EPA to DHA Ratio: Is There an Optimal Ratio?

Many omega-3 supplements state an EPA:DHA ratio – such as “18/12” or “2:1”. This is often accompanied by the claim that a particular ratio is “optimal” for a particular goal. This article puts that into context: what the authorised health claims on EPA and DHA actually say, which ratios typical products have and why there is no authorised statement on an “optimal” ratio. In short: the claims are about amounts – total EPA+DHA and the amount of DHA – not about the ratio.

What the authorised health claims say about EPA and DHA

Health claims on foods and food supplements may only be made if they have been authorised – in the EU by the European Commission, on the basis of scientific opinions from EFSA (EFSA Journal 2010;8(10):1796). The authorised claims for EPA and DHA are listed in Regulation (EU) No 432/2012; Great Britain kept the same claims in its own register after Brexit. What matters for this topic: each claim specifies which fatty acid counts and the daily amount from which it applies.

Authorised health claims for EPA and DHA (Regulation (EU) No 432/2012)

Authorised wording	What counts	Condition per day
“EPA and DHA contribute to the normal function of the heart.”	EPA+DHA combined	250 mg EPA+DHA
“DHA contributes to the maintenance of normal brain function.”	DHA only	250 mg DHA
“DHA contributes to the maintenance of normal vision.”	DHA only	250 mg DHA
“DHA and EPA contribute to the maintenance of normal blood triglyceride levels.”	EPA+DHA combined	2 g EPA+DHA
“DHA and EPA contribute to the maintenance of normal blood pressure.”	EPA+DHA combined	3 g EPA+DHA

The claims on triglyceride levels and blood pressure must be accompanied by the advice not to exceed a supplemental daily intake of 5 g EPA+DHA (Regulation (EU) No 432/2012; on safety: EFSA Journal 2012;10(7):2815). There is no authorised claim for EPA on its own.

Pregnancy and breastfeeding: an additional amount of DHA

There are two further authorised claims for pregnant and breastfeeding women: “Docosahexaenoic acid (DHA) maternal intake contributes to the normal brain development of the foetus and breastfed infants” and “… to the normal development of the eye of the foetus and breastfed infants”. Condition: a daily intake of 200 mg DHA in addition to the recommended daily intake of 250 mg EPA+DHA for adults (Regulation (EU) No 440/2011). Again, this is about an amount, not a ratio. Please discuss supplements with your GP or midwife. More in the article Omega-3 in pregnancy.

What this means for the ratio

For the heart claim, the ratio does not matter – only the sum of EPA and DHA counts. For brain function and vision, only the amount of DHA counts. An example: a standard “18/12” fish oil provides 180 mg EPA and 120 mg DHA per 1,000 mg of oil. That meets the condition of the heart claim (250 mg EPA+DHA), but the condition of the DHA claims for brain and vision (250 mg DHA) only with a little more than twice the amount. When you check a label, look at both values per daily serving: total EPA+DHA and DHA on its own.

How EPA and DHA differ

EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are long-chain omega-3 fatty acids. Biochemically, they have different roles. The following paragraphs describe these basics; they are not statements about the effects of supplements.

EPA: starting material for tissue hormones

The body uses EPA to form eicosanoids – short-lived signalling molecules such as prostaglandins and leukotrienes. In doing so, EPA competes with the omega-6 fatty acid arachidonic acid for the same enzymes (COX and LOX). More in the article EPA – eicosapentaenoic acid in detail.

DHA: building block of cell membranes

DHA is a building block of cell membranes and is found in particularly high proportions in the brain and retina. This is what the authorised claims on brain function and vision refer to. Details in the article DHA – docosahexaenoic acid in detail.

Conversion between EPA and DHA

The body can elongate EPA to DHA via several metabolic steps, but only to a small extent. This is irrelevant for the health claims: their conditions refer to the amount of DHA or EPA+DHA consumed. Read more about metabolism in the article What are omega-3 fatty acids?.

Typical EPA:DHA ratios in products

Labels such as “18/12” or “33/22” are percentages: the share of EPA and DHA in the oil. From these, you can work out the ratio and the amounts directly.

Typical product types and their EPA:DHA ratio

Product type	Typical ratio (EPA:DHA)	Example per 1,000 mg of oil
Standard fish oil “18/12”	1.5:1	180 mg EPA + 120 mg DHA = 300 mg EPA+DHA
Concentrate, e.g. “33/22”	1.5:1, depending on the manufacturer also EPA- or DHA-weighted	330 mg EPA + 220 mg DHA = 550 mg EPA+DHA
Algae oil	often DHA-weighted, sometimes barely any EPA	varies by product – check the label
Pure EPA (icosapent ethyl)	EPA only	prescription medicine, not a food supplement

With algae oil it is worth checking both values: some products provide almost exclusively DHA. For vegans, algae oil is the usual source of EPA and DHA. A comparison of the oil sources can be found in the article Krill oil, fish oil and algae oil compared.

Is there an “optimal” ratio?

Not in the sense of an authorised statement. None of the authorised health claims specifies an EPA:DHA ratio. Research has used products with very different ratios, mostly in specific groups and at amounts far above usual daily servings. Such results cannot simply be transferred to healthy people and are not intake recommendations. Statements such as “the optimal ratio for your goal” have no authorised basis.

What to look for when choosing a product

Our buying guide for high-quality omega-3 oil explains the quality criteria. You can estimate how much EPA+DHA you get from diet and supplements with the Omega-3 Requirements Calculator. The amounts at a glance are covered in the article Omega-3 daily dosage.

Frequently asked questions about the EPA:DHA ratio