Marine Phytoplankton vs Krill Oil

Krill oil and marine phytoplankton are both positioned as alternatives to standard fish oil, and both claim advantages in absorption and sustainability. But they are fundamentally different products: one is an animal-derived oil extracted from small crustaceans, and the other is a plant-based whole-food supplement from microalgae. The relevant questions are what each delivers, how the omega-3 is structured, and whether the sustainability claims hold up.

We manufacture phytoplankton supplements, so our position in this comparison is transparent. What follows is our honest assessment of both options, including where krill oil has genuine advantages we cannot match.

What Krill Oil Is and What It Actually Delivers

Krill oil comes from Antarctic krill (Euphausia superba), small crustaceans harvested from the Southern Ocean. It contains both EPA and DHA, primarily bound to phospholipids rather than the triglycerides found in standard fish oil.

The phospholipid structure is the basis of krill oil's main marketing claim: that it is better absorbed than fish oil. If you have seen this claim on a label, there is some published research behind it. But the evidence is not as definitive as the marketing implies, and the studies are relatively small.

Here is the number that matters more than the absorption story. A standard krill oil capsule typically delivers 60 to 120 mg combined EPA+DHA, compared to 300 to 500 mg in a standard fish oil capsule. Even if phospholipid binding improves absorption by 30 to 50 per cent (the upper end of published estimates), the arithmetic still leaves krill below fish oil's absolute delivery.

If you are trying to reach the 250 mg combined EPA+DHA threshold for the EFSA heart-function claim, check how many krill capsules that requires. The answer is usually two to three.

Krill oil also contains astaxanthin, a carotenoid pigment with antioxidant properties that gives it its red colour. This is a genuine differentiator from fish oil, though the amounts per capsule are small.

What Marine Phytoplankton Is and How It Differs

Phytoplankton supplements from Nannochloropsis are whole-cell powders, not oil extracts. The EPA is part of the intact organism, alongside chlorophyll, carotenoids, amino acids, B12, and micronutrients. The omega-3 is partially bound to polar lipids within the cell membrane, structurally different from both the triglyceride form in fish oil and the phospholipid form in krill.

Phytoplankton is EPA-dominant with minimal DHA. If you need DHA, phytoplankton alone does not provide it. You would combine it with a dedicated algae DHA supplement. We designed our range this way because no single microalgae species delivers both fatty acids at meaningful concentrations.

The nutrient profile beyond omega-3 is where the comparison shifts. Krill oil gives you EPA, DHA, and astaxanthin. Phytoplankton gives you EPA, chlorophyll, a full amino acid profile, carotenoids, and B12. If you are looking for omega-3 and nothing else, krill is simpler. If you want a broader nutritional contribution from a single supplement, phytoplankton covers more ground.

The Sustainability Question: Extraction vs Cultivation

Both products make sustainability claims. The reality behind them differs structurally.

Krill harvesting removes biomass from a wild marine ecosystem. Krill are a keystone species in the Antarctic food web, feeding whales, seals, penguins, and fish. The industry operates under catch limits set by CCAMLR, and current harvest levels represent a fraction of the estimated biomass.

But "sustainable" in this context means "within managed extraction limits from a wild population," not "no ecological impact." Climate change is already affecting krill populations independently of harvesting, and the interaction between the two pressures is not fully understood.

Microalgae grown in closed photobioreactors do not remove anything from a marine ecosystem. The organisms are cultivated using filtered water, nutrients, and light in a sealed system. The ecological footprint is energy and infrastructure, not extraction from wild stocks.

If the distinction between cultivation and extraction matters to your purchasing decision, the two products are not equivalent on this criterion.

Phytoplankton vs Krill Oil Point by Point

• Fatty acid profile: Krill provides both EPA and DHA at modest doses per capsule. Phytoplankton provides EPA only, with no meaningful DHA.
• Format: Krill comes as an extracted oil in softgel capsules. Phytoplankton is a whole-cell powder.
• Absorption: Krill's phospholipid-bound omega-3 may have a slight bioavailability edge. Phytoplankton's polar-lipid-bound EPA has a different but also potentially favourable structure. Neither has been shown to be definitively superior in large-scale human trials.
• Dose per serving: A typical krill capsule delivers less total EPA+DHA than fish oil or concentrated algae oil.
• Sustainability: Krill is wild-harvested from a managed fishery. Phytoplankton is cultivated with no wild extraction.
• Suitability: Krill is not vegan or vegetarian and is unsuitable for people with shellfish allergies. Phytoplankton is entirely plant-based.
• Additional nutrients: Krill contains astaxanthin. Phytoplankton contains chlorophyll, carotenoids, amino acids, B12, and micronutrients.

Who Should Choose Which Omega-3 Supplement

When Krill Oil Makes Sense

If you eat animal products and want combined EPA+DHA in a single capsule with a potential absorption advantage, krill is a reasonable option. Check the per-capsule EPA+DHA content against your target intake, because the lower dose per unit matters more than most buyers realise. If you are taking krill specifically for its astaxanthin content, that is a genuine feature phytoplankton does not replicate in the same form.

When Phytoplankton Is the Better Fit

If you are plant-based, have a shellfish allergy, or prioritise cultivation over wild extraction, phytoplankton covers the EPA side without animal ingredients. Pair it with an algae DHA supplement if you need both fatty acids. If you value the broader nutrient profile (B12, amino acids, chlorophyll), phytoplankton delivers more per serving beyond the omega-3.

The Honest Cost Comparison

If cost is your primary constraint, standard fish oil delivers more EPA+DHA per pound than either krill or phytoplankton. Krill oil is typically the most expensive option per milligram of omega-3. We would rather you knew that before making your decision.

Marine Phytoplankton vs Krill Oil FAQ

Is krill oil safe if you have a shellfish allergy?

No. Krill belong to the crustacean family, and the allergenic proteins that trigger reactions to prawns or crab may be present. If you carry a shellfish diagnosis, avoid this product category entirely and ask your GP about non-animal alternatives.

Does krill oil have more astaxanthin than phytoplankton?

It contains a different pigment profile. The red colour in krill capsules comes from astaxanthin, accumulated from the organism's own diet. Nannochloropsis produces fucoxanthin and beta-carotene instead. If you specifically want astaxanthin, a dedicated extract from Haematococcus algae delivers higher concentrations than any krill softgel.

How many krill capsules equal one fish oil capsule?

Usually two to three. A conventional marine oil softgel packs 300-500 mg of the target fats; a krill softgel holds 60-120 mg. Improved cellular uptake from the phospholipid carrier narrows the gap somewhat, but not enough to match on a single-capsule basis.

Can I pair microalgae powder with an algae-sourced DHA capsule instead?

Yes. The powder handles the eicosapentaenoic side; the capsule handles the docosahexaenoic side. Together they span both long-chain fats from cultivated, non-animal origins, sidestepping both the crustacean allergy concern and the wild-harvest question. You do end up managing two daily items rather than one.

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

Methodology and Disclosure

Phytality manufactures marine phytoplankton and algae-derived DHA supplements but does not sell krill oil. We have a commercial interest in this comparison. EFSA-authorised health claims are cited with their regulatory source. The krill bioavailability comparison reflects our assessment of published studies, which are limited in scale. The sustainability comparison reflects the structural difference between wild extraction and controlled cultivation, not a peer-reviewed lifecycle analysis.

Last reviewed: April 2026