What Are Microalgae?
Microalgae are microscopic, single-celled photosynthetic organisms that live in water. They are the foundation of aquatic food chains and the original producers of the long-chain omega-3 fatty acids (EPA and DHA) that fish accumulate through their diet. If you are taking an algae-based supplement, the active ingredients originate in these organisms.
We grow two species (Nannochloropsis gaditana and Chlorella vulgaris), and the difference between them in nutrient output, cultivation requirements, and label transparency is substantial enough that lumping them under "microalgae" tells you almost nothing useful.
Why Species Names Matter on Microalgae Supplement Labels
If you have encountered the term "microalgae" on a supplement label, it is worth knowing that it covers an enormous range of organisms. We work with several microalgae species in our product range. Marine phytoplankton from Nannochloropsis provides EPA. Chlorella provides protein, chlorophyll, and micronutrients. Schizochytrium provides DHA.
The species determines what you get, which is why we specify species names on our labels rather than relying on the generic term. It makes the label harder to scan at a glance and means we cannot compete on simplicity with brands that just say "marine algae blend."
If your product just says "microalgae" without naming the species, you cannot evaluate what is inside the capsule or powder you are taking each morning.
When you are comparing products in a shop, check whether the label names a species like Chlorella vulgaris or Nannochloropsis gaditana, or whether it simply says "microalgae blend." That single detail tells you whether the manufacturer is being transparent about what the product actually delivers at the dose printed on the back of the tub.
Microalgae at a Glance
When you pick up a tub in a health shop and see "microalgae" on the label, this is the frame that lets you ask the right questions.
- What they are: Single-celled photosynthetic organisms, mostly aquatic (not seaweed, not spirulina)
- Scale: Roughly 50,000 identified species; only five to seven are commercially cultivated for supplements
- Dominant producers: Spirulina at ~12,000 tonnes/year globally, Chlorella at ~5,000 tonnes; every other species is a fraction of those volumes
- Ecological role: Responsible for roughly half of global oxygen production
- Nutritional relevance: Original producers of EPA and DHA, rich in chlorophyll, carotenoids, protein
- What we grow: Nannochloropsis gaditana for EPA and Chlorella vulgaris for protein and chlorophyll, two of the handful with meaningful clinical data
What our research found
We reviewed published species production data, cultivation literature, and taxonomic classifications to establish what actually distinguishes commercially relevant microalgae from the broader category. Two findings stood out.
Out of roughly 50,000 identified microalgae species, only about five to seven are commercially cultivated for food supplements. Spirulina (Arthrospira) dominates global production at approximately 12,000 tonnes per year, followed by Chlorella at around 5,000 tonnes. Every other species is a fraction of those volumes.
Spirulina is technically a cyanobacterium, not a true microalga. It is a prokaryote, a bacterium, which means it lacks the membrane-bound organelles that define eukaryotic microalgae like Chlorella and Nannochloropsis. Spirulina does have genuine strengths: its protein content runs to around 60 per cent of dry weight, it is widely available, and decades of human food use have produced a strong safety record.
The caveats worth knowing are that cyanobacteria carry a contamination risk from microcystins that true microalgae do not, and spirulina's B12 is predominantly pseudovitamin B12, which human studies have not shown to be bioavailable in the way plant-based consumers need.
Sources
Cara Hayes, MSc Nutrition and Dietetics (University of Sydney), writes all content in the Phytality Knowledge Centre. Read our editorial policy.
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Consult your healthcare provider before starting any supplement.
Methodology and Disclosure
Phytality manufactures supplements from multiple microalgae species. We have a commercial interest in the microalgae category. Taxonomic descriptions reflect established biology. No EFSA-authorised health claims are cited.
Last reviewed: March 2026
