Eat fatty fish at least twice a week

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.

How to do it

1. Choose fatty, cold-water fish: salmon, sardines, mackerel, herring, or anchovies.
2. Aim for two 100–150 g servings per week — the amount most trials use.
3. Include at least one serving of oily sardines or mackerel: they are cheaper, lower in mercury, and just as nutrient-dense.
4. Bake, grill, or eat tinned — avoid deep-frying, which oxidizes the delicate omega-3 fats.

Evidence

Cross-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. (observational)

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.

Sources

• 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%.