Eat fatty fish at least twice a week
Salmon, sardines, mackerel, or herring — two servings a week for brain-critical omega-3s.
Key takeaways
- What it is: Salmon, sardines, mackerel, or herring — two servings a week for brain-critical omega-3s.
- Why it works: Fatty fish are the most bioavailable source of long-chain omega-3 fatty acids (EPA and DHA). DHA is a structural component of neuronal cell membranes; EPA has anti-inflammatory and eicosanoid-modulating effects. Low omega-3 status is associated with impaired serotonin and dopamine signaling, and populations with higher fish consumption consistently show lower rates of depression in cross-national comparisons.
- Evidence: Backed by observational / correlational evidence.
- Avoid: Relying only on plant-based ALA omega-3s (flaxseed, walnuts) and skipping fish — conversion of ALA to EPA/DHA in humans is inefficient, typically below 10%.
Why it works
Fatty fish are the most bioavailable source of long-chain omega-3 fatty acids (EPA and DHA). DHA is a structural component of neuronal cell membranes; EPA has anti-inflammatory and eicosanoid-modulating effects. Low omega-3 status is associated with impaired serotonin and dopamine signaling, and populations with higher fish consumption consistently show lower rates of depression in cross-national comparisons.
How to do it
- 1Choose fatty, cold-water fish: salmon, sardines, mackerel, herring, or anchovies.
- 2Aim for two 100–150 g servings per week — the amount most trials use.
- 3Include at least one serving of oily sardines or mackerel: they are cheaper, lower in mercury, and just as nutrient-dense.
- 4Bake, grill, or eat tinned — avoid deep-frying, which oxidizes the delicate omega-3 fats.
What the evidence says
ObservationalCross-national studies show a strong inverse relationship between fish consumption and depression rates. Meta-analyses of omega-3 supplementation trials find small-to-moderate antidepressant effects, especially for EPA-dominant preparations.
Honest caveat: Food-source omega-3 evidence is largely observational; supplementation RCTs show smaller and more variable effects. Fish eating correlates with many other healthy behaviors, making causal isolation difficult.
- — Hibbeln (1998), fish consumption and major depression cross-national comparison, Lancet
Common mistake
Relying only on plant-based ALA omega-3s (flaxseed, walnuts) and skipping fish — conversion of ALA to EPA/DHA in humans is inefficient, typically below 10%.
IX Coach asks about your weekly fish intake and, when it’s low, surfaces quick high-EPA meal ideas that fit your current food environment — not generic advice, but something actionable today.
Practice this with IX Coach →