Vitamin B12 Supplements: Who Needs Them, Best Form and How Much (UK)

Who may need a B12 supplement?

The NHS lists meat, fish, milk, cheese, eggs and some fortified breakfast cereals as good sources of B12. The people who need to think about a supplement are those who eat little or no animal food, or whose bodies struggle to absorb it.

NICE also lists colchicine, pregabalin, topiramate, some epilepsy medicines, coeliac disease and nitrous oxide use. If you take acid-reducing medicines for reflux, see our guide to acid reflux at night. For where B12 fits with other nutrients as you age, see supplements for men over 40 and 50 and supplements for women over 40.

What food has vitamin B12?

Vitamin B12 is found naturally in animal foods: meat, fish, eggs and dairy. Plants don’t make it, so vegans need foods fortified with B12, and the NHS says a supplement may be needed. Adults need about 1.5 micrograms a day, so a glass of milk and an egg already covers it for most people.

Figures are from NHS dietitians at Royal United Hospitals Bath and the British Dietetic Association’s One Blue Dot guide, which draws on UK food composition data. Brands vary, so check labels.

• Liver: the Bath dietitians advise eating it no more than once a week, and the NHS says to avoid liver in pregnancy because of its high vitamin A content.
• A vegan day: the BDA shows how fortified foods can add up: a 30g bowl of fortified cereal with 150ml of fortified plant drink (1.1 micrograms), a fortified soya yogurt alternative (0.6) and yeast extract on toast (0.6) give about 2.3 micrograms.
• Check plant drinks: organic plant drinks can’t be fortified, so they won’t contain B12.
• Seaweed and spirulina aren’t reliable sources, as the B12 in them is likely to be unusable by the body. See spirulina and the B12 myth.

For the best foods for every B vitamin, see our guide to B vitamins.

Pernicious anaemia: injections, not shop tablets

The NHS says pernicious anaemia is the most common cause of B12 deficiency in the UK. NICE now calls it autoimmune gastritis: the immune system damages the stomach cells that make intrinsic factor, which you need to absorb B12.

The NHS says that if low B12 is caused by a stomach or bowel problem or surgery, you won’t absorb enough from food or low-dose supplements (10 to 100 micrograms). Treatment is usually hydroxocobalamin injections, every other day at first, then every 2 to 3 months for life, or high-dose 1,000 microgram tablets if you can’t have injections. NICE recommends lifelong injections for autoimmune gastritis and after total gastrectomy.

Cyanocobalamin vs methylcobalamin, tablets vs sprays

NICE advises choosing a supplement with cyanocobalamin, methylcobalamin or adenosylcobalamin, as some products don’t contain enough, or the right type, to work. A 2017 review found every form is broken down to the same core molecule and rebuilt into the two active forms, whatever you swallow. Its authors, one of whom worked for a supplement company, favoured the “natural” forms but agreed most people would likely find all forms work about the same. Methylcobalamin is fine, but you don’t need to pay more for it.

Tablets, under-the-tongue tablets, sprays and injections

The NHS says there’s no noticeable difference in how much B12 you absorb from tablets, under-the-tongue tablets, capsules, mouth sprays or drops. In one small trial, 500 micrograms worked equally well under the tongue or swallowed. A 2018 Cochrane review found 1,000 to 2,000 micrograms a day by mouth raised blood levels as well as injections, though the evidence was low quality. A spray is simply handy if you dislike tablets. Injections are for people who can’t absorb B12 or have severe symptoms, and come from your GP.

How much B12 per day?

Shop supplements range from 10 to 1,000 micrograms, which looks huge next to 1.5 micrograms, because only a small share of a large dose is absorbed. In a Dutch trial, older people with mild deficiency needed 647 to 1,032 micrograms a day to bring blood markers back to normal. Many multivitamins contain B12 too, so check labels if you take more than one product.

How to take it and how long until you feel better

• Prescribed tablets: the NHS says swallow them whole with water, ideally on an empty stomach, at least 2 hours after eating and 30 minutes before your next meal.
• Shop supplements: follow the pack. The Vegan Society suggests chewing tablets or letting them dissolve in your mouth.
• Daily or weekly: pick whichever you’ll stick to. Taking it with breakfast is easy to remember.

How long to work: NICE says symptoms could start to improve within 2 weeks but may take up to 3 months, longer to clear completely, and can feel worse at first. Your GP should review you at about 3 months.

How long to take it: you may be able to stop once levels are normal and the cause is fixed. If you’re vegan, or can’t absorb B12, you may need it for life.

Get tested before you start

iIf you have symptoms, see your GP before you buy a supplement. Our guide to vitamin B12 deficiency symptoms covers the signs.

NICE tells doctors to take blood for B12 tests before starting treatment, and warns that shop supplements can raise test results without fully treating a deficiency. That can hide the cause, such as pernicious anaemia, which needs lifelong treatment. If you already take B12, tell your GP. A total B12 under 180 nanograms per litre confirms deficiency, and 180 to 350 is a grey area that may need a further test.

iSee your GP promptly if you have numbness, balance problems or vision changes, as the NHS says nerve problems from low B12 can sometimes be permanent. See pins and needles for other causes.

Does B12 give you energy?

Only if you’re low in it. These are the authorised health claims for B12 in Great Britain:

• Vitamin B12 contributes to the reduction of tiredness and fatigue.
• 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.

The NHS is clear that B12 supplements will only improve tiredness and lack of energy if they’re caused by low B12 levels. Topping up when your levels are normal, including with private “booster” injections, is unlikely to give you more energy.

iTiredness has many causes. See why am I always tired?, iron deficiency symptoms, brain fog and the best supplements for energy. If your GP also finds low iron, see iron tablets.

Can you have too much vitamin B12?

From supplements, the NHS says: “Taking 2mg or less a day of vitamin B12 in supplements is unlikely to cause any harm.” That’s 2,000 micrograms, far more than most shop supplements contain. The NHS also says there isn’t enough evidence to show what the effects of taking high doses every day may be, so don’t take more than you need.

• Prescribed doses: tablets for deficiency can be higher, and B12 injections (hydroxocobalamin) are prescribed and given by your GP surgery. Your doctor sets the dose and checks how you respond.
• Stacking products: B12 turns up in multivitamins, B complex tablets and sprays, so add up the labels if you take more than one.
• High blood B12: if you take B12 supplements or have injections, a high result often just reflects that, as NICE notes supplements raise test results. If you don’t take any B12 and a test comes back high, ask your GP what it means. A 2013 review found that a high level can sometimes point to another condition, such as liver or kidney disease, so your GP may want to look for a cause.

Safety, side effects and medicines

• Dose: the NHS says 2mg (2,000 micrograms) or less a day from supplements is unlikely to cause harm.
• Side effects: most people have none. B12 contains cobalt, so people allergic to cobalt can react. Call 999 if your lips, tongue or throat swell or you struggle to breathe.
• Medicines: metformin, PPIs such as omeprazole, H2 blockers and antacids can reduce how much B12 you absorb, so tell your pharmacist. The MHRA says don’t stop metformin without talking to your doctor.
• Pregnancy and breastfeeding: the NHS says cyanocobalamin is safe, but you don’t usually need B12 supplements unless your doctor advises it. If you’re vegan, ask your midwife.

The NHS lists a sore red tongue, sometimes with mouth ulcers, as a sign of low B12: see mouth ulcers. For how B12 compares with B6, see vitamin B6.

Does Evopure sell vitamin B12?

No. Evopure doesn’t make a B12 supplement, and if you’re low you need the dose your GP recommends.

Our Magnesium Glycinate Sleep Complex is a vegan, berry-flavoured bedtime drink with magnesium bisglycinate and citrate. Magnesium contributes to a reduction of tiredness and fatigue. See magnesium for energy. Our products are for adults only, and we don’t recommend them during pregnancy or breastfeeding.

Related guides

• Spirulina is not a reliable vegan B12 source: see spirulina and the B12 myth.
• Magnesium for PCOS, metformin and B12.
• How B12 fits with the other B vitamins.
• Vitamins for the immune system: who needs a supplement.
• Our guide to acid reflux explains how long omeprazole is usually taken and when to review it.
• If you’re comparing natural and synthetic forms, our guide to natural vs synthetic vitamins explains when each one wins.
• Our guide to dairy-free hot chocolate explains which UK plant milks are fortified and what to check on the carton.