[{"data":1,"prerenderedAt":278},["ShallowReactive",2],{"supplement-alpha-gpc":3,"supplement-article-titles":238},{"supplement":4,"related":74},{"slug":5,"name":6,"aliases":7,"categories":11,"tagline":13,"evidenceGrade":14,"evidenceSummary":15,"dose":16,"timing":22,"mechanism":23,"description":24,"effects":25,"safety":40,"sideEffects":41,"interactions":45,"references":48,"relatedCalculators":61,"relatedArticles":65,"relatedSupplements":69,"lastVerified":73},"alpha-gpc","Alpha-GPC",[8,9,10],"alpha-glycerylphosphorylcholine","choline alfoscerate","L-alpha glycerylphosphorylcholine",[12],"nootropic","The best-absorbed choline source, with real evidence in dementia, thinner evidence in healthy people, and an unresolved stroke-risk signal.","C","Clinical trials in Alzheimer's and vascular dementia show meaningful cognitive benefit. In healthy adults the evidence is limited to small studies of power output and reaction time. An observational analysis has linked chronic use to increased stroke risk.",{"low":17,"high":18,"unit":19,"label":20,"frequency":21},300,600,"mg","300-600 mg\u002Fday; dementia trials used 1,200 mg","once daily, or 30-60 minutes pre-training","30-60 minutes before training for the power and reaction-time effects; any time for general choline supply","Alpha-GPC crosses the blood-brain barrier efficiently and is cleaved to release choline, the direct precursor for acetylcholine — the neurotransmitter central to attention, learning, and neuromuscular signalling. It appears to raise brain choline more effectively than choline bitartrate or CDP-choline on a per-gram basis.","Alpha-GPC is what people buy when they have learned that most choline supplements do not reach the brain. Choline bitartrate, the cheap default, is poorly transported across the blood-brain barrier. Alpha-GPC crosses readily, which is why it dominates the serious end of the nootropic market alongside citicoline.\n\nIts strongest evidence is clinical rather than recreational. In Alzheimer's disease and vascular dementia, trials at 1,200 mg daily have shown meaningful improvement on cognitive and functional scales — including a large multicentre Italian trial — and it is prescribed as a drug for exactly this purpose in several European countries. In conditions where cholinergic neurons are dying, supplying the precursor makes obvious sense, and it appears to work.\n\nWhat that does not establish is benefit in a healthy twenty-eight-year-old whose cholinergic system is intact. The healthy-adult literature is thin: a handful of small studies report improved power output, faster reaction time, and increased growth hormone response to exercise, several of them conference abstracts rather than full papers. The physical-performance findings are arguably more consistent than the cognitive ones, which is not what most buyers expect.\n\nThe reason for caution is a genuine safety signal that most retailers do not mention. A secondary analysis of a large insurance database found that chronic alpha-GPC use was associated with a substantially increased ten-year risk of stroke. The proposed mechanism is that choline is converted by gut bacteria to TMAO, a metabolite independently linked to cardiovascular disease. This is observational, confounded by the fact that people prescribed alpha-GPC in that dataset had cognitive impairment and therefore higher baseline vascular risk, and it has not been confirmed in a trial. But it is not nothing, and it deserves to sit alongside the efficacy claims rather than beneath them.\n\nSensible use, then, is intermittent rather than daily: 300-600 mg before sessions where you want it, not a permanent fixture. If you have existing cardiovascular risk, the balance tips further toward caution, and citicoline — which carries no comparable signal — is a reasonable alternative.",[26,30,33,36],{"effect":27,"grade":28,"note":29},"Improves cognition in Alzheimer's and vascular dementia","B","clinical trials at 1,200 mg\u002Fday; prescribed as a drug in parts of Europe",{"effect":31,"grade":14,"note":32},"Increases power output and reaction time","small studies, several published only as abstracts",{"effect":34,"grade":14,"note":35},"Increases exercise-induced growth hormone response","transient, and of unclear practical consequence",{"effect":37,"grade":38,"note":39},"Enhances cognition in healthy young adults","D","little direct evidence; the main marketing claim","Well tolerated in trials, including long-duration dementia studies. The unresolved concern is an observational association between chronic use and increased stroke risk, plausibly mediated by TMAO production from choline. This has not been tested in a randomised trial, and the source population was confounded; there is no evidence-based intermittent schedule. People with cardiovascular disease or stroke risk should discuss it with a clinician before use rather than treating it as a routine daily supplement.",[42,43,44],"Headache — the most common complaint","Nausea, dizziness, and heartburn","Insomnia if taken late in the day",[46,47],"Additive with anticholinergic medication in opposite directions — may reduce their effect.","Theoretically additive with cholinesterase inhibitors such as donepezil.",[49,55],{"authors":50,"year":51,"title":52,"journal":53,"url":54},"De Jesus Moreno Moreno, M.",2003,"Cognitive improvement in mild to moderate Alzheimer's dementia after treatment with the acetylcholine precursor choline alfoscerate: a multicenter, double-blind, randomized, placebo-controlled trial","Clinical Therapeutics","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fs0149-2918(03)90023-3",{"authors":56,"year":57,"title":58,"journal":59,"url":60},"Marcus, L., et al.",2017,"Evaluation of the effects of two doses of alpha glycerylphosphorylcholine on physical and psychomotor performance","Journal of the International Society of Sports Nutrition","https:\u002F\u002Fdoi.org\u002F10.1186\u002Fs12970-017-0196-5",[62,63,64],"one-rep-max","grip-strength","phenotypic-age-calculator",[66,67,68],"strength-training-fundamentals","exploring-biomarkers","grip-strength-longevity",[70,71,72],"citicoline","caffeine","l-tyrosine","2026-08",[75,127,192],{"slug":70,"name":76,"aliases":77,"categories":80,"tagline":81,"evidenceGrade":28,"evidenceSummary":82,"dose":83,"timing":87,"mechanism":88,"description":89,"effects":90,"safety":100,"sideEffects":101,"interactions":105,"references":106,"relatedCalculators":119,"relatedArticles":122,"relatedSupplements":124,"lastVerified":73},"Citicoline",[78,79],"CDP-choline","cytidine diphosphate-choline",[12],"A choline source that doubles as a membrane-repair substrate, with respectable trial support for attention and memory.","Randomized trials show improved episodic memory in older adults and better attention at 250-500 mg\u002Fday. Effects in healthy young adults are smaller and less consistent.",{"low":84,"high":85,"unit":19,"frequency":86},250,500,"once daily","Morning or midday, with or without food. Some users find late doses mildly stimulating","Citicoline splits into choline and cytidine, which the brain reassembles into phosphatidylcholine — the main phospholipid of neuronal membranes — while the choline also feeds acetylcholine synthesis. It thus supplies both a neurotransmitter precursor and a membrane-repair substrate in one molecule.","Citicoline occupies a middle tier of the nootropic world that deserves more attention than it gets: cheaper claims get more marketing, flashier compounds get more forum posts, but citicoline quietly has some of the better randomized-trial support in the category.\n\nIts dual mechanism is what distinguishes it from plain choline supplements. Once absorbed it splits into choline and cytidine; the brain uses the pair to synthesize phosphatidylcholine, the structural phospholipid that neuronal membranes are largely built from, while the choline fraction also supports acetylcholine — the neurotransmitter most tied to attention and memory. You are supplying both a building material and a signaling precursor.\n\nThe trial record concentrates in two places. In older adults with age-associated memory decline, randomized controlled trials — including a well-run 2021 study — found improved episodic memory over 12 weeks at 500 mg daily. In attention, trials in both older and younger adults have found measurable improvements at 250-500 mg, though the younger-adult effects are subtler and less consistently replicated. For stroke recovery, where citicoline spent decades as a prescription drug in Europe and Japan, the largest modern trial came back null — worth knowing as context for older enthusiastic claims.\n\nAs a practical matter citicoline is easy to use well. The studied doses are 250-500 mg once daily, tolerability in trials has been excellent, and it pairs sensibly with regimens that increase acetylcholine demand. The honest framing: for adults noticing early memory slippage it has genuine, replicated support; for a sharp 25-year-old seeking an edge, expect something between subtle and nothing. That gradient — clear benefit where there is a deficit to repair, diminishing returns at a healthy baseline — is the recurring pattern across evidence-based nootropics, and citicoline illustrates it cleanly.",[91,94,97],{"effect":92,"grade":28,"note":93},"Improves episodic memory in older adults","500 mg\u002Fday over 12 weeks",{"effect":95,"grade":28,"note":96},"Improves attention","smaller effects in healthy young adults",{"effect":98,"grade":38,"note":99},"Aids post-stroke recovery","largest modern trial (ICTUS) was null","Excellent tolerability in trials at studied doses, including in elderly populations; decades of pharmaceutical use in Europe and Japan provide a long safety record.",[102,103,104],"Headache","Insomnia when taken late","GI upset (uncommon)",[],[107,113],{"authors":108,"year":109,"title":110,"journal":111,"url":112},"Nakazaki, E., et al.",2021,"Citicoline and memory function in healthy older adults: a randomized, double-blind, placebo-controlled clinical trial","Journal of Nutrition","https:\u002F\u002Fdoi.org\u002F10.1093\u002Fjn\u002Fnxab119",{"authors":114,"year":115,"title":116,"journal":117,"url":118},"Grieb, P.",2014,"Neuroprotective properties of citicoline: facts, doubts and unresolved issues","CNS Drugs","https:\u002F\u002Fdoi.org\u002F10.1007\u002Fs40263-014-0144-8",[120,121],"sleep","metabolic-age",[123],"biological-vs-chronological-age",[125,126],"bacopa-monnieri","phosphatidylserine",{"slug":71,"name":128,"aliases":129,"categories":133,"tagline":135,"evidenceGrade":136,"evidenceSummary":137,"dose":138,"timing":142,"mechanism":143,"description":144,"effects":145,"safety":156,"sideEffects":157,"interactions":162,"references":165,"relatedCalculators":184,"relatedArticles":186,"relatedSupplements":189,"lastVerified":73},"Caffeine",[130,131,132],"1,3,7-trimethylxanthine","coffee","caffeine anhydrous",[12,134],"performance","The most-used stimulant on earth, and one of the few supplements with strong evidence for both cognitive and physical performance.","A","Hundreds of trials and multiple umbrella reviews support caffeine for alertness, reaction time, and endurance performance. The effects are reliable, dose-dependent, and blunted — not erased — by habitual use.",{"low":139,"high":140,"unit":19,"frequency":141},100,400,"100-400 mg total per day; for performance, a single 3-6 mg\u002Fkg dose about 60 minutes before exercise, staying within the daily total","Morning or early afternoon. With a ~5 hour half-life, a hard cutoff 8+ hours before bed protects sleep — the caffeine half-life calculator shows your personal decay curve","Caffeine blocks adenosine receptors in the brain, suppressing the sleep-pressure signal that accumulates through the day. That antagonism raises alertness and perceived energy, and downstream effects on dopamine signaling and calcium handling in muscle contribute to its performance benefits.","Caffeine is the rare supplement that needs no introduction and still gets underestimated. Most people treat it as a habit; the research treats it as one of the most reliable ergogenic and cognitive aids ever tested. Umbrella reviews across hundreds of trials show consistent improvements in alertness, vigilance, and reaction time, plus a 2-4% improvement in endurance performance at doses of 3-6 mg per kg of body weight.\n\nThe cognitive story is mostly about restoring and defending baseline rather than raising it. Caffeine shines when you are sleep-deprived, fatigued, or mid-afternoon — states where adenosine has accumulated and there is something to block. In a fully rested brain the margin is smaller. That distinction matters for how you use it: as a tool deployed against fatigue, not a constant drip.\n\nTolerance is real but partial. Habitual users keep most of the performance benefit at the same dose, though the subjective jolt fades. What does not adapt is the half-life: roughly five hours for most adults, longer for slow CYP1A2 metabolizers and anyone on oral contraceptives. A 3 PM coffee still has half its caffeine circulating at 8 PM, which is why the highest-leverage caffeine decision is not the morning dose but the afternoon cutoff.\n\nThe safety ceiling for healthy adults sits around 400 mg per day per the major regulatory reviews, with single doses up to 200 mg considered safe. Pregnant women are advised to stay under 200 mg per day. Above the ceiling the returns invert: anxiety, tremor, heart palpitations, and wrecked sleep that quietly cancels the next day’s benefit. Pairing caffeine with L-theanine smooths the edge for people sensitive to jitters without dulling the alertness.",[146,148,151,154],{"effect":147,"grade":136},"Increases alertness and reaction time",{"effect":149,"grade":136,"note":150},"Improves endurance performance","2-4% at 3-6 mg\u002Fkg taken ~60 min before exercise",{"effect":152,"grade":28,"note":153},"Improves strength and power output","smaller and less consistent than the endurance effect",{"effect":155,"grade":136},"Raises daytime energy in sleep deprivation","Safe for healthy adults up to about 400 mg per day per EFSA and FDA reviews. It is still a stimulant: people with anxiety disorders, arrhythmias, or uncontrolled hypertension should be cautious, and pregnancy caps the advised intake at 200 mg per day.",[158,159,160,161],"Sleep disruption when taken too late","Jitteriness and anxiety at higher doses","Heart palpitations","Withdrawal headache on abrupt stopping",[163,164],"Amplifies other stimulants — do not stack with pre-workouts that already contain caffeine.","Some antibiotics (ciprofloxacin) and oral contraceptives slow caffeine clearance, effectively raising your dose.",[166,172,178],{"authors":167,"year":168,"title":169,"journal":170,"url":171},"Grgic, J., et al.",2020,"Wake up and smell the coffee: caffeine supplementation and exercise performance — an umbrella review of 21 published meta-analyses","British Journal of Sports Medicine","https:\u002F\u002Fdoi.org\u002F10.1136\u002Fbjsports-2018-100278",{"authors":173,"year":174,"title":175,"journal":176,"url":177},"McLellan, T. M., Caldwell, J. A., & Lieberman, H. R.",2016,"A review of caffeine’s effects on cognitive, physical and occupational performance","Neuroscience & Biobehavioral Reviews","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fj.neubiorev.2016.09.001",{"authors":179,"year":180,"title":181,"journal":182,"url":183},"EFSA Panel on Dietetic Products, Nutrition and Allergies",2015,"Scientific Opinion on the safety of caffeine","EFSA Journal","https:\u002F\u002Fdoi.org\u002F10.2903\u002Fj.efsa.2015.4102",[185,120],"caffeine-half-life",[187,188],"caffeine-half-life-sleep","sleep-optimization",[190,191],"l-theanine","creatine",{"slug":72,"name":193,"aliases":194,"categories":197,"tagline":198,"evidenceGrade":28,"evidenceSummary":199,"dose":200,"timing":203,"mechanism":204,"description":205,"effects":206,"safety":215,"sideEffects":216,"interactions":219,"references":222,"relatedCalculators":233,"relatedArticles":235,"relatedSupplements":236,"lastVerified":73},"L-Tyrosine",[195,196],"tyrosine","N-acetyl L-tyrosine (NALT)",[12],"A dopamine precursor that defends cognition during acute stress — cold, noise, sleep loss — and does little on an ordinary day.","A consistent set of controlled studies, much of it military-funded, shows preserved working memory and cognitive flexibility under acute stressors. Benefits in unstressed conditions are absent by design of the mechanism.",{"low":85,"high":201,"unit":19,"frequency":202},2000,"30-60 minutes before an anticipated stressor","30-60 minutes before the demanding event — a night shift, an exam, hard training in the cold. Not a daily-maintenance supplement","Tyrosine is the direct precursor to dopamine and norepinephrine. Sustained acute stress depletes these catecholamines faster than the rate-limiting synthesis step can replace them; a pre-loaded tyrosine pool buffers that depletion, preserving the cognition that depends on catecholamine signaling.","Most nootropics promise to lift your ceiling. Tyrosine’s pitch is different and better supported: it defends your floor. As the raw material your brain turns into dopamine and norepinephrine, it matters precisely when those neurotransmitters are being burned faster than they are replaced — which is what acute stress does.\n\nThe research base is unusually coherent because much of it comes from one funder with one question: the US military, asking whether soldiers could stay cognitively functional in brutal conditions. Across studies using cold exposure, sustained noise, high altitude, and sleep deprivation, tyrosine repeatedly preserved working memory, vigilance, and cognitive flexibility relative to placebo — differences that appeared only once the stressor was severe enough to degrade the placebo group. A widely cited review formalized the pattern: tyrosine works when demand outstrips supply, and not otherwise.\n\nThat conditionality is the whole user manual. Taking tyrosine daily as a general enhancer misreads the mechanism — on a normal day your synthesis keeps up and the extra precursor is just protein. The evidence-based use is situational: dose 500-2000 mg roughly 30-60 minutes before a defined, demanding stretch — an overnight shift, an exam, a competition in bad weather — and expect maintained sharpness rather than a felt buzz.\n\nSafety at these doses is good, with GI upset and headache the common complaints; as a plain amino acid it is also cheap. Two cautions are non-negotiable: tyrosine feeds the same pathway as thyroid hormone and levodopa, so anyone on thyroid medication or MAO inhibitors needs medical clearance first. And skip the N-acetyl form marketed as more bioavailable — the data actually shows NALT is mostly excreted unconverted. Plain L-tyrosine is the studied compound.",[207,210,212],{"effect":208,"grade":28,"note":209},"Preserves working memory under acute stress","cold, noise, altitude, sleep deprivation",{"effect":211,"grade":28},"Maintains cognitive flexibility during multitasking load",{"effect":213,"grade":38,"note":214},"Improves mood or cognition in unstressed conditions","the mechanism predicts no effect, and trials agree","Safe at studied doses as an amino acid also found in dietary protein. The important exceptions are pharmacological: it can interact with thyroid medication, levodopa, and MAO inhibitors.",[217,102,218],"GI upset","Mild jitteriness at the top of the dose range",[220,221],"Do not combine with MAO inhibitors (hypertensive risk).","Can alter thyroid medication and levodopa handling — get medical clearance if you take either.",[223,228],{"authors":224,"year":180,"title":225,"journal":226,"url":227},"Jongkees, B. J., et al.","Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands — a review","Journal of Psychiatric Research","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fj.jpsychires.2015.08.014",{"authors":229,"year":180,"title":230,"journal":231,"url":232},"Attipoe, S., et al.","Tyrosine for mitigating stress and enhancing performance in healthy adult humans: a rapid evidence assessment of the literature","Military Medicine","https:\u002F\u002Fdoi.org\u002F10.7205\u002FMILMED-D-14-00594",[234,120],"pss-10",[188,187],[71,237],"rhodiola-rosea",{"\u002Fblog\u002Fa1c-blood-sugar-guide":239,"\u002Fblog\u002Fascvd-heart-risk-guide":240,"\u002Fblog\u002Fbiological-vs-chronological-age":241,"\u002Fblog\u002Fcaffeine-half-life-sleep":242,"\u002Fblog\u002Fcalorie-deficit-guide":243,"\u002Fblog\u002Fcode-plunge-healthspan":244,"\u002Fblog\u002Fexploring-biomarkers":245,"\u002Fblog\u002Ffish-oil":246,"\u002Fblog\u002Fftp-functional-threshold-power":247,"\u002Fblog\u002Fgarmin-instinct-e-vs-instinct-3-vs-fenix-e":248,"\u002Fblog\u002Fgrip-strength-longevity":249,"\u002Fblog\u002Fheart-rate-training-zones":250,"\u002Fblog\u002Fhow-strong-am-i":251,"\u002Fblog\u002Fhydration-and-performance":252,"\u002Fblog\u002Fintermittent-fasting-evidence":253,"\u002Fblog\u002Fmagnesiumthreonate":254,"\u002Fblog\u002Fmenstrual-cycle-vital-sign":255,"\u002Fblog\u002Fmetabolic-age-explained":256,"\u002Fblog\u002Fnutrition-basics":257,"\u002Fblog\u002Foura-ring-4-vs-whoop-5":258,"\u002Fblog\u002Fpeptides-what-the-evidence-actually-shows":259,"\u002Fblog\u002Fpregnancy-weight-gain-guide":260,"\u002Fblog\u002Fprotein-for-muscle-growth":261,"\u002Fblog\u002Frace-time-prediction":262,"\u002Fblog\u002Fringconn-gen-2-vs-oura-ring-4-vs-galaxy-ring":263,"\u002Fblog\u002Fsamsung-galaxy-watch-ultra-2-vs-apple-watch-ultra-4":264,"\u002Fblog\u002Fsarcopenia-muscle-loss":265,"\u002Fblog\u002Fsleep-optimization":266,"\u002Fblog\u002Fstrength-training-fundamentals":267,"\u002Fblog\u002Funderstanding-bmr-tdee":268,"\u002Fblog\u002Funderstanding-body-composition":269,"\u002Fblog\u002Fusing-melatonin":270,"\u002Fblog\u002Fvdot-running-training":271,"\u002Fblog\u002Fvitamind":272,"\u002Fblog\u002Fvo2-max-guide":273,"\u002Fblog\u002Fwearable-health-tracking":274,"\u002Fblog\u002Fwhoop-mg-vs-whoop-5":275,"\u002Fblog\u002Fwhoop-vs-garmin-cirqa-vs-fitbit-air-vs-amazfit-helio":276,"\u002Fblog\u002Fwilks-vs-dots-powerlifting":277},"A1C: What Your Three-Month Blood Sugar Average Actually Predicts","Your 10-Year Heart Attack Risk: Making Sense of Your ASCVD Score","Biological Age vs Chronological Age: What Really Matters","Caffeine Half-Life: Why Your Afternoon Coffee Is Still Working at Midnight","Calorie Deficit 101: The Science of Sustainable Weight Loss","Cold Plunge and Healthspan: What the Evidence Actually Supports","Biomarkers: The Numbers That Actually Predict Your Health","Fish Oil and Omega-3s: What the Evidence Actually Supports","Functional Threshold Power: Why Cyclists Define Themselves by One Number","Garmin Instinct E vs Instinct 3 vs Fenix E: What Each Step Up Buys","Grip Strength: The Simplest Longevity Test in Medicine","Heart Rate Zone Training: A Complete Guide","How Strong Am I, Actually? Reading Strength Standards Honestly","Hydration and Performance: How Much Water Do You Really Need?","Intermittent Fasting: What the Research Actually Says in 2026","Magnesium Threonate: The Form That Actually Reaches Your Brain","Your Menstrual Cycle Is a Vital Sign — Here Is What to Track","Metabolic Age: What Your Smart Scale Is Actually Telling You","Nutrition Basics: Building a Solid Diet Without Overthinking It","Oura Ring 4 vs Whoop 5: Two Screenless Wearables, Two Different Philosophies","Peptides: What the Evidence Actually Shows","Pregnancy Weight Gain: The Range That Matters More Than the Number","Protein for Muscle Growth: How Much Do You Really Need?","How Fast Could You Run a Marathon? The Honest Math of Race Prediction","RingConn Gen 2 vs Oura Ring 4 vs Galaxy Ring: The Subscription Math","Galaxy Watch Ultra 2 vs Apple Watch Ultra 4: Your Phone Already Chose","Sarcopenia Starts Earlier Than You Think","Sleep Architecture: Understanding Your Sleep Cycles","Strength Training Fundamentals: Progressive Overload and One-Rep Max","BMR vs TDEE: Understanding Your Metabolism","Understanding Body Composition: Beyond the Scale","Melatonin: What It Actually Does and How to Use It Right","VDOT: Running Its Most Accurate Intensity System","Vitamin D: The Deficiency You Probably Have","VO2 Max Explained: The Gold Standard of Cardiovascular Fitness","Making Sense of Your Wearable Data: From Metrics to Action","Whoop MG vs Whoop 5.0: Is the ECG Worth $120 a Year?","Garmin Cirqa vs Amazfit Helio Strap vs Fitbit Air vs Whoop 5","Wilks vs DOTS: The Math Behind Ranking Powerlifters Fairly",1791499029742]