Compare vitamin B12 and B complex supplements on what you actually get: the amount of each B vitamin per daily dose, the form and the cost per day. The NHS says adults need about 1.5 micrograms of B12 a day and many tablets contain 1,000 micrograms, so we show you how to read the label before you buy.
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How much vitamin B12 do you need a day?
The NHS says adults aged 19 to 64 need about 1.5 micrograms of vitamin B12 a day, and that taking 2mg (2,000 micrograms) or less a day of vitamin B12 in supplements is unlikely to cause any harm.
If you eat meat, fish or dairy foods, the NHS says you should be able to get enough vitamin B12 from your diet. Other food sources include eggs and some fortified breakfast cereals.
What do 1,000 micrograms of B12 and %NRV mean?
Many B12 supplements contain hundreds of times the daily amount. The NRV (Nutrient Reference Value) for vitamin B12 is 2.5 micrograms, so the NHS daily amount of 1.5 micrograms is 60% NRV and a 1,000 microgram tablet is 40,000% NRV.
| B12 per daily dose | %NRV | How it compares with NHS advice |
|---|---|---|
| 1.5mcg | 60% | The daily amount for adults aged 19 to 64 |
| 10mcg | 400% | Over six times the NHS daily amount |
| 100mcg | 4,000% | About 67 times the NHS daily amount |
| 1,000mcg (1mg) | 40,000% | Half the most the NHS says is unlikely to cause harm |
| 2,000mcg (2mg) | 80,000% | The most the NHS says is unlikely to cause harm from supplements |
The NHS also says there's not enough evidence to show what the effects may be of taking high doses of vitamin B12 every day. "We want customers to understand what they're taking rather than simply choosing the highest numbers on the label," says Andy Arshad, who runs SupplementHQ. Our guide to reading a supplement label explains more.
Do vegans need a B12 supplement?
Often, yes. The NHS says sources for vegans are limited and a vitamin B12 supplement may be needed.
Vegan sources are fortified foods: breakfast cereals, unsweetened soya drinks, yeast extract and nutritional yeast flakes fortified with B12. The Vegan Society publishes its own B12 recommendations for vegans, covering fortified foods and daily or weekly supplements. Browse vegan supplements, and check the label for vegan suitability.
Methylcobalamin or cyanocobalamin: which form of B12?
Both are forms of vitamin B12. The Vegan Society says cyanocobalamin is the recommended form of vitamin B12 because it is the most stable, and that your body converts it into the two active forms, methylcobalamin and adenosylcobalamin.
Many products in this collection use methylcobalamin (sometimes listed as methyl-B12), which is usually marketed as more active and often costs more. We don't claim one form works better than the other for most people. Check the form on the label and compare the B12 per daily dose and cost.
What are the signs of B12 deficiency?
The NHS lists symptoms including extreme tiredness, a lack of energy, pins and needles, a sore red tongue, mouth ulcers and muscle weakness, among others. Some of these can happen without anaemia.
Don't try to diagnose this yourself with a supplement. The NHS says the most common cause of B12 deficiency in the UK is pernicious anaemia, where the immune system attacks healthy cells in the stomach, and that it is usually diagnosed with a blood test and often treated with injections. If you think you might be deficient, speak to your GP, especially as some damage may not be reversible.
What is a vitamin B complex?
A B complex is a single product that contains several B vitamins together, such as thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), B6, biotin, folate or folic acid, and B12. Amounts vary widely between products.
Check each B vitamin against the NHS figures. The NHS says not to take more than 10mg of vitamin B6 a day in supplements unless advised to by a doctor, that 1mg or less a day of folic acid is unlikely to cause harm, and that 17mg or less of nicotinic acid (a form of niacin) is unlikely to cause harm. High doses of nicotinic acid can cause skin flushes. High-strength B complex products can go above that B6 figure, so check the label carefully.
What does vitamin B12 do?
Where a product is at least a source of vitamin B12, authorised claims include "Vitamin B12 contributes to the reduction of tiredness and fatigue", "Vitamin B12 contributes to normal red blood cell formation", "Vitamin B12 contributes to normal functioning of the nervous system" and "Vitamin B12 contributes to normal energy-yielding metabolism".
These describe what B12 does as part of a normal diet. They don't mean taking more than you need gives you more energy.
B12 and folic acid: should you take them together?
Many products in this collection combine B12 with folate, folic acid or methylfolate, and that's a matter of choice. One thing to know: the NHS says taking doses of folic acid higher than 1mg can mask the symptoms of vitamin B12 deficiency.
If you're pregnant or trying for a baby, the NHS recommends 400 micrograms of folic acid a day until you're 12 weeks pregnant; see prenatal & fertility and speak to your midwife, GP or pharmacist.
How do you compare value on B12 supplements?
Compare the cost per daily dose, then check the B12 in that dose and its form. Tablets, sprays, liposomal liquids (B12 wrapped in tiny fat droplets) and B complex capsules all come in different pack sizes.
How to compare value (example figures, not real products): a £6 pot of 120 tablets, each 1,000mcg, one a day, costs 5p a day. A £12 oral spray giving 60 daily doses of 1,000mcg costs 20p a day, four times as much for the same amount of B12.
"Two products that look almost identical on the shelf can offer different value," says Andy. Go back to all vitamins & supplements or see multivitamins, which usually include B12.
We sell the products on this page. That's our commercial interest, and it's why we show the evidence alongside them. This page is general information for adults, not personalised medical advice. Food supplements should not replace a varied, balanced diet.
Written by Andy Arshad, SupplementHQ. Last reviewed 11 October 2026.