What is it?

Spirulina is a type of blue-green algae (cyanobacteria) that is rich in protein, vitamins, minerals, and antioxidants. It is widely used as a dietary supplement due to its dense nutritional profile and potential health benefits.

How does it work for medicinal purposes?

Spirulina works through its high nutrient content, particularly its antioxidants (such as phycocyanin), vitamins (such as B vitamins and vitamin E), and minerals (such as iron and magnesium). These components contribute to its anti-inflammatory, immune-boosting, and antioxidant properties, which support overall health and wellness.

What are the active ingredients that are important for its medicinal properties?

The primary active ingredients in spirulina include:

• Phycocyanin: An antioxidant and anti-inflammatory compound unique to spirulina.
• Beta-carotene: A precursor to vitamin A with antioxidant benefits.
• Protein: High-quality, complete protein source.
• Vitamins and Minerals: Particularly B vitamins, vitamin E, and iron.

What forms does it come in?

• Powder
• Tablets
• Capsules

What if I have an imbalance or deficiency?

There is no specific deficiency associated with spirulina itself. However, a diet lacking the nutrients found in spirulina, such as proteins, vitamins, and minerals, could lead to deficiencies in these essential nutrients, impacting overall health and wellness.

When was it first used for medicinal purposes?

Spirulina has been used for centuries by the Aztecs and other Mesoamerican cultures. It gained scientific attention in the mid-20th century as a potential food source due to its high nutrient content.

What does Spirulina help with?

Spirulina is a blue-green algae, sold as a powder or as tablets. Aztec people in Mexico and communities near Lake Chad in Africa ate it for centuries. It was sold as a "superfood" supplement starting in the late 1900s.

The overall evidence grade on file is B. The best human trials looked at blood fats, blood pressure, blood sugar and hay fever. Several popular uses rest on much thinner evidence.

• High cholesterol and high triglycerides
  Strong evidence — multiple human trials at 1–4.5 g a day over several weeks. Across multiple human trials, spirulina lowered LDL ("bad") cholesterol and triglycerides. HDL ("good") cholesterol nudged up a little. Doses were small, from 1 to 4.5 g daily, taken for several weeks.
  Evidence grade A · Traditional tier T1
• High blood pressure
  Good evidence — several human trials, most consistent at 4.5 g a day or more. In several studies, both the top and bottom blood pressure numbers fell by a modest amount. Results were steadiest at doses of 4.5 g a day or above. Lab work points to phycocyanin, its blue pigment, which acted as an antioxidant on blood vessels and on nitric oxide activity.
  Evidence grade B · Traditional tier T1
• High blood sugar in type 2 diabetes
  Good evidence — human trials in people with type 2 diabetes. In human trials in people with type 2 diabetes, fasting blood sugar fell. HbA1c, a marker of blood sugar over about three months, also fell. Researchers link this to a better insulin response and less oxidative stress.
  Evidence grade B · Traditional tier T1
• Hay fever and other nasal allergies
  Good evidence — placebo-controlled clinical trials in allergic rhinitis. In clinical trials, people with allergic rhinitis had less stuffy nose, sneezing and itching than people on placebo. Researchers think it calms the immune overreaction behind allergy signs, rather than just blocking symptoms. The trials tested weeks of daily use.
  Evidence grade B · Traditional tier T1
• Low iron and anemia
  Early evidence — small studies in older adults and in women. Studies in older adults and in women found higher hemoglobin and better anemia markers with regular use. Iron is well established to be needed for red blood cells, though that is general nutrition science. Spirulina is one plant source of iron, and the human studies so far are small.
  Evidence grade C · Traditional tier T1
• Inflammation and oxidative stress
  Early evidence — human studies of blood markers such as CRP. Human studies found lower CRP, a blood marker of inflammation. In lab studies, phycocyanin and other antioxidants in spirulina soaked up free radicals. These studies measured markers, not how people felt.
  Evidence grade C · Traditional tier T1
• Fatty liver (NAFLD)
  Early evidence — early human research in non-alcoholic fatty liver disease. Early human research in people with fatty liver disease found less liver fat. Liver enzyme levels also improved. Researchers link this to its antioxidant and cholesterol-lowering effects, but the work is preliminary.
  Evidence grade C · Traditional tier T1
• Exercise endurance and sore muscles after a workout
  Early evidence — small human trials in exercising adults. Small human trials found that people took longer to tire during exercise. Markers of muscle damage after a workout were lower. Researchers credit its antioxidant and anti-inflammatory activity; the trials were small.
  Evidence grade C · Traditional tier T1
• A weak immune system
  Early evidence — human studies measuring immune cells, not illness. In human studies, immune cell activity rose, including natural killer cells and antibody activity. Researchers also report changes in the gut immune lining. These studies counted lab markers only.
  Evidence grade C · Traditional tier T1

What Spirulina has not been shown to do

• It has not been shown to cut how often people catch colds or infections, since the immune studies measured cells in the lab, not illness.
• It has not been shown to replace blood pressure medicine; the drops seen in trials were modest.
• It has not been shown to replace diabetes medicine; trials tracked blood sugar markers only.
• It has not been shown to reverse liver disease; the fatty liver research is early and small.

How to read this:

Each grade above reflects the studies behind that one use, not the product as a whole. A means steady results from randomised human trials. B means at least one good human trial. C means small, mixed or early human work. D means weak or clashing human evidence, and insufficient means no human study on file. This page lists options and what studies found. It is not medical advice, and it is not a promise of results for you. Talk with your doctor, above all if you take medicine for blood pressure, blood sugar or cholesterol.

What can Spirulina help prevent?

• Progression of high LDL cholesterol to cardiovascular disease risk factors (through consistent lipid improvement)
• Iron-deficiency anemia in at-risk populations (pregnant women, vegetarians, older adults)
• Worsening of metabolic syndrome markers (blood sugar, blood pressure, and lipids simultaneously)

Spirulina is a standalone supplement and is not typically found in common foods. It can be consumed in its powdered form, added to smoothies, juices, and other recipes.

What are possible side effects?

Spirulina is generally well-tolerated, but possible side effects include:

Common (10-30%)

• Green discoloration of stool
• Gastrointestinal upset (e.g., gas, bloating, diarrhea)

Less Common (1-10%)

• Allergic reactions (e.g., rash, itching)
• Rare (<1%)
• Headache
• Muscle pain
• Insomnia

What’s the recommended daily dose?

The recommended daily dose of spirulina for adults typically ranges from 1 to 3 grams. Higher doses, up to 10 grams, have been used in some studies.

How many days does it take to work?

Some benefits of spirulina, such as increased energy and improved digestion, may be noticeable within a few days to a week. Long-term benefits, like improved cholesterol levels and immune function, may take several weeks to months to become apparent.

What time of day is best to take it?

Spirulina can be taken at any time of day. It is often recommended to split the dosage into two or three smaller doses taken with meals.

Is it best to take it with or without food?

It is best to take spirulina with food to enhance absorption and reduce the risk of gastrointestinal upset.