Which Nootropics Actually Have Evidence? 20 Common Ingredients, Graded (2026)

Last updated: November 2026 · By Tyler, cofounder of Avantera Health · Medically reviewed by Jill Ingenito, DO, FACOG

The short answer: Of 20 common nootropic ingredients, caffeine has the strongest and most consistent human research, for alertness, attention and reaction time. Bacopa, creatine and sage have moderate evidence, each for one kind of outcome, and so does caffeine taken with L-theanine. Six more, including L-tyrosine and alpha-GPC, rest on a few small trials or one narrow group of people. Eight have trials that disagree, Panax ginseng and guarana among them. Two have too little data to grade.

Key takeaways

• Caffeine is the only one of the 20 we grade Strong. Studies have measured its effect on alertness and attention from about 40 mg. Its effect on memory is mixed.
• Bacopa's results came after about 12 weeks of daily use. In the clearest trial, nothing showed at 5 weeks.
• Creatine's memory results were clearest in older adults, vegetarians and people short on sleep. Rested young adults showed little change.
• Trials often disagree. For eight of the 20, including well-known names like ginkgo and ginseng, some trials found a benefit and others of similar quality found none.
• Lion's mane research depends on the form. Fruiting body, fruiting-body extract and mycelium have each been tested in a few small trials, one, or none.
• Ginger, turmeric and black pepper aren't graded here. They're on nootropic labels for other jobs, explained near the end.

How we graded these 20 ingredients

We're Avantera Health, and we make a nootropic called Avantera Elevate, which contains 6 of the 20 ingredients below. So read this knowing who wrote it. The "In Elevate" column is there so you can see where our own ingredients land, including where their research is thin. For what each type of nootropic is and how it's thought to work, see our list of nootropics by type.

Every grade follows the same written rule:

• Healthy adults only. Grades come from placebo-controlled trials and reviews in healthy adults, including healthy older adults and healthy people under strain, such as night shifts, lost sleep or exams. Trials in people with a diagnosed condition weren't used.
• Strong: several trials in healthy adults plus a review or meta-analysis agreeing on the same outcome.
• Moderate: more than one controlled trial in healthy adults pointing the same way, or a meta-analysis built on small or uneven trials.
• Limited: one or two small trials in healthy adults, or results in only one narrow group of people.
• Mixed: trials or reviews of similar quality disagree.
• Limited data: fewer than two controlled trials in healthy adults on the outcome, too few to grade.

The doses column gives the range used across the trials, with the form. Where fewer than two trials exist, it says "limited data" rather than one study's dose. Each row lists 2 or 3 key trials, with a trial that found no benefit where an important one exists, and every trial links to its PubMed record. We checked each one against its abstract in October 2026. The list covers dietary-supplement ingredients sold over the counter in the US. A grade describes how consistent the research is. It doesn't describe how large the effect is.

20 nootropic ingredients, graded

Ingredient	Grade	What was measured	Who was studied	Doses studied (form)	Key trials	In Elevate
Caffeine	Strong	Alertness, attention, reaction time. Memory results are mixed	Healthy adults, both regular coffee drinkers and non-users; adults short on sleep	About 40 to 300 mg in one dose (caffeine in drinks or capsules)	Haskell 2005 (PMID 15678363); Einöther 2013, review (PMID 23241646); McLellan 2016, review (PMID 27612937)	Yes
Bacopa monnieri	Moderate	Recall of newly learned material and speed on attention tests, after about 12 weeks	Healthy adults 18 to 60; healthy older adults	300 to 450 mg a day of standardized extract, for about 12 weeks	Pase 2012, review (PMID 22747190); Kongkeaw 2014, meta-analysis (PMID 24252493); Stough 2001 (PMID 11498727)	Yes
Creatine	Moderate	Short-term and working memory	Healthy adults; clearest in older adults, vegetarians and people short on sleep	About 2 to 20 g a day of creatine monohydrate (often 5 g a day for weeks, or 20 g a day for 5 to 7 days)	Prokopidis 2023, meta-analysis (PMID 35984306); Rae 2003 (PMID 14561278); Rawson 2008, no benefit (PMID 18579168)	No
Sage	Moderate	Word recall, memory, attention and mental fatigue, mostly in the hours after one dose	Healthy young adults; healthy adults over 65	Spanish sage oil 25 to 150 µL; common sage extract 167 to 1,332 mg; dried leaf 300 to 600 mg	Tildesley 2003 (PMID 12895685); Kennedy 2011 (PMID 20937617); Scholey 2008 (PMID 18350281)	No
Citicoline (CDP-choline)	Limited	Attention errors after 28 days; memory for everyday events after 12 weeks; attention on the day, taken with caffeine	Healthy women 40 to 60; adults 50 to 85 with ordinary age-related memory complaints; young adults	250 to 2,000 mg a day of citicoline (most often the Cognizin brand)	McGlade 2012 (DOI; journal not in PubMed); Nakazaki 2021 (PMID 33978188); Bruce 2014 (PMID 25046515)	Yes
Lion's mane	Limited	Depends on the form (see the next table)	Healthy adults 18 to 50; healthy adults over 50	Varies by form and amount (see the next table)	Docherty 2023 (PMID 38004235); Saitsu 2019 (PMID 31413233); Surendran 2025 (PMID 40276537)	Yes (fruiting-body extract)
L-tyrosine	Limited	Working memory and task switching during stress or heavy demand	Healthy young adults in cold exposure, lost sleep or military training	Single doses from about 2 g up to 100 to 300 mg per kg of body weight	Jongkees 2015, review (PMID 26424423); Mahoney 2007 (PMID 17585971); van de Rest 2017 (PMID 29168741)	No
Alpha-GPC	Limited	Attention on a color-word test; vigilance unchanged	Healthy young men	250 to 630 mg, in one dose or daily for up to 7 days	Kerksick 2024 (PMID 39683633); Marcus 2017, no benefit (PMID 29042830)	No
Pine bark extract (Pycnogenol)	Limited	Working memory; attention and memory in studies without a placebo	Healthy adults 60 to 85 in the one placebo-controlled trial; students and older adults in the others	100 to 150 mg a day of Pycnogenol	Ryan 2008 (PMID 18701642); Luzzi 2011 (PMID 22108481); Belcaro 2015 (PMID 26635191)	No
Spearmint extract	Limited	Sustained attention; unclear in a second, smaller trial	Healthy, active adults; 10 men in an elite counterterrorism unit after a 24-hour operation without sleep	900 mg a day of one proprietary extract	Falcone 2019 (PMID 30802720); Ostfeld 2018, unclear (PMID 30566730)	No
L-theanine (on its own)	Mixed	Reaction time on attention tasks. Some tasks improved, others didn't	Healthy adults	50 to 400 mg in one dose; 200 mg a day for 4 weeks (pure L-theanine)	Gerolymos 2026, meta-analysis (PMID 42410082); Mátyus 2025, meta-analysis (PMID 41227106); Hidese 2019 (PMID 31623400)	Yes
Rhodiola rosea	Mixed	Mental fatigue during stress, such as night shifts and exams	Young doctors, military cadets, students, nursing students	About 100 to 576 mg of extract a day, or single doses of 370 to 555 mg (mostly the SHR-5 extract)	Ishaque 2012, review (PMID 22643043); Shevtsov 2003 (PMID 12725561); Punja 2014, no benefit (PMID 25268730)	Yes
Ginkgo biloba	Mixed	Memory, attention	Healthy young, midlife and older adults	120 to 240 mg a day of standardized leaf extract; single doses of 120 to 360 mg	Laws 2012, meta-analysis, no benefit (PMID 23001963); Solomon 2002, no benefit (PMID 12186600); Kennedy 2000 (PMID 11026748)	No
Panax ginseng	Mixed	Memory, mental arithmetic, mental fatigue	Healthy young adults, mostly in single-dose lab studies	200 to 600 mg in one dose, or 200 to 1,000 mg a day for up to 8 weeks (G115 extract or Korean red ginseng)	Geng 2010, Cochrane review (PMID 21154383); Reay 2005 (PMID 15982990); Reay 2010 (PMID 20737519)	No
Omega-3 (DHA and EPA)	Mixed	Memory, overall thinking scores	Healthy adults 18 to 45 who ate little DHA; healthy older adults	400 to 1,800 mg a day of EPA plus DHA from fish oil, or about 900 to 1,160 mg of DHA alone, for 6 months to over 3 years	Brainard 2020, review (PMID 32305302); van de Rest 2008, no benefit (PMID 18678826); Stonehouse 2013 (PMID 23515006)	No
Ashwagandha	Mixed	Self-rated stress and cortisol; memory and attention in a few trials	Stressed but otherwise healthy adults, mostly 20 to 55	300 mg a day of root extract in the trial cited; the meta-analysis pooled several extracts and amounts	Albalawi 2025, meta-analysis (PMID 40746175); Gopukumar 2021 (PMID 34858513)	No
Cocoa flavanols	Mixed	Attention, memory, processing speed	Healthy young and midlife adults; healthy older adults	About 260 to 994 mg of cocoa flavanols, in one dose or daily (drinks or extract capsules)	Scholey 2010 (PMID 19942640); Mastroiacovo 2015 (PMID 25733639); Vyas 2024, no effect after two years (PMID 38070683)	No
Guarana	Mixed	Response time, attention	Healthy young adults	37.5 to 500 mg of extract in one dose (about 4 to 130 mg of caffeine)	Hack 2023, meta-analysis (PMID 36678305); Kennedy 2004 (PMID 15582012); Gurney 2023 (PMID 36146946)	No
Magnesium L-threonate	Limited data	Overall thinking score, working and episodic memory	Adults 18 to 45 unhappy with their sleep (one trial)	Limited data	Lopresti 2025 (PMID 41601871); Hausenblas 2024, self-rated alertness only (PMID 39252819)	No
Phosphatidylserine	Limited data	Speed on a mental-arithmetic test (one trial)	18 resistance-trained young men; 16 healthy people tested after a lab stress task	Limited data	Parker 2011 (PMID 22017963); Baumeister 2008, brain-wave results only (PMID 18616866)	No

One pairing is graded separately because it has its own trials:

Pairing	Grade	What was measured	Who was studied	Doses studied (form)	Key trials	In Elevate
Caffeine with L-theanine	Moderate	Accuracy when switching between tasks, and alertness, within 2 hours of one dose	Healthy young adults	40 to 150 mg of caffeine with 97 to 250 mg of L-theanine, in one dose	Camfield 2014, meta-analysis (PMID 24946991); Owen 2008 (PMID 18681988); Haskell 2008 (PMID 18006208)	Yes

Lion's mane, graded by form

"Lion's mane" on a label can mean the whole mushroom (the fruiting body), an extract of it, the root-like mycelium, or a blend. Trials have used all of these, at very different amounts, so one grade and one dose would hide more than they show.

Form	Grade	What was found	Who was studied	Doses studied	Key trials
Fruiting body, dried powder	Limited	A higher score on a general thinking test after 12 weeks than placebo; faster times on some tasks within 2 hours of one dose, measured against the same people's starting point	Healthy adults over 50; healthy adults 18 to 50	About 1 to 3.2 g a day	Saitsu 2019 (PMID 31413233); La Monica 2023 (PMID 38140277)
Fruiting-body extract (such as 10:1)	Limited data	One trial of a single serving: overall thinking and mood unchanged at 90 minutes, one hand-dexterity task better	18 healthy adults 18 to 35	Limited data	Surendran 2025 (PMID 40276537)
Mycelium	Limited data	We found no placebo-controlled thinking trial of mycelium on its own in healthy adults	None found	Limited data	None found
Blend, or form not stated in the paper	Mixed	Faster on one attention task 60 minutes after one dose, with weaker 28-day results; no change after 4 weeks in a second trial	Healthy adults 18 to 45; college-age adults	About 1.8 to 10 g a day	Docherty 2023 (PMID 38004235); Grozier 2022 (PMID 36582308)

Across every form, lion's mane research in healthy people is early and small, with no meta-analysis yet. Much of the interest in it comes from lab and animal studies. When you compare labels, look for the part of the mushroom used, the extract ratio and what it's standardized to. More on how Elevate's lion's mane is made is on our lion's mane page.

What stands behind each grade

Strong: caffeine

Caffeine has many placebo-controlled trials and several reviews pointing the same way. Doses from about 40 to 300 mg improved alertness, attention and reaction time (McLellan et al., 2016), in regular coffee drinkers and in people who rarely have caffeine (Haskell et al., 2005). The effects are clearest in people short on sleep. Memory and complex reasoning results are mixed. For doses, half-life and how caffeine fits with coffee, see Is Caffeine a Nootropic?

Moderate: bacopa, creatine, sage, and caffeine with L-theanine

Bacopa has a review of 12-week trials whose most consistent finding was better recall of newly learned material (Pase et al., 2012), and a meta-analysis of trials lasting 12 weeks or more that found faster performance on attention tests (Kongkeaw et al., 2014). It isn't uniform: a 12-week trial in adults 40 to 70 found no memory or attention benefit over placebo (Lopresti et al., 2025). Creatine improved memory in a meta-analysis of healthy people, but the gain sat almost entirely in older adults, and young adults showed no effect (Prokopidis et al., 2023). Sage has several small crossover trials pointing the same way, almost all from one research group, and almost all testing a single dose. Caffeine with L-theanine was pooled in a meta-analysis that found better alertness and task-switching accuracy in the first 2 hours (Camfield et al., 2014).

Limited: six ingredients with thin or narrow research

Citicoline, lion's mane, L-tyrosine, alpha-GPC, pine bark extract and spearmint extract each have a few positive trials, but small ones, or ones in a single group. L-tyrosine's benefits show up under acute stress, like cold water or a night without sleep, and in adults 60 to 75 the higher doses made working memory worse (van de Rest et al., 2017). Pine bark extract has one placebo-controlled trial in healthy adults, in people aged 60 to 85 (Ryan et al., 2008). Spearmint extract has one positive trial in healthy adults, for sustained attention (Falcone et al., 2019), and a 10-person trial with unclear results (Ostfeld et al., 2018). Both used one company's extract.

Mixed: eight ingredients where trials disagree

Ginkgo's single-dose lab studies in young adults found faster attention (Kennedy et al., 2000), while a meta-analysis of healthy people (Laws et al., 2012) and a 6-week trial in 230 healthy adults over 60 (Solomon et al., 2002) found no difference from placebo on memory. Cocoa flavanols helped some tasks in small trials, but in-person testing of 573 older adults in the large COSMOS trial found no effect on overall thinking after two years (Vyas et al., 2024). Omega-3 showed benefits mainly in people who ate little DHA (Stonehouse et al., 2013), not in older adults overall (van de Rest et al., 2008). Guarana contains caffeine, and a meta-analysis found an overall effect too small to matter, apart from a small gain in response time (Hack et al., 2023). Ashwagandha's results are mixed: a 2025 meta-analysis found lower cortisol but no change in self-rated stress (Albalawi, 2025), while a 90-day trial in stressed, healthy adults found lower stress scores and better recall (Gopukumar et al., 2021). Panax ginseng, rhodiola and L-theanine taken on its own each have trials pointing both ways.

Limited data: magnesium L-threonate and phosphatidylserine

One placebo-controlled trial tested magnesium L-threonate on its own with standard thinking tests, in adults unhappy with their sleep (Lopresti et al., 2025). A second measured sleep and how alert people said they felt (Hausenblas et al., 2024). That's too little to grade.

Phosphatidylserine has one placebo-controlled trial in healthy adults that reports thinking-test scores: 18 young men solved mental-arithmetic problems faster after 14 days of a soy form (Parker et al., 2011). A second, in 16 healthy people, reports only brain-wave changes during thinking tasks after a stress test (Baumeister et al., 2008). That's too little to grade as well.

What a grade can't tell you

• How big the effect is. A Strong grade means the research agrees. Caffeine's effects are real and modest. A Limited ingredient could turn out larger or smaller once more trials exist.
• How long it takes. A grade doesn't say when an effect showed up. Caffeine was measured within the hour; bacopa's clearest results came after about 12 weeks. For each ingredient's timing, see How Long Do Nootropics Take to Work?
• Which part of thinking was tested. A grade covers the tests a trial used, not thinking in general. A faster Stroop time is a result about attention, not memory. For what each test asks people to do, see our guide to the thinking tests used in supplement studies.
• Whether it carries over to you. A result in night-shift doctors, vegetarians or adults over 65 may not apply to someone else. That's why the table lists who was studied.
• Which product matches the research. Many trials used one branded extract with its own standardization. The same plant name on another label isn't the same material.
• How ingredients act together. Most trials test one ingredient. Caffeine with L-theanine is the main pairing tested as a pair. A stack's label tells you what's in it and how much.
• Who paid for the trial. Several of the trials above were funded by, or have authors tied to, the company that makes the ingredient. The Sources list links each paper so you can check.

If you're pregnant or nursing, take medication, have a health condition or are under 18, check with a clinician before starting any supplement.

For more on reading a label, extract ratios and standardization, see How to Choose a Nootropic. For the ingredients studied for focus specifically, see Best Nootropic Ingredients for Focus, and for brain fog, Best Nootropic Ingredients for Brain Fog.

Supporting ingredients, and why they're on a label

Some nootropic labels, ours included, carry ingredients that aren't there for focus or memory. We left them out of the grades, because grading them on thinking tests would judge them on a job they weren't added to do. Here is the job each one does:

• Ginger root extract is in Elevate for stomach comfort. Some trials of bacopa reported occasional stomach upset, and ginger has a long research record for digestion; in healthy adults it sped up how fast the stomach emptied after a meal (Wu et al., 2008). It supports digestion and digestive comfort.*
• Turmeric root extract supports gut function.* It's in Elevate capsules for that job, not as a focus ingredient.
• Black pepper extract (piperine) is often paired with turmeric to support curcumin absorption. In an early study it raised blood levels of curcumin (Shoba et al., 1998); later trials have been less consistent.

How this applies to Elevate

Six of the 20 graded ingredients are in Avantera Elevate capsules: caffeine, L-theanine, citicoline (CDP-choline), bacopa, rhodiola and lion's mane. That includes the one ingredient we grade Strong, caffeine, and the pairing with a Moderate grade of its own, caffeine with L-theanine.

A cup of coffee's caffeine, with twice the L-theanine for calm, steady focus.* Each serving pairs 95 mg of caffeine (from green tea leaf) with 200 mg of L-theanine.

Elevate supports acetylcholine, your brain's memory messenger, two ways: CDP-choline and bacopa.* 200 mg of CDP-choline (citicoline) is a source of choline the body uses to make acetylcholine, and 300 mg of bacopa monnieri (standardized to 50% bacosides) is an herb studied for how it supports acetylcholine activity.*

The rest of the label: rhodiola rosea root extract, 300 mg, standardized to 3% salidrosides; and organic lion's mane, a 10:1 fruiting-body extract derived from 500 mg of lion's mane, standardized to 30% polysaccharides. The supporting ingredients are turmeric root extract (100 mg), ginger root extract (30 mg) and BioPerine black pepper extract (5 mg).

Nine ingredients. Every dose on the label. About $1.78 a day. Avantera Elevate lists all nine ingredients and every dose on the label, with no proprietary blends, and every batch is third-party tested. The certificates of analysis are on our quality page.

Elevate costs $49.95 for a 28-day supply, about $1.78 a day, with a 30-day money-back guarantee on your first order. Elevate ships as a subscription every 4 weeks, and you can pause, skip or cancel anytime from your account. The full label is on the Avantera Elevate product page and the Elevate Sour Gummies page, and what customers say is on our Avantera Elevate reviews page. More on two of the ingredients is on our bacopa and rhodiola pages.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Frequently asked questions

Which nootropic ingredients have the most evidence?

Of 20 common nootropic ingredients graded on human trials in healthy adults, caffeine has the strongest and most consistent research, for alertness, attention and reaction time at about 40 to 300 mg. Bacopa (recall after about 12 weeks), creatine (memory, clearest in older adults), sage and caffeine taken with L-theanine have moderate evidence.

Does lion's mane have evidence?

Lion's mane research in healthy adults is early and small, and it depends on the form. Fruiting-body powder has two small trials with some positive results. Fruiting-body extracts have one trial, and we found no placebo-controlled thinking trial of mycelium on its own in healthy adults. There is no single research dose, because trials used different forms at different amounts.

Why do nootropic trials disagree so often?

Many nootropic trials are small and short: most of the trials in the table above enrolled fewer than 100 people. They also differ in the form and amount of the ingredient, in who was studied and in which thinking tests were used, so two trials of the same ingredient name can measure different things. That's why a grade looks across several trials instead of trusting one.

Is creatine a nootropic?

Creatine has moderate evidence for memory. A meta-analysis of trials in healthy people found better memory scores overall, but the gain was concentrated in older adults, and young adults showed no effect. Trials used about 2 to 20 g a day of creatine monohydrate. Results were also clearer in vegetarians and in people short on sleep.

What does "limited data" mean in a nootropic evidence table?

In our table, "limited data" means there are fewer than two placebo-controlled trials in healthy adults on that outcome. That's too few to grade the ingredient, or to point to a research dose, so we show no single study's dose. It means the research hasn't been done yet. It doesn't mean the ingredient was tested and failed.

Are turmeric, ginger and black pepper nootropics?

Not in the sense of this list, so we didn't grade them on thinking tests. They appear on some nootropic labels for other jobs. In Avantera Elevate, ginger is there for stomach comfort, turmeric supports gut function, and black pepper extract is often paired with turmeric to support curcumin absorption.

Which of these ingredients are in Avantera Elevate?

Six of the 20: caffeine (95 mg), L-theanine (200 mg), citicoline (200 mg), bacopa (300 mg, standardized to 50% bacosides), rhodiola (300 mg, standardized to 3% salidrosides) and lion's mane (a 10:1 fruiting-body extract derived from 500 mg). Elevate also contains turmeric, ginger and black pepper extract, and lists every dose on its label.

Sources

1. Haskell CF, Kennedy DO, Wesnes KA, et al. Cognitive and mood improvements of caffeine in habitual consumers and habitual non-consumers of caffeine. Psychopharmacology (Berl), 2005. PMID 15678363
2. Einöther SJ, Giesbrecht T. Caffeine as an attention enhancer: reviewing existing assumptions. Psychopharmacology (Berl), 2013. PMID 23241646
3. McLellan TM, Caldwell JA, Lieberman HR. A review of caffeine's effects on cognitive, physical and occupational performance. Neurosci Biobehav Rev, 2016. PMID 27612937
4. Pase MP, Kean J, Sarris J, et al. The cognitive-enhancing effects of Bacopa monnieri: a systematic review of randomized, controlled human clinical trials. J Altern Complement Med, 2012. PMID 22747190
5. Kongkeaw C, Dilokthornsakul P, Thanarangsarit P, et al. Meta-analysis of randomized controlled trials on cognitive effects of Bacopa monnieri extract. J Ethnopharmacol, 2014. PMID 24252493
6. Stough C, Lloyd J, Clarke J, et al. The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects. Psychopharmacology (Berl), 2001. PMID 11498727
7. Lopresti AL, Smith SJ. The Effects of a Bacopa monnieri Extract (Bacumen(®)) on Cognition, Stress, and Fatigue in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Clin Drug Investig, 2025. PMID 41091332
8. Prokopidis K, Giannos P, Triantafyllidis KK, et al. Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev, 2023. PMID 35984306
9. Rae C, Digney AL, McEwan SR, et al. Oral creatine monohydrate supplementation improves brain performance: a double-blind, placebo-controlled, cross-over trial. Proc Biol Sci, 2003. PMID 14561278
10. Rawson ES, Lieberman HR, Walsh TM, et al. Creatine supplementation does not improve cognitive function in young adults. Physiol Behav, 2008. PMID 18579168
11. Tildesley NT, Kennedy DO, Perry EK, et al. Salvia lavandulaefolia (Spanish sage) enhances memory in healthy young volunteers. Pharmacol Biochem Behav, 2003. PMID 12895685
12. Kennedy DO, Dodd FL, Robertson BC, et al. Monoterpenoid extract of sage (Salvia lavandulaefolia) with cholinesterase inhibiting properties improves cognitive performance and mood in healthy adults. J Psychopharmacol, 2011. PMID 20937617
13. Scholey AB, Tildesley NT, Ballard CG, et al. An extract of Salvia (sage) with anticholinesterase properties improves memory and attention in healthy older volunteers. Psychopharmacology (Berl), 2008. PMID 18350281
14. McGlade E, Locatelli A, Hardy J, et al. Improved attentional performance following citicoline administration in healthy adult women. Food Nutr Sci, 2012. DOI 10.4236/fns.2012.36103 (journal not indexed in PubMed)
15. Nakazaki E, Mah E, Sanoshy K, et al. Citicoline and Memory Function in Healthy Older Adults: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial. J Nutr, 2021. PMID 33978188
16. Bruce SE, Werner KB, Preston BF, et al. Improvements in concentration, working memory and sustained attention following consumption of a natural citicoline-caffeine beverage. Int J Food Sci Nutr, 2014. PMID 25046515
17. Docherty S, Doughty FL, Smith EF. The Acute and Chronic Effects of Lion's Mane Mushroom Supplementation on Cognitive Function, Stress and Mood in Young Adults: A Double-Blind, Parallel Groups, Pilot Study. Nutrients, 2023. PMID 38004235
18. Saitsu Y, Nishide A, Kikushima K, et al. Improvement of cognitive functions by oral intake of Hericium erinaceus. Biomed Res, 2019. PMID 31413233
19. La Monica MB, Raub B, Ziegenfuss EJ, et al. Acute Effects of Naturally Occurring Guayusa Tea and Nordic Lion's Mane Extracts on Cognitive Performance. Nutrients, 2023. PMID 38140277
20. Surendran G, Saye J, Binti Mohd Jalil S, et al. Acute effects of a standardised extract of Hericium erinaceus (Lion's Mane mushroom) on cognition and mood in healthy younger adults: a double-blind randomised placebo-controlled study. Front Nutr, 2025. PMID 40276537
21. Grozier CD, Alves VA, Killen LG, et al. Four Weeks of Hericium erinaceus Supplementation Does Not Impact Markers of Metabolic Flexibility or Cognition. Int J Exerc Sci, 2022. PMID 36582308
22. Jongkees BJ, Hommel B, Kühn S, et al. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands: A review. J Psychiatr Res, 2015. PMID 26424423
23. Mahoney CR, Castellani J, Kramer FM, et al. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav, 2007. PMID 17585971
24. van de Rest O, Bloemendaal M, de Heus R, et al. Dose-Dependent Effects of Oral Tyrosine Administration on Plasma Tyrosine Levels and Cognition in Aging. Nutrients, 2017. PMID 29168741
25. Kerksick CM. Acute Alpha-Glycerylphosphorylcholine Supplementation Enhances Cognitive Performance in Healthy Men. Nutrients, 2024. PMID 39683633
26. Marcus L, Soileau J, Judge LW, et al. Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance. J Int Soc Sports Nutr, 2017. PMID 29042830
27. Ryan J, Croft K, Mori T, et al. An examination of the effects of the antioxidant Pycnogenol on cognitive performance, serum lipid profile, endocrinological and oxidative stress biomarkers in an elderly population. J Psychopharmacol, 2008. PMID 18701642
28. Luzzi R, Belcaro G, Zulli C, et al. Pycnogenol® supplementation improves cognitive function, attention and mental performance in students. Panminerva Med, 2011. PMID 22108481
29. Belcaro G, Dugall M, Ippolito E, et al. The COFU3 Study. Improvement in cognitive function, attention, mental performance with Pycnogenol® in healthy subjects (55-70) with high oxidative stress. J Neurosurg Sci, 2015. PMID 26635191
30. Falcone PH, Nieman KM, Tribby AC, et al. The attention-enhancing effects of spearmint extract supplementation in healthy men and women: a randomized, double-blind, placebo-controlled, parallel trial. Nutr Res, 2019. PMID 30802720
31. Ostfeld I, Ben-Moshe Y, Hoffman MW, et al. Effect of Spearmint Extract Containing Rosmarinic Acid on Physical and Executive Functioning After a Tactical Operation. J Spec Oper Med, 2018. PMID 30566730
32. Gerolymos C, Saddier E, Boyer L, et al. Cognitive and affective effects of L-Theanine: a systematic review and meta-analysis of 31 randomized trials. Mol Psychiatry, 2026. PMID 42410082
33. Mátyus RO, Szikora Z, Bodó D, et al. Promising, but Not Completely Conclusive-The Effect of l-Theanine on Cognitive Performance Based on the Systematic Review and Meta-Analysis of Randomized Placebo-Controlled Clinical Trials. J Clin Med, 2025. PMID 41227106
34. Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients, 2019. PMID 31623400
35. Camfield DA, Stough C, Farrimond J, et al. Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis. Nutr Rev, 2014. PMID 24946991
36. Owen GN, Parnell H, De Bruin EA, et al. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci, 2008. PMID 18681988
37. Haskell CF, Kennedy DO, Milne AL, et al. The effects of L-theanine, caffeine and their combination on cognition and mood. Biol Psychol, 2008. PMID 18006208
38. Ishaque S, Shamseer L, Bukutu C, et al. Rhodiola rosea for physical and mental fatigue: a systematic review. BMC Complement Altern Med, 2012. PMID 22643043
39. Shevtsov VA, Zholus BI, Shervarly VI, et al. A randomized trial of two different doses of a SHR-5 Rhodiola rosea extract versus placebo and control of capacity for mental work. Phytomedicine, 2003. PMID 12725561
40. Punja S, Shamseer L, Olson K, et al. Rhodiola rosea for mental and physical fatigue in nursing students: a randomized controlled trial. PLoS One, 2014. PMID 25268730
41. Laws KR, Sweetnam H, Kondel TK. Is Ginkgo biloba a cognitive enhancer in healthy individuals? A meta-analysis. Hum Psychopharmacol, 2012. PMID 23001963
42. Solomon PR, Adams F, Silver A, et al. Ginkgo for memory enhancement: a randomized controlled trial. JAMA, 2002. PMID 12186600
43. Kennedy DO, Scholey AB, Wesnes KA. The dose-dependent cognitive effects of acute administration of Ginkgo biloba to healthy young volunteers. Psychopharmacology (Berl), 2000. PMID 11026748
44. Geng J, Dong J, Ni H, et al. Ginseng for cognition. Cochrane Database Syst Rev, 2010. PMID 21154383
45. Reay JL, Kennedy DO, Scholey AB. Single doses of Panax ginseng (G115) reduce blood glucose levels and improve cognitive performance during sustained mental activity. J Psychopharmacol, 2005. PMID 15982990
46. Reay JL, Scholey AB, Kennedy DO. Panax ginseng (G115) improves aspects of working memory performance and subjective ratings of calmness in healthy young adults. Hum Psychopharmacol, 2010. PMID 20737519
47. Brainard JS, Jimoh OF, Deane KHO, et al. Omega-3, Omega-6, and Polyunsaturated Fat for Cognition: Systematic Review and Meta-analysis of Randomized Trials. J Am Med Dir Assoc, 2020. PMID 32305302
48. van de Rest O, Geleijnse JM, Kok FJ, et al. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial. Neurology, 2008. PMID 18678826
49. Stonehouse W, Conlon CA, Podd J, et al. DHA supplementation improved both memory and reaction time in healthy young adults: a randomized controlled trial. Am J Clin Nutr, 2013. PMID 23515006
50. Albalawi AA. Dual impact of Ashwagandha: Significant cortisol reduction but no effects on perceived stress - A systematic review and meta-analysis. Nutr Health, 2025. PMID 40746175
51. Gopukumar K, Thanawala S, Somepalli V, et al. Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults: A Randomized, Double-Blind, Placebo-Controlled Study. Evid Based Complement Alternat Med, 2021. PMID 34858513
52. Scholey AB, French SJ, Morris PJ, et al. Consumption of cocoa flavanols results in acute improvements in mood and cognitive performance during sustained mental effort. J Psychopharmacol, 2010. PMID 19942640
53. Mastroiacovo D, Kwik-Uribe C, Grassi D, et al. Cocoa flavanol consumption improves cognitive function, blood pressure control, and metabolic profile in elderly subjects: the Cocoa, Cognition, and Aging (CoCoA) Study: a randomized controlled trial. Am J Clin Nutr, 2015. PMID 25733639
54. Vyas CM, Manson JE, Sesso HD, et al. Effect of cocoa extract supplementation on cognitive function: results from the clinic subcohort of the COSMOS trial. Am J Clin Nutr, 2024. PMID 38070683
55. Hack B, Penna EM, Talik T, et al. Effect of Guarana (Paullinia cupana) on Cognitive Performance: A Systematic Review and Meta-Analysis. Nutrients, 2023. PMID 36678305
56. Kennedy DO, Haskell CF, Wesnes KA, et al. Improved cognitive performance in human volunteers following administration of guarana (Paullinia cupana) extract: comparison and interaction with Panax ginseng. Pharmacol Biochem Behav, 2004. PMID 15582012
57. Gurney T, Bradley N, Izquierdo D, et al. Cognitive effects of guarana supplementation with maximal intensity cycling. Br J Nutr, 2023. PMID 36146946
58. Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein(®)) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Front Nutr, 2025. PMID 41601871
59. Hausenblas HA, Lynch T, Hooper S, et al. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial. Sleep Med X, 2024. PMID 39252819
60. Parker AG, Gordon J, Thornton A, et al. The effects of IQPLUS Focus on cognitive function, mood and endocrine response before and following acute exercise. J Int Soc Sports Nutr, 2011. PMID 22017963
61. Baumeister J, Barthel T, Geiss KR, Weiss M. Influence of phosphatidylserine on cognitive performance and cortical activity after induced stress. Nutr Neurosci, 2008. PMID 18616866
62. Wu KL, Rayner CK, Chuah SK, et al. Effects of ginger on gastric emptying and motility in healthy humans. Eur J Gastroenterol Hepatol, 2008. PMID 18403946
63. Shoba G, Joy D, Joseph T, et al. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med, 1998. PMID 9619120