Note: Non-Spirulina species, such as Anabaena species, Aphanizomenon species, and Microcystis species, are possibly unsafe because they are usually harvested naturally and may be contaminated. This bottom line includes information about multiple species of blue-green algae, though the focus is spirulina.
The term spirulina refers to a large number of blue-green algae. Both Spirulina and non-Spirulina species are classified as blue-green algae and include: Aphanizomenon spp., Microcystis spp., Nostoc spp., and Spirulina spp. Most commercial products contain Aphanizomenon flos-aquae, Sprirulina maxima, and/or Spirulina platensis. These algae are found in the warm waters of the world, especially in Mexico and central Africa.
Spirulina is different from other blue-green algae because it has a spiral structure. Spirulina spp. are most often grown under controlled conditions and are less likely to be contaminated, compared to naturally harvested non-spirulina species.
Blue-green algae have been used as a source of protein, but may have harmful effects. Spirulina is rich in nutrients and contains up to 70 percent protein, B-complex vitamins, beta-carotene, vitamin E, and numerous minerals. Spirulina has been found to contain more beta-carotene than carrots.
Spirulina has been used since ancient times. It is believed to be useful as an antioxidant, antiviral, anticancer, weight loss aid, and cholesterol-lowering agent.
Blue-green algae and spirulina are sold in health food stores and over the Internet as food supplements in Canada, the United States, and Europe. Possible health benefits include improved digestion, better immune function, and relief from the symptoms of attention deficit hyperactivity disorder (ADHD), allergies, and fatigue. Some of these products may contain harmful compounds and should be used with caution. Blue-green algae also contain compounds called C-phycocyanins, which are used in food and cosmetics, and are known for their antioxidant and therapeutic potential.
The blue-green algae Aphanizomenon flos-aquae is produced in the same location in southern Oregon as the blue-green algae, Microcystis aeruginosais, which may cause cancer or liver damage, and there is a risk of contamination.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Early human studies found that spirulina may be effective in lowering cholesterol and triglyceride levels. Spirulina may decrease levels of low-density lipoprotein (LDL or "bad") cholesterol, while increasing levels of high-density lipoprotein (HDL or "good") cholesterol. More research is needed to further confirm these findings.
Spirulina may have anti-inflammatory effects and may improve nasal allergy symptoms. Spirulina has also been studied for possible effects on the immune system. More high-quality research is needed before a firm conclusion can be made.
Spirulina has been studied in runners for possible antioxidant effects. However, further study is needed in this area before conclusions can be made.
Spirulina extract plus zinc may be useful for the treatment of arsenic poisoning. More research is needed to confirm these findings.
Spirulina treatment may improve symptoms of attention deficit hyperactivity disorder (ADHD). A combination product that includes spirulina has been found to benefit some ADHD symptoms. More study is needed before conclusions can be made on spirulina use for this condition.
Spirulina is thought to benefit the liver through ant-inflammatory and antioxidant effects. However, early research has found conflicting results on the use of spirulina for chronic viral hepatitis (liver inflammation). More high-quality research is needed before firm conclusions can be made.
Early study suggests that spirulina treatment may delay fatigue after a two-hour run. However, more research is needed in this area to confirm these results.
Super blue-green algae has been studied for twitches of the eyelids and face. However, early research has found mixed results. Further study is needed in this area.
Spirulina supplements have been studied in people with HIV. Early research also suggests that spirulina may decrease the risk of pneumonia infections and increase insulin sensitivity. However, more information is needed in this area before a firm conclusion can be made.
Selenium enriched with spirulina has been used to treat irritable bowel syndrome (IBS) and long-term colon inflammation. Although treatment showed an improvement in symptoms, higher-quality research is needed on the potential effects of spirulina alone.
Spirulina has been studied as a food supplement in infant malnutrition. However, results have been mixed. More research is needed in this area.
Klamath algae may improve some symptoms of menopause, including anxiety and depression. Further study is needed before a firm conclusion can be made.
Spirulina has been studied as a possible treatment for oral leukoplakia (plaques in the mouth that may indicate cancer) in people who use alcohol and tobacco. However, more human research is needed before firm conclusions can be made in this area.
Early study in people with type 2 diabetes has found that two months of taking spirulina by mouth may benefit blood sugar and cholesterol levels. Spirulina may also increase sensitivity to insulin. However, more research is needed before conclusions can be made on the use of spirulina for blood sugar control in diabetics.
Spirulina is a popular therapy for weight loss and is sometimes marketed as a "vitamin-enriched" agent that reduces appetite. However, strong evidence is lacking. More research is needed on the use of spirulina for human weight loss.
There is currently a lack of strong evidence to support the use of spirulina for chronic fatigue syndrome. Limited research suggests that spirulina may lack benefit over placebo for the treatment of chronic fatigue. More high-quality research is needed in this field.
* Key to grades
A: Strong scientific evidence for this use B: Good scientific evidence for this use C: Unclear scientific evidence for this use D: Fair scientific evidence for this use (it may not work) F: Strong scientific evidence against this use (it likley does not work)
Tradition / Theory
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Adaptogen (decreases stress sensitivity), anaphylaxis inhibition (prevents severe allergic reaction), anemia, antacid, antibacterial, antifungal, anti-inflammatory, antispasmodic (prevents muscle spasms), antiviral, anxiety, arthritis, autoimmune disorders, blood thinner, bowel health, brain damage, cancer, chemotherapy side effects (doxorubicin), cirrhosis (severe liver scarring due to disease), clogged arteries, colon inflammation, cytomegalovirus (a usually harmless herpes virus), depression, digestion, energy booster, exhaustion, fatigue, fatty liver, fibromyalgia (long-term, body-wide pain), flu, . infection, hair loss, heart disease, heavy metal/lead toxicity, herpes simplex virus type 1, high blood pressure, immune enhancement, immune system regulation, infections (infectious diseases), iron deficiency, ischemia-reperfusion injury protection (tissue damage due to reduced oxygen), kidney dysfunction, kidney problems (caused by sodium oxalate), leukemia, liver disease (early-stage liver scarring), liver protection, measles, memory improvement, mood stimulant, mumps, nerve damage, neuroprotection, obstetric and gynecological disorders, Parkinson's disease, pneumonia, premenstrual syndrome (PMS), radiation sickness, skin disorders, skin papillomas (tumors), stomach acid reduction, stress, tardive dyskinesia (disorder causing uncontrolled movements), ulcers, warts, wound healing, yeast infection.
Spirulina is listed in the U.S. Food and Drug Administration (FDA) Generally Recognized as Safe (GRAS) list as an ingredient in all foods except infant formulas and foods under USDA's jurisdiction at levels up to a maximum of 250 milligrams per serving.
For allergic nasal symptoms, doses of 1,000-2,000 milligrams of spirulina have been taken by mouth daily for 12 weeks to six months.
For antioxidant benefits, 6 grams of spirulina has been taken by mouth daily for four weeks.
For arsenic poisoning, 250 milligrams of spirulina extract has been taken by mouth with 2 milligrams of zinc twice daily for 16 weeks.
For chronic viral hepatitis (liver inflammation), 500 milligrams of dry powder extract of spirulina has been taken by mouth three times daily for six months.
For type 2 diabetes, 1-19 grams of spirulina has been taken by mouth 1-2 times daily with meals for two months.
For exercise performance, 6 grams of spirulina has been taken by mouth for four weeks.
For eye disorders (eyelid twitch), super blue green algae has been taken by mouth for six months.
For HIV, 19 grams of spirulina has been taken daily with food for two months.
For high cholesterol, 1.4 grams of spirulina has been taken by mouth three times daily with meals for eight weeks. Doses of 2-4.5 grams of spirulina have been taken by mouth daily for six weeks to two months in the form of Multinal® and Spirulina maxima. Freeze-dried spirulina (40 pills, each containing 0.2 grams) has been taken by mouth daily for 16 weeks.
For immune function, 200 milligrams of spirulina in the form of Immulina® capsules have been taken 1-2 times daily for seven days.
For oral leukoplakia (mouth plaques that may indicate cancer), 1 gram of Spirulina fusiformis has been taken by mouth daily for up to one year.
For malnutrition, 5 grams of spirulina has been taken by mouth daily for three months. Doses of 20-100 grams of spirulina have been taken by mouth daily for 4-6 days.
For menopause, two 1,600 gram Klamath algae tablets (Klamin®) have been taken by mouth daily for eight weeks.
Children (under 18 years old)
For nutrition supplementation, 1-10 grams of spirulina has been taken by mouth daily for 14-90 days.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Avoid in people with known allergy or sensitivity to spirulina, blue-green algae species, or any of their parts.
Asthma, hives, and lip swelling have been reported with spirulina use.
Side Effects and Warnings
Spirulina is possibly safe when uncontaminated blue-green algae is taken by mouth in recommended doses.
Spirulina may cause bloating, breaks or lesions in the skin, bullae (fluid-filled skin blisters), changes in bone mineral density, changes in immune function, decreased appetite, dermatomyositis (muscle disease causing inflammation and rash), diarrhea or loose stools, digestive tract inflammation, emotional instability, facial flushing, giddiness, headache, high calcium levels, liver damage, lung infection, Lyngbya dermatitis (a type of skin rash caused by seaweed), muscle pain and weakness, nausea, reduced concentration, sleep problems, Stevens-Johnson Syndrome (a rare, severe skin disorder), stomach discomfort, sweating, vomiting, and weight loss.
Spirulina may increase the risk of bleeding. Caution is advised in people with bleeding disorders or taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
Spirulina may lower blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar. Blood sugar levels may need to be monitored by a qualified healthcare professional, including a pharmacist, and medication adjustments may be necessary.
Spirulina may cause low blood pressure. Caution is advised in people with low blood pressure or in those taking drugs or herbs and supplements that lower blood pressure.
Use cautiously in people who have phenylketonuria (a disorder in which the amino acid phenylalanine cannot be broken down). Spirulina may worsen this condition.
Use cautiously in people who are underweight or those with ADHD, autoimmune diseases, Cushing's disease, musculoskeletal diseases, nervous system diseases, osteoporosis, skin conditions, and stomach or intestine problems.
Use cautiously when taking products containing the blue-green algae species Anabaena spp., Aphanizomenon spp., and Microcystis spp., because they may contain heavy metals.
Use cautiously in people who are taking agents that affect the immune system and agents that promote weight loss or reduce appetite.
Avoid in children and in pregnant or breastfeeding women.
Avoid in people with known allergy or sensitivity to spirulina, blue-green algae species, or any of their parts.
Avoid immersion in bodies of water with high levels of Microcystis aeruginosa.
Avoid in people with liver disease.
Pregnancy and Breastfeeding
There is a lack of scientific evidence on the use of spirulina during pregnancy or breastfeeding. Avoid in pregnant or breastfeeding women.
Spirulina may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants ("blood thinners") such as warfarin (Coumadin®) or heparin, anti-platelet drugs such as clopidogrel (Plavix®), and non-steroidal anti-inflammatory drugs such as ibuprofen (Motrin®, Advil®) or naproxen (Naprosyn®, Aleve®).
Spirulina may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. People taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Spirulina may cause low blood pressure. Caution is advised in people taking drugs that lower blood pressure, including ACE inhibitors.
Spirulina may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be altered in the blood, and may cause altered effects or potentially serious adverse reactions. People using any medications should check the package insert, and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
Spirulina may increase the amount of drowsiness or sedation caused by some drugs. Examples include benzodiazepines such as lorazepam (Ativan®) or diazepam (Valium®), barbiturates such as phenobarbital, narcotics such as codeine, some antidepressants, alcohol, and agents that promote sleep. Caution is advised while driving or operating machinery.
Spirulina may also interact with agents that affect the immune system, agents that affect the kidneys, agents that promote weight loss or reduce appetite, agents that treat eye disorders, agents that treat heart disorders, agents that treat liver disorders, agents that treat nervous system disorders, agents that treat osteoporosis, agents that treat stomach and intestine disorders, antibiotics, anticancer agents, antihistamines, anti-inflammatory agents, antiviral agents, athletic performance enhancers, cholesterol-lowering agents, cisplatin, cyclophosphamide, cyclosporine, doxorubicin, gentamycin, and sunscreen agents.
Interactions with Herbs and Dietary Supplements
Spirulina may increase the risk of bleeding when taken with herbs and supplements that are believed to increase the risk of bleeding. Multiple cases of bleeding have been reported with the use of Ginkgo biloba, and fewer cases with garlic and saw palmetto. Numerous other agents may theoretically increase the risk of bleeding, although this has not been proven in most cases.
Spirulina may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
Spirulina may cause low blood pressure. Caution is advised in people taking herbs or supplements that lower blood pressure.
Spirulina may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements may be altered in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
Spirulina may increase the amount of drowsiness or sedation caused by some herbs or supplements, including those that promote sleep.
Spirulina may also interact with antibacterials, anticancer herbs and supplements, antihistamines, anti-inflammatory herbs and supplements, antioxidants, antiviral herbs and supplements, athletic performance enhancers, calcium, cholesterol-lowering herbs and supplements, chromium, copper, gamma-linolenic acid, herbs and supplements that affect the immune system, herbs and supplements that affect the kidneys, herbs and supplements that promote weight loss or reduce appetite, herbs and supplements that treat heart disorders, herbs and supplements that treat liver disorders, herbs and supplements that treat nervous system disorders, herbs and supplements that treat osteoporosis, herbs and supplements that treat stomach and intestine disorders, iron, nickel, phenylalanine, riboflavin, sunscreen herbs and supplements, and vitamins (including vitamin A, B1, B12, and E).
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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.