Most athletes know their ferritin and their testosterone, but not their omega-3 index. A shame, because it is one of the few blood values you can visibly shift within a few months through your diet. You measure it once, you adjust your intake, and you see it back.
I think the omega-3 index is underrated precisely because it links so directly to your behaviour. No genetic lottery, just a dial you can turn.
What is the omega-3 index?
The omega-3 index expresses the share of EPA and DHA as a percentage of all fatty acids in your red blood cell membranes. Because red blood cells last weeks, the index reflects your intake over a longer period, not your last fish meal. You measure it with the omega-3 index marker.
A low index counts as an unfavourable cardiovascular risk factor (von Schacky, 2007). So it is not a wellness number, but a marker that means something.
Why does your omega-3 index matter?
A higher omega-3 index is associated with a lower risk of death from heart disease. An analysis of ten cohorts found that people with a high index had clearly less risk than people with a low one (Harris, 2017). The Dutch Heart Foundation (Hartstichting) accordingly advises eating fish regularly as part of a heart-healthy pattern. For athletes, recovery also plays a role: EPA and DHA are involved in regulating inflammation after exertion.
| Omega-3 index | Zone | Roughly what it means |
|---|---|---|
| Below 4% | Unfavourable | Highest risk category, room to improve |
| 4 to 8% | In-between | Average for Western Europe, often too low |
| Above 8% | Favourable | The range named as a target zone |
The Dutch Nutrition Centre (Voedingscentrum) recommends two portions of fish per week, one of them oily fish. Most people in the Netherlands fall short of that, which explains why many index values sit in the in-between zone or lower.
Does fish oil or oily fish help?
Both oily fish and supplements can raise your index, though the effect on hard outcomes is nuanced. Meta-analyses of supplements show mixed but mostly modest benefits on cardiovascular disease (Hu, 2019). For your index itself, regular oily fish such as salmon or mackerel, or an EPA/DHA supplement, works.
The nice part is that you can measure the effect rather than believe it. Test, adjust your intake, and test again after a few months.
Omega-3 and your sports recovery
For athletes, the omega-3 index is more than a heart marker. EPA and DHA are building blocks of your cell membranes and play a role in regulating inflammatory responses after hard training. A low status is linked to less smooth inflammation regulation, which can slow your recovery. Hard proof that supplementation directly improves your performance is not there, and you should not claim it either. What does hold: removing a deficiency makes more sense than pumping a normal value higher.
My line: treat your omega-3 index as a deficiency check, not a doping agent. If you sit low, there is a gain to be had; if you are already in range, more probably adds little.
How much fish or supplement do you need?
The practice is simpler than many articles suggest. Two portions of oily fish per week, as the Dutch Nutrition Centre (Voedingscentrum) advises, already brings most people a good way towards the favourable zone. If that is not realistic on a structural basis, an EPA/DHA supplement is a reasonable substitute. With a supplement, look at the combined EPA and DHA content per capsule, not at the total fish oil weight, because that says little about the active substance.
How to test and improve your omega-3 index
Test your index as a baseline, then adjust your intake and follow the trend. A repeat measurement after three to four months shows whether your approach works, because that is how long it takes for your cell membranes to shift. If you wish, combine it with your ApoB and your triglycerides for a broader heart picture.
To measure your omega-3 index, compose a panel through our custom blood test or start with the lipids blood test for your heart risk. See also ApoB and the overview the 360 health panel.
My advice: do not guess at your omega-3 status, measure it. A low index is one of the easiest things to improve on purpose, and you see it back in your next measurement. If your value stays low despite changes, discuss it with your GP.
References
- Hartstichting (Dutch Heart Foundation). Fish and cardiovascular disease. Accessed 2026.
- Voedingscentrum (Dutch Nutrition Centre). Fish: how much and how often. Accessed 2026.
- Harris WS, Del Gobbo L, Tintle NL. The Omega-3 Index and relative risk for coronary heart disease mortality: Estimation from 10 cohort studies. Atherosclerosis. 2017. PMID: 28511049.
- Hu Y, Hu FB, Manson JE. Marine Omega-3 Supplementation and Cardiovascular Disease. Journal of the American Heart Association. 2019. PMID: 31567003.
- von Schacky C. Cardiovascular risk and the omega-3 index. Journal of Cardiovascular Medicine. 2007. PMID: 17876200.
Disclaimer
Every blood test result includes a professional assessment by a BIG-registered doctor. This article gives general information and is not a substitute for medical advice. A blood test is a tool to walk into the conversation with your GP better informed, not a diagnosis in itself. For treatment decisions, discuss your results with your GP.
Author
Enhanced Health
Dr. Naimi, BIG-registered physician, oversees the medical standards behind our content and assessments. Read our medical policy
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