How to Choose a Chlorella Supplement

Chlorella is one of the most widely sold algae supplements in the world, which means the quality range is enormous. You can find broken-cell-wall chlorella grown in controlled environments with batch-specific testing, and you can find whole-cell chlorella from unspecified origins with no testing documentation at all. Both will say "chlorella" on the front label. The difference is in the details you need to check yourself.

Check the Cell Wall Processing

This is the most practical quality filter for chlorella specifically. Chlorella has a tough cellulose cell wall that your digestive system cannot break down efficiently. If the cell wall is intact, much of the nutrient content passes through you unabsorbed.

"Broken cell wall" or "cracked cell wall" processing is the standard solution. It mechanically disrupts the cell wall to make the nutrients accessible. This is not a premium feature. It is a baseline requirement for a chlorella supplement that works as intended. If the label does not mention cell wall processing, the product may deliver less than its nutritional panel suggests.

Check the Species

The two main species in commercial chlorella supplements are Chlorella vulgaris and Chlorella pyrenoidosa. Both are genuine chlorella with broadly similar nutrient profiles, but they differ in some specifics (cell wall thickness, growth rate, and minor compositional variations). Most published research uses C. vulgaris.

If the label says only "chlorella" without a species name, you cannot verify which organism you are getting. This matters less than it does for marine phytoplankton (where species determines the fatty acid profile), but it is still a transparency marker worth noting.

Check the Growing Conditions

Chlorella is grown in open ponds, closed photobioreactors, and hybrid systems. The same cultivation method considerations that apply to marine phytoplankton apply here: open ponds introduce environmental exposure risks, while closed systems control for contamination at the point of production.

A significant proportion of the world's chlorella is produced in open-pond facilities in East and Southeast Asia. This does not automatically mean it is contaminated, but it means the purity depends on the specific location, water source, and testing regime. If the product does not disclose where and how the chlorella was grown, you are trusting the label without evidence.

Fermented Chlorella Broken-cell-wall fermented chlorella. 60% protein, high chlorophyll, tested for heavy metals. From £18.95

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Check the Heavy Metal Testing

Chlorella is the algae supplement most frequently discussed in the context of heavy metal contamination, for good reason. Algae are efficient accumulators of whatever is in their growing environment, and chlorella's widespread open-pond cultivation creates more environmental exposure pathways than controlled systems.

Look for third-party testing covering lead, cadmium, arsenic, and mercury. The results should be batch-specific and from an independent laboratory. "Tested for purity" as a label claim without accessible documentation is insufficient for this product category. We test every batch of our chlorella products and consider this non-negotiable.

Check the Dose and Nutrient Panel

Chlorella supplements vary widely in serving size, from 1 gram to 10 grams daily. At 3 to 5 grams, you get a meaningful broad-spectrum micronutrient contribution. Below 2 grams, the nutrient delivery becomes marginal for most components.

The nutrients to check on the panel are protein (should be 50 to 60% of the powder weight), iron, chlorophyll, and B vitamins. If the product claims B12 content, be aware of the pseudocobalamin caveat: some strains produce a form of B12 the body cannot reliably use. A dedicated B12 supplement remains more reliable if B12 is your priority.

What to Be Sceptical About

"Detoxification" remains chlorella's most common marketing claim and the one with the least regulatory support. No EFSA-authorised health claim exists for chlorella as a detoxification agent. If a product leads with detox claims, its marketing has outrun its evidence. We explain our approach in our article on how we evaluate health claims.

Be equally cautious of products claiming "organic" chlorella without specifying what organic certification means in the context of aquaculture. Organic standards for algae cultivation are not as well-established as for terrestrial agriculture, and the label may mean less than you assume.

Tablets vs Powder

Chlorella comes in tablets and powder. Tablets are convenient and tasteless but often contain binding agents. Powder is more versatile (mix into smoothies, water, or food) and typically free of additives, but the taste is distinctly green and earthy. Neither format is inherently better. Choose based on how you will actually use it consistently.

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 fermented chlorella. Quality criteria in this article are based on published regulatory standards and nutrition science, not brand preference. Where we reference our own testing practices, this is disclosed. All evaluative statements represent our editorial judgement.

Last reviewed: March 2026

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