Vitamin B12 Deficiency Symptoms

Causes of B12 deficiency

It is a fact that many people who suffer from a deficiency of vitamin B12 do not have the problem diagnosed, and in many cases do not even realise they have this condition. This is because they put the symptoms down to a number of other everyday issues and thus the problem can be overlooked for a long time. If you want to find out more, please read on!

Most people are unaware of the symptoms of vitamin B12 deficiency; indeed many of them can be confused with other conditions. Therefore if they experience them, they have no idea that they could be in danger of real health issues. A chronic lack of this vitamin in the body is very serious indeed. Suffering from a long-term lack of vitamin B12 can lead to the onset of several serious illnesses. These include anemia, heart disease and and increased risk of some types of cancer.


Some people are more prone to this form of deficiency than others, which we also discuss on this page. Fortunately once the problem is diagnosed there are a range of ways the condition can be treated.

Once you have read through this page, if you suspect that you may be suffering from a B12 deficiency, it is vital that you seek help from your doctor or another medical professional immediately.

RDI Vitamin B12

  • 2.4µg Adults
  • 2.6µg Pregnant women
  • 2.8µg Breastfeeding women
  • 2.4µg Children 14-18 years
  • 1.8µg Children 9-13 years
  • 1.2µg Children 4-8 years
  • 0.9µg Toddler 1-3 years
  • 0.5µg Infants 7-12 months
  • 0.4µg Infants 0-6 months

What is Vitamin B12?

B12 is a member of the ‘B-complex’ vitamin family. Much like the other essential vitamins and minerals that are covered on this website, it has a fundamental role to play when it comes to the health and well being of the human body. In fact, it is crucial on a cellular level, which means it is vital to every part of your body. B12 is a water-soluble vitamin and can only be found naturally inside animal products. However, synthetic forms are readily available, and they are known by a variety of names. These include:

  • Aquocobalamin
  • Cobrynamide
  • Cobinamide
  • Cobamide
  • Cobalamin
  • Cyanocobalamin
  • Hydrocobalamin
  • Methylcobalamin
  • Nitrotocobalamin

You will notice that these names all include part of the word ‘cobalt’ in them. This is because the mineral cobalt is found at the centre of this vitamin. This structure is known as an organometallic compound;  B12 is the only essential nutrient to have this structure. The different names refer to the chemical structure of the various forms of this vitamin, and need not concern us here.

Do you want to learn more about foods that contain this important nutrient and also what the benefits of vitamin B12 are? Then please take a look at our Vitamin B12 foods page which has this information and a lot more besides!

What is a Vitamin B12 Deficiency?

Put simply, a B12 deficiency is where the body is lacking in this essential nutrient. However, the actual situation is rather more complex. This is because once the body has used up its stores of this vitamin, it will begin to display the various vitamin B12 deficiency symptoms that we will cover in the next section.

While there are many symptoms that can occur from a lack of B12 in the body, what is more unpleasant are the chronic illnesses that these symptoms can lead to. Along with iron and folate, vitamin B12 is one of the nutrients that is critical for the formation of red blood cells. Therefore a deficiency in any of these will lead to widespread symptoms. If you have insufficient red blood cells, they will not be able to carry sufficient oxygen around your body.

If these B12 deficiency symptoms are not treated then this can lead to anemia and also damage to your neurological and nervous systems. In severe cases this can be irreversible.

Vitamin B12 is absorbed in the intestines. However it is unusual because it requires a special protein in order for this to happen effectively. This protein, called intrinsic factor (IF), is released by cells in the stomach. Under certain conditions, the stomach does not make enough intrinsic factor. When this happens the intestine cannot properly absorb vitamin B12 into the blood. This condition is known as pernicious anemia (a different condition to the anemia caused by lack of red blood cells) and we will discuss it below in more detail.

Vitamin B12 Dosage

You can find out the recommended daily amount of vitamin B12 at the top right of the page.


In this section we cover vitamin B12 deficiency symptoms, so it is likely the most important part of the page. If you are experiencing one or several of these symptoms then it is important to seek advice from a qualified health professional as soon as possible. They will be able to confirm whether or not you have a lack of B12 or whether there is another underlying medical condition causing these symptoms that needs further investigation.

B12 deficiency symptoms include:

  • Heart palpitations
  • Redness and soreness of the tongue
  • Extreme tiredness
  • Anemia
  • Tingling or numbness in the feet, much like pins and needles
  • Muscle weakness
  • Confusion
  • Paranoia
  • Problems with balance
  • White spots on the skin
  • Feeling depressed
  • Lapses in memory
  • Problems with understanding and judgement
  • Feeling nervous
  • Paleness to skin
  • Feeling exhausted and being short of breath after only light or moderate exercise
  • Loss of appetite

As you can see, many of these symptoms are also signs of other illnesses Therefore it is important to seek medical advice and not just go ahead with self-diagnosis. The sooner you see a doctor and get tested for a vitamin B12 deficiency the sooner you can have the condition treated.

People with a vitamin B12 deficiency often disregard the symptoms as regular signs of being rundown and stressed out from everyday life. However, if you have several of these symptoms it is worth getting checked out rather than potentially letting the condition go undiagnosed.

What are the causes of vitamin B12 deficiency symptoms?

There are several causes of vitamin B12 deficiency. We will cover these below.

  • Pernicious anemia is an autoimmune condition that affects the stomach. It is the main cause of vitamin B12 deficiency in the UK. Vitamin B12 is absorbed into your body through the stomach, by way of the protein IF (intrinsic factor) which attaches itself to the vitamin. Pernicious anaemia causes your immune system to attack the stomach cells that produce IF, so you can no longer absorb vitamin B12. The exact cause is unknown, but it is more common in certain groups of people. These include people with a family history of the condition, in women over 60, and those with another autoimmune condition, such as Addison’s disease or vitiligo.
  • Some people can develop a vitamin B12 deficiency through a diet that does not contain enough of this nutrient. This is more common in people with a very poor diet because B12 is primarily found in meat, fish and dairy products. People following a vegan diet may also be more susceptible. As stores of B12 in the body can last several years, it can take a long time for dietary problems to show up through deficiency symptoms.
  • Some stomach conditions or operations can prevent your body from absorbing enough vitamin B12. For example, a gastrectomy (surgical procedure where part of your stomach is removed) will increase your risk of developing a vitamin B12 deficiency. Certain conditions affecting the intestines can also affect your B12 absorption. Crohn’s disease (a long-term condition that causes inflammation of the digestive system lining) can sometimes stop your body getting enough vitamin B12.

Vitamin B12 and medication

Certain types of medication can lead to a reduction of B12 in your body. Indigestion medications can make a deficiency worse. This is because some kinds inhibit the production of stomach acid which is needed to release vitamin B12 from your food. However, B12 can be stored in the body for a year or two, so short term use of these medicines is unlikely to cause problems. There is also a condition known as functional vitamin B12 deficiency. In this condition there is a problem with proteins that help transport B12 between cells. Unfortunately this condition occurs regardless of B12 levels in the blood, however it is very rare.
B12 deficiency is more common in older people. It affects around 1 in 10 people aged 75 and over and 1 in 20 people aged between 65 and 74.


Although it is uncommon, B12 deficiency can lead to complications. This is more likely you’ve been lacking in the vitamin for some time. Potential complications can include:

  • Temporary infertility
  • Heart conditions
  • Neurological changes (things affecting your nervous system)
  • Pregnancy complications and birth defects
  • Pernicious anemia can increase the risk of developing stomach cancer.

It is also worth noting that taking large amounts of folic acid (over 1000 mg per day) can have an unexpected effect; it can treat B12-related anemia without treating the underlying vitamin B12 deficiency. This can cause problems because if it is not noticed, a B12 deficiency can eventually cause irreversible damage to the nervous system. This is a particular concern for older people as it becomes more difficult to absorb B12 as you get older.


The best way to get vitamin B12 into your body is through foods rich in this nutrient, through the use of supplements or sometimes via combination of the two. Both of these can easily be bought in supermarkets or online. If you only have a borderline deficiency, a change in your diet and oral supplements may be all that is needed. In the case of tablets, it is a good idea to take them at the same time every day. This way, it becomes a routine and you won’t forget!


However, for a more severe deficiency, B12 supplements are usually given by injection at first. People say if you’re used to the deficiency symptoms, a shot of B12 is like getting a regular energy boost!

Depending on whether your B12 deficiency is related to your diet, you will either require B12 tablets between meals or regular shots. Treatment may be necessary for the rest of your life, but your medical practitioner will discuss this with you. In any case, if you are treating the condition yourself with vitamin B12 rich foods, this is probably something you will want to continue in the long term to prevent it from reoccurring.