Afternoon slumps, extreme fatigue and brain fog are being MISTAKEN for symptoms of the menopause – but millions of women could have troubles reversed with a shot of this crucial vitamin

Vitamin B12 has long been the quiet workhorse of nutrition – essential yet often overlooked because we generally get enough through a balanced diet.

But that assumption is starting to shift. As weight-loss injections reshape how we eat and plant-based diets become increasingly popular, deficiencies in this vital nutrient are more common. This can lead to fatigue, low mood, muscle aches, brain fog and memory problems.

Around 6 per cent of people in the UK are classed as deficient – rising in some estimates to 25 per cent in over-60s.

And that may only be the tip of the iceberg, as a recent report from the National Institute for Health and Care Excellence suggests a further fifth of adults may have sub-optimal levels: they may not meet the definition for deficiency, but many still experience symptoms.

Vitamin B12 is needed to produce red blood cells, support nerve health and help make our DNA. Unlike some nutrients, the body cannot produce it, so it must come from diet – or supplements.

If levels drop too low for too long, you risk pernicious anaemia – where red blood cells become unusually large and less efficient at transporting oxygen.

This can lead to fatigue, muscle weakness and neurological symptoms such as balance problems and short-term memory loss. In more severe cases it can result in long-term nerve damage.

Vitamin B12 is found mainly in animal products such as meat, fish, eggs and dairy. But even people who consume enough B12 can struggle to absorb it

Dietitian Duane Mellor says we only need a small amount of vitamin B12 – only 1.5microgram [mcg] per day for adults – which you can easily get from one egg or a glass of milk

Vitamin B12 is found mainly in animal products such as meat, fish, eggs and dairy – and some breakfast cereals and plant milks are fortified with it.

However, even people who consume enough B12 can struggle to absorb it.

‘We don’t actually need a large amount – only 1.5microgram [mcg] per day for adults, which you could easily get from having, for example, a glass of milk and one egg – the problem lies in how it’s broken down in the gut,’ says Duane Mellor, a dietitian and an honorary associate professor at Leicester University.

As he explains, stomach acid breaks down B12 from food so it can then bind to a special protein called intrinsic factor and then be ‘absorbed in the last part of the small bowel – but certain groups of people aren’t as good at absorbing it’.

He adds: ‘This includes the over-60s, partly because of age-related changes in the cells that produce intrinsic factor.’

People with conditions such as coeliac disease are also more vulnerable due to their damaged gut lining – as are those taking medications that reduce stomach acid such as PPIs (proton pump inhibitors) to treat heartburn.

A fast-growing group adding to the B12 deficiency figures is those on GLP-1 weight-loss injections, such as Wegovy and Mounjaro.

As Dr Mellor explains: ‘The medication dampens down the activity of the vagus nerve, which connects the brain to the gut and is responsible for triggering acid to be secreted. This means food is not broken down well and so vitamin B12 is less absorbed.

‘Plus, people on GLP-1s eat less – so unless they’re choosing a diet that is high in meat, fish, eggs or dairy, their B12 intake will be low.’

Another issue is that some experts feel the recommended daily amount (RDA) of vitamin B12 in the UK is too low.

UK guidelines suggest 1.5mcg – but in the US that figure is 2.4mcg, for example, and recent research suggests an adequate intake should actually be as high as 4mcg – a recommendation now used in countries including Germany and Switzerland, says Dr Mellor.

And those following plant-based diets need a daily supplement of at least 10mcg, advises the British Dietetic Association (for severe deficiencies injectable doses can be as high as 2,000mcg).

Supplements now come in a range of forms – but are they equally effective? We asked Dr Mellor to assess a selection; we then rated them.

Budget pill

Boots vitamin B12, three packs of 180 tablets, £22.80, boots.com

DOSE: 10mcg

COST PER DAY: 4p

CLAIM: ‘Ideal for those following a vegan or vegetarian diet. Reduces tiredness and fatigue.’

EXPERT VERDICT: There are different forms of B12 used in supplements, but unless you have a gut problem it won’t make much difference: some products contain methylcobalamin and adenosylcobalamin, ‘active forms’ which mean they’re ready for use by the body – but synthetic cyanocobalamin is most common in supplements, and is converted in the body to the active form. In healthy people, without gut conditions, cyanocobalamin is easily absorbed via the gut. It’s unclear which form this product contains.

The dose is fine for maintenance, but isn’t high enough to rebuild B12 stores in someone with a genuine deficiency. This is the cheapest way to get your B12 of all those reviewed here. 7/10

CAPSULES

Cytoplan vitamin B12 methylcobalamin & adenosylcobalamin, £10.99 for 60, cytoplan.co.uk

DOSE: 1,000mcg

COST PER DAY: 18p

CLAIM: ‘High potency capsules.’

EXPERT VERDICT: This is a very high dose – the second highest here – so only needed for a more serious deficiency.

Although it contains active forms of B12, as a swallowed capsule it still relies on intrinsic factor (made in the stomach) for absorption. For this reason, tablets and capsules are not ideal for anyone with gut absorption problems (e.g. older people and those with inflammatory bowel diseases or who are taking certain medications such as PPIs) – as they may not be well absorbed.

These patients would do better with a product absorbed in the mouth, such as a spray. 5/10

SACHET

Cymbiotika liposomal vitamin B12 + B6, £47.95 for 28 sachets, cymbiotika.co.uk

DOSE: 1,000mcg

COST PER DAY: £1.71

CLAIM: ‘In a liposomal delivery system ensuring superior stability and absorption.’

EXPERT VERDICT: B12 absorption normally requires exposure to stomach acid and intrinsic factor. Encasing the vitamin in a liposome – essentially a fat bubble – may interfere with this process. I’d need to see independent data to support the claims.

The added vitamin B6 is unnecessary for most people, as it is easily obtained through diet.

Given the high cost and lack of clear benefit this is not one I’d recommend. 1/10

SPRAY

Healthspan vitamin B12 blackcurrant oral spray, £13.99 for 15ml, healthspan.co.uk

DOSE: 250mcg

COST PER DAY: 14p

CLAIM: ‘Enters the bloodstream quickly – ideal for those who find swallowing tablets difficult.’

EXPERT VERDICT: Getting the vitamin sublingually (absorbed via the tissues in the mouth) means it goes straight into the bloodstream and bypasses the gut – which could be useful for those with gut absorption issues, such as the over-65s or those who have inflammatory bowel conditions.

Studies suggest sublingual B12 can be as effective as the injections prescribed for deficiency. The key is in the technique: hold it in the mouth for 30-60 seconds rather than swallowing. 9/10

LIQUID

Global Healing vitamin B12, £32.95 for 30ml, healf.com

DOSE: 5,000mcg

COST PER DAY: £1.09

CLAIM: ‘Delivers three bioactive forms of B12 for rapid absorption.’

EXPERT VERDICT: B12 is one of the few vitamins thought to have no safe upper limit – any excess is just removed in urine. But it’s worth noting that most studies only go up to 2mg daily. For most people this dose is unnecessarily high.

This is an expensive product – and despite the claim, there are only two bioactive forms of B12: the third type in this, hydroxocobalamin, would be converted in our bodies before it is used. 5/10

LOZENGES

Seeking Health Hydroxo B12 with folinic acid, £17.99 for 60, healf.com

DOSE: 1,000mcg

COST PER DAY: 30p

CLAIM: A ‘methyl-free’ option, this ‘blends B12 with folic acid, to help you feel energised’.

EXPERT VERDICT: Vitamin B12 and folate work together for energy production, but supplementation is only necessary if levels of both are low. Folate is found in wholegrains, fruit and veg.

A small number of people report sensitivity to ‘methylated’ B vitamins – that is, active, ready-to-use forms. So if you have noticed symptoms such as agitation or poor sleep when taking B12 in the past, a methyl-free version might be a good choice.

Like sprays, lozenges allow absorption in the mouth, which could be useful for some. 7/10

VITAMIN SHOT

Centrum energy and vitality B12, £16 for 15 shots, boots.com

DOSE: 500mcg

COST PER DAY: £1.07

CLAIM: ‘Each small bottle contains a shot of high-dose vitamin B12, with zinc and niacin.’

EXPERT VERDICT: The dose is higher than most people need, but not high enough to treat deficiency. The small amounts of zinc and niacin are negligible and easily obtained from a balanced diet.

This also contains the sweeteners sorbitol and mannitol, which can have a laxative effect if consumed in large amounts. This is one to skip. 2/10

GUMMIES

WeightWorld vitamin B12 gummies, £12.99 for 120, weightworld.uk

DOSE: 1000mcg

COST PER DAY: 11p

CLAIM: ‘Potent vitamin B12 in its activated form for high absorption.’

EXPERT VERDICT: Gummies offer a convenient option for those who dislike tablets, and because they begin breaking down in the mouth, some B12 absorption can occur there.

Sugar is the first and second ingredient – you won’t get too much in per gummy, but many people might prefer to avoid added sugar. 5/10