Phytoplankton vs Other Microalgae

Walk into a health shop and you will find marine phytoplankton, chlorella, spirulina, and algae oil capsules shelved together under "algae supplements," as though they were the same thing in different packaging. They are not. They are different organisms, from different biological kingdoms in some cases, with different nutrient profiles and different reasons to be in your routine.

The confusion costs real money. If you buy chlorella expecting omega-3, you will not get it. If you buy algae oil expecting the broad micronutrient profile of whole-cell phytoplankton, you will not get that either. Each one does something the others cannot, and understanding where they diverge is the only way to avoid paying for the wrong supplement twice.

We sell products from multiple microalgae species, so we have a direct interest in you understanding these differences rather than guessing. Honest comparison is better for you and, frankly, better for us.

Why Phytoplankton and Microalgae Are Not the Same Thing

"Phytoplankton" is an ecological term, not a taxonomic one. It describes any microscopic photosynthetic organism that drifts in water. That includes true microalgae like Nannochloropsis and Chlorella, but also cyanobacteria like spirulina, which are biologically closer to bacteria than to algae. Supplement labels rarely make this distinction, and neither do most comparison articles.

For you, the practical consequence is straightforward. When a product says "microalgae" or "phytoplankton," it is telling you almost nothing about what is inside. The species name is what matters. Nannochloropsis gives you EPA. Chlorella gives you chlorophyll and protein. Arthrospira gives you phycocyanin and protein. Filing them all under "algae" is like filing salmon and kelp under "seafood" and assuming they serve the same nutritional purpose.

If you are comparing products on a shelf, the species name on the label is the first thing worth checking. If there is no species name, you cannot evaluate what you are buying.

Marine Phytoplankton vs Chlorella: EPA Against Chlorophyll

This is the comparison that trips up most buyers, because both are green powders, both are whole-food supplements, and both sit in the same aisle. The difference is what each one actually delivers in meaningful quantities.

Where Phytoplankton Wins: EPA Omega-3

Marine phytoplankton from Nannochloropsis gaditana is one of the few whole-food sources of EPA (eicosapentaenoic acid) outside of fish. Chlorella contains trace amounts of alpha-linolenic acid (ALA), but your body converts ALA to EPA at roughly 5-10%, which means the effective EPA contribution from chlorella is negligible. If omega-3 is your reason for buying, phytoplankton is the one you want.

We formulate our ULTANA Phytoplankton around Nannochloropsis specifically because the EPA concentration is high enough to be nutritionally relevant at supplement doses. Not all phytoplankton species deliver this. Tetraselmis, for instance, is more protein-focused and would not serve the same purpose.

Where Chlorella Wins: Chlorophyll, Protein, and Iron

Chlorella has the highest chlorophyll concentration of any commonly consumed food, roughly 3-5% of dry weight. It is also 40-60% protein and contains meaningful amounts of iron, B12 analogues, and a broad mineral profile. If your priority is a concentrated whole-food green with protein density, chlorella makes a stronger case than phytoplankton.

One detail most comparisons miss: fermented chlorella has its cell wall broken down during processing, which improves digestibility. Standard chlorella requires "cracked cell wall" processing to achieve the same thing. If you are choosing between the two forms, the preparation method affects how much you actually absorb. We use fermented chlorella in our range for this reason.

When You Need Both Microalgae Supplements

If you want EPA omega-3 and concentrated chlorophyll from whole-food sources, you need both. They serve separate jobs. We formulate them as separate products because pretending one covers everything would be misleading. Our Phytoplankton Super Greens combines phytoplankton, chlorella, and spirulina for readers who want the broadest spectrum in a single scoop.

Marine Phytoplankton vs Spirulina: Omega-3 Against Protein and Phycocyanin

Spirulina (Arthrospira platensis) is not technically an alga at all. It is a cyanobacterium, biologically closer to bacteria than to eukaryotic microalgae like Nannochloropsis or Chlorella. It has been consumed for centuries and is one of the most studied supplement ingredients on the market, but its nutritional strengths lie in completely different territory from phytoplankton.

Spirulina's Strengths: Protein Density and Phycocyanin

At 55-70% protein by dry weight, spirulina has the highest protein density of any microalgae supplement. It also produces phycocyanin, a blue-green pigment with antioxidant properties that does not exist in any true microalgae. If phycocyanin is what you are after, spirulina is the only option.

The catch is dosage context. At typical supplement doses of 3-5g per day, the absolute protein contribution is modest: roughly 2-3.5g. You are not replacing a meal. If protein density is your primary reason for choosing spirulina, be realistic about what supplement-level servings deliver compared to food sources.

What Spirulina Lacks: Any Meaningful Omega-3

Spirulina provides no EPA, no DHA, and barely any ALA. If someone has recommended "algae for omega-3" and you reach for spirulina, you will get zero useful omega-3. This is the single most common mix-up we encounter. The algae-to-omega-3 connection applies to specific species, not to the category as a whole.

We covered the chlorella vs spirulina comparison separately in its own article. The short version: spirulina wins on protein and phycocyanin, chlorella wins on chlorophyll and mineral breadth, phytoplankton wins on EPA.

Marine Phytoplankton vs Algae Oil: EPA Against DHA

This comparison confuses buyers because both are marketed as "algae omega-3," and the assumption is that they are interchangeable. They are not. The omega-3 fatty acid each one provides is different, and that difference matters for how you build a supplement routine.

The EPA and DHA Split in Algae Supplements

Nannochloropsis phytoplankton delivers EPA. Schizochytrium algae oil delivers DHA. EPA and DHA serve different biological functions: EPA is associated with inflammatory response modulation, while DHA is a structural component of brain and retinal tissue. The EFSA-authorised health claim for heart function requires a combined 250 mg of EPA and DHA daily under Regulation (EU) No 432/2012.

If your current routine includes only one of these, you have half the picture. Our phytoplankton vs algae oil guide covers the full comparison.

Whole-Cell Phytoplankton vs Extracted Algae Oil

Beyond the EPA/DHA distinction, the format difference matters. Whole-cell Nannochloropsis powder delivers EPA alongside chlorophyll, carotenoids, and amino acids. Extracted algae oil strips out everything except the fatty acids.

If you open a tub of phytoplankton powder, what you see is a fine dark green substance with a faintly marine smell. If you open a bottle of algae oil capsules, you see amber softgels with no green pigment at all. You are not choosing between two versions of the same thing. You are choosing between a whole-food matrix and an isolated extract.

Neither is wrong. But if you assume they are interchangeable because both labels say "algae," you will misunderstand what you are taking.

How to Read a Microalgae Supplement Label

If you are standing in a health shop or scrolling through product listings, three checkpoints separate a considered purchase from an expensive guess.

Species name. A label that says "marine phytoplankton" or "microalgae blend" without naming the species is asking you to trust a category. For EPA, look for Nannochloropsis. For chlorophyll, look for Chlorella vulgaris or Chlorella pyrenoidosa. If the species is absent, you cannot evaluate what you are buying.

Quantified nutrients per serving. Your body does not respond to adjectives like "omega-3 rich" or "nutrient dense." Look for milligrams of EPA, DHA, or chlorophyll on the nutritional information panel. If those numbers are missing, you cannot compare the product to anything else on the shelf. This is especially important with phytoplankton products, where EPA content varies significantly between species and cultivation methods.

Cultivation method. Closed photobioreactors produce cleaner, more consistent biomass than open ponds. Most reputable producers state their method because it is a genuine differentiator. If the product page says nothing about how the algae was grown, that silence is itself informative. If you see two products with similar labels and very different prices, the cultivation method is usually the reason.

Microalgae Supplement FAQ

Can you take phytoplankton, chlorella, and spirulina together?

Yes. Their nutrient profiles are complementary, not competing. You would be combining EPA (phytoplankton), chlorophyll and protein (chlorella), and phycocyanin and protein (spirulina). There is no known interaction concern. The practical consideration is cost: three separate supplements add up. If budget is a factor, prioritise based on whichever nutrient gap matters most to you.

Which microalgae supplement gives you the most for your money?

That depends entirely on what you are trying to achieve. Spirulina is typically the cheapest per gram. Chlorella sits in the middle. Phytoplankton tends to cost more because closed-system cultivation is more expensive. But comparing price per gram across species that deliver completely different nutrients is not a meaningful comparison. Compare cost per milligram of the specific nutrient you need.

Is one microalgae supplement enough, or do you need several?

No single microalgae supplement covers EPA, DHA, high-dose chlorophyll, phycocyanin, and concentrated protein simultaneously. If your goal is omega-3, phytoplankton handles EPA and a separate algae oil handles DHA. If your goal is broad whole-food nutrition, a multi-algae blend covers more ground. The honest answer is that "enough" depends on what gap you are filling, and most people benefit from being specific about that before spending.

Are microalgae supplements safe during pregnancy?

Consult your GP or midwife before taking any microalgae supplement during pregnancy or breastfeeding. DHA supplementation during pregnancy is supported by some evidence, but dosage and source matter. EPA from phytoplankton has mild anticoagulant effects at high intakes (generally above 2-3g combined EPA and DHA daily), though standard supplement doses sit well below that threshold.

Do microalgae supplements interact with medications?

EPA and DHA can interact with blood-thinning medications such as warfarin. Chlorella contains vitamin K, which may also affect anticoagulant therapy. Spirulina may interact with immunosuppressant drugs. If you are on any regular medication, check with your GP before adding a microalgae supplement to your routine.

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 supplements from multiple microalgae species, including Nannochloropsis gaditana (phytoplankton), fermented Chlorella, and blends incorporating spirulina. We have a direct commercial interest in all species discussed in this article. Compositional data for each species reflects published literature cited above.

The EFSA-authorised health claim for EPA and DHA is cited under Regulation (EU) No 432/2012 with its intake condition stated. Protein percentages reflect ranges reported across multiple published analyses and vary by cultivation conditions. Comparisons between species are based on established compositional differences documented in peer-reviewed reviews.

Where we describe our product range and species selection, this reflects our published product specifications. Fermented chlorella cell-wall breakdown is documented in published literature on microalgae processing methods.

Last reviewed: March 2026.