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.

How it works

Blue-green algae have a high protein, iron, and other mineral content which is absorbed when taken orally. Blue-green algae are being researched for their potential effects on the immune system, swelling (inflammation), and viral infections.


Not Proven
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.


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.


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.


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.


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.

As a source of dietary protein, B-vitamins, and iron.
Boosting the immune system.
Premenstrual syndrome (PMS).
Heart disease
Wound healing
Other conditions.


Possibly safe

Blue-green algae products that are free of contaminants, such as liver-damaging substances called microcystins, toxic metals, and harmful bacteria, are POSSIBLY SAFE for most people when used short-term. Doses up to 19 grams per day have been used safely for up to 2 months. Lower doses of 10 grams per day have been used safely for up to 6 months. Side effects are typically mild and may include nausea, vomiting, diarrhea, abdominal discomfort, fatigue, headache, and dizziness

Possibly unsafe

But blue-green algae products that are contaminated are POSSIBLY UNSAFE, especially for children. Children are more sensitive to contaminated blue-green algae products than adults.Contaminated blue-green algae can cause liver damage, stomach pain, nausea, vomiting, weakness, thirst, rapid heartbeat, shock, and death. Don't use any blue-green algae product that hasn't been tested and found free of microcystins and other contamination.



Pregnancy and breast-feeding: Not enough is known about the use of blue-green algae duringpregnancyandbreast-feeding. Stay on the safe side and avoid use.

"Auto-immune diseases" such as multiple sclerosis (MS), lupus (systemic lupus erythematosus, SLE), rheumatoid arthritis (RA), pemphigus vulgaris (a skin condition), and others: Blue-green algae might cause the immune system to become more active, and this could increase the symptoms of auto-immune diseases. If you have one of these conditions, it's best to avoid using blue-green algae.

Bleeding disorders: Blue-green algae might slow blood clotting and increase the risk of bruising and bleeding in people with bleeding disorders.

Phenylketonuria: The spirulina species of blue-green algae contains the chemical phenylalanine. This might make phenylketonuria worse. Avoid Spirulina species blue-green algae products if you have phenylketonuria.


Always consult with your doctor.
Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Blue-green algae might increase the immune system. By increasing the immune system, blue-green algae might decrease the effectiveness of medications that decrease the immune system.Some medications that decrease the immune system include azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), corticosteroids (glucocorticoids), and others.Blue-green algae might slow blood clotting. Taking blue-green algae along with medications that also slow clotting might increase the chances of bruising and bleeding.Some medications that slow blood clotting include aspirin; clopidogrel (Plavix); nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), and naproxen (Anaprox, Naprosyn, others); dalteparin (Fragmin); enoxaparin (Lovenox); heparin; warfarin (Coumadin); and others.

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