Vitamin B12 for Vegans: The Complete UK Guide
B12 deficiency can take years to develop and cause serious, potentially irreversible nerve damage. Here is everything vegans need to know about supplementing safely.
Why B12 is non-negotiable on a plant-based diet
Vitamin B12 is found almost exclusively in animal products. Plants do not produce it, and the small amounts found in fermented foods or algae are not bioavailable forms. This is not controversial — it is established nutritional science. Every person following a vegan diet who is not supplementing is running down their B12 stores. Liver stores can last 3–5 years, which is why deficiency often develops insidiously and is diagnosed late.
Consequences of B12 deficiency
Megaloblastic anaemia — large, dysfunctional red blood cells
Peripheral neuropathy — tingling or numbness in hands and feet
Cognitive impairment and memory problems
Fatigue and weakness
Subacute combined degeneration of the spinal cord (severe, potentially irreversible)
The nerve damage caused by B12 deficiency can be permanent if left untreated long enough. This is why regular supplementation — not waiting for symptoms — is the only rational approach.
Which B12 form should vegans take?
Methylcobalamin
The active form of B12 — does not need to be converted by the body. Generally preferred for neurological support. More expensive but readily used.
Cyanocobalamin
The most studied and stable form. Converted to active forms in the body. Works well for most people and is cheaper. The main form used in the landmark B12 supplementation studies.
How much B12 do you need?
B12 absorption works on a saturation basis — the more you take at once, the smaller the percentage absorbed. For a 1000mcg oral dose, only about 1% is absorbed via passive diffusion (i.e., around 10mcg). This is why high-dose supplements work despite their apparently enormous dose.
High-dose daily (1000mcg): simple and well-established
Lower daily dose (25–100mcg cyanocobalamin): may suit those who prefer to stay closer to physiological doses
Sublingual or spray: useful for those with absorption issues
Our top pick: Simply Supplements Vitamin B12 1000mcg
Methylcobalamin form at 1000mcg — the active form at the correct dose for vegans using high-dose daily supplementation. Competitively priced with 180 tablets in a pack.
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