Research review
Does fish oil help with stress?
Only two small randomized trials have tested fish oil against a stress outcome directly — one in medical students before exams, one in pregnant women — both at doses well above a typical label, and neither has been repeated.
The evidence doesn't support fish oil as a treatment for stress. Only two small randomized trials have tested it against a stress-related outcome directly, in narrow groups — medical students before exams, and pregnant women — using doses and forms well above a typical fish oil label, with results that haven't been repeated elsewhere.
What the evidence doesn't support
It doesn't support fish oil as a way to lower stress in a general adult population — no trial has tested that broad a group. It doesn't support one specific dose for stress, because the two trials below used different forms and amounts, neither close to a typical fish oil serving. And it doesn't support fish oil as a treatment for a diagnosed stress-related disorder; both trials measured self-reported stress or anxiety symptoms in healthy volunteers under a specific stressor, not a clinical condition.
What the trials found
A 2011 randomized, placebo-controlled trial gave 68 medical students either 2.5 g/day of omega-3 (2,085 mg EPA and 348 mg DHA — well above a typical fish oil serving) or a placebo for 12 weeks, with blood drawn during a lower-stress period and again before an exam. Compared with placebo, the omega-3 group showed a 14% decrease in a lab marker of inflammation (LPS-stimulated interleukin-6) and a 20% decrease in anxiety symptom scores, with no significant change in depressive symptom scores. The authors described it as early evidence that omega-3 might affect anxiety symptoms in people without a diagnosed anxiety disorder — a single, small trial in a specific population under a specific stressor (exams), not a general finding about everyday stress.
A separate 2014 randomized trial gave 64 pregnant women 450 mg/day of DHA or a placebo, starting between 16 and 21 weeks of pregnancy. At 30 weeks, the DHA group reported lower scores on the Perceived Stress Scale (27.4 versus 29.5) and a smaller cortisol response to a standardized lab stress test than the placebo group. The trial was small and unevenly split (43 women on DHA versus 21 on placebo), studied only pregnant women in one income and demographic group, and hasn't been replicated since. It's a specific, notable signal — not an established finding for pregnant women generally, and not a basis for a pregnancy dosing recommendation.
Questions people ask
Does fish oil help with stress?
Two small trials found signals worth reporting — less inflammation and fewer anxiety symptoms in medical students under exam stress, and lower perceived stress and cortisol reactivity in pregnant women — but both used doses and forms far from a typical label amount, in narrow populations, and neither has been repeated. That's not enough evidence to call fish oil a stress reliever for a general population.
What dose of omega-3 is used for stress?
The two trials above used 2.5 g/day of an EPA-heavy blend and 450 mg/day of DHA alone — different forms and doses, tested in different populations. Neither trial establishes a "stress dose," and no amount for stress has been evaluated outside those two studies.
Does omega-3 lower cortisol?
One small trial in pregnant women found a smaller cortisol response to a lab stress test after DHA supplementation. That's a single result in a specific population; it hasn't been tested and confirmed in a general adult population.
Can fish oil help with anxiety?
That's a related but separate question with its own, larger body of research — see does fish oil help with anxiety? for the dedicated review.
When to talk to a doctor
Stress that's persistent, overwhelming, or affecting sleep, work or relationships is worth discussing with a doctor. Fish oil is not a treatment for a stress-related disorder. If you're pregnant, ask your doctor or midwife before adding any supplement — the trial above doesn't set a recommended amount for pregnancy, and this page doesn't either.
Related reading: does fish oil help with anxiety?, fish oil benefits: what the research does and doesn't show, and who should not take fish oil.
Sources
- 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.