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Head-to-head evidence comparison — which supplement is right for you?
Ashwagandha vs NAC: NAC has the stronger overall evidence (6 vs 7.5/10); they're alternatives for reduce anxiety & stress — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
NAC 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
Likely helps
5 of 6 studies with measurable effects showed benefit.
Top outcomes
300-600mg daily (standardized extract)
Morning for daytime stress, Evening for sleep support
KSM-66 or Sensoril standardized extract
600-1800mg daily
Away from food, Split into 2-3 doses
NAC capsules or powder
2-4 weeks
2-4 weeks
2-4 weeks
First week
4-8 weeks
2-4 weeks
1-2 weeks
Immediate
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.
Efficacy of N-Acetylcysteine in Polycystic Ovary Syndrome: Systematic Review and Meta-Analysis
Nutrients (2025) · Meta analysis · n=2515
Twenty-two studies (n = 2515) were included.
Efficacy of N-acetylcysteine for patients with depression: An updated systematic review and meta-analysis
General hospital psychiatry (2024) · Meta analysis · n=904
Our findings indicate that adjunctive NAC can ameliorate depressive symptoms in patients with psychiatric problems, particularly bipolar disorder.
N-acetylcysteine as a treatment for substance use cravings: A meta-analysis
Addiction biology (2024) · Meta analysis · n=623
The most targeted substance in the clinical trials was alcohol (3/9; 33.3%), followed by tobacco (2/9; 22.2%) and multiple substances (2/9; 22.2%).
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.
Three pooled analyses tie a dose to a result. A meta-analysis of 13 studies in 4,155 patients (PMID 26324807) found fewer exacerbations with NAC (RR 0.75), with 600 mg a day sufficient in chronic bronchitis without airway obstruction and doses above 600 mg (it recommends 1,200 mg or more) also effective in spirometry-confirmed COPD (RR 0.75). Adverse reactions were not dose-dependent. A meta-analysis of 775 patients on NAC and 789 on placebo (PMID 31598901) found RR 0.81 and says under 1,200 mg a day for at least 3 months seems effective. A network meta-analysis of 7 trials in 2,753 COPD patients (PMID 31133026) at 1,200 mg a day found NAC shortened exacerbations but, unlike erdosteine, did not reduce the risk of having one, and it was well tolerated. No source shows a larger effect at 1,200 mg than at 600 mg, so the curve stays flat. 1,200 mg is the highest dose these sources report.
AI-estimated from published studies. Interpret as directional guidance.
NAC has a higher evidence score (6/10 vs 7.5/10) and wins in 2 of 3 categories.
For reduce anxiety & stress, Ashwagandha has a higher relevance score (95 vs 52).
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.
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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.