Updated: October 2026
Spirulina, in short
Spirulina is a deep blue-green algae grown in fresh water and dried into a powder or tablets. It is one of the most protein-dense foods available, providing plant protein that contains all nine essential amino acids, along with a natural pigment called phycocyanin.
This guide covers what spirulina is, why it is so protein-rich, what else it provides, how to add it to meals, and its long history as a traditional food.
When most people think of protein they picture meat or fish – but gram for gram, spirulina is one of the most protein-dense foods on the planet.
Here are the questions people ask most. For more, see our natural health and herbal tips guide.
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What is spirulina?
Spirulina is a deep blue-green algae, grown in fresh water and dried into a fine powder or pressed into tablets.
It has been eaten as a food for centuries and is valued today as a high-protein ingredient.
Its vivid colour comes from natural pigments, including one called phycocyanin.
Is spirulina really high in protein?
Yes – spirulina is one of the most protein-dense foods there is, and contains all nine essential amino acids.
Dried spirulina is about 57% protein by weight, though we tend to eat it by the spoonful rather than the plateful.
Protein contributes to a growth in muscle mass and to the maintenance of normal muscle mass and bones.
A typical 3 to 5 g teaspoon of spirulina provides about 1.7 to 2.9 g of protein, against a daily reference intake of 50 g, so it is best enjoyed regularly as one small part of a varied and balanced diet and a healthy lifestyle.
What else does spirulina provide?
Beyond protein, spirulina is naturally high in iron, and contains the natural pigment phycocyanin.
That concentrated protein and iron is a big part of its appeal.
Most people use it as a small daily addition rather than a main ingredient.
How do you use spirulina?
A teaspoon (around 3 to 5g) stirred into a smoothie or juice is the easiest way to enjoy it.
Its strong flavour blends best with fruit, so smoothies and juices are the usual home for it.
Start small, since a little goes a long way.
Has spirulina been eaten traditionally?
Yes – spirulina has a long history as a food, famously harvested from lakes by the Aztecs centuries ago.
It has been valued as a food across different cultures for generations.
It is a genuinely fascinating ingredient with real heritage – well worth reading up on if it interests you.
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Last updated: October 2026
This article is for general information only and is not medical advice. We make no medical claims. If you have a health concern, please speak to your GP or pharmacist.
