I was exhausted, wobbly on my feet and plagued by brain fog. 1 in 5 adults over 60 have this hidden condition. Doctors regularly miss it – and left untreated it’s fatal. These are the warning signs you MUST know

For Zita Wells it took a ‘funny turn’ while shopping at her local drugstore for her to realize that something was very wrong with her health.

The pet carer, 45, had been feeling more tired than usual in recent months – and regularly found herself breathless on dog walks that once felt effortless.

‘I couldn’t understand why I felt so exhausted, but as it happened so slowly there didn’t seem to be anything I could pinpoint,’ said Zita. ‘I was usually super-active but my body just felt like it was made of lead. I tried to get more sleep but that didn’t help.’

Then, while out shopping for an upcoming vacation, she encountered a new sensation.

‘I was overcome with a strange feeling of weakness and wobbliness, and found myself sliding to the ground, despite being totally conscious,’ she says. ‘My body became floppy. One moment I just felt a bit vacant, and the next I was on the floor.’

After booking an urgent appointment with her primary care physician, Zita was sent for blood tests. Within days she had an answer: she was severely deficient in vitamin B12, an essential nutrient responsible for producing red blood cells, repairing DNA and maintaining a healthy brain and nervous system.

‘I didn’t know what B12 was until I learned that I was deficient in it,’ said Zita. ‘But as soon as I heard the symptoms listed, it all made sense.’

Experts say Zita, from Sussex in the UK, is one of a growing number middle-aged being affected by a silent epidemic of vitamin B12 deficiency – dubbed the ‘hidden hunger.’

While it is a global problem, current estimates suggest about one in 25 American adults have vitamin B12 deficiency. It becomes far more common with age, with around one in five adults over 60 showing at least one abnormal biomarker linked to low vitamin B12 status.

The rise in vitamin B12 deficiency is being driven by the increasing number of Americans living longer, taking more medications that interfere with absorption and adopting more plant-based diets.

It can cause a wide range of vague symptoms, including fatigue, brain fog, a sore tongue and tingling in the hands and feet. 

Yet many cases are overlooked or are diagnosed only after months or years, because symptoms developing slowly – and the fact they tend to be non-specific and common to many other problems.

But even more concerningly, they say, available tests for the condition are also deeply unreliable – correctly identifying it just 50 per cent of the time. As a result, millions of Americans could be living with deficiencies for years – risking irreversible nerve damage, heart failure and even death.

‘Two decades ago the medical establishment thought that nutrition in developed countries was no longer a problem – because we eat plenty of food,’ says Professor Martin Warren, a synthetic biologist at the Quadram Institute.

‘It’s only in the past five years or so that people have begun discovering the worrying problems we’re still having with nutrition levels. And vitamin B12 deficiency is a key example of that.

‘More and more people are struggling with it. And the older you get, the more common it is. Yet we still don’t have adequate testing – or enough awareness about the condition. People are slipping through the net.’

Also known as cobalamin, vitamin B12 is found mainly in animal products such as meat, fish, eggs, milk and cheese.

Most people will get enough of the nutrient from a normal, balanced diet alone – the recommended intake is 1.5 micrograms a day, which can be found in two large hard-boiled eggs, or a 3-ounce serving of beef.

But those who follow a vegetarian diet are far more likely to have insufficient levels – while vegans are at particularly high risk of deficiency.

People who eat a diet high in ultra-processed foods may also be more at risk, research suggests, as high-sugar, high-salt and high-fat products ‘crowd out’ more nutritious staples, leading to deficiencies.

In most cases, vitamin B12 deficiency causes relatively mild symptoms, such as fatigue, pale skin, a sore or swollen tongue, and difficulty with concentration and memory. However, in severe or prolonged cases it can lead to serious complications, including vision loss, heart problems, cognitive decline, dementia-like symptoms, stroke and, in rare instances, psychosis.

The condition made headlines this year after the death of university student Georgina Owen, 21, who took her own life while experiencing what a coroner described as ‘delusional beliefs’ linked to a severe vitamin B12 deficiency caused by her vegan diet and failure to take supplements.

An inquest heard that Ms Owen, from Essex, had displayed erratic behavior and a marked deterioration in her mental health in the weeks leading up to her death.

Most of the time, when B12 deficiency is caused by a restrictive diet, experts say the solution is simple – vitamin B12 supplements are available over the counter and work well for most. Others, however, are unable to absorb the vitamin regardless of how much they consume, requiring regular B12 injections to keep their levels up.

The autoimmune condition pernicious anemia can cause B12 deficiency when immune cells attack healthy cells in the stomach, rendering it unable to absorb vitamin B12.

Certain drugs – including proton pump inhibitors such as omeprazole, which reduce stomach acid, and the diabetes medication metformin – can also cause B12 deficiency by blocking the body’s ability to absorb it.

But another group are also at high risk of developing the condition: older adults.

‘As we get older, our bodies produce less stomach acid,’ says Professor Warren. ‘This is what breaks down food and releases vitamin B12 into our system – so as a result, adults over 60 are much more likely to become deficient.’

As we age, he adds, we also tend to eat less – which can further exacerbate the issue.

The trouble with this, experts say, is that vitamin B12 becomes more important for our bodies as we get older. A number of studies published in recent years have investigated the role the vitamin plays in aging and muscle function – and revealed a disturbing truth. One 2026 study from Cornell University found that low vitamin B12 could interfere with the DNA inside muscle cells – causing muscle wasting and loss of strength.

While the body naturally loses muscle as it ages – leading to an increased risk of injury, higher blood sugar levels and reduced mobility – vitamin B12 deficiency could hasten the process, the researchers warned.

However, maintaining adequate levels of the vitamin could reverse the problem, another recent study from the University of Alabama found, after examining the effect of vitamin B12 supplementation in older female mice.

This could be an especially important area of research, says Professor Warren, given our growing understanding of the importance of muscle to healthy aging – with studies increasingly suggesting that muscle strength is a better predictor of lifespan and mortality than body mass index (BMI). 

‘Older adults are more likely to be taking medications that block vitamin B12 absorption, as well as naturally producing less stomach acid, so it becomes a perfect storm,’ says Professor Warren.

‘It’s much more common than people realize. In a room of 20 people, one person, statistically, will have vitamin B12 deficiency. If it’s a room of people over 50, that rises to one in five.

‘Many more people than realize it may need to take vitamin B12 supplements.’

Despite its prevalence, detecting the condition remains difficult.

The first hurdle, says Dr Ali Niklewicz, a nutrition scientist and researcher at the University of Surrey, is that the symptoms of a vitamin B12 deficiency can also be attributed to a wide range of other conditions.

‘Tiredness, fatigue, tingling in the hands and feet, brain fog – these are all quite vague,’ she explains. ‘And many people can have a B12 deficiency for a very long time without realizing it.’

Many women, like Lucy Smith, wrongly attribute the signs of deficiency to menopause, which can cause similar fatigue and cognitive impairment, says Professor Warren.

Some believe they have dementia, he adds – and some may even end up being wrongly diagnosed with the condition.

‘Although there’s more awareness now about vitamin B12 deficiency, there’s still very little expertise on the clinical side. Nutrition has dropped off the curriculum for medical students in recent decades,’ says Professor Warren.

But even more concerningly, he says, existing tests for the condition are deeply flawed.

‘The most common blood test measures the total amount of vitamin B12 in blood serum – but this marker is remarkably unreliable,’ he adds.

‘Because we only need a tiny amount of vitamin B12 in the first place, it’s a very hard thing to measure. When someone is already deficient, you’re measuring a tiny amount of a tiny amount. As a result, there’s less than a 50/50 chance that you’ll get the right diagnosis if you are deficient. It’s not really a test that’s worth doing, but we’re still using it.’

Better ways of testing for the condition do exist – but they’re more expensive and less widely available.

‘There are tests that, rather than looking for vitamin B12 in the blood, look for the cells that vitamin B12 helps produce after it’s absorbed by the body. When these aren’t there, it strongly implies a lack of the vitamin – and is a much better measure of deficiency. But they’re much more costly tests to run,’ Professor Warren says. 

At present, patients who are tested for the condition but whose results don’t clearly show a deficiency, are often turned away without treatment.

This was the experience of Catherine Watkin, 57, who spent more than two decades suffering from a vitamin B12 deficiency that was so severe it often left her unable to work.

‘I was a recruiter in London in my early 30s when I suddenly began feeling unbelievably exhausted. I could hardly function – despite changing nothing else in my routine,’ says Catherine. ‘I went to so many doctors and alternative practitioners over the years but they could never find out what was wrong – despite doing numerous blood tests.

‘By my 50s I began to develop neurological symptoms as well – searing pain in the tips of my fingers and brain impairment – and was having to take a lot of time off work.

‘Even taking a shower would exhaust me to the point of having to lie down.’

Over the past 15 years, Catherine tried treatment after treatment to cure herself, spending an estimated $135,000 on therapies for her thyroid and adrenal glands, and even having dental work – but to no avail.

Then, 18 months ago, a new doctor, after hearing her symptoms, immediately suggested vitamin B12 deficiency.

After finding a private clinic in Cambridge, in the UK, Catherine was put on a course of vitamin B12 injections, despite her levels showing up as normal on blood tests.

Within just weeks of the first injection, she felt her tiredness begin to melt away.

‘It was miraculous,’ she adds. ‘Today, I’m totally symptom-free. I’m back to living my full, normal life. I just wish I had figured it out earlier.’

While testing remains as it is, the best route to getting more people diagnosed with the condition is to raise awareness, say experts.

Anyone – particularly if over the age of 50 – experiencing the typical symptoms of vitamin B12 deficiency should raise them with their doctor and ask for a vitamin B12 test, they advise.

And as for doctors, says Professor Warren, even if results appear to be in a gray area, it’s better to be safe than sorry.

‘If a patient is getting borderline vitamin B12 test results, doctors should refer them for a more detailed test. Then see if there’s an improvement after taking vitamin B12 – and the best way to do this is by getting an injection.’

For those concerned but who don’t have a deficiency, it’s worth simply being more conscious of what you eat, particularly as you age, says Dr Niklewicz.

‘If you eat a mainly plant-based diet, make sure to take supplements,’ she says. ‘Older adults on various medications are also at increased risk.’

But be sure to take any vitamin B12 supplements with a meal – she warns – as this will allow for much better absorption of the vitamin because of the spike in stomach acid needed to digest food.

‘It’s important that people are aware of vitamin B12 and nutritional deficiencies in general,’ says Dr Niklewicz. ‘But the good thing about it is that, once it’s found, it’s very treatable.’