Two bowls with spirulina powder and tablets

Top 5 health benefits of spirulina

Registered nutritionist Nicola Shubrook takes a closer look at this food supplement, explaining what it is, which benefits it offers, plus any potential downsides.

What is spirulina?

Spirulina is an algae that grows naturally in mineral-rich waters. Typically sold as a dark-green powder and intended for use as a food supplement, it has not to date been subject to extensive research.


Discover our full range of health benefit guides. Keen to make use of spirulina? Try our delicious green breakfast smoothie.

Nutritional benefits of spirulina

1 tbsp (7g) dried spirulina:

  • 20kcal / 85kj
  • 4.0g protein
  • 0.5g fat
  • 1.5g carbohydrate
  • 0.3g fibre
  • 95mg potassium
  • 2.0mg iron
  • 1.0mg vitamin C
  • 0.18g salt

Top 5 health benefits of spirulina

1. Source of antioxidants

A process called oxidation can lead to ongoing inflammation and damage to cells, which may over time lead to chronic disease and potentially cancer. Spirulina is packed with antioxidant compounds, one of which, phycocyanin, is responsible for spirulina’s dark blue-green colour – it also helps dampen oxidation and inhibit inflammation. Studies suggest phycocyanin has potential benefits, including anti-inflammatory propertiesoxidative stress protection and neuroprotective qualities.

2. May reduce high blood pressure

A study examining the effects of a daily dose of 4.5g of spirulina for six weeks reported reduced systolic and diastolic blood pressure.

3. May help in the management of cholesterol

Rich in compounds that have antioxidant properties, spirulina helps prevent damage to fatty compounds like cholesterol. It also appears to help manage total cholesterol, lowering the so-called ‘bad’ low-density lipoprotein (LDL) cholesterol and elevating ‘good’ high-density lipoprotein (HDL).

4. May have cancer protective properties

Animal studies suggest supplementation with spirulina may have value in protecting against cancer. The mechanism by which it does this may be by activating immune cells called natural killer cells, which help our defence against tumours. More human trials are needed, but of those conducted, results look encouraging.

5. May alleviate hay fever

Spirulina appears to reduce the inflammation of nasal airways, which is a classical symptom of allergic rhinitis or hay-fever. In one study, it was seen to significantly improve symptoms such as sneezing, nasal congestion and itching.

Most of the studies that have been conducted to date have been either on animals or small human trials, so more research is needed before any health claims relating to spirulina can be confirmed.

Is spirulina safe for everyone?

Those with the condition called phenylketonuria (PKU) should avoid spirulina completely as it contains an amino acid called phenylalanine, which those with this condition cannot metabolise. Anyone with an autoimmune condition such as rheumatoid arthritis, lupus or multiple sclerosis should also avoid spirulina.

Others who should check with their GP before taking spirulina include those taking prescription medication, pregnant or breastfeeding women, and anyone younger than 18.

Always make sure you buy spirulina from a known source and choose a reputable brand, as there has been concern in the past that it may be contaminated with toxins from bacteria, including microcystins. Spirulina is also known to absorb heavy metals from the water it is grown in.

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This article was last reviewed on 31 August 2021 by Kerry Torrens.

Kerry Torrens BSc. (Hons) PgCert MBANT is a registered nutritionist with a post graduate diploma in personalised nutrition & nutritional therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years, she has been a contributing author to a number of nutritional and cookery publications, including BBC Good Food.

Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Applied Nutrition and Nutritional Therapy (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at


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