Does Marine Phytoplankton Contain DHA?

No. If you are taking a marine phytoplankton supplement, the species inside is almost certainly Nannochloropsis, and Nannochloropsis produces EPA in concentration but no DHA. Turn the bottle over and check the nutritional information panel: you will see EPA listed in milligrams and no DHA figure at all.

That is not a defect or a formulation shortcut. It is the biology of the organism. Nannochloropsis gaditana lacks both the Δ4-desaturase and the ELOVL2 elongase enzymes needed to convert EPA into DHA. Its fatty acid synthesis pathway stops at EPA. Published lipid analyses consistently describe the species as "completely devoid of endogenous DHA."

Fish accumulate DHA because they eat many different microalgae across a food web. A supplement made from one species gives you one species' output.

If your goal is DHA from a plant source, you need a different organism entirely. We produce both an EPA-rich phytoplankton and a separate algae-derived DHA supplement for this reason, because no single commercially cultivated microalgae species delivers both fatty acids at levels worth putting on a label.

Why Most Marine Phytoplankton Supplements Contain EPA, Not DHA

The answer sits in the biochemistry of the species used. Nannochloropsis gaditana, which accounts for the vast majority of marine phytoplankton supplements on the market, produces EPA as the end point of its long-chain omega-3 synthesis. In biological terms, EPA is its terminal fatty acid product. The elongase and desaturase enzymes that would convert EPA onward to DHA are not functionally active in this species.

This is worth understanding because it means no amount of processing, extraction, or concentration will produce meaningful DHA from Nannochloropsis biomass. You cannot extract what the organism does not make. Published lipid analyses of Nannochloropsis gaditana consistently show DHA below 1% of total fatty acids, while EPA is the dominant long-chain omega-3 by a wide margin (Ma et al., 2016).

If you see a marine phytoplankton product making claims about DHA content, check the species. Either it uses a different organism (in which case "marine phytoplankton" on the label is doing a lot of heavy lifting as a category term), or the DHA figure is so small that quoting it is technically accurate but practically misleading.

We state the EPA content per serving on our labels because you deserve to know which fatty acid you are actually getting.

Which Microalgae Species Produce DHA

DHA production in the microalgae world is dominated by a handful of species, and none of them are the photosynthetic green organisms most people picture when they hear "phytoplankton." The main commercial DHA producers are heterotrophs, organisms that grow in the dark on carbon-rich feed stocks rather than photosynthesising in sunlight.

Schizochytrium: The Industry Standard for Algae DHA

Schizochytrium is the species behind most algae-derived DHA oil capsules you will find in a health shop. It produces DHA at high concentrations, making it commercially viable for extraction into concentrated oil. The trade-off is that it delivers very little EPA. If you pick up an algae omega-3 supplement and the label shows high DHA with minimal EPA, Schizochytrium is almost certainly the source organism.

This creates a practical mirror image with Nannochloropsis. One species gives you EPA without DHA. The other gives you DHA without EPA. If you need both from plant sources, you are looking at two products, not one.

Isochrysis and Other Photosynthetic DHA Producers

Isochrysis galbana is a genuinely photosynthetic microalga that produces moderate amounts of DHA alongside some EPA. On paper, it looks like it could solve the dual-fatty-acid problem. In practice, published analyses show the concentrations of both are lower than what the specialist producers deliver (Ryckebosch et al., 2014).

You get some of each, but not enough of either to meet EFSA intake thresholds from a standard supplement dose without taking handfuls of capsules.

The arithmetic does not work at supplement scale. The DHA per gram of Isochrysis biomass is too low to make a meaningful DHA claim, and its EPA per gram falls well short of what Nannochloropsis delivers. A supplement that provides modest amounts of both is a supplement that does neither job well at realistic doses.

How to Read an Omega-3 Supplement Label for DHA Content

If you are comparing omega-3 supplements in a health shop or online, the label is where most of the confusion starts. "Rich in omega-3" tells you nothing useful. "Contains DHA" without a milligram figure tells you almost nothing useful. Here is what to look for and what to ignore.

Find the per-serving breakdown. The number that matters is milligrams of DHA per dose, not total omega-3, not total fat, and not a percentage of fatty acids. Some labels quote "total omega-3" prominently while burying the EPA and DHA split in smaller text.

Your body does not respond to a category total. It responds to specific fatty acids at specific doses.

Check whether DHA is listed at all. A Nannochloropsis-based phytoplankton supplement that omits DHA from its panel is being honest. One that lists "omega-3 (as EPA and DHA)" without specifying the DHA amount per serving is being less helpful than it should be.

If you cannot find a milligram figure for DHA, assume the product does not deliver it in useful quantities.

Watch for "omega-3 from algae" marketing. This phrase covers everything from concentrated Schizochytrium DHA oil to whole-cell phytoplankton powder with trace DHA. Two products under that umbrella can have completely different fatty acid profiles.

The species name is what separates them. We name Nannochloropsis gaditana on our labels for this reason. If the species is not on the label, the label is not giving you enough information to choose.

Meeting EFSA Intake Conditions for DHA from Plant Sources

The EFSA-authorised health claims for DHA set specific thresholds that matter if you are building your omega-3 intake from supplements. DHA contributes to the maintenance of normal brain function at 250 mg daily. DHA contributes to the maintenance of normal vision at 250 mg daily.

These are separate from the combined EPA and DHA claim for heart function, which requires 250 mg of both together (Commission Regulation (EU) No 432/2012).

If you are taking a Nannochloropsis phytoplankton supplement alone, you are contributing EPA toward the heart-function claim but not meeting the brain-function or vision thresholds. Those require DHA specifically, and trace amounts do not count toward the 250 mg threshold.

This is not a criticism of phytoplankton as a supplement. It is a statement about what one species can and cannot deliver.

For a plant-based reader trying to reach these thresholds without fish oil, the practical calculation is straightforward. You need a dedicated DHA source. Most algae DHA oil capsules from Schizochytrium deliver 200-300 mg DHA per capsule, which puts you at or near the EFSA threshold in a single dose.

Pair that with a phytoplankton supplement for EPA and you have covered both fatty acids from non-animal sources. We produce ULTANA Phytoplankton for the EPA side and Clean Omega DHA for the DHA side precisely because no single product in our range could honestly serve both claims.

Marine Phytoplankton and DHA FAQ

Does Nannochloropsis contain any DHA at all?

Technically, yes. Trace amounts of DHA appear in lipid analyses of Nannochloropsis gaditana, typically below 1% of total fatty acids. At standard supplement doses, this translates to a fraction of a milligram per serving. It is present in the analytical sense but not in any quantity your body can use toward the 250 mg daily threshold for EFSA health claims.

Can you get enough DHA for pregnancy from marine phytoplankton?

No, not from a Nannochloropsis-based supplement. During pregnancy, the EFSA-authorised claim states that maternal intake of DHA contributes to normal brain and eye development of the foetus at 200 mg DHA daily on top of the standard 250 mg EPA+DHA. A phytoplankton supplement delivers EPA but not the DHA your body specifically needs during pregnancy.

If you are pregnant and building your omega-3 intake from plant sources, a dedicated algae DHA supplement is not optional. Speak to your GP or midwife about the right dose for your situation.

Will future phytoplankton strains produce both EPA and DHA?

Researchers are working on genetically modified and selectively bred strains that could produce both fatty acids at commercially relevant levels. Some laboratory strains of Nannochloropsis have been engineered to express the missing desaturase enzymes. None of these are commercially available yet, and regulatory approval for genetically modified microalgae in food supplements is a separate hurdle. For now, the two-species approach remains the practical answer for plant-based EPA and DHA coverage.

Is algae DHA oil the same as marine phytoplankton?

No. "Algae DHA oil" is typically extracted from Schizochytrium, a heterotrophic marine organism that grows in fermentation tanks without light. Marine phytoplankton supplements use photosynthetic species like Nannochloropsis, grown in light-exposed cultivation systems. They produce different fatty acids, come from different organisms, and serve different nutritional purposes. The word "algae" on the label covers both, which is part of the confusion.

Can you take marine phytoplankton and algae DHA oil together?

Yes. They are complementary. Phytoplankton from Nannochloropsis provides EPA. Algae oil from Schizochytrium provides DHA. Taken together, they cover both long-chain omega-3 fatty acids from non-animal sources.

Check the combined EPA and DHA total against the EFSA thresholds relevant to your health goals, and discuss dosing with your GP if you are on blood-thinning medication. EPA can have mild anticoagulant effects at high combined intakes (generally above 2-3g daily), though standard supplement doses fall well below this.

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult your GP before starting any supplement.

Methodology and Disclosure

Phytality manufactures marine phytoplankton supplements from Nannochloropsis gaditana and sells a separate algae-derived DHA product. We have a direct commercial interest in both. Fatty acid profile descriptions reflect published lipid analyses of Nannochloropsis species cited above, consistent with our own product development data.

EFSA-authorised health claims for EPA and DHA are cited under Regulation EU 432/2012 with intake conditions stated. Species comparisons (Nannochloropsis, Schizochytrium, Isochrysis) reflect established compositional differences documented in published reviews (Ryckebosch et al., 2014; Ma et al., 2016). The description of genetically modified strains reflects published research status and does not constitute a product claim.

The recommendation to use two separate supplements for EPA and DHA coverage reflects the current state of commercially available microalgae species as documented in the cited literature.

Last reviewed: March 2026. Next review due: March 2027.