behaviour in older adults with chronic cerebral disorders but no evidence of benefit on attention. In acute ischemic stroke, a dose-response RCT (Clark 1997) found better functional outcomes, with 500mg the optimal dose.
A
L-Theanine
L-theanine is a non-protein amino acid found primarily in green tea.
100–200mg/day (trials pairing it with caffeine used roughly 1:1 to 1.7:1 theanine:caffeine)
7
A 2026 meta-analysis of 31 RCTs (n=1,168) found a single 200mg dose taken 30–60 minutes before testing improved choice reaction time; its acute stress effect was modest and driven by high-risk-of-bias studies, and anxiety effects were inconsistent. With caffeine, RCTs (Haskell et al., 2007; Kahathuduwa 2016) and an 11-RCT meta-analysis (Camfield 2014) show the combination beats either compound alone on attention and reaction time. The one alpha-wave (MEG) trial found higher alpha activity at 2 hours, and only in people with higher trait anxiety.
C
Rhodiola Rosea
Rhodiola is an adaptogen that modulates the HPA (hypothalamic-pituitary-adrenal) axis, reducing cortisol output under stress.
200–600mg/day (standardised to 3% rosavins, 1% salidroside)
9
Small SHR-5 extract trials found less mental fatigue: a 2003 RCT in 161 military cadets after a single dose, a 2000 crossover trial in 56 physicians on night duty over two weeks (Darbinyan et al.), and a 2000 pilot in students during exams. The Swedish burnout RCT (Olsson et al., 2008, n=60, 576mg/day) ran 28 days — not 12 weeks — and improved burnout and attention scores versus placebo, while depression scores improved equally in both groups. A 2012 systematic review of 11 trials rated every included study at high or unclear risk of bias and called the evidence contradictory.
A
Phosphatidylserine
Phosphatidylserine (PS) is a phospholipid that forms a critical component of neuronal cell membranes.
100–300mg/day (benefit shown mainly in older adults with memory complaints or MCI)
5
RCTs in older adults with memory complaints or mild cognitive impairment report memory benefits, though often only in subgroups: soy PS at 100–300mg/day for 6 months helped only participants with low baseline scores (Kato-Kataoka 2010), and marine PS-DHA at 300mg/day improved immediate verbal recall in an exploratory 15-week trial (Vakhapova 2010). A 2026 network meta-analysis in MCI/Alzheimer's found PS 100mg improved MMSE but not the stricter ADAS-Cog scale. In healthy children, a 12-week RCT of 100mg sunflower PS found no effect on primary or secondary outcomes (Friling 2025; authors include staff of IFF, the product's manufacturer). A positive 2024 MCI trial (Duan 2024; BYHEALTH co-authors) gave only 31.5mg PS inside a multi-ingredient formula. The FDA's qualified health claim for dementia risk must be labelled as based on 'very limited and preliminary' research.
A
Alpha-GPC
Alpha-GPC (alpha-glycerylphosphorylcholine) is the most bioavailable choline precursor.
300–600mg/day (the positive Alzheimer's trial used 1200mg/day)
9
A multicenter RCT in mild-to-moderate Alzheimer's dementia (De Jesus Moreno, 2003, n=261) found 1200mg/day improved ADAS-Cog, MMSE and global scores versus placebo at 90 and 180 days, and a 2023 meta-analysis supports benefit in cerebrovascular cognitive impairment. In healthy men, a single 315–630mg dose improved Stroop performance but not N-Back or Flanker (Kerksick 2024). Sports trials are inconsistent: a lower-body force gain after 6 days at 600mg (Bellar 2015), no strength effect at 250–500mg for 7 days, and no power-output effect after a single 630mg dose.
A
Ashwagandha (KSM-66)
Ashwagandha (Withania somnifera) is an Ayurvedic adaptogen.
300–600mg/day (KSM-66 extract)
6
A 2012 RCT in chronically stressed adults (Chandrasekhar et al., KSM-66 600mg/day, 60 days; extract supplied by its maker Ixoreal Biomed) found serum cortisol fell 27.9% versus 7.9% on placebo and perceived stress fell 44%. A 2024 meta-analysis of 9 RCTs confirmed significant reductions in perceived stress, anxiety and cortisol, though a 2019 crossover trial of a low-dose extract in older overweight men found no cortisol effect. A 2017 RCT (Choudhary et al., 300mg twice daily, 8 weeks) improved memory and executive function — in adults with mild cognitive impairment, not healthy adults. Liver-injury case reports exist, and Denmark banned ashwagandha supplements in 2023.
A
Huperzine A
Huperzine A is extracted from Huperzia serrata (Chinese club moss).
100–200mcg/day in the trials (micrograms, not milligrams; 50mcg consumer doses were not tested separately)
10
Chinese RCTs show Huperzine A improved memory and learning in Alzheimer's patients (Xu et al., 1995: 58% vs 36% improved at 200mcg/day over 8 weeks) and in adolescent students (Sun et al., 1999: 100mcg/day for 4 weeks). A 2013 meta-analysis of 20 RCTs found significant benefits in Alzheimer's disease, but rated most trials at high risk of bias; the 2008 Cochrane review concluded the evidence is inadequate to recommend it, and a 2012 Cochrane review found no eligible trials in mild cognitive impairment. A 2019 RCT after traumatic brain injury found no memory benefit over placebo.
C
L-Tyrosine (NALT)
L-Tyrosine is an amino acid precursor to dopamine, norepinephrine, and epinephrine.
100–150mg/kg in the key stress trials (about 7–10g for a 70kg adult); consumer products give flat 500–2000mg doses
8
Military and stress trials found tyrosine reduced performance decline during one night of sleep loss (Neri et al., 1995, 150mg/kg), noise stress (Deijen & Orlebeke, 1994, 100mg/kg) and a combat training course (Deijen et al., 1999, 2g/day) — but neither Deijen trial found any effect on mood. Other trials were null or negative: tyrosine did not protect cognition or performance under exercise heat stress (Coull 2016, 150mg/kg), and 2g worsened cognitive flexibility under high cognitive load (Robson 2019). A 2015 narrative review (Jongkees et al.) concluded benefits are conditional on short-term stress that depletes dopamine and norepinephrine.
A
Caffeine
Caffeine is an adenosine receptor antagonist.
100–200mg for cognitive enhancement
8
Caffeine is one of the most extensively studied psychoactive compounds. A 2016 review (McLellan, Caldwell & Lieberman — a narrative review, not a meta-analysis) found low-to-moderate doses (~40–300mg) consistently improve alertness, vigilance, attention and reaction time, with less consistent effects on memory and executive function. A 2010 Cochrane review of shift workers and a 2026 meta-analysis of 7 military sleep-loss RCTs confirmed gains in attention, vigilance and complex task performance. Side effects rise with dose, and the European Food Safety Authority (EFSA, 2015) sets 200mg per single dose and 400mg/day as safe for healthy adults — 200mg/day for pregnant women.
A
Ginkgo Biloba
Ginkgo Biloba extract (standardised to 24% ginkgo flavone glycosides and 6% terpene lactones) works primarily by improving cerebral blood flow through vasodilation and platelet-activating factor (PAF) inhibition.
240mg/day of standardised extract EGb 761 in the positive trials (120mg/day appears under-dosed)
4
The NIH-funded GEM trial (DeKosky 2008, n=3,069, 240mg/day, median 6.1 years) found no reduction in dementia or Alzheimer's incidence in people aged 75+. For existing cognitive impairment and dementia, a meta-analysis of 9 RCTs (Tan et al., 2015, 22–26 weeks, mainly 240mg/day EGb 761) found benefits on cognition and daily living, concentrated in patients with neuropsychiatric symptoms. The 2026 Cochrane review of 82 RCTs found small-to-moderate benefits in dementia (low-certainty evidence) but little or no effect in mild cognitive impairment. A 2013 review rated the dementia evidence low quality, noting most trials were pharmaceutical-industry sponsored. Ginkgo raises bleeding risk with warfarin.
B
DHA (Omega-3)
Docosahexaenoic acid (DHA) is the primary structural omega-3 fatty acid in the brain, constituting ~40% of polyunsaturated fatty acids in neuronal membranes.
900mg–1.2g DHA/day (the dose range of the positive trials)
2
DHA is essential for brain development and maintenance, but RCT results are mixed. A 2012 Cochrane review (n=4,080) found no cognitive benefit of omega-3 supplements in cognitively healthy older adults, and a 2025 meta-analysis found no meaningful ADAS-Cog benefit once Alzheimer's has developed. Two 6-month RCTs were positive: 900mg DHA/day improved learning and recognition memory in age-related cognitive decline (Yurko-Mauro et al., 2010 — sponsored by the algal-DHA maker Martek, with a Martek employee as lead author), and 1.16g/day improved memory and working-memory reaction times in healthy adults aged 18–45 with low DHA intake (Stonehouse 2013). A 2021 NIH-funded meta-analysis (n=81,210) found omega-3 supplements raise atrial fibrillation risk, more so above 1g/day.
B
Maritime Pine Bark Extract
Maritime Pine Bark Extract (Pinus pinaster) contains proanthocyanidins — potent polyphenol antioxidants that cross the blood-brain barrier.
100–200mg/day (Pycnogenol or equivalent standardised extract)
6
A 2014 Pycnogenol study (Belcaro et al.) in healthy professionals aged 35–55 reported small but significant cognitive improvements and a 30.4% drop in plasma free radicals after 12 weeks at 150mg/day — but it was a non-randomized product-evaluation registry study, not an RCT. A 2011 controlled (non-randomized) study in students (Luzzi et al.) reported better attention, memory and exam scores over 8 weeks. Both come from the same Irvine3 Labs / Chieti-Pescara author group, which has published numerous Pycnogenol studies; Pycnogenol is a Horphag Research trademark, and these trials are widely reported as industry-supported, though no sponsor is disclosed in the abstracts. The independent 2020 Cochrane review rated the evidence for every pine bark outcome it assessed as very low certainty. A 2025 network meta-analysis ranked Pycnogenol highly for mild cognitive impairment but cautioned about heterogeneity.
A
Acetyl-L-Carnitine (ALCAR)
Acetyl-L-Carnitine (ALCAR) is an acetylated form of L-Carnitine that crosses the blood-brain barrier more effectively than plain L-Carnitine.
1500–3000mg/day (every positive trial reviewed used at least 1.5g/day)
6
A 2003 meta-analysis of double-blind RCTs (Montgomery et al.) found a modest but significant advantage for ALCAR over placebo in mild cognitive impairment and mild Alzheimer's disease at 1.5–3g/day, apparent by 3 months and growing over time. A 2018 meta-analysis of 12 RCTs (Veronese et al., n=791) found a large reduction in depressive symptoms, comparable to antidepressants with fewer adverse effects, most clearly in older adults. A 2022 RCT in pre-frail older adults (3g/day) improved MMSE and walking distance. A 2020 critical review still calls its role in dementia "under debate". No healthy-young-adult trial was found.
B
Lutemax 2020
Lutemax 2020 is a patented marigold extract providing lutein and two zeaxanthin isomers (RR- and RS-meso-zeaxanthin) in a roughly 5:1 ratio.
12–27mg/day total lutein + zeaxanthin in trials (lutein-dominant, roughly 5:1)
10
Of the trials we reviewed, two name Lutemax 2020 as their material, both run or funded by its maker, OmniActive: a skin-tone trial and a screen-use trial (below); the cognitive evidence comes from lutein and zeaxanthin trials that do not name Lutemax 2020, one of which was funded and supplied by OmniActive (Stringham 2019). In healthy young adults, 12mg/day for 12 months raised MPOD and improved visual memory (Renzi-Hammond 2017 — co-authored by Abbott Nutrition staff, with material from DSM, a Lutemax competitor); 22mg/day for 12 months improved memory in adults with low macular pigment (Power 2018, funded by the European Research Council); and 13–27mg/day for 6 months improved memory, attention and processing speed (Stringham 2019, funded by OmniActive, which supplied the supplements). A 2023 meta-analysis found xanthophylls speed photostress (glare) recovery, and two OmniActive-funded trials also reported better glare and photostress recovery versus placebo: the screen-use trial below and a 12-month trial in 59 young adults (Stringham 2016). The maker's skin trial (Juturu 2016; two of three authors employed by OmniActive, which makes Lutemax) tested skin tone, not cognition. For screen-related eye symptoms the two trials disagree: in 48 students with 6+ hours of daily screen time, 24mg/day of the Lutemax 2020 formulation for 6 months reduced self-rated eye strain, eye fatigue and headache frequency and improved sleep quality versus placebo (Stringham 2017; funded by OmniActive, and the first author consults for it), though a separate report by OmniActive staff on a 48-person, 24mg/day, 6-month trial of the same design found the sleep difference significant at 3 months but not at 6 months (Culver 2018, not indexed in PubMed); in 70 heavy screen users a different lutein/zeaxanthin product (Lute-gen, 10mg lutein + 2mg zeaxanthin isomers; funded by its supplier, Bio-gen Extracts) improved tear production, tear-film stability and photo-stress recovery over 6 months, but self-rated eye strain, visual fatigue, sleep and attention did not differ from placebo (Lopresti & Smith 2025).
C
Oat Straw Extract
Oat Straw (Avena sativa) extract works primarily by inhibiting phosphodiesterase type 4 (PDE4) and monoamine oxidase B (MAO-B).
430–1600mg/day in trials; 800mg or less may be optimal — higher doses underperformed
5
Four small RCTs, all with manufacturer involvement: a 2011 trial (Berry et al.) in elderly people with below-average cognition found a single 1600mg dose reduced Stroop errors, but 2400mg did no better than placebo; a 2012 trial by the same group found 1500mg/day for 12 weeks had no effect on any cognitive measure in healthy older adults (material supplied by Frutarom); a 2015 trial (Kennedy et al., two Frutarom employees as co-authors) found 800mg improved speed, delayed recall and executive function in adults 40–65 with memory complaints, concluding the optimal dose is at or below 800mg; and a 2020 trial (Kennedy et al., two Anklam Extrakt employees as co-authors) found 430–1290mg improved working memory and multitasking over 4 weeks, with no effect on mood. No trial has measured cerebral blood flow.
C
Zynamite (Mangifera indica)
Zynamite is a patented extract of Mangifera indica (mango leaf) standardised to >60% mangiferin.
140–300mg/day (standardised to >60% mangiferin); 300mg showed no cognitive benefit in the largest trial
4
The largest and most independent trial (Dodd et al., 2024, n=114, Northumbria University with a PepsiCo co-author) gave a single 300mg dose of mango leaf extract and found no cognitive benefit — participants made more subtraction errors than on placebo. An earlier pilot (López-Ríos et al., 2020, n=16, all four authors Nektium employees) used 500mg, not 300mg, and found only a marginal reaction-time signal. Two sprint trials (2018, 2019; lead authors affiliated with Nektium, the manufacturer) combined 140mg with quercetin or luteolin and improved sprint power output, but measured no cognitive outcome. Three of the four trials are manufacturer-authored.
B
Dynamine (Methylliberine)
Dynamine (methylliberine) is a purine alkaloid found in kucha tea leaves, structurally related to caffeine and theacrine.
100–150mg/day (150mg is the highest dose tested in humans; 200mg has never been tested)
3
Only three human RCTs have tested methylliberine. The only one measuring cognition with methylliberine alone (La Monica et al., 2023, n=25, 100mg/day) found better self-rated concentration, motivation, mood and energy, but a negligible effect on objective cognitive tests (Stroop, Trail Making B). A 4-week safety trial (VanDusseldorp et al., 2020, n=125, 100–150mg/day) found no clinically significant cardiovascular or blood changes; it did not test cognition. A third trial (Cintineo 2022) tested it only inside a caffeine + theacrine combination. Both methylliberine-specific trials were funded in whole or part by Compound Solutions, which sells Dynamine, and a La Monica co-author holds patents on methylliberine.
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