Everything you need to know about B12 deficiency and how to treat it

Fatigue and muscle weakness. Memory loss and confusion. Pins and needles. The signs of B12 deficiency are vague, wide-ranging and usually develop gradually. It’s something that tends to impacts us as we age – but young people can suffer with it too.

And new evidence suggests that, as we age, even those who are not “deficient” could be unknowingly experiencing symptoms and would benefit from a higher intake.

A recent American study of 231 healthy volunteers, whose median age was 71, found that those with lower B12 levels (but still in the normal range) showed signs of neurological and cognitive decline when performing a battery of timed tests in comparison with participants with higher levels.

So what is B12 doing for us, and how do we keep our levels up?

A B12 deficiency can result in brain fog, fatigue and poor co-ordination, among other issues.Credit: Getty Images

The seven vitamin B12 deficiency symptoms

“B12 is essential for a functioning nervous system, healthy red blood cell formation and DNA synthesis,” says Dr Sabine Donnai, GP and longevity doctor. “It plays a role in the conversion of protein and fat into energy, and the formation of neurotransmitters and hormones that control our brain function.” B12 is closely linked to folate (also known as B9). They play similar roles in the body and B12 is crucial for folate metabolism – a vital bodily process that allows cells to function properly – and vice versa.

A deficiency has a very wide impact.

1. Lack of energy

“Unexplained general tiredness and fatigue, maybe breathlessness too, can be a sign of vitamin B12 deficiency,” says Donnai. “If B12 levels are low, the red blood cells will struggle to form, which means you won’t have enough oxygen delivered to any part of your body or your organs, whether it’s kidneys, brain, heart or lungs.”

2. Strange sensations

These could include burning, numbness or pins and needles in hands, legs and feet.

“We need B12 to make the ‘myelin sheath’, the protective layer that surrounds nerve cells,” says Dr Geoff Mullan, functional medicine practitioner at Human People. That layer allows for the efficient transmission of our nerve signals. “Without it, you stop conducting so well. If it goes on for long enough, the nerve damage can be permanent.”

3. Unsteadiness on the legs

Or other difficulties with coordination. This damage to the nerves and spinal cord can also lead to impaired balance and unsteadiness, as well as difficulty with motor skills.

4. Memory loss

“We need B12 to make new neurotransmitters,” says Mullan. The nerve damage and brain atrophy caused by a B12 deficiency can mirror the symptoms of dementia.

5. Brain fog

This can manifest as difficulty thinking and reasoning. People with a vitamin B12 deficiency will often describe being unable to focus or concentrate, and can struggle to complete tasks. “You’ll struggle to ‘activate’, i.e. start tasks, and also ‘do’, i.e. continue tasks,” says Mullan, “as all your mental and physical systems are struggling.”

6. Depression, agitation, anxiety and mood swings

“B12 is important in the formation of serotonin, which helps regulate mood, sleep and appetite,” says Mullan. It’s also involved in the production of dopamine and norepinephrine, other neurotransmitters that play a key role in mood.

7. Poor oral health

Recurrent mouth ulcers, painful cracks at the corners of the mouth and a sore, inflamed tongue.

“In serious cases, the tongue almost becomes smooth and glossy like the inside of your cheeks, where usually the tongue should be rough,” says Donnai. (This is called “glossitis” and is probably caused by lack of oxygen and nutrients reaching the tongue.)

How to diagnose a B12 deficiency

It’s easy to test your B12 level through your GP or pharmacy – you can buy at-home tests too. “If you are going to use the at-home tests, make sure they have the CE mark,” says Donnai. One problem with at-home finger-prick tests is that, if not done properly, you can squeeze out serum, dilute the result and get an inaccurate reading. Any results should be taken to the doctor. Understanding whether you have a deficiency is more complicated than a single number, says Donnai. “We usually conduct tests that won’t be done in isolation. It will require measuring haemoglobin levels and red blood cells too.”

How to treat a B12 deficiency

Injection
The fastest way to correct a serious deficiency is through a course of B12 injections called hydroxocobalamin, typically given every other day over a two-week period. Injections are the only treatment for people whose deficiency is a result of a condition called pernicious anaemia which prevents the absorption of B12 in the intestine. With injection, B12 is delivered directly to the bloodstream, bypassing the digestive system. In cases of pernicious anaemia, injections are required for life.

Nasal spray
This is an option for people who don’t like injections, again bypassing the digestive system and delivering B12 directly to the bloodstream through the nasal lining. “I am not a fan of sprays as dosing with them can be erratic, although absorption is often high,” says Mullan. “The only patients I have seen with dangerously high vitamin D levels are people using sprays.”

Tablet
“For most people whose B12 deficiency is dietary-related, a high strength tablet works just as well as injections, and they are a lot less expensive,” says Mullan. “The best ones are those that are absorbed in the mouth and come in its active form, methylcobalamin.” For adults with diet-related B12 deficiency, the usual dose is 50 to 150 micrograms taken once a day. For adults with a B12 deficiency not caused by diet, it’s one or two 1000-microgram tablets taken once or twice a day.

What causes B12 deficiency?

Diet
“A vegan diet is probably the biggest cause,” says Donnai. “A B12 deficiency is one of the biggest problems a vegan can face.” B12 is found mainly in animal products – meat, fish and dairy. (Dairy is important, even if you eat fish and meat, as it makes B12 more “bio-available”.) However, high-meat, low-veg diets can also be a problem. “People on Atkins-type diets restrict the intake of foods that are rich in folate, like fruits, vegetables and wholegrains, and if you are lacking folate, your B12 can’t work properly,” explains Donnai.

Low stomach acid
People who are on proton pump inhibitors to reduce acid in their stomach are at risk of B12 deficiency. “It’s a massive cause,” says Mullan. “When you eat a piece of protein, B12 is bound on and you need stomach acid to release it. If you don’t have the acid, it doesn’t happen.” (This is why B12 supplements that are absorbed in the mouth work better when the stomach isn’t doing its job.) Metformin, the medication taken for Type 2 diabetes, can also lead to B12 deficiency.

Coeliac disease
B12 deficiency is common in cases of coeliac disease, especially when untreated. The damage caused by coeliac disease to the small intestine can prevent the absorption of nutrients. Other conditions that can cause B12 deficiency include Crohn’s disease and chronic pancreatitis.

Age
Vitamin B12 deficiency becomes more common as we age, affecting around one in 10 people aged 75 or over and one in 20 people aged over 65. This is partly because digestion slows down and stomach acid decreases, so the capacity to absorb B12 declines too. “Ageing itself requires more energy and more repairing needs to be done and so the need for B12 is higher,” says Donnai. “At the same time, as we age, we tend to eat a less varied diet.”

Alcohol
Alcohol affects B12 levels in many ways. It decreases stomach acid which we need to release B12 from food, and also irritates the lining of the stomach and intestines, leading to gastritis, which also reduces absorption.

Pernicious anaemia
Pernicious anaemia is an autoimmune disease which prevents the absorption of B12. When B12 is released from food, it binds on to a transporter called intrinsic factor, which then transports the B12 through the small intestine where it will be absorbed. When someone has pernicious anaemia, the body attacks the cells which produce this intrinsic factor. Without this key transporter, the B12 can’t be transported and utilised. Although the condition can occur at any age, peak occurrence is at 60 years of age and it’s more prevalent in women. Anyone with a confirmed B12 deficiency should also be tested for intrinsic factor antibodies.

What foods are highest in B12?

“You need to be eating as varied a diet as possible in order to keep your B12 and folate levels up together,” says Nicola Shubrook, a nutritionist with Urban Wellness. “For B12, it’s animal products – meat, fish and dairy. If you’re a vegan, there is fortified nutritional yeast. Folate-rich foods are leafy green vegetables, broccoli, peas, citrus fruits, chickpeas and kidney beans.” Vegemite or Marmite is another vegetarian source of B12, although with a very high salt content. One 8g serving provides 76 per cent of the recommended B12 daily intake.

“The NHS guidelines recommend 1.5mcg of B12 for adults each day,” says Shubrook.

How long does it take to recover from vitamin B12 deficiency?

“It depends how low and serious the deficiency is,” says Donnai. “If you’ve been feeling fatigued and are just below the norm, you’ll be fine after a week. If it’s a significant deficiency where your nervous system is affected, it might take months to get back to normal.”

Vitamin B12 is water-soluble so leftover amounts will leave the body through urine and there is little risk of “overdosing”.

The Telegraph UK

Make the most of your health, relationships, fitness and nutrition with our Live Well newsletter. Get it in your inbox every Monday.