Spirulina is a blue-green algae that provides protein, vitamins, minerals, carotenoids, and antioxidants. Specifically, spirulina contains B vitamins, beta-carotene, vitamin E, manganese, zinc, copper, calcium, potassium, magnesium, iron, selenium, zeaxanthin, and the essential fatty acid gamma linolenic acid.
Sixty-two percent of spirulina is composed of amino acids, making it a rich source of protein, and because it includes 22 essential amino acids, the total protein is nutritionally superior to legume protein, but inferior to meat protein. Spirulina is available dried and freeze dried, as well as in pill, powder, or flake form as a supplement.
According to www.nutritiondata.com, 1 cup of dried spirulina contains:
- 325 calories
- 9 grams (g) of fat
- 3 g saturated of fat
- 1174 milligrams (mg) of sodium
- 27 g of carbohydrate
- 4 g of fiber
- 3 g of sugar
- 64 g of protein
- 13% Daily Value (DV) of vitamin A
- 13% DV of calcium
- 19% DV of vitamin C
- 177% DV of iron
The site notes that this food is very low in cholesterol; a good source of vitamin K, pantothenic acid, magnesium, and potassium; and a very good source of protein, thiamine, riboflavin, niacin, iron, copper and manganese.
Test tube and animal studies have provided some evidence that spirulina may:
- Bolster the immune system (although in one study, it seemed that spirulina was immunosuppressive)
- Protect against allergic reactions
- Improve lung function in asthmatics
- Improve insulin and glucose levels in rats with diabetes
- Have antiviral and anticancer properties (specifically to stomach, liver, breast, and oral cancers)
In test tubes, spirulina also has boosted the growth of probiotics. In addition, spirulina has demonstrated activity against herpes, mumps, measles, cytomegalovirus, influenza, and human immunodeficiency virus (HIV) in test tubes.
In a placebo-controlled study, spirulina seemed to reduce leukoplasia in people who chewed tobacco. Lesions were more apt to disappear in those taking the spirulina, when compared to individuals taking placebos.
Liver damage and cirrhosis
Some preliminary evidence shows that spirulina may aid in protecting the liver against damage and cirrhosis in individuals with chronic hepatitis. A spirulina-supplemented diet prevented carbon tetrachloride-induced fatty liver in rats. In a case series of three patients diagnosed with nonalcoholic fatty liver disease, 4.5 g/day of spirulina for 3 months improved liver function tests and lipid profiles. Rats and mice given spirulina were protected against cadmium toxicity, lead acetate damage, and mercuric chloride-induced oxidative stress in tests. Giving mice spirulina before dosing them with acetaminophen and galactosamine protected them against liver damage.
Renal and urinary system
Spirulina reduced cisplatin-induced nephrotoxicity in rats. Gentamicin-induced kidney damage in rats was reversed when spirulina (1 g/kilogram [kg] of body weight/day) was given intraperitoneally. In a small, randomized, placebo-controlled trial, spirulina given concurrently with zinc increased excretion of arsenic in the urine and decreased the hair-content of arsenic in people with long-term exposure to arsenic.
In a 6-month, double-blind, placebo-controlled study of 150 patients with allergic rhinitis, it was found that 2 g/day of spirulina improved diary-based symptom scores of nasal discharge, when compared to the placebo group.
In two small clinical studies, improvements in fasting blood glucose and lipid profiles were observed in people given spirulina. It is hypothesized that the fiber content of the spirulina is possibly responsible or that the peptides and polypeptides of the spirulina proteins have insulin-stimulating actions. In rabbits fed a high-cholesterol diet, spirulina lowered serum triglycerides, total cholesterol, and low-density lipoprotein (LDL) at 8 weeks. High-density lipoprotein (HDL) also was markedly increased. A study done on people with diabetes showed reduced triglycerides with 8 g/day of spirulina. In healthy volunteers, 4.5 g of spirulina for 6 weeks decreased blood pressure, total cholesterol, and LDL, while increasing HDL levels.
Skeletal muscle protein
Young rats fed spirulina as the sole source of protein had a greater increase in skeletal muscle protein, when compared to rats given casein as the sole source of protein. When malnourished children in West Africa were given spirulina supplementation for 8 weeks, they gained weight and had increased hemoglobin levels. Similar results were demonstrated in HIV-positive children.
In one study, spirulina increased time to fatigue, decreased the rate of carbohydrate oxidation, and increased the rate of fat oxidation in athletes.
In mice with arthritis, phycocyanin (found in spirulina) acted as a scavenger against reactive oxygen species and increased anti-inflammatory activity. These findings were repeated in other studies. In rats, collagen-induced arthritis was inhibited by a dose of 400 mg/kg of spirulina each day.
Rats treated with rosiglitazone that were given 500 mg/kg/day of oral spirulina showed inhibition of osteoporosis.
A dose of 180 mg/kg of spirulina given as a pretreatment in a rat cerebral ischemia-reperfusion injury model reduced neurologic deficits and histological changes.
Bone marrow cells
Spirulina was found to protect both mouse and human bone marrow cells against gamma radiation.
A clinical study found that men who were given spirulina for 3 months had enhanced interferon production and natural killer cell capacity.
Anemia and immunosenescence
Elderly men who were given spirulina supplements for 6–12 weeks had improved anemia and immunosenescence.
Other study findings
Some, although not all, studies have suggested that spirulina is an antioxidant, but clinical importance is not demonstrated. No clinical studies have shown spirulina to help people wanting to lose weight. Studies have found that spirulina is ineffective for treating chronic fatigue and amyotrophic lateral sclerosis, although a rat study showed evidence that spirulina could protect neural stem cells and aid their growth.
The Natural Medicines Comprehensive Databasedeems that there is insufficient evidence to rate the effectiveness of blue-green algae for all conditions.
Dosing and precautions
Spirulina is not recommended for anyone younger than 18 years of age. A standard dose is 2000–3000 mg/day. In studies, doses have ranged from 1–10 g/day. Before starting any supplement, individuals should discuss this with their doctor, especially women who are pregnant or breastfeeding (spirulina sometimes is contaminated with mercury). People with phenylketonuria (PKU) should not take spirulina. People with an autoimmune disease, such as multiple sclerosis, rheumatoid arthritis, or lupus, should avoid spirulina.
Reports of immunoblistering and rhabdomyolysis have occurred in people taking spirulina. A case of spirulina-associated hepatotoxicity was reported. Spirulina sometimes is contaminated with microcystins, neurotoxic anatoxin-a, and heavy metals, including mercury, cadmium, arsenic, and lead).
References and recommended readings
Drugs.com. Spirulina. Available at: http://www.drugs.com/npp/spirulina.html. Accessed February 27, 2013.
MedlinePlus. Blue-green algae. Available at: http://www.nlm.nih.gov/medlineplus/druginfo/natural/923.html. Accessed February 27, 2013.
NutritionData.com. Seaweed, spirulina, dried. Available at: http://nutritiondata.self.com/facts/vegetables-and-vegetable-products/2765/2. Accessed February 27, 2013.
University of Maryland Medical Center. Spirulina. Available at: http://www.umm.edu/altmed/articles/spirulina-000327.htm. Accessed February 27, 2013.
Contributed by Elaine M. Koontz, RD, LD/N
Review Date 2/13