[{"data":1,"prerenderedAt":215},["ShallowReactive",2],{"supplement-l-tyrosine":3,"supplement-article-titles":175},{"supplement":4,"related":63},{"slug":5,"name":6,"aliases":7,"categories":10,"tagline":12,"evidenceGrade":13,"evidenceSummary":14,"dose":15,"timing":20,"mechanism":21,"description":22,"effects":23,"safety":33,"sideEffects":34,"interactions":38,"references":41,"relatedCalculators":53,"relatedArticles":56,"relatedSupplements":59,"lastVerified":62},"l-tyrosine","L-Tyrosine",[8,9],"tyrosine","N-acetyl L-tyrosine (NALT)",[11],"nootropic","A dopamine precursor that defends cognition during acute stress — cold, noise, sleep loss — and does little on an ordinary day.","B","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":16,"high":17,"unit":18,"frequency":19},500,2000,"mg","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.",[24,27,29],{"effect":25,"grade":13,"note":26},"Preserves working memory under acute stress","cold, noise, altitude, sleep deprivation",{"effect":28,"grade":13},"Maintains cognitive flexibility during multitasking load",{"effect":30,"grade":31,"note":32},"Improves mood or cognition in unstressed conditions","D","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.",[35,36,37],"GI upset","Headache","Mild jitteriness at the top of the dose range",[39,40],"Do not combine with MAO inhibitors (hypertensive risk).","Can alter thyroid medication and levodopa handling — get medical clearance if you take either.",[42,48],{"authors":43,"year":44,"title":45,"journal":46,"url":47},"Jongkees, B. J., et al.",2015,"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":49,"year":44,"title":50,"journal":51,"url":52},"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",[54,55],"pss-10","sleep",[57,58],"sleep-optimization","caffeine-half-life-sleep",[60,61],"caffeine","rhodiola-rosea","2026-08",[64,126],{"slug":60,"name":65,"aliases":66,"categories":70,"tagline":72,"evidenceGrade":73,"evidenceSummary":74,"dose":75,"timing":79,"mechanism":80,"description":81,"effects":82,"safety":93,"sideEffects":94,"interactions":99,"references":102,"relatedCalculators":120,"relatedArticles":122,"relatedSupplements":123,"lastVerified":62},"Caffeine",[67,68,69],"1,3,7-trimethylxanthine","coffee","caffeine anhydrous",[11,71],"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":76,"high":77,"unit":18,"frequency":78},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.",[83,85,88,91],{"effect":84,"grade":73},"Increases alertness and reaction time",{"effect":86,"grade":73,"note":87},"Improves endurance performance","2-4% at 3-6 mg\u002Fkg taken ~60 min before exercise",{"effect":89,"grade":13,"note":90},"Improves strength and power output","smaller and less consistent than the endurance effect",{"effect":92,"grade":73},"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.",[95,96,97,98],"Sleep disruption when taken too late","Jitteriness and anxiety at higher doses","Heart palpitations","Withdrawal headache on abrupt stopping",[100,101],"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.",[103,109,115],{"authors":104,"year":105,"title":106,"journal":107,"url":108},"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":110,"year":111,"title":112,"journal":113,"url":114},"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":116,"year":44,"title":117,"journal":118,"url":119},"EFSA Panel on Dietetic Products, Nutrition and Allergies","Scientific Opinion on the safety of caffeine","EFSA Journal","https:\u002F\u002Fdoi.org\u002F10.2903\u002Fj.efsa.2015.4102",[121,55],"caffeine-half-life",[58,57],[124,125],"l-theanine","creatine",{"slug":61,"name":127,"aliases":128,"categories":132,"tagline":133,"evidenceGrade":134,"evidenceSummary":135,"dose":136,"timing":141,"mechanism":142,"description":143,"effects":144,"safety":152,"sideEffects":153,"interactions":157,"references":159,"relatedCalculators":170,"relatedArticles":172,"relatedSupplements":173,"lastVerified":62},"Rhodiola Rosea",[129,130,131],"golden root","arctic root","rhodiola",[11,71],"An adaptogen with real trials behind its anti-fatigue claim — and a research base that thins out fast beyond it.","C","Placebo-controlled trials support reduced fatigue and better mental performance under stress, but many are small, older, and of mixed quality. The anti-fatigue signal is the credible core.",{"low":137,"high":138,"unit":18,"label":139,"frequency":140},200,600,"200-600 mg\u002Fday standardized to ~3% rosavins, 1% salidroside","once daily, morning","Morning on an empty stomach. Taken late it can be mildly stimulating for some users","Rhodiola’s rosavins and salidroside appear to modulate the stress response — moderating cortisol release and influencing monoamine signaling — which is the proposed basis for its anti-fatigue effects. Adaptogen is a marketing-era word; the testable claim is better performance under stress and fatigue.","Rhodiola grows in the cold high latitudes of Europe and Asia, and its modern reputation rests on a specific, testable claim: it helps you think and perform when you are run down. That claim has more legitimate trial support than most herbs can muster — and less than its fans assume.\n\nThe credible core is fatigue. Placebo-controlled trials in stressed populations — physicians on night duty, students during exams, adults with diagnosed burnout — repeatedly found reduced fatigue scores and better performance on attention and mental-arithmetic tasks under rhodiola, typically at 200-600 mg of standardized extract daily. The pattern echoes caffeine’s: the benefit appears when there is a deficit to work against. A rested, unstressed person has little to gain.\n\nBeyond fatigue, the evidence thins quickly. Physical-performance trials are split, with a few showing modestly improved endurance and most showing nothing. Mood results are preliminary. And the field’s methodological quality is a genuine caveat — many studies are small, short, and from an era of looser standards, which is why a compound with this many positive results still grades a C rather than a B.\n\nIf you try it, buy on standardization: the studied extracts specify roughly 3% rosavins and 1% salidroside, and adulteration is common in this category because genuine Rhodiola rosea root is expensive. Take it in the morning — a minority of users find it activating enough to disturb sleep — and evaluate it during a genuinely demanding stretch, not a calm one, since a fatigue-buffer is invisible without fatigue. Side effects in trials were sparse and mild: occasional dizziness, dry mouth, jitteriness. As adaptogens go, rhodiola is the one with the most honest case; it is still a case that should be stated modestly.",[145,148,150],{"effect":146,"grade":13,"note":147},"Reduces fatigue under stress","the best-replicated finding, in stressed and burnout populations",{"effect":149,"grade":134},"Improves mental performance when fatigued",{"effect":86,"grade":31,"note":151},"trials split, mostly null","Well tolerated in trials up to 12 weeks with mild, infrequent side effects. Long-term safety data is limited, and product adulteration is a real quality concern in this category.",[154,155,156],"Dizziness","Dry mouth","Jitteriness or insomnia if taken late",[158],"Theoretical serotonergic and stimulant additivity — check with your prescriber if you take antidepressants (SSRIs\u002FMAOIs) or stimulant medication.",[160,165],{"authors":161,"year":17,"title":162,"journal":163,"url":164},"Darbinyan, V., et al.","Rhodiola rosea in stress induced fatigue — a double blind cross-over study of a standardized extract with a repeated low-dose regimen on the mental performance of healthy physicians during night duty","Phytomedicine","https:\u002F\u002Fdoi.org\u002F10.1016\u002FS0944-7113(00)80055-0",{"authors":166,"year":167,"title":168,"journal":163,"url":169},"Hung, S. K., Perry, R., & Ernst, E.",2011,"The effectiveness and efficacy of Rhodiola rosea L.: a systematic review of randomized clinical trials","https:\u002F\u002Fdoi.org\u002F10.1016\u002Fj.phymed.2010.08.014",[54,171],"training-load",[57],[174,5],"ashwagandha",{"\u002Fblog\u002Fa1c-blood-sugar-guide":176,"\u002Fblog\u002Fascvd-heart-risk-guide":177,"\u002Fblog\u002Fbiological-vs-chronological-age":178,"\u002Fblog\u002Fcaffeine-half-life-sleep":179,"\u002Fblog\u002Fcalorie-deficit-guide":180,"\u002Fblog\u002Fcode-plunge-healthspan":181,"\u002Fblog\u002Fexploring-biomarkers":182,"\u002Fblog\u002Ffish-oil":183,"\u002Fblog\u002Fftp-functional-threshold-power":184,"\u002Fblog\u002Fgarmin-instinct-e-vs-instinct-3-vs-fenix-e":185,"\u002Fblog\u002Fgrip-strength-longevity":186,"\u002Fblog\u002Fheart-rate-training-zones":187,"\u002Fblog\u002Fhow-strong-am-i":188,"\u002Fblog\u002Fhydration-and-performance":189,"\u002Fblog\u002Fintermittent-fasting-evidence":190,"\u002Fblog\u002Fmagnesiumthreonate":191,"\u002Fblog\u002Fmenstrual-cycle-vital-sign":192,"\u002Fblog\u002Fmetabolic-age-explained":193,"\u002Fblog\u002Fnutrition-basics":194,"\u002Fblog\u002Foura-ring-4-vs-whoop-5":195,"\u002Fblog\u002Fpeptides-what-the-evidence-actually-shows":196,"\u002Fblog\u002Fpregnancy-weight-gain-guide":197,"\u002Fblog\u002Fprotein-for-muscle-growth":198,"\u002Fblog\u002Frace-time-prediction":199,"\u002Fblog\u002Fringconn-gen-2-vs-oura-ring-4-vs-galaxy-ring":200,"\u002Fblog\u002Fsamsung-galaxy-watch-ultra-2-vs-apple-watch-ultra-4":201,"\u002Fblog\u002Fsarcopenia-muscle-loss":202,"\u002Fblog\u002Fsleep-optimization":203,"\u002Fblog\u002Fstrength-training-fundamentals":204,"\u002Fblog\u002Funderstanding-bmr-tdee":205,"\u002Fblog\u002Funderstanding-body-composition":206,"\u002Fblog\u002Fusing-melatonin":207,"\u002Fblog\u002Fvdot-running-training":208,"\u002Fblog\u002Fvitamind":209,"\u002Fblog\u002Fvo2-max-guide":210,"\u002Fblog\u002Fwearable-health-tracking":211,"\u002Fblog\u002Fwhoop-mg-vs-whoop-5":212,"\u002Fblog\u002Fwhoop-vs-garmin-cirqa-vs-fitbit-air-vs-amazfit-helio":213,"\u002Fblog\u002Fwilks-vs-dots-powerlifting":214},"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",1791499028989]