Omega-3 for Runners: Is Fish Oil Worth It? EPA and DHA Explained

Omega-3 is one of the most talked-about supplements for runners, and one of the most confusing to buy. This guide explains what Omega-3 actually is, why many UK runners fall short, what it can and cannot legally be said to do, and how to read a fish oil label. It combines our two earlier Omega-3 articles.

What is Omega-3?

Omega-3s are a family of fatty acids. Three matter most:

• EPA (eicosapentaenoic acid) – found mainly in oily fish.
• DHA (docosahexaenoic acid) – also from oily fish; a major structural fat in the brain and eyes.
• ALA (alpha-linolenic acid) – found in flax, chia and walnuts. The body converts only a small amount of ALA into EPA and DHA, so plant sources do not replace fish.

Why UK runners often fall short

The NHS recommends at least two portions of fish a week, one of them oily, such as salmon, mackerel, sardines or herring. Most adults in the UK eat well below that. If oily fish is not a weekly habit for you, your EPA and DHA intake is probably low.

What Omega-3 does (the authorised claims)

• EPA and DHA contribute to the normal function of the heart (with a daily intake of 250mg EPA and DHA).
• DHA contributes to the maintenance of normal brain function and normal vision (with a daily intake of 250mg DHA).

These are the claims permitted in Great Britain, listed on the GB nutrition and health claims register. You will see other brands promise less soreness, faster recovery or better joints. Research into Omega-3 and exercise recovery is active and interesting, but those are not authorised claims, and we do not make them. For the heart side in more detail, read Omega-3 and heart health for endurance athletes.

How to read a fish oil label

Do not read the front of the bottle. Turn it over. A capsule that says “1,000mg fish oil” might contain only 300mg of actual EPA and DHA. What matters is:

• EPA and DHA per serving in milligrams, not total fish oil.
• Servings per day needed to hit that figure.
• Freshness: vitamin E is often added to protect the oil from oxidation.
• Where it is made and whether it is tested.

How RunnerVits Omega-3 compares

High-Strength Omega-3 provides 2,000mg fish oil per two-capsule serving, including 1,000mg EPA and 500mg DHA, with vitamin E for freshness. That comfortably exceeds the 250mg thresholds for both authorised claims. It is made in the UK with no fillers.

How to take it

• Take it with a meal that contains some fat, usually breakfast.
• Consistency matters more than timing; it is a daily habit, not a pre-run product.
• Pair it with your Morning Runner Essentials so both happen at once.

Who should be careful

If you take blood-thinning medication, are due to have surgery, or are pregnant, speak to your GP before starting a high-strength fish oil.

FAQs

Is fish oil good for runners?

For runners who eat little oily fish, it is a practical way to top up EPA and DHA, which contribute to normal heart function. It is not a performance product.

Can I get enough from food?

Yes, if you eat oily fish every week. If you do, you may not need a supplement.

Where does Omega-3 fit in a marathon block?

As part of your daily morning routine. See the full plan in our marathon supplements guide.

Food supplements should not be used as a substitute for a varied, balanced diet and healthy lifestyle. Speak to your GP before taking supplements if you are pregnant, breastfeeding, on medication or have a medical condition.