Does chlorella have vitamin B12?

Some chlorella supplements do contain vitamin B12, and lab analysis has found chlorella's form to be the active, true version rather than the inactive look-alike found in spirulina — but a survey of 15 commercial microalgae powders measured B12 at trace levels in every sample tested. Whether a specific chlorella product supplies a meaningful amount depends on that product, not on chlorella as an ingredient in general.

Why chlorella is marketed as a B12 source

Vitamin B12 is normally found in meaningful amounts only in animal foods, which is why vegans and vegetarians are more often screened for low B12 status. Algae are one of the few plant-based sources anyone has found it in at all, which is where chlorella's B12 reputation comes from. A 2002 laboratory analysis tested several edible algae and algal health foods, including chlorella tablets, using a microbiological assay for B12 activity. It found that chlorella tablets, like green and purple laver, were dominated by true, active vitamin B12 — unlike spirulina tablets, where an inactive look-alike compound (pseudovitamin B12) made up most of the total. That's a meaningful distinction: a corrinoid compound that shows up on a B12 assay isn't automatically usable by the body, and this analysis is one of the few to check.

The one human study

A small 2015 open-label study tested whether chlorella supplementation changed B12 status in people already showing signs of low B12. Seventeen vegan or vegetarian adults with an elevated baseline methylmalonic acid (MMA) level — a marker that rises when B12 status is low — added 9 grams of Chlorella pyrenoidosa to their daily diet for about 60 days. MMA fell by an average of roughly 34%, with 15 of the 17 participants showing at least a 10% drop; homocysteine trended down and blood B12 trended up, while red-blood-cell measures didn't change. That's a real, biologically plausible signal, but it's one small trial with no placebo group and no blinding, at 9 grams a day — well above what a typical capsule or powder serving provides.

But most products haven't been measured this carefully

A 2021 laboratory analysis of 15 commercially available microalgae powders — spanning chlorella, spirulina and several other species — measured actual B12 content directly and found it below 0.02 mg (20 micrograms) per 100 grams of dry powder in every single sample. On a typical few-gram daily serving, that upper bound works out to well under 1 microgram — a small fraction of the roughly 2.4 micrograms adults need per day. The same analysis found nutrient levels varied strongly between products and species generally, not just for B12. Put together with the studies above, the honest picture is: chlorella's B12, when present, does appear to be the usable form, but how much of it is actually in a given bottle is inconsistent and, in the products actually tested, small.

Questions people ask

Does chlorella have B12?

Some of it, in some products — chlorella tablets have tested as containing mostly the active form of B12 rather than an inactive look-alike. But a direct measurement of 15 commercial powders found only trace amounts in every one tested, so "chlorella" alone doesn't tell you how much B12, if any, a specific product actually supplies.

Is chlorella a reliable B12 source for vegans?

Based on what's been tested, not reliably. One small, uncontrolled study found a high dose (9 g/day) improved B12 markers over 60 days, which is encouraging but far from proof at typical serving sizes. A separate composition survey found trace B12 levels in commercial powders. If you're vegan or vegetarian and depend on a plant source for B12, ask a doctor about checking your B12 level directly rather than assuming any supplement is supplying enough.

How much B12 is in chlorella powder?

It varies by product and isn't something we can state as one number — the one lab survey that measured it directly found it consistently low (below 20 mcg per 100 g) across every commercial powder tested, spirulina and chlorella alike. Check a specific product's label for a stated B12 amount in micrograms rather than assuming from the ingredient name.

Related reading: what is chlorella?, chlorella benefits: what's established and what isn't, and how much chlorella should you take a day?.