Plant-based nutrition › Vitamin B12
Vitamin B12 on a plant-based diet
Vitamin B12 is not reliably found in plants. It is made by bacteria, not the plant itself. On a plant-based diet, get it from fortified foods (nutritional yeast, fortified plant milks, some cereals) or, most dependably, a daily supplement. UK adults need 1.5µg a day, though supplement doses are higher because absorption is limited.
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Vitamin B12 keeps your nerves and red blood cells healthy and supports brain function. A long-term shortfall can cause tiredness, pins and needles, and, if ignored, irreversible nerve damage, so it is the one nutrient no plant-based eater should leave to chance.
Why plant-based diets fall short
B12 is produced by bacteria and reaches the food chain mainly through animal products. Unwashed plants and fermented foods are not reliable sources, and neither is spirulina or nori: they contain inactive analogues that can even interfere with real B12. That leaves fortified foods and supplements.
How to get enough
Two routes work: several portions of fortified food every day (check the label carries B12), or, simpler and more reliable, a supplement. Because you absorb only a small amount at once, a single larger dose a few times a week, or a daily 25–100µg tablet, is more effective than the tiny 1.5µg daily figure suggests. Follow the product or your GP’s advice.
Could you be low?
Fatigue, tingling and low mood have many causes, and this page cannot diagnose you. If you have gone months without a reliable B12 source, ask your GP for a simple blood test rather than guessing.
How much do you need?
| Group | Per day |
|---|---|
| Adults (19–50) | 1.5µg |
| Adults (51+) | 1.5µg |
| Breastfeeding | 2µg |
Source: NHS; SACN/COMA Dietary Reference Values.
Best plant-based and fortified sources
| Food | Serving | Amount | % of RNI |
|---|---|---|---|
| Fortified nutritional yeast | 2 tbsp (16g) | 4µg | 267% |
| Yeast extract (Marmite) | thinly spread (8g) | 1.9µg | 127% |
| Fortified soya milk | 1 cup (240ml) | 0.9µg | 60% |
| Fortified oat milk | 1 cup (240ml) | 0.9µg | 60% |
| Fortified almond milk | 1 cup (240ml) | 0.9µg | 60% |
| Fortified pea milk | 1 cup (240ml) | 0.9µg | 60% |
| Fortified coconut milk drink | 1 cup (240ml) | 0.9µg | 60% |
| Fortified breakfast cereal | 1 bowl (40g) | 0.6µg | 40% |
Common questions
Is nutritional yeast a good source of B12?
Only if it is fortified. Check the label says it contains B12. Unfortified nutritional yeast contains none. Fortified versions are a genuinely useful source, but most people still pair them with a supplement.
Do vegans really need a B12 supplement?
Effectively, yes, unless you eat fortified foods reliably every day. A supplement is cheap, safe and removes the guesswork, which is why UK dietitians recommend it.
Can I get B12 from seaweed or spirulina?
No. These contain B12 analogues that do not work as human B12 and may interfere with the real thing. Use fortified foods or a supplement instead.