Slideshows Images Quizzes

Blue-Green Algae

font size

What other names is Blue-green Algae known by?

AFA, Algae, Algas Verdiazul, Algues Bleu-Vert, Algues Bleu-Vert du Lac Klamath, Anabaena, Aphanizomenon flos-aquae, Arthrospira fusiformis, Arthrospira maxima, Arthrospira platensis, BGA, Blue Green Algae, Blue-Green Micro-Algae, Cyanobacteria, Cyanobactérie, Cyanophycée, Dihe, Espirulina, Hawaiian Spirulina, Klamath, Klamath Lake Algae, Lyngbya wollei, Microcystis aeruginosa and other Microcystis species, Nostoc ellipsosporum, Spirulina Blue-Green Algae, Spirulina fusiformis, Spirulina maxima, Spirulina platensis, Spiruline, Spiruline d'Hawaii, Tecuitlatl.

What is Blue-green Algae?

"Blue-green algae" refers to several species of bacteria that produce blue-green colored pigments. They grow in salt water and some large fresh water lakes.

Blue-green algae have been used for food for several centuries in Mexico and some African countries. They have been sold as a supplement in the US since the late 1970s.

Blue-green algae products are used for many conditions, but so far, there isn't enough scientific evidence to determine whether or not they are effective for any of them.

Blue-green algae are taken by mouth as a source of dietary protein, B-vitamins, and iron. They are also taken by mouth for anemia and to stop unintentional weight loss. They are also used for attention deficit-hyperactivity disorder (ADHD), hay fever, diabetes, stress, fatigue, anxiety, depression, weight loss, and premenstrual syndrome (PMS) and other women's health issues such as menopause.

Some people use blue-green algae for treating precancerous growths inside the mouth, twitching of the eyelids, boosting the immune system, improving memory, increasing energy and metabolism, improving exercise performance, lowering cholesterol, preventing heart disease, healing wounds, and improving digestion and bowel health. Blue-green algae is also taken by mouth for high blood pressure, HIV/AIDS and HIV-related conditions, cancer, fatty liver disease, hepatitis C, and arsenic poisoning.

Blue-green algae are applied inside the mouth to treat gum disease.

Blue green algae is also used as a food or for food coloring.

Blue-green algae are commonly found in tropical or subtropical waters that have a high-salt content, but some types grow in large fresh water lakes. The natural color of these algae can give bodies of water a dark-green appearance.

Some blue-green algae products are grown under controlled conditions. Others are grown in a natural setting, where they are more likely to be contaminated by bacteria, liver poisons (microcystins) produced by certain bacteria, and heavy metals. Choose only products that have been tested and found free of these contaminants.

You may have been told that blue-green algae are an excellent source of protein. But, in reality, blue-green algae are no better than meat or milk as a protein source and cost about 30 times as much per gram.

Insufficient Evidence to Rate Effectiveness for...

  • Seasonal allergies (hayfever). Early research shows that taking 2 grams per day of blue-green algae by mouth for 6 months might relieve some allergy symptoms in adults.
  • Insulin resistance due to HIV medication. Early research shows that taking 19 grams per day of blue-green algae by mouth for 2 months increases insulin sensitivity in people with insulin resistance due to HIV medication.
  • Arsenic poisoning. Early research shows that taking 250 mg of blue-green algae and 2 mg of zinc by mouth twice daily for 16 weeks reduces arsenic levels and the effects of arsenic on the skin in people living in areas with high arsenic levels in the drinking water.
  • Attention deficit-hyperactivity disorder (ADHD). Early research shows that dissolving 3 mL of a product containing blue-green algae, peony, ashwagandha, gotu kola, bacopa, and lemon balm (Nurture and Clarity, Tree of Healing-LD, Israel) into 50-60 mL of water and drinking three times daily for 4 months improves ADHD in children aged 6 years to 12 years who haven't taken other treatments for ADHD.
  • Tics or twitching of the eyelids (blepharospasm or Meige syndrome). Early research shows that taking a specific blue-green algae product (Super Blue-Green Algae, Cell Tech, Klamath Falls, OR) at a dose of 1500 mg daily for 6 months does not reduce eyelid spasms in people with blepharospasm.
  • Diabetes. An early study shows that people with type 2 diabetes who take 1 gram of a blue-green algae product (Multinal, New Ambadi Estate Pvt. Ltd., Madras, India) by mouth twice daily for 2 mouths have lower blood sugar levels.
  • Exercise performance. An early study shows that men who jog regularly are able to sprint for longer periods of time before becoming tired when they take 2 grams of blue-green algae three times daily for 4 weeks.
  • Hepatitis C. Research on the effects of blue-green algae in people with chronic hepatitis C has been inconsistent. One study shows that taking 500 mg of spirulina blue-green algae by mouth three times daily for 6 months results in greater improvements in liver function compared to milk thistle in adults with hepatitis C who were not yet treated or were unresponsive to other treatments. However, another study shows that taking blue-green algae for one month worsens liver function in people with hepatitis C or hepatitis B.
  • HIV/AIDS. Research on the effects of blue-green algae in people with HIV/AIDS has been inconsistent. Some early research shows that taking 5 grams of blue-green algae by mouth daily for 3 months reduces the incidences of infections, stomach and intestinal problems, feelings of tiredness, and breathing problems in patients with HIV/AIDS. However, taking blue-green algae does not appear to improve CD4 cell counts or reduce viral load in HIV patients.
  • High cholesterol. Early research shows that blue-green algae lowers cholesterol in people with normal or slightly elevated cholesterol levels. However, the research findings have been somewhat inconsistent. In some studies, blue-green algae only lower low-density lipoprotein (LDL or "bad") cholesterol. In other studies, blue-green algae lower total cholesterol and LDL cholesterol, and increase high-density lipoprotein (HDL or "good") cholesterol.
  • High blood pressure. Early research shows that taking 4.5 grams per day of blue-green algae by mouth for 6 weeks reduces blood pressure in some people with high blood pressure.
  • Long-term fatigue. Early research shows that taking 1 gram per day of blue-green algae by mouth three times daily for 4 weeks does not improve fatigue in adults with long-term complaints of fatigue.
  • Malnutrition. Early research on the use of blue-green algae in combination with other dietary treatments for malnutrition in infants and children shows conflicting results. Weight gain was seen in undernourished children who were given spirulina blue-green algae with a combination of millet, soy and peanut for 8 weeks. However, in another study, children up to 3 years-old who were given 5 grams of blue-green algae daily for 3 months did not gain weight more than those given general treatments to improve nutrition alone.
  • Menopausal symptoms. An early study shows that taking 1.6 grams per day of a blue-green algae product by mouth daily for 8 weeks lowers anxiety and depression in women going through menopause. However, it doesn't appear to reduce symptoms such as hot flashes.
  • Obesity. Research on the effects of blue-green algae in people who are overweight or obese has been inconsistent. One early study shows that taking a specific blue-green algae product (Multinal, New Ambadi Estate Pvt. Ltd.) at a dose of 1 gram taken two or four times per day by mouth for 3 months slightly improve weight loss in overweight adults. However, another early study shows that taking 2.8 grams of spirulina by mouth three times per day for 4 weeks does not improve weight loss in obese adults who are also following a reduced-calorie diet.
  • Precancerous mouth sores (oral leukoplakia). Early research shows that taking 1 gram of spirulina blue-green algae daily by mouth for 12 months reduces oral leukoplakia in people who chew tobacco.
  • Gum disease (periodontitis). Early research shows that injecting a gel containing blue-green algae into the gums of adults with gum disease improves gum health.
  • Anxiety.
  • As a source of dietary protein, B-vitamins, and iron..
  • Boosting the immune system..
  • Premenstrual syndrome (PMS)..
  • Depression.
  • Digestion.
  • Heart disease.
  • Memory.
  • Wound healing.
  • Other conditions..
More evidence is needed to rate the effectiveness of blue-green algae for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Therapeutic Research Faculty copyright

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Women's Health

Find out what women really need.

Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations

Health Solutions From Our Sponsors