Fish Oil and Omega-3: How Much to Take and How to Choose

Fish oil is one of the most commonly used supplements. People choose it for the omega-3 fatty acids EPA and DHA, which are found mostly in oily fish.

In this article you will learn what EPA and DHA are needed for, how much you need per day and how to find the actual omega-3 content on the label.

What are omega-3 fatty acids?

Omega-3 is a group of fatty acids. The three most important ones are:

• EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) – found in oily fish, seafood and algae;
• ALA (alpha-linolenic acid) – found in flaxseeds, chia seeds, walnuts and rapeseed oil.

The body converts ALA into EPA and DHA only in small amounts.³ That is why flaxseeds do not replace fish if you want to get EPA and DHA.

What are EPA and DHA needed for?

Doses higher than 2–3 g are not a daily requirement. It is worth discussing them with a doctor. From supplements, it is not recommended to exceed 5 g of EPA and DHA combined per day.¹

Is eating fish enough?

Often, yes. 1–2 portions of oily fish per week (salmon, mackerel, herring, sardines) provide about 250 mg of EPA and DHA per day.² A supplement can be useful if you do not eat fish, eat it rarely, or are vegetarian or vegan.

How to read the label

The most important rule: 1000 mg of fish oil is not 1000 mg of omega-3. A capsule contains oil, and EPA and DHA make up only a part of it.

Example. The label says "Fish Oil 1000 mg" and below it "EPA 180 mg, DHA 120 mg". This means one capsule contains 300 mg of omega-3. To get 250 mg, one capsule is enough. If a serving is 2 capsules, calculate the amount for two capsules.

Freshness can be checked simply: good-quality fish oil does not have a sharp, spoiled-fish smell. If the smell is strong, it is better to throw the product away.

What do studies say about the heart?

In a large study, 25,871 adults took 1 g of omega-3 per day or a placebo for about 5 years. In healthy people, the number of cardiovascular events did not differ significantly.⁴ This means that a supplement does not replace a healthy diet, physical activity and treatment prescribed by a doctor.

When to talk to a doctor

• You take blood-thinning medicines – higher doses of omega-3 may increase their effect.³
• You have a heart rhythm disorder – in studies, doses above 1 g per day were associated with a higher likelihood of atrial fibrillation.⁵
• You are pregnant – do not take cod liver oil because of its vitamin A content.⁶
• You have surgery coming up or want to give the supplement to a child.

Selected omega-3 products

Commercial information. These are products available in our shop. This is not an effectiveness ranking. Before buying, check the composition and instructions for use on the product page.

Frequently asked questions

When is the best time to take fish oil?

With a meal. This makes it easier to avoid a fishy aftertaste. If it still bothers you, the capsules can be kept in the refrigerator, or the dose can be split into two parts.

Do you need fish oil during pregnancy?

During pregnancy and breastfeeding, taking an additional 200 mg of DHA per day on top of the usual 250 mg of EPA and DHA contributes to the normal development of the eyes and brain of the foetus and breastfed infants.¹¹ Choose fish oil or algae oil rather than cod liver oil.⁶

How much omega-3 is safe?

For adults, up to 5 g of EPA and DHA per day from supplements is considered a safe amount.¹² For most people, considerably less is enough – 250–500 mg per day.

Scientific sources

1. Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods (consolidated version). EUR-Lex
2. EFSA NDA Panel. Scientific opinion on dietary reference values for fats, including saturated fatty acids, polyunsaturated fatty acids, monounsaturated fatty acids, trans fatty acids, and cholesterol. EFSA Journal. 2010;8(3):1461. doi:10.2903/j.efsa.2010.1461
3. NIH Office of Dietary Supplements. Omega-3 Fatty Acids – Fact Sheet for Health Professionals. ods.od.nih.gov
4. Manson JE, Cook NR, Lee IM et al. Marine n-3 fatty acids and prevention of cardiovascular disease and cancer. N Engl J Med. 2019;380(1):23–32. doi:10.1056/NEJMoa1811403
5. Gencer B, Djousse L, Al-Ramady OT 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;144(25):1981–1990. doi:10.1161/CIRCULATIONAHA.121.055654
6. NHS. Vitamins, supplements and nutrition in pregnancy. nhs.uk
7. NOW Foods. Omega-3 Fish Oil, Molecularly Distilled, 200 softgels. Product label.
8. Osavi. Super Strong Omega 3, 500 EPA / 250 DHA, 60 softgels. Product label.
9. NOW Foods. Omega-3 Fish Oil Liquid, Lemon, 500 ml. Product label.
10. Nordic Naturals. Algae DHA, 500 mg, 60 softgels. Product label.
11. Commission Regulation (EU) No 440/2011 on the authorisation of certain health claims made on foods and referring to children's development and health. EUR-Lex
12. EFSA NDA Panel. Scientific opinion on the tolerable upper intake level of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA). EFSA Journal. 2012;10(7):2815. doi:10.2903/j.efsa.2012.2815