The Most Important Types of Nutritional Algae

If you walk into a health-food shop looking for an algae supplement, you will encounter four or five organisms marketed under the same broad category. They are not interchangeable. Each has a distinct biology, a different nutrient profile, and a different reason to exist in your supplement routine. This is the field guide to the species that actually matter for human nutrition.

We reviewed published compositional analyses for each species and drew on our cultivation experience with Nannochloropsis gaditana to put this together.

Nannochloropsis gaditana (Marine Phytoplankton)

A marine eustigmatophyte and one of the richest plant sources of EPA omega-3. This is the species we grow for our ULTANA Phytoplankton. Its standout contribution is long-chain omega-3, which freshwater algae and cyanobacteria do not provide in meaningful quantities. It also contains chlorophyll, carotenoids (including violaxanthin), and a complete amino acid profile. We covered the full nutritional breakdown in our Nannochloropsis deep dive.

Best for: plant-based EPA omega-3. Gap: no DHA content.

We chose Nannochloropsis gaditana specifically because EPA content held consistent across cultivation batches in our closed photobioreactor. Other marine species drifted more with temperature variation. Stability mattered as much as the peak EPA figure.

Chlorella vulgaris (Chlorella)

A freshwater green alga, roughly 50 to 60% protein by dry weight, with the highest chlorophyll concentration of any common food source. Chlorella also provides iron, B vitamins, lutein, and a complete amino acid profile. The cell wall requires breaking or fermentation for adequate nutrient absorption. We covered the evidence-backed benefits and the fermented vs regular distinction in separate articles.

Best for: broad-spectrum micronutrition, chlorophyll, and plant protein. Gap: no EPA or DHA.

We produce our chlorella through a fermentation process precisely because cell-wall pre-digestion made a measurable difference to the nutrient release we were targeting. A standard dried powder at the same dose delivers less.

Schizochytrium (Algae DHA)

A marine heterotroph (it does not photosynthesise) that produces DHA in high concentrations. This is the species behind most commercial algae oil capsules, including our Clean Omega DHA. It is cultivated through fermentation rather than photobioreactor systems, and the oil is extracted and concentrated into softgel capsules.

Best for: plant-based DHA for vegans and during pregnancy. Missing: EPA, chlorophyll, and broad-spectrum micronutrients.

We source DHA oil from Schizochytrium because fermentation gives better batch-to-batch consistency on DHA concentration than any photosynthetic algae can. The process is sealed, the substrate is controlled, and the oil profile is predictable.

Arthrospira platensis (Spirulina)

Technically a cyanobacterium rather than a true microalga. Spirulina is 55 to 70% protein by dry weight and contains phycocyanin, a blue pigment with antioxidant properties unique to cyanobacteria. It also provides iron, B vitamins, and beta-carotene. Its cell membrane is more easily digested than chlorella's, so no special cell-wall processing is required. We compared it directly to chlorella in our chlorella vs spirulina article.

Best for: protein density, phycocyanin, and iron. Absent: EPA, DHA, and high chlorophyll.

We do not produce spirulina, but we evaluated it during product development. In our assessment, it lost to chlorella on micronutrient density and to Nannochloropsis on omega-3 content. Where it wins is protein per gram and ease of digestion for people with sensitive digestive systems.

Haematococcus pluvialis

A freshwater microalga and the primary commercial source of natural astaxanthin. Under stress conditions, Haematococcus produces astaxanthin as a self-protective pigment. The cultivation process reflects this biology: a growth phase under optimal conditions, then a stress phase with nutrient deprivation or high light intensity to trigger pigment accumulation. No other supplement species in common use requires a deliberate stress phase to produce what you are buying.

You will find Haematococcus astaxanthin products at premium prices in the same supplement aisle as chlorella and phytoplankton. The comparison matters: this species does one thing well and nothing else. If you are managing a vegan omega-3 shortfall, or want to consolidate multiple nutrients into fewer capsules, it serves neither goal.

Best for: dedicated astaxanthin supplementation. Not a substitute for: omega-3, protein, chlorophyll, or general micronutrients, each of which requires a different species.

Why Species Matters More Than Category

A label that says "algae supplement" without specifying the species is not giving you the information you need to make a good choice. Nannochloropsis and Schizochytrium both produce omega-3, but different types: EPA and DHA respectively. Chlorella and spirulina both provide protein, but with different processing requirements and pigment profiles.

Category shopping is how you end up with a chlorella tub when you needed EPA. Choosing by species is how you avoid that mistake. We explain what to check in our guides to choosing phytoplankton and chlorella supplements.

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 Nannochloropsis, Chlorella, and algae-derived DHA oil. We have a commercial interest in these species. Nutrient profile summaries reflect published compositional analyses. Spirulina's classification as a cyanobacterium reflects standard taxonomy. Haematococcus is included for completeness; Phytality does not currently manufacture astaxanthin products. No EFSA-authorised health claims are cited in this article.

Last reviewed: March 2026