Omega-3 and fish oil (EPA and DHA): what it does and how much you need
Omega-3 fats (EPA, DHA and ALA) are part of every cell membrane and matter for the heart, blood vessels, lungs, immune system and brain. There is no set daily amount for EPA and DHA (the adequate intake for plant ALA is 1.6 grams for men and 1.1 grams for women), and for supplements the FDA's guide of up to 5,000 milligrams (5 grams) a day of EPA and DHA combined from supplements is the usual ceiling. Fish oil is not all omega-3: a standard 1,000 milligram fish oil capsule holds about 300 milligrams of EPA and DHA, so check the EPA and DHA lines on the label. High doses can add to the effect of blood thinners such as warfarin.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
In the UK
In the UK, adults need no set amount; the NHS advises at least 2 portions of fish a week, 1 of them oily. Fish oil is not all omega-3: a standard 1,000 milligram fish oil capsule holds about 300 milligrams of EPA and DHA, so check the EPA and DHA lines on the label. High doses can add to the effect of blood thinners such as warfarin.
How much you need and the upper limit
| US (NIH) | UK (NHS) | |
|---|---|---|
| Adults need | No set daily amount for EPA and DHA (the adequate intake for plant ALA is 1.6 grams for men and 1.1 grams for women) | No set amount; the NHS advises at least 2 portions of fish a week, 1 of them oily |
| Upper limit | The FDA's guide of up to 5,000 milligrams (5 grams) a day of EPA and DHA combined from supplements | No NHS figure given |
The UK figure is the amount the NHS says is unlikely to cause harm. Figures are for adults.
Cautions
- Fish oil is not all omega-3: a standard 1,000 milligram fish oil capsule holds about 300 milligrams of EPA and DHA, so check the EPA and DHA lines on the label. High doses can add to the effect of blood thinners such as warfarin.
Food sources
- Salmon, mackerel and sardines
- Tuna
- Flaxseed
- Chia seeds
- Walnuts
- Rapeseed (canola) oil
Dose questions
Quick answers
- What does omega-3 (EPA and DHA) do?
- Omega-3 fats (EPA, DHA and ALA) are part of every cell membrane and matter for the heart, blood vessels, lungs, immune system and brain.
- How much omega-3 (EPA and DHA) do adults need?
- There is no set daily amount for EPA and DHA (the adequate intake for plant ALA is 1.6 grams for men and 1.1 grams for women) (US, NIH). In the UK: no set amount; the NHS advises at least 2 portions of fish a week, 1 of them oily (NHS).
- What is the upper limit for omega-3 (EPA and DHA)?
- US: The FDA's guide of up to 5,000 milligrams (5 grams) a day of EPA and DHA combined from supplements.
- Which foods have omega-3 (EPA and DHA)?
- Salmon, mackerel and sardines, tuna, flaxseed, chia seeds, walnuts, rapeseed (canola) oil.
- What should I watch out for with omega-3 (EPA and DHA)?
- Fish oil is not all omega-3: a standard 1,000 milligram fish oil capsule holds about 300 milligrams of EPA and DHA, so check the EPA and DHA lines on the label. High doses can add to the effect of blood thinners such as warfarin.
Sources
- NIH Office of Dietary Supplements fact sheet
https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/ - NHS vitamins and minerals guidance
https://www.nhs.uk/conditions/vitamins-and-minerals/others/
Ask Supplement Check yourself
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In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/supplementcheck/mcp and ask: “How much fish oil is too much? Is 3000 mg a day OK?”