How much EPA + DHA do I need?

“How much omega-3 should I take?” The honest answer: it depends on where you're starting from. Here's UK guidance, what the research shows, and how to work out the dose that's right for you.

What the UK recommends

The Scientific Advisory Committee on Nutrition (SACN) and the NHS advise at least two portions of fish a week, one of which should be oily — broadly equating to a population-average target of around 450 mg of combined EPA + DHA per day. That's a sensible floor, but it's a population average, not a personalised target.

What the research actually shows

Most omega-3 research measures the Omega-3 Index, not intake — because it bypasses all the variation in absorption and metabolism. The landmark dose-response work (Walker et al., 2019) found that raising your Omega-3 Index by 1% takes roughly 370 mg of EPA + DHA per day for about four to five months, though this varies by person.

So if you're at 4% and want to reach 8%, that's about 4 × 370 = ~1,480 mg EPA + DHA per day, sustained for several months. Someone starting at 6% needs far less. This is exactly why generic advice breaks down — and why measuring first is worth it.

From food

  • A portion of oily fish (salmon, mackerel, sardines) provides roughly 1,500–3,000 mg EPA + DHA.
  • White fish (cod, haddock) and tinned tuna provide much less.
  • Plant sources (flax, chia, walnuts) provide ALA, which converts to EPA/DHA very inefficiently (under 5%).

The bottom line

450 mg/day is a reasonable general floor. If you have a specific goal, the right dose is higher and depends on your starting level — so the fastest way to stop guessing is to measure, then retest in three to four months to confirm it's working.

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