Spirulina

Story

Connected to · 4

antagonism · 1

Vitamin B12
Most of the B12 in spirulina is pseudo-B12 (an analogue): it looks much like real B12 but the body cannot use it, and it may interfere with using real B12. So relying on spirulina for B12 on a vegan diet is dangerous and, left long enough, can lead to nerve damage; use a B12 supplement or fortified foods instead.

contrast · 3

Chlorella
The two are often sold together as the "algae twins", but they do not even belong to the same kingdom: chlorella is a eukaryotic green alga, and spirulina is a cyanobacterium. Chlorella has a higher share of genuine B12 and far more chlorophyll. What they truly share is superfood marketing and uneven product quality: in one analysis, microcystin toxins were found in algae supplements only when they contained another cyanobacterium, AFA.
Astaxanthin
Store shelves often lump together two unrelated molecules: real astaxanthin comes from a red microalga (Haematococcus pluvialis) and is an orange-to-deep-red carotenoid, while the blue Blue Majik is phycocyanin, a protein from spirulina. A product labeled "blue astaxanthin" is essentially selling the two as one.
Microplastics
Chlorophyll, chlorella and spirulina products are marketed as binding microplastics, but there is no evidence that they do, and spirulina has its own problem with heavy-metal contamination. To cut exposure, reducing it at the source does more than swallowing a binder.

Read full story

Stop 1/5

It's a bacterium, not an alga

EVIDENCEREVIEW 1

READ THE ORIGINAL

Spirulina is not, strictly speaking, an alga. It is a cyanobacterium — the kind of microbe that rises as a film on the surface of a pond — and it belongs to a completely different family from kelp or nori.

Its nutrition is genuinely decent: the dry powder is 60–70% protein, with iron, β-carotene and a fatty acid that is rare in food. But the real question was never whether it has nutrients. It is how much it adds to what you already eat. The nutrition table in the ads is calculated per 100 g of dry powder, while a daily serving is a few grams. Scaled back to that, one egg, one serving of red meat or half a carrot matches or beats it.

The two things that deserve real caution are different. Most of the B12 on the label is pseudo-B12, a look-alike the human body cannot use, so a strict vegan who relies on it for B12 is left short. And powder grown in open ponds can also carry heavy metals and algal toxins from the water.

Educational content, not medical advice — consult a clinician.

Back

Spirulina

Story

Connected to · 4

antagonism · 1

Vitamin B12
Most of the B12 in spirulina is pseudo-B12 (an analogue): it looks much like real B12 but the body cannot use it, and it may interfere with using real B12. So relying on spirulina for B12 on a vegan diet is dangerous and, left long enough, can lead to nerve damage; use a B12 supplement or fortified foods instead.

contrast · 3

Chlorella
The two are often sold together as the "algae twins", but they do not even belong to the same kingdom: chlorella is a eukaryotic green alga, and spirulina is a cyanobacterium. Chlorella has a higher share of genuine B12 and far more chlorophyll. What they truly share is superfood marketing and uneven product quality: in one analysis, microcystin toxins were found in algae supplements only when they contained another cyanobacterium, AFA.
Astaxanthin
Store shelves often lump together two unrelated molecules: real astaxanthin comes from a red microalga (Haematococcus pluvialis) and is an orange-to-deep-red carotenoid, while the blue Blue Majik is phycocyanin, a protein from spirulina. A product labeled "blue astaxanthin" is essentially selling the two as one.
Microplastics
Chlorophyll, chlorella and spirulina products are marketed as binding microplastics, but there is no evidence that they do, and spirulina has its own problem with heavy-metal contamination. To cut exposure, reducing it at the source does more than swallowing a binder.

Read full story

Stop 1/5

It's a bacterium, not an alga

EVIDENCEREVIEW 1

READ THE ORIGINAL

Spirulina is not, strictly speaking, an alga. It is a cyanobacterium — the kind of microbe that rises as a film on the surface of a pond — and it belongs to a completely different family from kelp or nori.

Its nutrition is genuinely decent: the dry powder is 60–70% protein, with iron, β-carotene and a fatty acid that is rare in food. But the real question was never whether it has nutrients. It is how much it adds to what you already eat. The nutrition table in the ads is calculated per 100 g of dry powder, while a daily serving is a few grams. Scaled back to that, one egg, one serving of red meat or half a carrot matches or beats it.

The two things that deserve real caution are different. Most of the B12 on the label is pseudo-B12, a look-alike the human body cannot use, so a strict vegan who relies on it for B12 is left short. And powder grown in open ponds can also carry heavy metals and algal toxins from the water.

Educational content, not medical advice — consult a clinician.