Take a B12 tablet every day if you are vegan, over 65, or have taken metformin or an acid-reducing medicine for years. One 1,000 µg tablet a day covers it. Otherwise, meat, fish, eggs and dairy usually give you enough.
The amount for every age is in the UK B12 chart.
Ready to buy:
Solgar Vitamin B12 1000 µg Sublingual Nuggets
£0.13 a day. Cyanocobalamin, the form used in the main dose trial, and labeled suitable for vegans. A tub of 250 lasts about 8 months.
Which B12 is right for you?
The right B12 tablet depends on why you take it.
Over 65, or on metformin? Your body may take in less B12 from food.
The NHS says low B12 or folate affects about 1 in 20 people aged 65 to 74 and 1 in 10 aged 75 or over. Metformin and years of acid-reducing medicines can lower B12 too. One 1,000 µg tablet a day, like our pick above, is a simple fix. Have a blood test first if you can, because tablets raise the result.
Vegan? You need B12 from a tablet or fortified food.
B12 is not found naturally in fruit, vegetables or grains, so the NHS says vegans may not get enough. Some yeast extracts, breakfast cereals and soy products have it added. Our pick is labeled suitable for vegans. If you prefer methylcobalamin, this 1,000 µg tablet is labeled suitable for vegans too.
Natures Aid Vitamin B12 1000 µg Sublingual
£0.12 a day
Blood test says your B12 is low? Your GP sets the treatment.
NICE counts a total B12 result under 180 ng/L as low and 180 to 350 ng/L as possibly low. Treatment usually starts with hydroxocobalamin injections. For pernicious anaemia, the most common cause in the UK, injections usually continue every 2 to 3 months for life. When tablets are used for poor absorption, NICE says they should give at least 1 mg (1,000 µg) a day, the dose of our pick.
B12 already normal? A small tablet keeps it topped up.
If you eat little meat or dairy but your level is normal, 100 µg a day is many times what you need. It is too small to correct low B12.
Solgar Vitamin B12 100 µg Tablets
£0.09 a day
How much vitamin B12 per day in the UK?
| Who | B12 a day |
|---|---|
| Children 1 to 3 | 0.5 µg |
| Children 4 to 6 | 0.8 µg |
| Children 7 to 10 | 1 µg |
| Children 11 to 14 | 1.2 µg |
| Children 15 to 18 | 1.5 µg |
| Adults 19 and over | about 1.5 µg |
The US figure is higher (2.4 µg) because UK and US experts set their values separately. Children should take an adult tablet only on a doctor’s advice.
What % NRV means on a UK label
UK labels compare B12 with a reference amount of 2.5 µg, called the NRV. So a 100 µg tablet shows 4,000% NRV and a 1,000 µg tablet shows 40,000%. The big number is normal for B12. Some labels write µg as mcg; they are the same unit.
Why so many tablets are 1,000 µg
Your body takes in only about 1.3% of a 1,000 µg tablet, roughly 13 µg (US NIH). That is still far more than the 1.5 µg you need, so a big tablet works. Under the tongue or swallowed makes no clear difference (Sharabi 2003).
Is high-dose B12 safe?
The NHS says 2 mg (2,000 µg) or less of B12 a day from supplements is unlikely to cause harm. That is two 1,000 µg tablets. It also says there is not enough evidence to show what higher doses taken every day may do.
Frequently asked questions
How often should I take B12 to stay topped up?
A daily tablet is the simplest habit. If your B12 was low because of your diet, the NHS says you may be advised to take tablets every day between meals. Some UK labels, like Jarrow’s Methyl B-12 lemon chewable, direct one 1,000 µg tablet every 2 days.
Is 250 µg of B12 a day enough?
For keeping a normal level, yes. It is many times the 1.5 µg adults need. In a trial of older adults with mildly low B12, about 650 to 1,000 µg a day worked best (Eussen 2005).
I have 1 mg cyanocobalamin tablets and very low B12. Can I take two?
See a GP before you add more. Very low B12 is usually treated with injections at the start, and NICE says treatment should not wait for test results when there are signs of nerve damage with anaemia.
Related guides
- Vitamin D dosage in the UK: the NHS advice and what to buy
- Magnesium dosage in the UK: how much a day, and which kind
- Methylcobalamin vs cyanocobalamin (US guide): why neither form works better
Sources
- NHS. Vitamins and minerals: B vitamins and folic acid (vitamin B12). Last reviewed August 3, 2020; read October 15, 2026.
- NHS. Vitamin B12 or folate deficiency anaemia (reviewed February 20, 2023) and Treatment.
- NICE. Vitamin B12 deficiency in over 16s: diagnosis and management (NG239), published March 6, 2024: recommendations 1.2, 1.3.3, 1.3.9 and 1.5.5 (re-read October 16, 2026).
- Public Health England. Government Dietary Recommendations (2016), Tables 3 and 4.
- Regulation (EU) No 1169/2011 Annex XIII as retained in GB: nutrient reference values (vitamin B12 2.5 µg).
- US NIH Office of Dietary Supplements. Vitamin B12 fact sheet for health professionals (updated July 2, 2025): absorption.
- Institute of Medicine. Dietary Reference Intakes, chapter 9: Vitamin B12. National Academies Press, 1998.
- Eussen SJ, et al. Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial. Arch Intern Med. 2005. PMID 15911731; Sharabi A, et al. Br J Clin Pharmacol. 2003. PMID 14616423
- Prices: each brand’s own UK list price for one tablet a day (solgar.co.uk, naturesaid.co.uk), read October 15, 2026. Amazon’s price may differ.