Chlorella

    Researchedby:
    Brady Holmer

    Fact-checked

    by:

    Nick Milazzo
    Last Updated: March 19, 2024

    Chlorella is a freshwater green alga commonly used as a plant-based source of vitamin B12 for vegans and vegetarians. It’s a rich source of micronutrients and may have benefits for cardiometabolic health, immune function, pregnancy, and exercise performance.

    examine-databaseExamine Database

    Chlorella is most often used for Immunity & Infectious Disease. The Examine Database covers Nonalcoholic Fatty Liver Disease, High Blood Pressure, and 11 other conditions and goals.

    34 references on this page
    2,689 participants in 6 trials and 5 meta-analyses

    What is chlorella?

    Chlorella is a green microalga that is primarily composed of protein (up to 60% of its dry weight), including all of the essential and nonessential amino acids, with the most abundant of these being glutamate, leucine, aspartate, and lysine. Chlorella also contains fatty acids — mostly alpha-linolenic acid and linoleic acid — and carbohydrates, most of which are polysaccharides (dietary fibers), including alpha-glucans and beta-glucans.[3]

    Chlorella is also a rich source of micronutrients, including the minerals sodium, potassium, iron, calcium, magnesium, and zinc; vitamins A, C, E, K1 and the B vitamins (notably vitamin B12); and carotenoids, including astaxanthin, zeaxanthin, beta-carotene, and lutein. Because chlorella is a rich source of vitamin B12, it’s often consumed as a plant-based source of this nutrient by vegans and vegetarians.

    What’s the difference between chlorella and spirulina?

    What are chlorella’s main benefits?

    Although the evidence in humans is somewhat limited, chlorella appears to reduce blood pressure[4] and enhance immune system function.[5] For pregnant women, chlorella supplementation is well-tolerated, may reduce the risk of pregnancy-associated anemia, is associated with less leg edema, and increases levels of immunoglobulin A in breast milk.[6][7]

    Chlorella has synergistic effects with exercise on body composition and metabolic health.[8][9] It also may be ergogenic, improving maximal and submaximal exercise performance in healthy adults, adults with overweight/obesity, and trained athletes.[10][11][12]

    Should vegans and vegetarians supplement with chlorella?

    Does chlorella improve exercise performance?

    What are chlorella’s main drawbacks?

    Because chlorella contains a cellulose cell wall (unlike spirulina), it must undergo mechanical processing to break down these cell walls before human consumption to avoid gastrointestinal side effects like nausea, vomiting, and stomach pain.[13] Furthermore, some studies have confirmed that chlorella is an allergen, so some individuals (notably children) may be sensitive to it or want to avoid its consumption.[14]

    How does chlorella work?

    Supplementing with chlorella reduces oxidative stress and increases the activity of enzymatic and non-enzymatic antioxidants in rats[15] and increases antioxidant activity (by increasing levels of catalase and superoxide dismutase) in male smokers.[16] In humans, chlorella has notable antilipidemic, antihypertensive, and antihyperglycemic effects — it reduces total and LDL cholesterol, systolic and diastolic blood pressure, and blood glucose.[17][18]

    The blood-glucose-lowering effects of chlorella may be due to its ability to improve insulin sensitivity and glucose uptake in the liver and skeletal muscles;[19][20] these effects may be more potent when chlorella is combined with exercise training.[21] Certain constituents of chlorella bind to digested dietary fat, increase the scavenging of LDL cholesterol, and reduce the absorption of sterols in the intestine, explaining chlorella’s cholesterol-lowering effects.[22][23][24]

    Chlorella has exhibited detoxifying effects. It inhibited the intestinal absorption of dioxins (environmental contaminants and pollutants) in animal models and the absorption of heterocyclic amines in humans.[25] Chlorella also reduced mercury levels in the hair and blood of healthy adults.[26][27]

    What are other names for Chlorella

    Note that Chlorella is also known as:
    • Chlorella pyrenoidosa
    • Chlorella vulgaris
    • Chlorella sorokiniana
    • Green algae

    Dosage information

    In the scientific literature, the total daily dose of chlorella ranges from 6 to 10 grams per day. Although there aren’t clear reasons for this range, it appears to be somewhat effective. Higher doses have not been sufficiently tested, and the optimal dose of supplemental chlorella is not known.

    For exercise performance, most studies use a dose of 6 grams per day for 3–4 weeks, although emerging research suggests that even a single acute dose (6 grams) of chlorella increases plasma levels of lutein, beta-carotene, and zeaxanthin for up to 72 hours.[1]

    Doses of up to 10–15 grams per day appear to be safe. Cardiovascular benefits have been observed with 4 grams per day, and more than 1.5 grams per day seems to be necessary to benefit glycemic control in type 2 diabetes.[2]

    Examine Database: Chlorella

    Research FeedRead all studies

    Frequently asked questions

    What is chlorella?

    Chlorella is a green microalga that is primarily composed of protein (up to 60% of its dry weight), including all of the essential and nonessential amino acids, with the most abundant of these being glutamate, leucine, aspartate, and lysine. Chlorella also contains fatty acids — mostly alpha-linolenic acid and linoleic acid — and carbohydrates, most of which are polysaccharides (dietary fibers), including alpha-glucans and beta-glucans.[3]

    Chlorella is also a rich source of micronutrients, including the minerals sodium, potassium, iron, calcium, magnesium, and zinc; vitamins A, C, E, K1 and the B vitamins (notably vitamin B12); and carotenoids, including astaxanthin, zeaxanthin, beta-carotene, and lutein. Because chlorella is a rich source of vitamin B12, it’s often consumed as a plant-based source of this nutrient by vegans and vegetarians.

    What’s the difference between chlorella and spirulina?

    Chlorella is a single-cell green alga that lives in freshwater, while spirulina, despite its common name of “blue-green algae”, is a genus of cyanobacteria that forms filamentous, multicellular colonies in saltwater. The nutrient profiles of chlorella and spirulina are quite similar — both contain carbohydrates, protein, folate, riboflavin, thiamine, iron, and polyunsaturated fatty acids, though chlorella contains more omega-3 fatty acids while spirulina is higher in omega-6 fatty acids. Spirulina also contains copper, which is absent from chlorella. Chlorella has higher levels of vitamin A, iron, magnesium, niacinamide, and phosphorus compared to spirulina.[3][32] Finally, while chlorella supplements are a good source of vitamin B12, the B12 in spirulina supplements is often biologically-inactive pseudovitamin B12.[29]

    One key difference between these two microalgae is the way they’re produced: as a cyanobacterium, spirulina lacks a cellulose cell wall, and once it’s harvested and dried, it’s ready for consumption. This characteristic also improves spirulina’s bioavailability.[33] On the other hand, chlorella in its natural form does contain a cellulose cell wall, which must be broken down mechanically to make chlorella fit for human consumption.[34]

    What are chlorella’s main benefits?

    Although the evidence in humans is somewhat limited, chlorella appears to reduce blood pressure[4] and enhance immune system function.[5] For pregnant women, chlorella supplementation is well-tolerated, may reduce the risk of pregnancy-associated anemia, is associated with less leg edema, and increases levels of immunoglobulin A in breast milk.[6][7]

    Chlorella has synergistic effects with exercise on body composition and metabolic health.[8][9] It also may be ergogenic, improving maximal and submaximal exercise performance in healthy adults, adults with overweight/obesity, and trained athletes.[10][11][12]

    Should vegans and vegetarians supplement with chlorella?

    Diets that exclude meat are associated with lower intakes of several B vitamins, including B2 (riboflavin), B3 (niacin), and B12 (cyanocobalamin). Notably, chlorella is a good source of vitamin B12 and may contain up to 400 micrograms of B12 per 100 grams of chlorella, depending on the source and the growing conditions; to put this in context, 400 micrograms of vitamin B12 is almost 200% of the recommended daily amount of B12 for adults.[3] For this reason, chlorella is often consumed as a plant-based source of vitamin B12 (and other B vitamins) by vegans and vegetarians.

    Vegans with a vitamin B12 deficiency who supplemented with 9 grams of chlorella per day for 60 days reduced their levels of serum methylmalonic acid (an index of B12 deficiency) and homocysteine and increased their serum B12.[28]. In one cross-sectional study, vegans who reported consuming chlorella and/or nori (seaweed sheets made from a type of purple algae that also contains vitamin B12)[29] had serum levels of vitamin B12 almost twice as high as those not consuming these foods.[30]

    Does chlorella improve exercise performance?

    Several components of chlorella — essential and non-essential amino acids, fatty acids, pigments, vitamins, and minerals — make it attractive as an ergogenic aid for sports and exercise. Unfortunately, it’s hard to know which components of chlorella might be responsible for its exercise-related benefits.

    A few studies have noted that a chlorella-derived supplement increased maximal oxygen consumption (i.e., VO2max or VO2peak) after 4 weeks.[10][11] In trained cyclists, 21 days of chlorella supplementation (6 grams per day) reduced their heart rate and blood lactate levels during a 1-hour submaximal cycling test and increased their average peak power during a set of short sprints. Hemoglobin — the oxygen-carrying protein in our blood — also increased after chlorella supplementation.[12] Supplementing with chlorella (1.2 grams per day) for 7 days also reduced the inflammatory response and improved insulin sensitivity after eccentric exercise (downhill running).[31]

    Combining chlorella with exercise may also have benefits for reducing blood glucose and improving insulin sensitivity,[21] as well as reducing waist circumference, visceral fat, total fat mass, and markers of atherosclerosis in women with overweight and obesity.[8][12]

    What are chlorella’s main drawbacks?

    Because chlorella contains a cellulose cell wall (unlike spirulina), it must undergo mechanical processing to break down these cell walls before human consumption to avoid gastrointestinal side effects like nausea, vomiting, and stomach pain.[13] Furthermore, some studies have confirmed that chlorella is an allergen, so some individuals (notably children) may be sensitive to it or want to avoid its consumption.[14]

    How does chlorella work?

    Supplementing with chlorella reduces oxidative stress and increases the activity of enzymatic and non-enzymatic antioxidants in rats[15] and increases antioxidant activity (by increasing levels of catalase and superoxide dismutase) in male smokers.[16] In humans, chlorella has notable antilipidemic, antihypertensive, and antihyperglycemic effects — it reduces total and LDL cholesterol, systolic and diastolic blood pressure, and blood glucose.[17][18]

    The blood-glucose-lowering effects of chlorella may be due to its ability to improve insulin sensitivity and glucose uptake in the liver and skeletal muscles;[19][20] these effects may be more potent when chlorella is combined with exercise training.[21] Certain constituents of chlorella bind to digested dietary fat, increase the scavenging of LDL cholesterol, and reduce the absorption of sterols in the intestine, explaining chlorella’s cholesterol-lowering effects.[22][23][24]

    Chlorella has exhibited detoxifying effects. It inhibited the intestinal absorption of dioxins (environmental contaminants and pollutants) in animal models and the absorption of heterocyclic amines in humans.[25] Chlorella also reduced mercury levels in the hair and blood of healthy adults.[26][27]

    Update History

    References

    1. ^Serra AT, Silva SD, Pleno de Gouveia L, Alexandre AMRC, Pereira CV, Pereira AB, Partidário AC, Silva NE, Bohn T, Gonçalves VSS, Real G, Escudero P, Fernández N, Matias AA, Bronze MRA Single Dose of Marine Increases Plasma Concentrations of Lutein, β-Carotene and Zeaxanthin in Healthy Male Volunteers.Antioxidants (Basel).(2021-Jul-22)
    2. ^Amir Mehdi Hosseini, Seyed Ali Keshavarz, Ensieh Nasli-Esfahani, Fatemehsadat Amiri, Leila JananiThe effects of Chlorella supplementation on glycemic control, lipid profile and anthropometric measures on patients with type 2 diabetes mellitusEur J Nutr.(2021 Feb 2)
    3. ^Bito T, Okumura E, Fujishima M, Watanabe FPotential of as a Dietary Supplement to Promote Human Health.Nutrients.(2020-Aug-20)
    4. ^Shimada M, Hasegawa T, Nishimura C, Kan H, Kanno T, Nakamura T, Matsubayashi TAnti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens.(2009 Jun)
    5. ^Otsuki T, Shimizu K, Iemitsu M, Kono ISalivary secretory immunoglobulin A secretion increases after 4-weeks ingestion of chlorella-derived multicomponent supplement in humans: a randomized cross over studyNutr J.(2011 Sep 9)
    6. ^Shiro Nakano, Hideo Takekoshi, Masuo NakanoChlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant womenPlant Foods Hum Nutr.(2010 Mar)
    7. ^Nakashima Y, Ohsawa I, Konishi F, Hasegawa T, Kumamoto S, Suzuki Y, Ohta SPreventive effects of Chlorella on cognitive decline in age-dependent dementia model mice.Neurosci Lett.(2009-Oct-30)
    8. ^Sanayei M, Izadi A, Hajizadeh-Sharafabad F, Amirsasan R, Kaviani M, Barzegar Ain combination with high intensity interval training in overweight and obese women: a randomized double-blind clinical trial.J Diabetes Metab Disord.(2021-Jun)
    9. ^Sanayei M, Hajizadeh-Sharafabad F, Amirsasan R, Barzegar AHigh-intensity interval training with or without chlorella vulgaris supplementation in obese and overweight women: effects on mitochondrial biogenesis, performance and body composition.Br J Nutr.(2022-Jul-28)
    10. ^Umemoto S, Otsuki TChlorella-derived multicomponent supplementation increases aerobic endurance capacity in young individuals.J Clin Biochem Nutr.(2014-Sep)
    11. ^Zempo-Miyaki A, Maeda S, Otsuki TEffect of -derived multicomponent supplementation on maximal oxygen uptake and serum vitamin B concentration in young men.J Clin Biochem Nutr.(2017-Sep)
    12. ^Gurney T, Brouner J, Spendiff OThe Efficacy of Chlorella Supplementation on Multiple Indices of Cycling Performance.J Diet Suppl.(2024)
    13. ^Lorenzo K, Santocildes G, Torrella JR, Magalhães J, Pagès T, Viscor G, Torres JL, Ramos-Romero SBioactivity of Macronutrients from in Physical Exercise.Nutrients.(2023-Apr-30)
    14. ^Tiberg E, Dreborg S, Björkstén BAllergy to green algae (Chlorella) among children.J Allergy Clin Immunol.(1995-Aug)
    15. ^Vijayavel K, Anbuselvam C, Balasubramanian MPAntioxidant effect of the marine algae Chlorella vulgaris against naphthalene-induced oxidative stress in the albino rats.Mol Cell Biochem.(2007-Sep)
    16. ^Lee SH, Kang HJ, Lee HJ, Kang MH, Park YKSix-week supplementation with Chlorella has favorable impact on antioxidant status in Korean male smokersNutrition.(2010 Feb)
    17. ^Sherafati N, Bideshki MV, Behzadi M, Mobarak S, Asadi M, Sadeghi OEffect of supplementation with Chlorella vulgaris on lipid profile in adults: A systematic review and dose-response meta-analysis of randomized controlled trials.Complement Ther Med.(2022-Jun)
    18. ^Fallah AA, Sarmast E, Habibian Dehkordi S, Engardeh J, Mahmoodnia L, Khaledifar A, Jafari TEffect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trials.Clin Nutr.(2018-Dec)
    19. ^Jong-Yuh C, Mei-Fen SPotential hypoglycemic effects of Chlorella in streptozotocin-induced diabetic mice.Life Sci.(2005-Jul-15)
    20. ^Cherng JY, Shih MFImproving glycogenesis in Streptozocin (STZ) diabetic mice after administration of green algae Chlorella.Life Sci.(2006-Feb-09)
    21. ^Horii N, Hasegawa N, Fujie S, Uchida M, Iemitsu K, Inoue K, Iemitsu MEffect of combination of chlorella intake and aerobic exercise training on glycemic control in type 2 diabetic rats.Nutrition.(2019)
    22. ^Ryu NH, Lim Y, Park JE, Kim J, Kim JY, Kwon SW, Kwon OImpact of daily Chlorella consumption on serum lipid and carotenoid profiles in mildly hypercholesterolemic adults: a double-blinded, randomized, placebo-controlled study.Nutr J.(2014-Jun-11)
    23. ^Cherng JY, Shih MFPreventing dyslipidemia by Chlorella pyrenoidosa in rats and hamsters after chronic high fat diet treatment.Life Sci.(2005-May-13)
    24. ^Gurney T, Spendiff OAlgae Supplementation for Exercise Performance: Current Perspectives and Future Directions for Spirulina and Chlorella.Front Nutr.(2022)
    25. ^Morita K, Matsueda T, Iida T, Hasegawa TChlorella accelerates dioxin excretion in rats.J Nutr.(1999-Sep)
    26. ^Lee I, Tran M, Evans-Nguyen T, Stickle D, Kim S, Han J, Park JY, Yang MDetoxification of chlorella supplement on heterocyclic amines in Korean young adults.Environ Toxicol Pharmacol.(2015-Jan)
    27. ^Maruyama et al.Chlorella supplementation decreases methylmercury concentrations of hair and blood in healthy volunteersFundamental Toxicological Sciences.(2018)
    28. ^Merchant RE, Phillips TW, Udani JNutritional Supplementation with Chlorella pyrenoidosa Lowers Serum Methylmalonic Acid in Vegans and Vegetarians with a Suspected Vitamin B₁₂ Deficiency.J Med Food.(2015-Dec)
    29. ^Watanabe F, Yabuta Y, Bito T, Teng FVitamin B₁₂-containing plant food sources for vegetarians.Nutrients.(2014-May-05)
    30. ^Rauma AL, Törrönen R, Hänninen O, Mykkänen HVitamin B-12 status of long-term adherents of a strict uncooked vegan diet ("living food diet") is compromisedJ Nutr.(1995 Oct)
    31. ^Samadi M et alEffect of Chlorella vulgaris supplementation with eccentric exercise on serum interleukin 6 and insulin resistance in overweight menSport Sci Health.(Jun 2020)
    32. ^FoodData Central
    33. ^de la Jara et al.Impact of dietary Arthrospira (Spirulina) biomass consumption on human health: main health targets and systematic reviewJ Appl Phycol.(May 2018)
    34. ^Chlorella and spirulina microalgae as sources of functional foods, nutraceuticals, and food supplements; an overviewMOJ Food Processing & Technology.(2018-01-19)

    Examine Database References

    1. Vaccine Augmentation - Halperin SA, Smith B, Nolan C, Shay J, Kralovec JSafety and immunoenhancing effect of a Chlorella-derived dietary supplement in healthy adults undergoing influenza vaccination: randomized, double-blind, placebo-controlled trialCMAJ.(2003 Jul 22)
    2. Immunity - Otsuki T, Shimizu K, Iemitsu M, Kono ISalivary secretory immunoglobulin A secretion increases after 4-weeks ingestion of chlorella-derived multicomponent supplement in humans: a randomized cross over studyNutr J.(2011 Sep 9)
    3. Blood Pressure - Shimada M, Hasegawa T, Nishimura C, Kan H, Kanno T, Nakamura T, Matsubayashi TAnti-hypertensive effect of gamma-aminobutyric acid (GABA)-rich Chlorella on high-normal blood pressure and borderline hypertension in placebo-controlled double blind studyClin Exp Hypertens.(2009 Jun)
    4. Blood Pressure - Ayatollahi SA, Asgary S, Ghanbari F, Karimi R, Kobarfard F, Sarfaraz S, Nazim U, Mohammadi Pour PQuantifying the Impact of Algae Supplement on Blood Pressure: Systematic Review and Meta-analysis of Randomized Controlled Trials.Curr Probl Cardiol.(2022-Nov)
    5. Blood Pressure - Fallah AA, Sarmast E, Habibian Dehkordi S, Engardeh J, Mahmoodnia L, Khaledifar A, Jafari TEffect of Chlorella supplementation on cardiovascular risk factors: A meta-analysis of randomized controlled trials.Clin Nutr.(2018-Dec)
    6. Anti-Oxidant Enzyme Profile - Lee SH, Kang HJ, Lee HJ, Kang MH, Park YKSix-week supplementation with Chlorella has favorable impact on antioxidant status in Korean male smokersNutrition.(2010 Feb)
    7. Anemia Risk - Shiro Nakano, Hideo Takekoshi, Masuo NakanoChlorella pyrenoidosa supplementation reduces the risk of anemia, proteinuria and edema in pregnant womenPlant Foods Hum Nutr.(2010 Mar)
    8. Fibromyalgia Symptoms - Merchant RE, Carmack CA, Wise CMNutritional supplementation with Chlorella pyrenoidosa for patients with fibromyalgia syndrome: a pilot studyPhytother Res.(2000 May)
    9. Fasting Glucose - Ding KX, Gao TL, Xu R, Cai J, Zhang HQ, Sun YY, Zhong F, Ma AGQuantifying the Effect of Supplementation with Algae and Its Extracts on Glycolipid Metabolism: A Meta-Analysis of Randomized Controlled Trials.Nutrients.(2020-Jun-08)
    10. High-density lipoprotein (HDL) - Sherafati N, Bideshki MV, Behzadi M, Mobarak S, Asadi M, Sadeghi OEffect of supplementation with Chlorella vulgaris on lipid profile in adults: A systematic review and dose-response meta-analysis of randomized controlled trials.Complement Ther Med.(2022-Jun)
    11. Liver Enzymes - Samira Yarmohammadi, Reza Hosseini-Ghatar, Sahar Foshati, Mojgan Moradi, Niloofar Hemati, Sajjad Moradi, Mohammad Ali Hojjati Kermani, Mohammad Hosein Farzaei, Haroon KhanEffect of Chlorella vulgaris on Liver Function Biomarkers: a Systematic Review and Meta-AnalysisClin Nutr Res.(2021 Jan 29)