Spirulina is a type of blue-green algae that is rich in protein, vitamins, minerals, carotenoids, and antioxidants that can help protect cells from damage. It contains nutrients, including B complex vitamins, beta-carotene, vitamin E, manganese, zinc, copper, iron, selenium, and gamma linolenic acid (an essential fatty acid).

Spirulina -- like any blue-green algae -- can be contaminated with toxic substances called microcystins. It can also absorb heavy metals from the water where it is grown. For these reasons, it is important to buy spirulina from a trusted brand.

Test tube and animal studies suggest spirulina may boost the immune system, help protect against allergic reactions, and have antiviral and anticancer properties. However, there is no proof that spirulina has these, or any, benefits in people. More research is needed.

Immune Support

A number of animal and test tube studies suggest that spirulina increases production of antibodies, infection-fighting proteins, and other cells that improve immunity and help ward off infection and chronic illnesses, such as cancer. However, it has not been tested in people. In one clinical trial that involved humans, another type of blue-green algae called chlorella did not boost the immune response to flu vaccine.

Protein Supplement

Amino acids make up 62% of spirulina. Because it is a rich source of protein and other nutrients, spirulina has been used as a nutritional supplement. However, although spirulina contains a certain level of protein, you would need to take very large quantities to see any effect. Other sources of protein, such as nuts, legumes, whole grains, and meat, provide protein in smaller servings.

Allergic Reactions

Animal and test tube studies suggest that spirulina may protect against allergic reactions by stopping the release of histamines, substances that contribute to allergy symptoms, such as a runny nose, watery eyes, hives, and soft-tissue swelling. But whether these preliminary studies will help people with allergies is not known.

Antibiotic-related Illnesses

Although antibiotics destroy unwanted organisms in the body, they may also kill "good" bacteria called probiotics, such as Lactobacillus acidophilus. This can cause diarrhea. In test tubes, spirulina has boosted the growth of L. acidophilus and other probiotics. More research is needed to determine whether spirulina will have the same effect in people.

Infection

Test tube studies suggest that spirulina has activity against herpes, influenza, and HIV. But researchers don’t know whether it would also work in people.

Oral Cancer

In one placebo-controlled study, taking spirulina seemed to reduce a precancerous lesion known as leukoplasia in people who chewed tobacco. Lesions were more likely to go away in the spirulina group than in the placebo group. More research in this area is needed.

Liver Disorders

Preliminary evidence suggests that spirulina may help protect against liver damage and cirrhosis (liver failure) in people with chronic hepatitis. Without more research, however, it is impossible to say whether spirulina offers any real benefit.

Eye Diseases

Spirulina contains a high concentration of zeaxantuin, an important nutrient linked to eye health. As such, spirulina may help reduce the risk of cataracts and age-related macular degeneration. More research is needed.

Spirulina is a microscopic algae that flourishes in warm climates and warm alkaline water. It is available dried and freeze-dried.

Spirulina is available in pill or powder form, or as flakes. Most of the spirulina consumed in the United States is grown in a laboratory. There are many different spirulina species, only some of which are identified on labels of commercially-available products. Spirulina maxima (cultivated in Mexico) and Spirulina platensis (cultivated in California) are the most popular.

Pediatric

Although spirulina has been used in children, researchers don’t know the safe and effective dose for those under 18. Don't give spirulina to a child without talking to your doctor first.

Adult

Ask your health care provider to help you determine the right dose for you. A standard dose is 4 - 6 tablets (500 mg each) per day.

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

Spirulina appears safe, even at high doses. However, it can be contaminated with other substances that can be toxic. It is important to buy a reputable brand of spirulina.

If you are pregnant or breastfeeding, talk to your doctor before taking spirulina.

People with a metabolic condition called phenylketonuria (PKU) should avoid taking spirulina. People with this rare condition cannot metabolize the amino acid phenylalanine. Spirulina is rich in all amino acids, including phenylalanine.

If you have an autoimmune disease, such as multiple sclerosis, rheumatoid arthritis, or lupus, you should avoid spirulina. Theoretically, it could stimulate your immune system and make your condition worse.

There are no reports in the scientific literature to suggest that spirulina interacts with any conventional medications. However, it is possible that spirulina might interfere with drugs given to suppress the immune system, including:

• Adalimumab (Humira)
• Azathioprine (Imuran)
• Cyclosporine (Neoral)
• Etanercept (Enbrel)
• Infliximab (Remicade)
• Leflunomide (Arava)
• Methotrexate
• Mycophenolate (CellCept)

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