Vitamin B12 is found naturally only in animal foods, so vegans, and many people who eat little meat, fish, eggs or dairy, rely on fortified foods or a supplement. The NHS says adults need about 1.5 micrograms a day. Supplements use cyanocobalamin, methylcobalamin or hydroxocobalamin; all provide B12. A B-complex adds the other seven B vitamins in one tablet. Vitamin B12 contributes to the reduction of tiredness and fatigue and to normal red blood cell formation.
1. Who may need vitamin B12
- Vegans and many vegetarians — B12 is not naturally present in plant foods.
- Older adults — absorption of B12 from food can fall with age.
- People taking some long-term medicines (for example certain diabetes or indigestion medicines) — ask your GP whether your B12 should be checked.
- People with pernicious anaemia or absorption problems usually need B12 injections from their GP rather than tablets.
2. Forms of B12 compared
| Form | What it is | Where you’ll see it |
|---|---|---|
| Cyanocobalamin | Stable, low-cost synthetic form; the body converts it | Most supplements and fortified foods |
| Methylcobalamin | One of the two active forms used in the body | Higher-priced supplements |
| Hydroxocobalamin | Natural form; used in NHS injections | Injections, some supplements |
| Adenosylcobalamin | The other active form in the body | Some combination supplements |
3. How much B12?
The NHS says adults aged 19–64 need about 1.5 micrograms (mcg) a day, and that taking 2mg (2,000mcg) or less a day from supplements is unlikely to cause harm. Supplements often contain far more than the daily need (for example 1,000mcg), because only a small share of a large oral dose is absorbed.
4. B12 on its own, or a B-complex?
| Vitamin B12 only | Vitamin B-complex | |
|---|---|---|
| Contains | B12 only, usually at a high dose | All eight B vitamins: B1, B2, B3, B5, B6, B7 (biotin), B9 (folic acid) and B12 |
| Suits | Topping up B12 specifically, e.g. a vegan diet | Covering all the B vitamins in one daily tablet |
| Good to know | Many people take both: a B-complex for the full range and extra B12 on a plant-based diet. | |
5. What B vitamins do (authorised claims)
- Vitamin B12 contributes to normal energy-yielding metabolism, normal functioning of the nervous system, normal psychological function, normal red blood cell formation, normal function of the immune system, and the reduction of tiredness and fatigue.
- Biotin contributes to the maintenance of normal hair and normal skin.
- Folate contributes to maternal tissue growth during pregnancy. The NHS advises 400mcg of folic acid a day before pregnancy and until 12 weeks of pregnancy.
6. JeaKen B vitamins
| Product | What’s in it | Pack | Price |
|---|---|---|---|
| Vitamin B12 1000mcg | Methylcobalamin, 1000mcg per capsule, timed release; vegan | 120 capsules (4 months at one a day) | £23.95 (about 20p a day) |
| Vitamin B-Complex | All eight B vitamins including B12, biotin and folic acid | 365 tablets (a year at one a day) | £23.95 (about 7p a day) |
Prices correct at the time of writing; see each product page for the current price.
Frequently asked questions
Who needs a vitamin B12 supplement?
Vegans and many vegetarians, because B12 is found naturally only in animal foods. Older adults and people on some long-term medicines may also have lower B12; ask your GP if you are unsure.
Is methylcobalamin better than cyanocobalamin?
Both provide vitamin B12. Cyanocobalamin is stable and low cost and is converted by the body; methylcobalamin is one of the active forms. Choose on preference and price.
How much vitamin B12 do adults need?
The NHS says adults aged 19–64 need about 1.5 micrograms a day, and that 2mg (2,000mcg) a day or less from supplements is unlikely to cause harm.
Is 1000mcg of B12 too much?
1000mcg is within the NHS guidance of 2,000mcg a day or less from supplements. Only a small share of a large oral dose is absorbed.
Should I take B12 or a B-complex?
Take B12 alone to top up B12 specifically, for example on a vegan diet. A B-complex covers all eight B vitamins in one tablet; some people take both.
Does vitamin B12 help with tiredness?
Vitamin B12 contributes to the reduction of tiredness and fatigue. Ongoing tiredness can have many causes, so speak to your GP if it continues.
Food supplements should not be used as a substitute for a varied and balanced diet. If you take any medication, are pregnant or breastfeeding, speak to your GP or pharmacist before starting a supplement.
Sources
- NHS — “Vitamin B” (B12 daily needs and safe upper amount) and “Vegetarian and vegan diet” guidance.
- NHS — folic acid advice before and during pregnancy.
- GB Nutrition and Health Claims Register — authorised health claims for vitamin B12, biotin and folate.
