Omega-3s: EPA vs DHA, and what the label hides

Omega-3 is treated like a single nutrient on most labels. It isn't, and the difference decides whether the bottle in your hand is doing what you bought it for.

The three that matter, and why two of them are the point

ALA is the only omega-3 that's strictly essential, and it's the one with an official number: the Adequate Intake for adult women is 1.1 g/day. Your body converts ALA into EPA and DHA — but at a rate of less than 15%, which is why NIH concludes that consuming EPA and DHA directly is the only practical way to raise your levels of them.

DHA is the structural one: it's especially concentrated in the retina, brain and sperm, and it accumulates fastest in late pregnancy and early childhood. EPA is more associated with the triglyceride and inflammatory end of things.

What the guidance actually says about dose

Here is the part most supplement copy gets wrong. NIH states plainly that recommended amounts of EPA and DHA have not been established. There is no RDA to hit.

What exists instead is more specific and more modest. The American Heart Association recommends one to two servings of seafood a week. For people with existing heart disease, about 1 g/day of EPA plus DHA is the figure used. And the AHA does not recommend omega-3 supplements for people who aren't at high cardiovascular risk. Prescription omega-3s at 4 g/day do lower triglycerides — that's a treatment dose, not a wellness one.

So anyone quoting a precise daily target for the general population is inventing it.

What to actually read on the label

Total EPA + DHA per serving, not the fish oil number. A typical supplement provides 1,000 mg of fish oil containing only 180 mg EPA and 120 mg DHA — so the headline figure is roughly three times the amount of the thing you actually wanted.

For context on how far most people are from the studied doses: US adults average about 90 mg of EPA and DHA a day from food.

The honest bottom line

Eat the fish if you can — that's the version with the guidance behind it. If you supplement, read the EPA and DHA line, pick a ratio matched to what you're actually after, and don't expect a general-population dose target to exist, because it doesn't.