Loading…
We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Head-to-head evidence comparison — which supplement is right for you?
Ashwagandha vs Caffeine: Caffeine has the stronger overall evidence (9.5 vs 7.5/10); they're alternatives for boost daily energy — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
Caffeine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
4 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Probably helps
5 of 9 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Ashwagandha and Caffeine have evidence — compare verdict strength side-by-side.
300-600mg daily (standardized extract)
Morning for daytime stress, Evening for sleep support
KSM-66 or Sensoril standardized extract
100-200mg
Morning, About 60 minutes before exercise
Pill/capsule for precise dosing
and 3 more not shown
2-4 weeks
2-4 weeks
2-4 weeks
First week
15-45 minutes
30-60 minutes
30-60 minutes
30-60 minutes
Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis
Explore (NY) (2024) · Meta analysis · n=558
Significant effect on the Perceived Stress Scale (PSS) (MD = -4.72, 95 % CI = [-8.45 to -0.99]).
Effects of Withania somnifera Extract in Chronically Stressed Adults: A Randomized Controlled Trial
Nutrients (2024) · Rct · n=131
8-week double-blind RCT in adults with self-reported high stress comparing an aqueous root and leaf extract at 125, 250 and 500 mg a day with placebo (131 enrolled, 98 analysed).
Plant-derived nootropics and human cognition: A systematic review
Critical reviews in food science and nutrition (2023) · Systematic review
Bacopa monnieri improves language, learning and memory.
Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis
Nutrients (2020) · Meta analysis
A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials
Critical reviews in food science and nutrition (2019) · Meta analysis · n=606
Thirteen RCTs with 606 participants were included in the meta-analyses.
Effect of Caffeine and Nitrates Combination on Exercise Performance, Heart Rate and Oxygen Uptake: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=95
The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
The points come from one 8-week dose-comparison RCT of an aqueous root and leaf extract at 125, 250 or 500 mg a day against placebo in adults with self-reported high stress (PMID 38732539, 131 enrolled, 98 analysed). All three doses reduced perceived stress and were reported as safe, and the authors describe the effect as dose-dependent. The abstract gives no per-dose effect sizes, so the curve shows only that ordering, not how large each step is. It also does not show whether doses above 500 mg add more. Trials of other extracts (root-only extract at 600 mg a day, PMID 23439798, and a 240 mg extract, PMID 31517876) are not on this axis because milligrams of different extracts are not equivalent.
Exercise trials dose caffeine by body weight, so this curve is in mg per kg, taken about an hour before exercise. A meta-analysis of 46 placebo-controlled trials found a small but clear endurance benefit at moderate doses of 3 to 6 mg/kg (PMID 29876876), and the ISSN position stand reports consistent benefits across that range, a possible minimum as low as 2 mg/kg, and a high rate of side effects at 9 mg/kg with no extra benefit (PMID 33388079), so the curve is flat above 3 mg/kg while side effects rise. 4.5 mg/kg raised time to exhaustion and VO2max in 23 elite endurance athletes (PMID 34033621), and 3 mg/kg raised muscular endurance and strength in 29 resistance-trained adults (PMID 39246027). No single optimal dose is established, and no safe ceiling is plotted: the pregnancy and lactation limits in the safety section apply to total daily intake.
AI-estimated from published studies. Interpret as directional guidance.
Caffeine has a higher evidence score (9.5/10 vs 7.5/10) and wins in 2 of 3 categories.
For boost daily energy, Caffeine has a higher relevance score (98 vs 60).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
The honest tier list — proven staples vs situational vs mostly marketing. The hub the other guides feed into.
Selenium helps; iodine can WORSEN Hashimoto’s. The honest take on "thyroid support".
CoQ10, zinc, selenium, carnitine modestly help sperm parameters — but live-birth evidence is weak.
Ashwagandha, L-theanine, magnesium, saffron — what actually helps stress, and the safety caveats.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.