What is vitamin B12 and why you should consider taking it
Vitamin B12 is one of those nutrients I think many of us have heard of without necessarily knowing what it actually does. It often gets mentioned alongside tiredness and energy, while supplement companies sometimes make it sound as though taking extra B12 will give everyone an instant boost. In reality, vitamin B12 has some very important jobs in the body, but that doesn’t mean we all need to rush out and buy a supplement.
Vitamin B12 is needed to help make healthy red blood cells and keep the nervous system working properly. In the UK, adults need around 1.5 micrograms of vitamin B12 a day, and many people can get what they need from their normal diet. There are, however, some groups who are more likely to struggle to get or absorb enough B12, which is why it’s useful to understand where it comes from and what can cause a deficiency.
As someone who has been vegetarian since I was a child, vitamins such as B12 are something I’ve been aware of for a long time. It is particularly relevant if you eat little or no animal produce, although diet is certainly not the only reason somebody can become deficient.
What is vitamin B12 and why do we need it?
Vitamin B12, sometimes called cobalamin, is one of the B vitamins and is involved in making red blood cells and keeping the nervous system healthy. Your body can store vitamin B12 for quite a long time, which means a deficiency caused by dietary changes might not necessarily become apparent straight away.
You might have seen B12 supplements marketed for energy, brain function or even stress and anxiety. I think it’s important to make a distinction here between getting enough B12 because your body needs it and assuming that taking extra will somehow give you superhuman energy.
A B12 deficiency can cause tiredness and a lack of energy, so correcting a genuine deficiency may understandably make somebody feel considerably better. That doesn’t mean taking more and more B12 will continually increase your energy if you’re already getting enough.
If you’re feeling unusually tired, it’s also worth remembering there are many possible causes. Iron deficiency, thyroid problems, poor sleep, stress and numerous medical conditions can all cause fatigue, so it’s better to find out what’s actually going on rather than assuming you need a particular vitamin.
What are the symptoms of vitamin B12 deficiency?
Vitamin B12 deficiency can cause a surprisingly wide range of symptoms, and some of them are quite vague. Feeling extremely tired or weak, having little energy, headaches, indigestion, a reduced appetite, palpitations and a sore or red tongue can all occur with vitamin B12 or folate deficiency.
B12 deficiency can also affect the nervous system, which is one reason it is important not to ignore it. Pins and needles, numbness, muscle weakness, problems with balance or coordination and changes involving memory or thinking can sometimes occur.
The difficulty is that none of these symptoms automatically means you have a B12 deficiency. Tiredness in particular has so many possible causes that trying to diagnose yourself according to a list on the internet probably won’t get you very far.
If you’re experiencing symptoms that concern you, particularly neurological symptoms such as unexplained numbness, pins and needles or problems with balance, speak to your GP rather than simply buying a B12 supplement and hoping for the best. Vitamin B12 deficiency can usually be investigated with blood tests alongside your symptoms, and finding out why your levels are low is important too.
Which foods contain vitamin B12?
Vitamin B12 is naturally found mainly in animal-derived foods, so meat and fish are good sources. Eggs, milk, cheese and other dairy products also provide B12, which means many vegetarians will get some through their normal diet.
As a vegetarian myself, eggs and dairy products have always been part of my diet, but obviously that isn’t the case for everybody. If you follow a vegan diet, fortified foods and/or an appropriate B12 supplement become particularly important because plant foods aren’t generally reliable natural sources of vitamin B12.
You’ll find B12 added to some breakfast cereals, yeast extracts and plant-based milk alternatives, although not every product is fortified and the amount can vary considerably. If you’re relying on fortified foods, checking the nutrition label rather than assuming every plant milk or cereal contains B12 is a sensible habit.
One thing I wouldn’t do is become obsessed with finding one magical B12-rich food. As with most areas of nutrition, looking at your overall diet is usually much more useful than focusing on an individual ingredient.
Can vegetarians become deficient in vitamin B12?
It’s certainly possible, although being vegetarian doesn’t automatically mean you’re deficient.
Vegetarians who regularly eat eggs and dairy products have dietary sources of B12 available to them, whereas somebody who eats very little of those foods may have a lower intake. Vegans need to pay particular attention to B12 because reliable natural plant sources are very limited.
If you’ve recently changed to a vegetarian or vegan diet, a B12 deficiency might not appear immediately because the body can store vitamin B12 for several years. That long delay is another reason I think it’s worth thinking about B12 as part of planning a balanced plant-based diet rather than waiting until symptoms develop.
This doesn’t make vegetarian or vegan diets inherently unhealthy. It simply means there are particular nutrients worth knowing about, just as there are nutritional considerations with any way of eating.
B12 deficiency isn’t always caused by your diet
This is probably the most important change I wanted to make to this guide because vitamin B12 is so often discussed as though deficiency simply means somebody hasn’t eaten the right foods.
You can eat plenty of B12 and still become deficient if your body can’t absorb it properly.
Pernicious anaemia is an autoimmune condition that prevents the body absorbing B12 properly and is a common cause of B12 deficiency in the UK. Conditions affecting the stomach or intestines can also interfere with absorption, as can some types of stomach surgery.
Crohn’s disease is one example of a condition that can affect B12 absorption. Certain medicines can also be involved, including proton pump inhibitors (PPIs) and metformin, although that doesn’t mean you should stop taking prescribed medication because you’ve read this. If a medicine could be contributing to a deficiency, that’s something to discuss with the healthcare professional looking after you.
Nitrous oxide can also interfere with vitamin B12, which is another potential cause doctors may consider.
All of this is why simply taking a multivitamin isn’t necessarily the answer if you’re experiencing symptoms. If there is an underlying problem with absorbing or using B12, finding that cause can affect what treatment you need.
Do you need a vitamin B12 supplement?
Whether you need a B12 supplement depends largely on your diet, your health and whether you have a diagnosed deficiency.
Someone following a vegan diet is much more likely to need a reliable source of supplemental or fortified B12 because ordinary plant foods aren’t a dependable source. Other people may be advised to take supplements because of their diet or individual circumstances.
If you eat a varied diet containing reliable sources of B12 and don’t have a condition affecting its absorption, you shouldn’t assume you need a high-dose supplement simply because B12 is important.
There’s also a difference between taking a supplement to ensure an adequate dietary intake and treating an actual vitamin B12 deficiency. If a blood test shows you’re deficient, the appropriate treatment depends partly on why you’re deficient and whether you have neurological symptoms. Some people can be treated with B12 tablets, while others require B12 injections.
That’s something to arrange through your GP or appropriate healthcare professional rather than deciding for yourself that you need private vitamin injections.
Are B12 sprays better than tablets?
You may have seen vitamin B12 sold as tablets, capsules, drops and mouth sprays, and clever marketing can make some of the more unusual formats sound as though they’re automatically absorbed better.
I wouldn’t choose a product on that assumption.
A spray might be more convenient for somebody who dislikes swallowing tablets, while somebody else may find a tablet considerably easier and cheaper. The important questions are whether you actually need a supplement and whether the product provides an appropriate source of B12 for your circumstances.
If you’ve been diagnosed with a deficiency, particularly one caused by problems absorbing B12 rather than simply not eating enough of it, follow the treatment recommended by your healthcare professional instead of replacing it with an over-the-counter spray.
How is vitamin B12 deficiency diagnosed and treated?
If your GP suspects vitamin B12 deficiency, blood tests can look at things including your haemoglobin, red blood cells, vitamin B12 and folate levels. Your symptoms matter too, because blood-test results aren’t always interpreted completely in isolation.
More information from the NHS about Vitamin B12 Deficiency.
If tests suggest you’re deficient, further investigation may sometimes be needed to work out why. That could include looking for pernicious anaemia or considering whether your diet, medication or another condition could be contributing.
Treatment then depends on the cause.
A diet-related deficiency may be treated with B12 tablets and dietary changes, whereas people who cannot absorb B12 properly may need regular injections. Some people need treatment for a relatively short period, while others require B12 replacement for life.
This is another reason I wouldn’t recommend simply taking supplements indefinitely without knowing whether you need them. If your B12 really is low, knowing why is potentially much more useful than just knowing which supplement was on offer in Boots that week.
Should you worry about getting enough vitamin B12?
For most people, B12 isn’t something that needs to become another nutritional worry. If you eat foods that naturally contain it, you’re probably already getting B12 as part of your normal diet, while people eating a vegan diet can plan reliable fortified foods and supplements into theirs.
What I think is useful is being aware of the situations in which deficiency is more likely and recognising that symptoms shouldn’t simply be dismissed or treated with random supplements.
I also think we need to be careful about the way vitamins are marketed. Vitamin B12 is essential, but essential doesn’t mean that taking extra automatically gives you extra energy, better mental health or a healthier body.
If you’re tired all the time or experiencing symptoms that could indicate a deficiency, finding the cause is much more useful than guessing.
For me, that’s probably the most sensible way to think about B12. Make sure your diet contains reliable sources, supplement appropriately if your diet requires it, and if you suspect you’re deficient, speak to your GP so you can find out whether B12 is actually the problem.
Other articles you might find helpful
If you are interested in nutrition and keep a check on what vitamins and minerals you have, these articles may also be helpful.
- Everything you need to know about Iron and Iron-rich foods
- Vitamin D guide
- Signs of vitamin deficiency in kids
- The importance of vitamin A in a diet
- The nutritional value of cranberries
- Why do you need vitamin b for energy
- Calcium – all you need to know about calcium-rich foods
