How much omega-3 do you need a day?
About 450mg of EPA and DHA, says the British Heart Foundation. But a 1000mg fish oil capsule can hold just 250mg of it. One line on the label shows your real dose.
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How much omega-3 should I take a day?
If you take a supplement, aim for about 450mg of EPA and DHA a day. These are the two omega-3s found in fish.
There’s no UK government amount for omega-3. The advice is 2 portions of fish a week, one of them oily, each about 140g cooked.
The British Heart Foundation (BHF) says roughly 450mg a day is what that fish gives you. The British Dietetic Association (BDA), the UK body for dietitians, uses the same 450mg figure.
- Below 450 mgUnder the BHF’s roughly 450mg.
- 450 to just under 2000 mgAround or above the BHF figure.
- 2000 up to 5000 mgHigh doses. Europe’s food safety body (EFSA): supplements up to 5g raise no safety concerns for adults.
- Above 5000 mgOver 5g. Packs making the 2g or 3g claims must tell you not to go over this from supplements.
Sources: BHF; EFSA; UK claims register
Think of 450mg as the fish you’d eat in a week, spread over 7 days. A capsule only matches that fish if it carries that much.
Your next step: find your pack and look for the EPA and DHA in each daily dose.
How much omega-3 is in 1000mg fish oil?
Often far less than 1000mg. The big number on the front is the weight of fish oil, not of omega-3.
Which? checked four UK own-brand 1000mg capsules. Each held 250mg of EPA and DHA. A 1500mg high strength one held 375mg.
Source: Which?
That line is EPA plus DHA. It sits in the nutrition panel on the back, per capsule or per daily dose. Which? says the dose is often two or three capsules, so check how many.
So two of those 1000mg capsules give 500mg. And 2000mg of the same oil gives 500mg too, not 2000mg.
Taking cod liver oil instead? It works differently, so see cod liver oil vs fish oil.
What does high strength omega-3 mean?
Less than you’d think. One retailer told Which? there’s no legal or industry-wide definition of high strength omega-3.
Which? found one high strength pack could give seven times as much as another. Some gave at least 1000mg of EPA and DHA a dose.
| On the pack | What it means | Source |
|---|---|---|
| 1000mg or 2000mg | Total fish oil, not omega-3. | Which? |
| Source of omega-3 | At least 40mg EPA plus DHA per 100g and per 100kcal. | UK claim rules |
| High omega-3 | At least 80mg EPA plus DHA per 100g and per 100kcal. | UK claim rules |
| High, max or triple strength | No legal or industry-wide definition, a retailer told Which?. | Which? |
Sources: Which?; UK nutrition claims
So skip the strength words. Divide the price by the mg of EPA and DHA in a daily dose to compare packs.
Vegan? Algae oil gives EPA and DHA too. See vegan omega-3.
Do I need an omega-3 supplement?
Most people don’t. The BHF says you don’t need one unless your doctor prescribed it. Research suggests the benefits come from food.
A Cochrane review, a big summary of trials, pooled 86 trials in 162,796 people, mostly using capsules. More EPA and DHA had little or no effect on deaths and heart and circulation events.
It may slightly cut the risk of heart disease events and deaths. It lowers triglycerides, a blood fat, by about 15%.
NICE, which writes guidance for the NHS, says don’t offer omega-3 to prevent heart disease. The one exception is a prescribed omega-3 called icosapent ethyl. It’s for some adults on statins with heart disease and raised triglycerides.
Before you buy an omega-3
- Add up the EPA and DHA in a daily dose. Compare it with about 450mg.
- Check how many capsules make one dose.
- Choose fish oil or algae oil, not fish liver oil.
- Keep vitamin A to 1.5mg a day at most, from food and supplements together.
- Pregnant or trying for a baby? Avoid fish liver oil and supplements with vitamin A.
- Take medicines that affect blood clotting? Speak to your doctor first.
Prefer food? See foods high in omega-3.
Weighing up a blend? Read omega 3-6-9 supplements.
Is 2000mg of omega-3 too much?
Not for most adults, going by Europe’s food safety body (EFSA). It says supplements of up to 5g of EPA and DHA a day don’t raise safety concerns for adults. That covers bleeding, blood sugar and the immune system.
| EPA plus DHA a day | What it’s linked to | Source |
|---|---|---|
| 2g | Amount for the claim that it helps keep triglycerides normal. | UK claim rules |
| 3g | Amount for the claim that it helps keep blood pressure normal. | UK claim rules |
| 4g | Prescription dose with the highest risk of an uneven heartbeat, in people with heart risks. | MHRA |
| 5g | Supplements up to this raise no safety concerns for adults. | EFSA |
Sources: UK claims register; MHRA; EFSA
That 4g row is about prescription omega-3 for high triglycerides. The MHRA is the UK medicines regulator. It says this raises the risk of an uneven, often fast heartbeat called atrial fibrillation in people with heart disease or heart risk factors.
It may affect up to 1 in 10 people taking these medicines. The MHRA can’t say what this means for people taking shop supplements who don’t have heart disease or major heart risks.
Side effects are usually mild: a bad taste, bad breath, headache, heartburn, feeling sick or diarrhoea.
On omega-3 for triglycerides? See how to lower triglycerides. Never stop or change a prescribed medicine without your prescriber.
When to speak to a GP
Get help if:
- You take medicines that affect blood clotting and want to try fish oil. The BHF says check with your doctor first.
- You take prescribed omega-3 and get palpitations, dizziness, shortness of breath or tiredness. The MHRA says talk to your doctor.
- You have palpitations that keep happening or are getting worse. The NHS says see a GP.
- Call 999 if you have a fast or uneven heartbeat with chest pain, shortness of breath, sweating, or feeling or being sick. Call too if it comes with fainting, dizziness or falling, a severe headache, or weakness or numbness on one side of your face or body. The same goes for blurred vision or loss of sight, confusion or trouble speaking.
- If you’re allergic to fish and react after taking fish oil, call 999 if your lips, mouth, throat or tongue suddenly swell, or your throat feels tight. Call too if you’re breathing very fast or struggling to breathe or swallow. The same goes if your skin, tongue or lips turn blue, grey or pale, or you suddenly feel very confused, drowsy or dizzy. Call if someone faints and can’t be woken, or a child is limp, floppy or not responding like normal.
Curious about your own level? Read about the omega-3 blood test.