How Much Omega-3, 6 and 9 Do I Need Daily? The UK Figures in mg

There is no official UK supplement dose for omega-3. The UK advice is food: at least two portions of fish a week, one of them oily, which SACN calculated supplies about 450 mg a day of the long-chain omega-3s EPA and DHA. The label yardsticks are 250 mg of EPA and DHA a day (EFSA's adequate intake and the heart-claim threshold), 250 mg of DHA for the brain and vision claims, and 2 g of the plant omega-3 ALA for its cholesterol claim. Above about 1 g a day of EPA and DHA the large trials show a rising risk of atrial fibrillation, so more is not better, and EFSA puts the upper safe supplemental intake at 5 g.^{1, 2, 3, 4} Omega-6 and omega-9 need no supplement figure; ordinary diets cover both, and the "2:1:1 ratio" this page once quoted was invented.⁵

• Food: two portions of fish a week, one oily, about 450 mg EPA+DHA a day^{1, 2}
• Ceiling: the AF signal rises above 1 g a day; EFSA's upper safe intake is 5 g EPA+DHA^{3, 4}
• Units: a 1,000 mg fish oil capsule holds about 300 mg EPA+DHA; a flaxseed 3-6-9 capsule holds ALA and no EPA or DHA

How many mg of omega-3 per day?

It depends which omega-3 and for what. Every figure below is EPA and DHA, or ALA, never milligrams of oil.

How much omega-3 in food should I consume per day?

Enough fish to meet the NHS advice: at least two 140 g portions a week, one of them oily (salmon, mackerel, sardines, herring, trout or fresh tuna).² SACN worked out that this pattern averages about 450 mg of EPA and DHA a day; the figure describes the fish advice rather than setting a target.¹ For ALA, two tablespoons of ground flaxseed, a tablespoon of flaxseed oil, or 25 g of chia seeds or walnuts each supply about 2 g, the cholesterol-claim amount. Food and supplements are not rivals: a portion of oily fish delivers several days' worth of a typical capsule in one sitting, a daily capsule a steady few hundred milligrams. What foods are high in omega-3, 6 and 9 lists amounts per portion.

How to read the EPA and DHA figure on a label

Find the line that gives EPA and DHA in milligrams; the big number on the front is usually the weight of oil. Three worked examples:

• "1,000 mg fish oil": standard fish oil is about 18% EPA and 12% DHA, so one capsule carries about 300 mg of EPA and DHA, a little above the 250 mg heart-claim figure and well under 1 g.
• "500 mg algal oil": read the DHA line; algal products run from about 200 to 550 mg DHA per serving, and the 250 mg DHA threshold is the yardstick.
• "1,386 mg omega 3-6-9": a flaxseed capsule's figure is ALA plus linoleic plus oleic acid, with no EPA or DHA. A two-capsule serving typically supplies several hundred milligrams of ALA with smaller amounts of linoleic and oleic acid, set against the 2 g ALA cholesterol-claim threshold, often with vitamin E, which contributes to the protection of cells from oxidative stress.³

Gummies follow the same rule: a two-gummy serving of a vegan omega-3 gummy typically holds tens of milligrams of algal DHA, read against the 250 mg DHA brain and vision threshold, and any vitamins added carry their own wording, for example vitamin D contributes to the maintenance of normal bones and teeth, and vitamins A and C contribute to the normal function of the immune system.³ Algae omega-3 vs fish oil, cod liver oil and krill gives the typical figures by source.

Is 1,000 mg of omega-3 too much?

No, and it is usually less than it sounds: "1,000 mg" on a fish oil pot is oil, about 300 mg of EPA and DHA. A true 1,000 mg is roughly what the largest prevention trials used. VITAL gave 25,871 adults 840 mg a day for five years with no excess of bleeding, cancer or serious harm.⁶ Pooled across 40 trials, doses in that range cut heart attacks by about 13% and coronary deaths by about 9%, with no change in overall deaths or strokes.^{7, 8} The reason not to go higher is atrial fibrillation: across seven large trials the relative risk of new AF was 12% higher at 1 g or less and 49% higher above 1 g, from a low starting rate of a few per cent over five years.⁴ Triglycerides fall about 15%, in proportion to dose, but the 2 to 4 g range where that matters belongs under a doctor's care, and EFSA's 5 g ceiling is a safety limit, not a target.^{3, 8} Is 500 mg too much? No; it sits between the fish advice and the trial dose.

How often should I take omega-3, 6 and 9?

Daily, with a meal, at the label dose. Red-cell omega-3 levels respond to average intake over three to five months, so a missed day changes nothing and a weekly handful is the wrong shape: in a five-month dose-ranging trial, the daily amount alone explained 68% of the rise in the omega-3 index.⁹ When to take omega-3, 6 and 9 has the absorption evidence, and should omega-3 be taken daily works through the diet question for people who do and do not eat oily fish.

How much mg of omega-3 and omega-6 do I need daily?

For omega-6, nothing from a supplement. Linoleic acid is essential, and EFSA's adequate intake is 4% of energy, about 9 g a day on a 2,000 kcal diet, which cooking oils, spreads, nuts and seeds supply without effort.⁵ Higher linoleic acid intake tracks lower, not higher, heart disease risk in pooled cohort data, and raising it in randomised trials caused no harm.^{10, 11} The old "2:1:1 ratio" had no source: EFSA sets separate intakes for each fatty acid and no ratio, and every health claim built on an omega-6 to omega-3 ratio was rejected as unsubstantiated.^{3, 5} The useful question is how much EPA and DHA you get, not how much omega-6 you cut; the differences between omega-3, 6 and 9 explains why.

What are the signs I might be taking too much omega-3?

At supplement doses the signs are digestive and mild: fishy burps, loose stools, nausea and a lingering taste, commoner with larger single doses. Above about 1 g a day the concern is a new irregular heartbeat, so palpitations on a high dose are a reason to see your GP.⁴ Easy bruising or nosebleeds in someone on warfarin, a DOAC or aspirin should be reported to the anticoagulant clinic, although the pooled surgical data show no increase in bleeding with fish oil.¹² The side effects of omega-3, 6 and 9 has the full list; the Wellgard omega-3 guide covers the outcomes.

Frequently asked questions

Do I need to take omega-6 supplements or is it already in my diet?

It is already in your diet, above the 4% of energy adequate intake, from cooking oils, spreads, nuts and seeds.⁵ The linoleic acid in a flaxseed 3-6-9 capsule is there because flaxseed oil naturally contains it.

How often do I need to take omega-9, and do I need it every day?

There is no requirement. Oleic acid is non-essential: the body makes it, and olive oil, rapeseed oil, avocados and nuts supply it by the gram.

How much omega-3 per day for seniors?

The same figures. VITAL's 840 mg a day was taken by adults over 50 for five years without excess harm; 1.8 g a day in 70 to 82 year olds after a heart attack almost doubled new AF, so older adults have the strongest reason to stay at or below 1 g unless a cardiologist says otherwise.^{6, 13}

How much omega-3 should I take for memory?

The authorised claim is 250 mg of DHA a day for maintenance of normal brain function, not a promise of sharper memory. Is omega-3 good for your brain sets out what the trials found.

Sources

1. Scientific Advisory Committee on Nutrition and Committee on Toxicity. Advice on fish consumption: benefits and risks. 2004. gov.uk (PDF).
2. NHS. Fish and shellfish. nhs.uk/live-well/eat-well/food-types/fish-and-shellfish-nutrition.
3. Department of Health and Social Care. Great Britain nutrition and health claims (NHC) register. gov.uk.
4. Gencer B, et al. Effect of long-term marine omega-3 fatty acids supplementation on the risk of atrial fibrillation in randomized controlled trials of cardiovascular outcomes: a systematic review and meta-analysis. Circulation, 2021. PubMed 34612056.
5. EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific opinion on dietary reference values for fats. EFSA Journal, 2010. doi.org/10.2903/j.efsa.2010.1461.
6. Manson JE, et al. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer. New England Journal of Medicine, 2019. PubMed 30415637.
7. Bernasconi AA, et al. Effect of omega-3 dosage on cardiovascular outcomes: an updated meta-analysis and meta-regression of interventional trials. Mayo Clinic Proceedings, 2021. PubMed 32951855.
8. Abdelhamid AS, et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, 2020. PubMed 32114706.
9. Flock MR, et al. Determinants of erythrocyte omega-3 fatty acid content in response to fish oil supplementation: a dose-response randomized controlled trial. Journal of the American Heart Association, 2013. PubMed 24252845.
10. Marklund M, et al. Biomarkers of dietary omega-6 fatty acids and incident cardiovascular disease and mortality. Circulation, 2019. PubMed 30971107.
11. Hooper L, et al. Omega-6 fats for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, 2018. PubMed 30488422.
12. Begtrup KM, et al. No impact of fish oil supplements on bleeding risk: a systematic review. Danish Medical Journal, 2017. PubMed 28552094.
13. Myhre PL, et al. Omega-3 fatty acid supplements and risk of atrial fibrillation and 'micro-atrial fibrillation': a secondary analysis from the OMEMI trial. Clinical Nutrition, 2023. PubMed 37515843.

This article is general information, not medical advice. If you take anticoagulant or antiplatelet medicines, have a heart rhythm condition or are pregnant, speak to your GP or anticoagulant clinic before adding an omega-3 supplement.