Research review
Fish oil vs ashwagandha: what the research does and doesn't show
Fish oil and ashwagandha are sometimes compared for stress, but they don't have comparable evidence behind them. Ashwagandha has a meta-analysis of 9 trials in 558 people; fish oil has two small trials in narrow populations, and no trial has tested the two against each other.
The evidence doesn't support treating fish oil and ashwagandha as comparable stress supplements — the research behind them isn't close to the same size. Ashwagandha has a meta-analysis of 9 trials in 558 people; fish oil's stress evidence is two small trials in narrow groups, neither repeated since, and no trial has tested the two against each other.
What the evidence doesn't support
It doesn't support fish oil as a stress reliever for a general population — only two small trials have tested it directly, each in a specific group (medical students before an exam, pregnant women), at doses above a typical label. It also doesn't support a head-to-head comparison between fish oil and ashwagandha for stress, or a combined-supplement recommendation — nobody has tested either.
What the trials found
A 2017 randomized, double-blind, placebo-controlled trial gave 64 adults with a history of chronic stress 600 mg/day (300 mg twice daily) of a high-concentration, full-spectrum ashwagandha root extract for 60 days. The treatment group had significantly lower scores on stress-assessment scales and significantly lower serum cortisol than placebo at day 60, with mild, comparable adverse effects between groups. A later meta-analysis pooled 9 randomized controlled trials, 558 people total, published 2000-2022. Pooled results favored ashwagandha over placebo on the Perceived Stress Scale, the Hamilton Anxiety Scale, and serum cortisol; doses varied across the 9 included trials, and four reported mild to moderate adverse events.
Fish oil's evidence is smaller and narrower. A 2011 randomized, double-blind trial gave 68 medical students 2.5 g/day of omega-3 (mostly EPA) for 12 weeks, with blood drawn during a lower-stress period and again before an exam. The omega-3 group had 14% less of an inflammation marker and 20% fewer anxiety symptoms than placebo around the exam period. A 2014 trial gave 64 pregnant women 450 mg/day of DHA or placebo from 16-21 weeks gestation; at 30 weeks, the DHA group reported lower perceived stress and a smaller cortisol response to a lab stress test than placebo. Neither fish oil trial has been repeated, and neither generalizes past its specific population — students under exam stress, and pregnant women — to a stress recommendation for adults generally.
| Ashwagandha | Fish oil | |
|---|---|---|
| Trial evidence | 1 dedicated RCT (64 people) + a meta-analysis of 9 RCTs (558 people) | 2 small RCTs (68 and 64 people), neither repeated |
| Populations studied | Adults with chronic stress; mixed adult samples across 9 trials | Medical students before an exam; pregnant women |
| Consistency | Multiple trials pointing the same direction | Two isolated trials in different, narrow populations |
Questions people ask
Is ashwagandha better than fish oil for stress?
Ashwagandha has more, and more consistent, trial evidence behind it for stress specifically — a meta-analysis of 9 trials versus fish oil's two small trials in narrow groups. That's a difference in the evidence base, not a tested head-to-head result, since no trial has compared the two directly.
Can I take fish oil and ashwagandha together?
There's no documented interaction between the two at typical supplement doses, and no trial has tested combining them specifically for stress or any other outcome.
Does fish oil lower cortisol like ashwagandha does?
One small trial in pregnant women found a smaller cortisol response to a lab stress test with DHA versus placebo. That's a single trial in a specific population, not the repeated finding ashwagandha's evidence shows across several trials.
When to talk to a doctor
Stress that's persistent, or that interferes with daily life, work or sleep, is worth raising with a doctor. Neither fish oil nor ashwagandha is a treatment for a stress or anxiety disorder, and nothing in the evidence above supports using either as a substitute for an evaluation. If you take medication for any condition, or are pregnant or nursing, talk to a doctor before adding a supplement.
Related reading: does fish oil help with stress?, magnesium glycinate and ashwagandha, and fish oil vs collagen.
Sources
- A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults In a 60-day trial, 600 mg/day of a concentrated ashwagandha extract lowered stress-scale scores and cortisol more than placebo in adults with chronic stress.
- Effects of Ashwagandha (Withania Somnifera) on stress and anxiety: A systematic review and meta-analysis Pooling 9 trials in 558 people, ashwagandha lowered perceived stress, anxiety-scale scores and cortisol more than placebo.
- Omega-3 supplementation lowers inflammation and anxiety in medical students: a randomized controlled trial A 2011 RCT of 68 medical students found 2.5 g/day of omega-3 (mostly EPA) for 12 weeks was associated with 14% less inflammation and 20% fewer anxiety symptoms than placebo, measured around an exam-stress period, in people without an anxiety disorder diagnosis.
- Association between fatty acid supplementation and prenatal stress in African Americans: a randomized controlled trial A 2014 RCT of 64 pregnant women found 450 mg/day of DHA was associated with lower self-reported perceived stress and a smaller cortisol response to a lab stress test at 30 weeks of pregnancy, versus placebo, in a small, demographically narrow sample.
*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.