Who benefits from supplements

The gap between REDUCE-IT (high-dose EPA, high-risk) and null low-dose trials means the right dose, form and population are still debated.

EPA vs DHA vs combined

Whether purified EPA, DHA or a mix is best for a given goal is not fully settled.

Omega-3 (EPA/DHA), honestly

EPA and DHA are essential fats your body can’t make well. The clearest effect is on blood triglycerides; the cardiovascular story is more nuanced than the fish-oil marketing suggests. Food first, supplement to fill a gap.

What they are

Omega-3s EPA and DHA come from oily fish and algae. DHA is a major structural fat in the brain and eyes; EPA is more anti-inflammatory. ALA (from flax/walnuts) is a plant omega-3 the body converts poorly to EPA/DHA.

Where the EPA+DHA actually comes from

Where the EPA+DHA actually comes from — an illustrative chart on this page. Figures use honest, cited or clearly-illustrative data; they are visual aids, not personal measurements.

What the evidence shows

Lowers blood triglycerides — The clearest, most reliable effect — dose-dependent, especially useful when triglycerides are high. (established)
Cardiovascular benefit is dose- and population-dependent — High-dose purified EPA cut cardiovascular events in high-risk people already on statins (REDUCE-IT). But general low-dose fish-oil supplements in already-healthy people showed little benefit in large trials — the truth is in between the "does nothing" and "miracle" camps. (emerging)
Structural role in brain and eyes — DHA is a building block of the brain and retina; adequate intake (usually via fish) is linked with better cognitive and eye ageing. (established)
Food first — Two portions of oily fish a week covers most people. Supplement mainly if you rarely eat fish or need to lower triglycerides; choose quality products to limit oxidation. (note)

What’s oversold

“Fish oil fixes everything” — Broad claims for mood, joints and general prevention outrun the evidence, especially at the low doses in most supplements. (hype)

What we still don’t know

Who benefits from supplements The gap between REDUCE-IT (high-dose EPA, high-risk) and null low-dose trials means the right dose, form and population are still debated.
EPA vs DHA vs combined Whether purified EPA, DHA or a mix is best for a given goal is not fully settled.

Key terms

EPA An omega-3 fat (eicosapentaenoic acid), more anti-inflammatory; the form used in high-dose cardiovascular trials.
DHA An omega-3 fat (docosahexaenoic acid), a structural building block of the brain and retina.
ALA A plant omega-3 (from flax, walnuts) that the body converts only poorly to EPA/DHA.
Triglycerides A blood fat; high levels raise cardiovascular risk, and omega-3 reliably lowers them.