Chlorella Nutrient Profile

Chlorella is approximately 60% protein by dry weight, which is exceptionally high among plant foods — comparable to defatted soybean flour and considerably higher than beef or chicken on a dry-weight basis. More importantly, the chlorella amino acid profile is complete: all nine essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine) are present in proportions that meet the FAO/WHO reference amino acid pattern. Chlorella is also dense in chlorophyll (1-3% by dry weight, the highest of any commonly consumed plant), in mixed carotenoids led by beta-carotene, and in iron. The most contentious area of chlorella nutrition is its vitamin B12 content: chlorella does contain B12-like compounds, but the dominant fraction in most samples is pseudovitamin B12 — an inactive analog that does not satisfy human B12 requirements and may actually block uptake of authentic B12 from other sources. Vegans should not rely on chlorella for B12.

Table of Contents

1. 60% Protein by Dry Weight — The Headline Number
2. Complete Amino Acid Profile — All Nine Essentials
3. Chlorophyll — The Densest Natural Source
4. Beta-Carotene and Mixed Carotenoids
5. Iron — Bioavailability and the Anemia Use Case
6. The B12-Analog Controversy — Pseudovitamin B12
7. Other Vitamins (B-Complex, K1, Folate)
8. Other Minerals (Magnesium, Potassium, Zinc, Selenium)
9. Omega-3 Fatty Acids (Alpha-Linolenic Acid)
10. Nucleic Acid Content and the Purine / Gout Caution
11. Chlorella vulgaris vs Chlorella pyrenoidosa
12. Key Research Papers
13. Connections

60% Protein by Dry Weight — The Headline Number

The most-cited nutritional headline for chlorella is its protein content: approximately 50-65% protein by dry weight, depending on the species (vulgaris vs pyrenoidosa), the strain, and the growing conditions. The midpoint commonly quoted is 60%. For comparison:

The practical caveat: nobody eats chlorella as a primary protein source. A daily 3-5 g chlorella supplement supplies 1.8-3 g of protein — a small fraction of the 50-150 g typical adult protein requirement. The protein content is nutritionally interesting for two reasons that are not "daily protein intake":

1. Quality of the amino acid profile — the 3 g of chlorella protein supplied per day is high-quality complete protein, supplying small but well-balanced amounts of all nine essential amino acids. This is more notable for vegetarians and vegans rounding out an otherwise plant-restricted profile than for omnivores already getting complete protein from animal sources.
2. The historical context — the Japanese Tamiya project of the 1950s was specifically aimed at chlorella as a scalable protein source for postwar food security. The protein content is why governments and the Rockefeller Foundation funded the work. The transition from "chlorella as staple food" to "chlorella as supplement" happened in the 1970s once it became clear that the taste and the cell-wall digestibility problem made staple-food use impractical.

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Complete Amino Acid Profile — All Nine Essentials

The amino acid composition of chlorella is the property that elevates it from "high protein" to "high-quality protein." All nine essential amino acids are present:

Chlorella exceeds the FAO/WHO essential amino acid reference for every required amino acid — the technical definition of a "complete protein." Notably, chlorella is high in lysine (often limiting in cereal grains) and adequate in methionine + cysteine (often limiting in legumes), which makes it complementary to both grain-based and legume-based vegetarian diets. The branched-chain amino acid (BCAA: leucine, isoleucine, valine) content is exceptionally high, on par with whey protein, which is the biochemical basis for the muscle-recovery and muscle-protein-synthesis claims occasionally made for chlorella in athletic populations.

The non-essential amino acid profile is also useful nutritionally:

• Glutamine and glutamate — substrates for hepatic glutathione synthesis and gut enterocyte energy metabolism
• Glycine — second component of glutathione, also substrate for collagen synthesis
• Arginine — substrate for nitric oxide synthesis and immune cell function
• Alanine — gluconeogenic substrate and ammonia transport carrier
• Proline — collagen synthesis substrate

For the broader essential amino acid context, see our Amino Acids index.

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Chlorophyll — The Densest Natural Source

Chlorella derives its name from the Greek chloros ("green") because its chlorophyll content is exceptionally dense — approximately 1-3% by dry weight, the highest of any commonly consumed plant or algae. For comparison, fresh spinach is approximately 0.05% chlorophyll by wet weight, parsley about 0.1%, and most green vegetables in the 0.01-0.1% range. A 3 g chlorella dose delivers approximately 30-90 mg of chlorophyll, comparable to the doses used in formal chlorophyll-intervention trials.

Chlorophyll itself is the green photosynthetic pigment, structurally a porphyrin ring with a central magnesium atom. The molecule has several relevant biological effects:

• Aflatoxin and mycotoxin binding — the planar porphyrin ring binds aflatoxin, polycyclic aromatic hydrocarbons, and heterocyclic amines via pi-pi stacking interactions, preventing absorption from the gut. The Egner Qidong trial used 100 mg chlorophyllin three times daily and reduced urinary aflatoxin-DNA adducts by 55% in a high-exposure Chinese population.
• Mild antioxidant activity — chlorophyll scavenges hydroxyl radicals and singlet oxygen, contributing to gut and serum antioxidant capacity
• Magnesium delivery — the central magnesium atom contributes a small amount of bioavailable magnesium upon chlorophyll digestion
• Wound-healing and odor-reducing applications — topical chlorophyllin has been used as a wound-deodorizing agent and as part of pressure-ulcer treatment
• Gut transit effects — high chlorophyll intake can produce a green tint to the stool, which is benign but visually noticeable to first-time chlorella users

The conversion of dietary chlorophyll to chlorophyllin (the more water-soluble form used in most cancer-prevention trials) occurs during digestion as the magnesium is displaced and the phytol tail is cleaved. Both forms have biological activity, though chlorophyllin is the better-characterized intervention molecule.

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Beta-Carotene and Mixed Carotenoids

Chlorella contains significant amounts of beta-carotene (the same provitamin A carotenoid found in carrots, sweet potatoes, and dark leafy greens), plus lutein, zeaxanthin, alpha-carotene, and several other carotenoids in smaller amounts. The total carotenoid content of dried chlorella is approximately 0.1-0.4% by weight, varying by species and growing conditions.

The biological relevance:

• Provitamin A activity — beta-carotene is cleaved in the gut by BCMO1 (beta-carotene-15,15'-monooxygenase) to two molecules of retinal, which can be reduced to retinol (the active form of vitamin A). The conversion is regulated by retinol status, so vitamin A toxicity from chlorella beta-carotene is essentially impossible.
• Macular protective effect of lutein and zeaxanthin — these two carotenoids are concentrated in the macula of the eye and contribute to filtering blue light and reducing macular degeneration risk (the AREDS2 trial substituted lutein and zeaxanthin for beta-carotene in the macular protective formulation).
• Antioxidant activity — all carotenoids are lipid-soluble antioxidants, scavenging singlet oxygen and lipid peroxyl radicals
• Cellular communication — some carotenoids modulate gap junction communication between cells, a mechanism relevant to tumor suppression

The chlorella carotenoid content is one of the legitimate "superfood" claims for the algae — it supplies a mixed carotenoid spectrum more typical of dark leafy greens than of single-source supplements. For the broader vitamin A and beta-carotene discussion, see our Beta-Carotene vs Preformed Retinol page.

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Iron — Bioavailability and the Anemia Use Case

Chlorella contains approximately 130-150 mg of iron per 100 g dry weight — a remarkably high concentration that makes it one of the densest plant-source iron foods. A 3-5 g daily chlorella dose supplies approximately 4-7 mg of iron, a substantial fraction of the daily requirement (8 mg/day for adult men, 18 mg/day for menstruating women).

The clinically interesting question is bioavailability. Plant-source iron (non-heme iron) is generally less bioavailable than animal-source heme iron, but chlorella iron has been reported in several Japanese studies to have unusually high absorption — perhaps because of co-presence with vitamin C and other carotenoids that enhance non-heme iron absorption, perhaps because the cellular packaging of chlorella iron in a chlorophyll-rich matrix mimics aspects of heme structure. The Nakano 2010 pregnant-women trial documented reduced anemia rates in chlorella-supplemented pregnant women, providing real-world clinical evidence that the iron is bioavailable enough to make a measurable difference in iron status.

Practical recommendations:

• Chlorella is a reasonable iron-supportive nutrient for menstruating women and vegetarians/vegans who often run low on iron stores
• It is not a substitute for ferrous sulfate or other prescription-strength iron in iron-deficiency anemia, where doses of 60-200 mg elemental iron per day are typically needed
• Chlorella iron does not produce the GI distress (constipation, nausea, dark stools) common with ferrous sulfate, which may make it useful as an ongoing maintenance supplement after iron repletion
• The chlorella iron load is small enough that hereditary hemochromatosis patients can use chlorella without concern about iron overload

For more on iron and anemia, see our Iron page.

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The B12-Analog Controversy — Pseudovitamin B12

The vitamin B12 content of chlorella is the most contentious area of its nutritional profile, and one where popular marketing claims diverge sharply from the scientific reality.

The marketing claim: "Chlorella is a rich vegan source of B12, with concentrations of 100-300 mcg per 100 g dry weight." This is technically true as a measurement of total corrinoid compounds (the chemical family that includes B12 and its analogs) detected by typical assays.

The scientific reality, established primarily by the Watanabe group at Tottori University in Japan over many years of research: most of the corrinoid in chlorella (and in spirulina, and in most algae) is pseudovitamin B12 — an inactive analog that does not satisfy human B12 requirements. The active form of B12 (adenosylcobalamin, methylcobalamin, or the dietary precursors cyanocobalamin and hydroxocobalamin) is present in much smaller amounts and is variably contaminated by the inactive analogs. The inactive pseudovitamin B12 not only fails to satisfy human B12 needs, it can compete with authentic B12 for intrinsic factor binding and intestinal absorption, potentially worsening B12 status in someone who relies on chlorella as their primary B12 source.

Important caveats:

• Some samples of chlorella (especially certain strains and growing conditions) contain higher fractions of active B12 than others. The Yaeyama Chlorella research group has demonstrated that their broken-cell-wall product contains a meaningful fraction of authentic methylcobalamin and adenosylcobalamin alongside the pseudovitamin component.
• The Watanabe 2014 Nutrients review (cited below) is the most-cited summary of the topic and the most authoritative assessment of which algae/plant sources can or cannot be relied upon for vegan B12
• Spirulina is generally regarded as worse than chlorella for B12 reliability — the spirulina pseudovitamin fraction is even higher and the active fraction lower
• Nori (the dried seaweed used in sushi) does contain meaningful authentic B12 and is a more reliable plant-source option, though the amount per serving is small

The bottom line for vegans: do not rely on chlorella as your sole B12 source. Use a cyanocobalamin or methylcobalamin supplement (typical dose: 1000 mcg orally several times per week, or 25-100 mcg daily) and use chlorella for its other nutritional and detoxification benefits. Periodic serum B12 + methylmalonic acid + homocysteine testing is the responsible way to monitor B12 status in any vegan or vegetarian. For more on B12 specifically, see our Vitamin B12 page.

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Other Vitamins (B-Complex, K1, Folate)

Beyond the contentious B12 question, chlorella supplies measurable amounts of several B vitamins and other water-soluble micronutrients:

• Folate — approximately 100-150 mcg per 100 g dry weight, supplying 3-7 mcg per typical 3-5 g daily dose. Useful supplementary intake but not a major folate source.
• Niacin (B3) — approximately 20-25 mg per 100 g dry weight, a small but meaningful contribution to daily intake
• Riboflavin (B2) — approximately 4-5 mg per 100 g dry weight, contributing to flavin cofactor pools for redox enzymes
• Pyridoxine (B6) — approximately 1-1.5 mg per 100 g dry weight, a modest contribution
• Vitamin K1 — chlorella is chlorophyll-rich, and chlorophyll is biosynthetically related to phylloquinone (K1). The K1 content is significant enough to interact with warfarin (clinical caution noted earlier) and to make a meaningful contribution to daily vitamin K intake
• Pantothenic acid (B5), thiamine (B1), biotin (B7) — present in small but measurable amounts
• Vitamin E — modest amounts of mixed tocopherols (alpha and gamma)
• Vitamin C — low to moderate amounts; chlorella is not a primary vitamin C source

The aggregate effect is that chlorella functions as a modest broad-spectrum multivitamin in addition to its specific functional roles. It is not a substitute for a dedicated multivitamin in someone with frank deficiency, but it adds a measurable nutritional floor to the diet.

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Other Minerals (Magnesium, Potassium, Zinc, Selenium)

Beyond the heavy iron content discussed above, chlorella supplies a mineral profile typical of green leafy plants:

• Magnesium — approximately 300-350 mg per 100 g dry weight, derived in part from the chlorophyll central atoms. A 3-5 g daily dose supplies 9-18 mg magnesium, a modest contribution.
• Potassium — approximately 1000-1500 mg per 100 g dry weight
• Calcium — approximately 200-400 mg per 100 g dry weight
• Phosphorus — approximately 800-1200 mg per 100 g dry weight
• Zinc — approximately 70 mg per 100 g dry weight, exceptionally high. A 5 g daily dose supplies approximately 3.5 mg zinc, a meaningful fraction of daily intake (RDA: 8-11 mg).
• Selenium — variable depending on growing-water selenium content. Some Japanese and Taiwanese chlorella products are deliberately enriched with selenium to supply pharmacologically active doses (100-200 mcg per dose) for thyroid and antioxidant support.
• Iodine — small amounts; chlorella is not a major iodine source and should not substitute for sea vegetables or supplements in iodine-deficient diets
• Manganese, copper — trace amounts

The mineral profile is broadly aligned with what one would expect from a dense plant-source food — high in the minerals that plants accumulate efficiently (magnesium, potassium, iron, zinc), low in the minerals that plants accumulate poorly (iodine, sodium).

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Omega-3 Fatty Acids (Alpha-Linolenic Acid)

Chlorella contains a modest amount of omega-3 fatty acids, predominantly alpha-linolenic acid (ALA), the 18-carbon plant-source omega-3. Total ALA content is approximately 0.5-1 g per 100 g dry weight, so a 5 g daily dose supplies roughly 25-50 mg ALA — a small contribution to the recommended 1-2 g/day plant-source omega-3 intake.

Chlorella is not a meaningful source of the longer-chain marine omega-3s EPA and DHA. Some chlorella products contain trace EPA/DHA, but the amounts are too small to be nutritionally significant. For EPA/DHA, the canonical sources remain fish, fish oil, or microalgae-derived EPA/DHA products (Schizochytrium or Crypthecodinium — not chlorella).

The ALA-to-EPA conversion efficiency in humans is poor (typically 5-10%) and the ALA-to-DHA conversion is even worse (1-5%), so ALA cannot fully substitute for direct EPA/DHA intake. Chlorella ALA is best viewed as a small contribution to the omega-3 background, not as a primary intervention. For more, see our Omega-3 Fatty Acids page.

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Nucleic Acid Content and the Purine / Gout Caution

Chlorella is approximately 4-5% nucleic acids (DNA and RNA) by dry weight — very high, reflecting the algae's rapid cell-division rate. While nucleic acids are a normal dietary constituent, very high intake can elevate serum uric acid through purine metabolism. Each gram of nucleic acid yields approximately 250 mg of purines, which the liver metabolizes to uric acid. A 5 g daily chlorella dose contributes approximately 60 mg of purine nitrogen — modest compared to a serving of organ meats or anchovies but non-trivial for someone with gout, hyperuricemia, or kidney stone history.

Practical implications:

• Healthy adults without uric acid concerns: chlorella nucleic acid is harmless and may even contribute beneficially as nucleotide substrate for cellular regeneration (the basis of the CGF concept)
• Patients with gout, hyperuricemia, or recurrent uric acid kidney stones: limit chlorella to 1-2 g/day, or substitute with spirulina (lower nucleic acid content), or avoid algal supplements entirely
• Patients on uric-acid-lowering medication (allopurinol, febuxostat): chlorella is generally compatible but worth monitoring serum uric acid after introducing it

The Chlorella Growth Factor (CGF) extract is even higher in nucleic acid content than whole chlorella because the manufacturing process concentrates the cell-interior contents. CGF-fortified products should be used cautiously by gout patients.

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Chlorella vulgaris vs Chlorella pyrenoidosa

The two species most commonly sold as "chlorella" are Chlorella vulgaris and Chlorella pyrenoidosa (the latter has been taxonomically reclassified by some workers as Auxenochlorella pyrenoidosa or as a member of Parachlorella, but is still sold under the pyrenoidosa name commercially).

The differences are modest but real:

The practical reading: both species produce essentially the same clinical effects when sold as broken-cell-wall preparations from quality suppliers. C. pyrenoidosa has marginally higher chlorophyll and CGF content and is the species used in most of the Japanese clinical research literature, which makes it the slightly preferred choice when the supplemental purpose aligns specifically with the published research applications (heavy-metal chelation, detoxification, immune support). C. vulgaris is interchangeable for most general-purpose use cases and is often somewhat less expensive.

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Key Research Papers

1. Watanabe F et al. (2014). Vitamin B12-containing plant food sources for vegetarians. Nutrients. — PubMed
2. Kanazawa K et al. (1995). Studies on availability of vitamin B12 from algal food sources. Journal of Nutritional Science and Vitaminology. (Pseudovitamin B12 documentation in spirulina and chlorella.) — PubMed
3. Becker EW (2007). Micro-algae as a source of protein. Biotechnology Advances. (Comprehensive review of algal protein, including chlorella.) — PubMed
4. Tokusoglu O, Unal MK (2003). Biomass nutrient profiles of three microalgae: Spirulina platensis, Chlorella vulgaris, and Isochrysis galbana. Journal of Food Science. — PubMed
5. Henrikson R (2009). Earth Food Spirulina (Spirulina and chlorella comparative nutrition reference). — PubMed
6. Panahi Y et al. (2016). A randomized controlled trial of chlorella on metabolic parameters and inflammatory markers in NAFLD patients. Journal of Dietary Supplements. — PubMed
7. Egner PA et al. (2001). Chlorophyllin intervention reduces aflatoxin-DNA adducts in individuals at high risk for liver cancer. PNAS. (Chlorophyll bioactivity reference.) — PubMed
8. Bito T et al. (2016). Bioactive compounds of edible purple laver Porphyra sp. (Nori), and active vitamin B12 reference. Bioscience, Biotechnology, and Biochemistry. — PubMed
9. Day AG et al. (2009). Safety evaluation of a high lipid content algae, Chlorella protothecoides. Regulatory Toxicology and Pharmacology. — PubMed
10. Lordan S et al. (2011). Marine bioactives as functional food ingredients: potential to reduce the incidence of chronic diseases. Marine Drugs. — PubMed
11. Safi C et al. (2014). Morphology, composition, production, processing and applications of Chlorella vulgaris: A review. Renewable and Sustainable Energy Reviews. (Comprehensive technical review of C. vulgaris.) — PubMed
12. Merchant RE, Andre CA (2001). A review of recent clinical trials of the nutritional supplement Chlorella pyrenoidosa in the treatment of fibromyalgia, hypertension, and ulcerative colitis. Alternative Therapies in Health and Medicine. — PubMed

PubMed Topic Searches

• PubMed: Chlorella protein and amino acids
• PubMed: Chlorella pseudovitamin B12
• PubMed: Chlorella chlorophyll and aflatoxin
• PubMed: Chlorella iron bioavailability
• PubMed: Chlorella nucleic acid and gout

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Connections

• Chlorella Overview
• Chlorella Benefits Hub
• Chlorella for Heavy Metal Chelation
• Chlorella for Detoxification
• Chlorella for Immune Function
• Spirulina
• Vitamin B12
• Beta-Carotene vs Preformed Retinol
• Iron
• Magnesium
• Zinc
• Selenium
• All Amino Acids
• Leucine
• Lysine
• Omega-3 Fatty Acids

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