Spirulina

Spirulina is a blue-green algae grown in warm, alkaline water. The type used in supplements is Arthrospira platensis. Dried spirulina is roughly 55 to 70 percent protein and holds two natural pigments: green chlorophyll and blue phycocyanin. Together they give the powder its dark colour and its strong, pond-like smell. Nothing is extracted or concentrated, so what you buy is the whole dried algae. Shoppers often compare it with chlorella, a green freshwater algae with a different nutrient profile and a tougher cell wall.

The forms differ in dosing and taste, not in the algae

Powder, tablets and capsules all start as the same dried biomass. Tablets are pressed powder. Capsules are the same powder in a shell. What changes is how much you get per serving and how much you taste. One level teaspoon of powder holds about as much as six 500 mg tablets, which is why tablet packs run into the hundreds. Powder gives you the most control per gram and stirs into smoothies. Tablets and capsules hide the taste and travel better. For anyone following a plant-based diet, powder is usually the cheaper way to take a larger daily amount.

Where it grows matters more than the label design

Algae take up what surrounds them. Spirulina from open, uncontrolled water can pick up heavy metals, or toxins from other cyanobacteria growing alongside it. That makes cultivation and batch testing more important here than for most plant ingredients. Three things are worth checking on a pack: a named growing region, the stated species, and testing for heavy metals and microcystins. Organic certification tells you how the algae were grown. It is not the same thing as a contaminant test.

How we choose the spirulina we stock

We list spirulina from controlled cultivation only, never wild-harvested algae, and we ask brands for batch results on heavy metals and microcystins before a product goes live. We prefer plain pressed tablets and pure powder over green blends, because you can then see exactly how many grams you take. A combination only earns a place when it makes sense, spirulina with chlorella being the obvious one. We buy directly from the brands, our compliance team checks every label, and independent labs spot-check batches. You can read how we select brands and products.

Who it suits, and what a daily dose realistically does

Spirulina is a nutrient-dense food, not a quick fix. It suits people who eat little or no animal protein, anyone who wants a compact source of plant protein and iron, and people who simply want to add greens without cooking. Where a serving delivers a significant amount of iron, that iron contributes to the reduction of tiredness and fatigue and to the normal function of the immune system. The amount per serving differs a lot per product, so read the label rather than the front of the pack.

• Powder: largest amounts, lowest cost per gram, noticeable taste
• Tablets: pressed powder, easy to count, high tablet numbers per day
• Capsules: no taste, smallest amount per unit

Most people take 2 to 5 grams a day and judge the result after three to four weeks of consistent use. Start with a small amount if your stomach is sensitive, then build up over a week or two. You will find spirulina alongside the rest of our herbal and plant range.