Supplement
Vitamin B12 for women
Vitamin B12 is a vitamin with EFSA-authorised roles in normal energy-yielding metabolism, normal functioning of the nervous system, normal red blood cell formation and reducing tiredness and fatigue. It has no reliable plant source, so the NHS specifically advises anyone on a vegan diet to get it from fortified foods or a supplement. Absorption can also become less efficient with age or certain medications. Speak to your GP or pharmacist before starting B12, especially for persistent tiredness.
What it does
Vitamin B12 is an essential vitamin. The roles permitted under EFSA-authorised health claims are factual and modest:
- Vitamin B12 contributes to normal energy-yielding metabolism.
- Vitamin B12 contributes to normal functioning of the nervous system.
- Vitamin B12 contributes to normal red blood cell formation.
- Vitamin B12 contributes to the reduction of tiredness and fatigue.
These are general nutritional roles, not a claim that B12 treats a specific symptom. The NHS advises confirming a deficiency with a blood test if you have symptoms, rather than self-treating on the assumption it is B12.
Who it is for
Anyone on a vegan diet is specifically flagged by the NHS as needing a reliable B12 source, since it has no plant source. Absorption can also decline with age and with some long-term medications. Outside of these groups, most people eating meat, fish, eggs or dairy regularly get enough from diet alone; a supplement is not automatically needed. See our life-stage nutrient table for how the RNI changes across pregnancy and breastfeeding.
What to look for when buying
- B12 has no reliable plant source, so anyone following a vegan diet is specifically flagged by the NHS as needing a supplement or fortified foods, not just "most vegans".
- Absorption issues are common in older adults and those on certain medications (including long-term metformin or PPIs); if you are in either group and feel persistently tired, mention it to your GP rather than assuming a supplement will fix it.
- Forms vary (cyanocobalamin, methylcobalamin); the amount in micrograms on the label matters more than the form for most people, so compare that first.
- Unexplained tiredness, tingling or memory problems should be checked with a blood test before self-treating, since B12 deficiency has specific causes that supplementing alone will not address.
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Check it yourself
Check any product's microgram amount against the recommended daily intake lookup and the upper safe limit checker before you buy.
Frequently asked questions
Do I need a B12 supplement if I am vegan?
B12 has no reliable plant source, so the NHS specifically advises anyone on a vegan diet to get it from fortified foods or a supplement, not to assume a varied plant diet covers it. This is one of the few nutrients where the diet type itself, not just individual variation, changes the advice.
Can B12 deficiency cause tiredness?
EFSA-authorised claims include that B12 contributes to the reduction of tiredness and fatigue, and to normal red blood cell formation. But tiredness has many causes, so if it is persistent, a blood test is the right next step rather than assuming B12 is the answer and self-treating.
Am I more likely to be low in B12 as I get older?
Absorption can become less efficient with age, and certain long-term medications (including metformin and some acid-reducing medicines) are known to affect B12 absorption. If either applies to you and you feel persistently tired or notice tingling, mention it to your GP.
What is the difference between B12 forms on a label?
The two common forms are cyanocobalamin and methylcobalamin. For most people the amount in micrograms matters more than the specific form; if you have a particular reason to prefer one form, your GP or pharmacist can advise.
This is information, not medical advice, and is not a substitute for a registered clinician. Persistent tiredness, tingling or memory changes should be checked with a blood test rather than self-treated.
Editor, Her Vitals
Oliver leads Her Vitals's editorial coverage of women's life-stage health and supplements. He curates and reviews existing branded products across trying to conceive, pregnancy, postnatal, perimenopause, menopause and the senior years, weighing what the evidence supports against guidance from bodies such as EFSA, the NHS and NICE, and is clear that the content is information rather than medical advice.
Last reviewed: 8 June 2026
Reviewed by Oliver Mackman, Editor. Editorial review against published guidance; not a clinical review.