Blue-green algae produce blue-green colored pigments and are high in protein, iron, and other minerals. They grow in saltwater and some large freshwater lakes. They have been used for food for several centuries in Mexico and some African countries. In the US, they've been sold in supplements since the late 1970s.
People use blue-green algae for treating high blood pressure and as a protein supplement. It's also used for high levels of cholesterol or other fats (lipids) in the blood, diabetes, obesity, and many other conditions. But there is no good scientific evidence to support these other uses.
Some blue-green algae products are grown under controlled conditions. Others are grown in a natural setting, where they're more likely to be contaminated. Only use products that have been tested and are free of contaminants such as heavy metals, liver toxins called microcystins, and harmful bacteria. Don't confuse blue-green algae with other algaes, like Ascophyllum nodosum, Ecklonia cava, Fucus Vesiculosis, or Laminaria.
Uses & Effectiveness
Possibly Effective for
Insufficient Evidence for
- Hay fever. Early research shows that taking blue-green algae by mouth might relieve some allergy symptoms in adults.
- Insulin resistance caused by drugs used to treat HIV/AIDS (antiretroviral-induced insulin resistance). Early research shows that taking blue-green algae by mouth increases insulin sensitivity in people with insulin resistance due to HIV/AIDS medication.
- Athletic performance. The effect of blue-green algae on athletic performance is unclear. Most early research shows that taking blue-green algae does not improve athletic performance. But not all research agrees.
- A blood disorder that reduces levels of protein in the blood called hemoglobin (beta-thalassemia). Early research shows that taking blue-green algae by mouth might reduce the need for blood transfusion and improve heart and liver health in children with this condition.
- Tics or twitching of the eyelids (blepharospasm). Early research shows that taking blue-green algae does not reduce eyelid spasms in people with blepharospasm.
- Diabetes. Early research shows that taking blue-green algae by mouth might improve cholesterol levels by a small amount in people with type 2 diabetes.
- Hepatitis C. Some early research shows that blue-green algae might improve liver function in people with hepatitis C. But other research shows that it might actually worsen liver function.
- HIV/AIDS. Early research shows that blue-green algae does not improve CD4 cell counts or reduce viral load in people with HIV. But it might reduce infections, stomach and intestinal problems, feelings of tiredness, and breathing problems in some people.
- High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). Early research shows that blue-green algae lowers cholesterol in people with normal or slightly elevated cholesterol levels. But not all research agrees.
- A condition caused by a poor diet or the body's inability to absorb nutrients. Some early research shows that giving blue-green algae to undernourished children along with a nutritious diet can increase weight gain. But not all research agrees.
- Symptoms of menopause. An early study shows that taking blue-green algae by mouth lowers anxiety and depression in women going through menopause. However, it doesn't appear to reduce symptoms such as hot flashes.
- Mental alertness. An early study shows that taking blue-green algae improves feelings of mental tiredness and scores on a mental math test.
- Obesity. Some early research shows that taking blue-green algae by mouth slightly improves weight loss. In addition, some early research shows that taking blue-green algae might improve levels of cholesterol in adults with obesity. But other studies show no weight loss with blue-green algae.
- White patches inside the mouth that are usually caused by smoking (oral leukoplakia). Early research shows that taking blue-green algae by mouth reduces mouth sores in people who chew tobacco.
- A serious gum infection (periodontitis). Early research shows that injecting a gel containing blue-green algae into the gums of adults with gum disease improves gum health.
- A grouping of symptoms that increase the risk of diabetes, heart disease, and stroke (metabolic syndrome).
- Arsenic poisoning.
- Attention deficit-hyperactivity disorder (ADHD).
- Low levels of healthy red blood cells (anemia) due to iron deficiency.
- Premenstrual syndrome (PMS).
- Build up of fat in the liver in people who drink little or no alcohol (nonalcoholic fatty liver disease or NAFLD).
- Indigestion (dyspepsia).
- Heart disease.
- Wound healing.
- Other conditions.
But blue-green algae products that are contaminated are possibly unsafe. Contaminated blue-green algae can cause liver damage, vomiting, weakness, rapid heartbeat, shock, and death. Don't use any blue-green algae product that hasn't been tested and found to be free of microcystins and other contaminants.
Special Precautions and Warnings
But blue-green algae products that are contaminated are possibly unsafe. Contaminated blue-green algae can cause liver damage, vomiting, weakness, rapid heartbeat, shock, and death. Don't use any blue-green algae product that hasn't been tested and found to be free of microcystins and other contaminants. Pregnancy and breast-feeding: There isn't enough information available to know if it is safe to use blue-green algae when pregnant or breast-feeding. Contaminated blue-green algae products contain harmful toxins that might be transferred to an infant during pregnancy or through breast milk. Stay on the safe side and avoid use.
Children: Blue-green algae are possibly unsafe for children. Children are more sensitive to contaminated blue-green algae products than adults.
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.
Surgery: Blue-green algae might lower blood sugar levels. There is some concern that it might interfere with blood sugar control during and after surgery. Stop using blue-green algae at least 2 weeks before a scheduled surgery.
Medications that decrease the immune system (Immunosuppressants) interacts with BLUE-GREEN ALGAE
Blue-green algae can increase the activity of the immune system. Some medications, such as those used after a transplant, decrease the activity of the immune system. Taking blue-green algae along with these medications might decrease the effects of these medications.
Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs) interacts with BLUE-GREEN ALGAE
Blue-green algae might slow blood clotting. Taking blue-green algae along with medications that also slow blood clotting might increase the risk of bruising and bleeding.
Medications for diabetes (Antidiabetes drugs) interacts with BLUE-GREEN ALGAE
Blue-green algae might lower blood sugar levels. Taking blue-green algae along with diabetes medications might cause blood sugar to drop too low. Monitor your blood sugar closely.
Be cautious with this combination
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.
This copyrighted material is provided by Natural Medicines Comprehensive Database Consumer Version. Information from this source is evidence-based and objective, and without commercial influence. For professional medical information on natural medicines, see Natural Medicines Comprehensive Database Professional Version.
© Therapeutic Research Faculty 2020.