What is spirulina and does it have any health benefits?

30th March, 2021 • 4 min read

Spirulina is a blue-green algae that grows in freshwater and saltwater. In some cultures, spirulina has been added to food for its believed health benefits for centuries. These days, it’s commonly found in health stores as a supplement in capsules, tablets and powder form.

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Over recent years, spirulina has gained ‘superfood’ status, but are its reported benefits – which include helping with diabetes, high blood pressure, anxiety and depression – backed by evidence? We take a look at some of spirulina’s popular health claims.

What makes spirulina special?

You might have heard that spirulina is rich in protein, but did you know that protein makes up 60% of its content? In fact, the protein levels in spirulina are higher than in most vegetables.

Spirulina is also packed with nutrients, including:

  • an antioxidant called beta-carotene
  • vitamin B1 (thiamine)
  • vitamin B2 (riboflavin)
  • vitamin B3 (niacin)
  • copper
  • iron
  • magnesium
  • an essential fatty acid called gamma linolenic acid

What are the potential health benefits of spirulina?

Though more research is needed to back up these findings, spirulina might help with high cholesterol, high blood pressure, diabetes and depression.

High cholesterol

Eating too much fatty food, particularly saturated fat, can cause

high cholesterol
– which may increase heart disease risk. Some studies show that the protein found in spirulina may lower cholesterol levels and improve heart health.

High blood pressure (hypertension)

A few studies suggest that taking spirulina may help lower blood pressure in those with

high blood pressure
. That’s because taking spirulina leads to an increase in nitric oxide in the body, which relaxes blood vessels and reduces blood pressure.


The protein found in spirulina is also believed to help reduce the type of fat (triglycerides) that can harden the arteries and raise diabetes risk.

Depression and anxiety

Although there are claims that spirulina can be effective in treating depression and anxiety, there’s not enough scientific evidence to conclude this for sure.

Other conditions

A small number of studies suggest spirulina may help with malnutrition, maintaining a healthy immune system and helping to relieve symptoms of allergies to pollen, animal hair and dust.

How much spirulina should you take?

Due to a lack of good evidence on how much spirulina you should take to experience possible benefits, it’s best to always read the supplement label and follow dosing instructions carefully.

Does spirulina have any side effects?

Side effects from taking spirulina are generally mild but can include:

  • nausea
  • vomiting
  • diarrhoea
  • discomfort in your tummy
  • fatigue
  • headache
  • dizziness

Is spirulina safe for everyone to use?

Spirulina can grow under controlled conditions or in nature. When spirulina grows in a natural environment, there’s a higher risk it can be contaminated with harmful bacteria and heavy metals. It’s important to use spirulina supplements that have been tested and are free of contaminants.

Speak to your doctor before taking spirulina if:

  • you’re taking immunosuppressant medication or medication for diabetes or blood clotting (spirulina can interfere with these medications)
  • you’re pregnant or breastfeeding
  • you have an autoimmune disease like multiple sclerosis, lupus or rheumatoid arthritis

Spirulina is not recommended for use by children.

Key points

  • spirulina is a blue-green algae that’s been used as a food supplement for centuries
  • it’s high in protein and is a good source of nutrients, minerals and vitamins
  • some evidence suggests spirulina might be helpful in treating high blood pressure, high cholesterol, diabetes, depression and anxiety
  • speak to your doctor before taking spirulina if you’re on certain types of medication
  • children and people who are pregnant or breastfeeding shouldn’t take spirulina

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.