Vitamin B12 1,000 µg
Non-negotiable on a vegan diet. Pointless otherwise, unless deficiency is proven.
The short version
What it does On a plant-based diet, it prevents a deficiency that damages nerves, sometimes irreversibly.
What it does not do If you eat meat regularly, it serves no purpose. And spirulina contains none: its analogues are inactive and even distort the test.
What the studies say
Pawlak’s review of B12 status in vegetarians and vegans shows a high prevalence of deficiency, often with no symptoms at first. B12 does not exist in bioavailable form in the plant kingdom: there is no debate on that point.
Deficiency sets in slowly — liver stores cover several years — which is why you can feel fine for a long time. The neurological damage of prolonged deficiency can be irreversible.
On a vegan or strictly vegetarian diet, this is not optional. In an omnivore who eats meat regularly, it is pointless.
How to take it
Essential on a vegan diet, strongly recommended for vegetarians. Relevant after 60, or on metformin or a proton pump inhibitor, which reduce absorption. Pointless in an omnivore with no risk factor.
Absorption saturates: one large weekly dose — 2,000 µg — is as effective as a small daily one, and easier to keep up. Sublingual forms have not shown real superiority, but do no harm.
Get serum B12 measured and, better, homocysteine or methylmalonic acid, which detect deficiency earlier. Check every two years on a plant-based diet.
What is inside
Cyanocobalamin or methylcobalamin. Cyanocobalamin is the most stable and best documented; methylcobalamin is an active form but less stable in light.
Cyanocobalamin is enough and costs less — it is the form used in most studies. Methylcobalamin is justified in a documented mutation, which is rare.
Algae and spirulina presented as B12 sources: they contain inactive analogues that can even distort the blood test. It is a common and serious mistake on a vegan diet.
Cautions
- In anaemia, test B12 AND folate before supplementing
- Masks folate deficiency if taken blind
The three options
Methyl + cyanocobalamin, 2,000 µg
2,000 µg, and both forms
Methylcobalamin and cyanocobalamin in the same list: the first is directly active, the second is the best documented. 1,941 reviews. At 2,000 µg you are well above requirement — harmless, but that is a weekly dose, not a daily one.
For whom — A long-standing vegan diet.
Cyanocobalamin 1,000 µg
1,000 µg, but silica [nano]
Cyanocobalamin, the best documented form, 365 tablets, 1,341 reviews. The anti-caking agent carries the [nano] marker: it is permitted, but if you avoid nanomaterials, take the option below — its list is two lines long.
For whom — The default choice on a plant-based diet.
Methylcobalamin, one-year format
Two ingredients, a year’s supply
Cellulose and vitamin B12 as methylcobalamin, 1,000 µg, 365 tablets, 1,399 reviews. The methyl form is directly active: fewer trials behind it than cyanocobalamin, no less measured effect.
For whom — Long-term use — do not let anyone sell you dearer methylcobalamin without a reason.
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