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.

    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]

    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