Vitamin B12 deficiency causes, symptoms and treatments

Vitamin B12, also known as cobalamin, is one of the most important micronutrients essential for the proper functioning of the body. Despite its great importance, it was not discovered as such until the middle of the 20th century. It was in 1956 when a team of researchers discovered its structure following a study on pernicious anaemia. This type of anemia occurs when a person has difficulty absorbing cobalamin, which causes symptoms such as fatigue, weakness. Although, there are certain neurological symptoms of vitamin B12 deficiency that are much more important, B12 is one of the most important to enjoy a good quality of life as it plays a key role in the metabolism of blood cells and the nervous system.

When a person has very low levels of vitamin B12 for a long period of time, an excessive amount of homocysteine builds up in the body, an amino acid produced by the body itself. The excessive accumulation of this amino acid increases the probability of suffering a cardiovascular accident, among others, as it causes damage to the arteries. Of course, excess vitamin B12 in the body is not good either, nor is any nutritional excess.

What is vitamin B12 in the body for?

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This vitamin is one of the most important micronutrients for the body; it is often essential for its proper functioning and therefore to ensure good health and, consequently, quality of life.

Vitamin B12 has many functions in the body:

  • First, it is responsible for the production of adrenal hormones.
  • Secondly, it is responsible for metabolizing fats and carbohydrates, which is essential for good cardiovascular health.
  • Third, cobalamin forms red blood cells, which carry oxygen to the cells.
  • Fourth, this vitamin helps to absorb iron, which is key to preventing anaemia.
  • And, in fifth and last place, among the main ones, it optimizes the development of the body’s nervous system.

Is it serious to have vitamin B12 deficiency in our body?

Symptoms of vitamin B12 deficiency headache

Although it may seem like an extraordinary pathology, vitamin B12 deficiency is a very common disorder. Clinical studies recently conducted in Framingham, USA, have reported that 25% of adults suffer from it.

It is clear that gravity is not such that this deficiency is considered an emergency, although, as long as you do not have adequate levels of cobalamine in your body, you have to remedy it. A separate case is that of the second and third world population where it is very difficult or practically impossible to eat a complete and balanced diet. In this regard, we can say that one of the basic actions of NGOs and humanitarian aid associations is precisely to keep the essential nutrients for the body stable and in the right quantity.

Well, the fact is that this deficiency poses great health risks for both adults and children, as vitamin B12 performs almost vital functions.

  • On the one hand, this nutrient is one of the main producers of energy in the body, reducing fatigue and increasing endurance.
  • On the other hand, it favours the assimilation of nutrients such as iron, which is one of the keys to the proper functioning of the body.
  • In addition, it helps, as we have said, in the production of red blood cells in the blood, which are key so that it has the nutrients necessary to feed all the cells and that these, in turn, work optimally.
  • It also strengthens the cardiovascular system.
  • And finally, it improves the mood and gives us vitality.

Therefore, the benefits of this nutrient in the human body are many, both physically and mentally, not to mention the other secondary benefits that are obtained by taking the recommended amount of this nutrient.

Causes of B12 deficiency in the organism

The causes that cause a lack of this nutrient in the body can be many and varied:


As a person ages, they are more likely to have cyanocobalamin deficiency in the body. This has to do with two aspects. On the one hand, older people tend to consume fewer B12-containing foods and, in addition, fewer B12-containing foods. On the other hand, once the stomach is over 50 years old, it loses much of its ability to process food as it had been doing until then, which intervenes in the long process that cobalamin carries out in our body.

Vegetarianism or Veganism

Foods of vegetable origin contain just enough of this micronutrient. B12 is mostly found in food of animal origin such as beef, salmon or eggs. Therefore, in vegetarian or vegan people it is very frequent that a low level of this micronutrient is suffered because their diet, as ethically positive as it may be, is not unbalanced and insufficient in nutritional level, therefore it is obligatory to supplement with this vitamin.


Taking certain medications can also lead to lower levels of vitamin B12 in the body. It is usually given with medicines to treat stomach ulcers, which reduce the stomach’s ability to absorb this vitamin. Although there are many more, it is important to consult with a physician for each medication that is taken because sometimes its harm may be greater than its benefit.

Coffee shop

In addition to all of the above causes, a coffee consumption of more than four cups per day can lead to a reduction in blood cobalamin levels. Drinking coffee is beneficial for us, but it should not be abused, even if we can feel immediate positive effects, such as increased activity or lucidity.


There are certain pathologies, especially related to absorption problems, which also prevent B12 from being useful in our body, even when consumed in a healthy and balanced diet.

Symptoms caused by vitamin B12 deficiency

The lack of vitamin B12 is one of the most common nutritional deficiencies that exist if we speak of it at a slight level. In addition to this, this micro-nutrient is one of the most important for the organism. Therefore, it is a pathology that can become relatively serious over time and to which it is essential to remedy, although the levels of cyanocobalamine we present are almost those recommended. Otherwise, the consequences for health can be disastrous in the medium and long term.

  • One of the main functions in the body is energy production. Therefore, if there is a deficiency of this nutrient, it is common for the person to feel weak and fatigued for no apparent reason. This is the main symptom that occurs in practically 100% of patients suffering from this pathology.
  • Another very common symptom is numbness of certain areas of the body, especially in the hands and feet. In addition, there are cases in which people feel a great tingling in the extremities, which presents as acute and intense.
  • Having low vitamin B12, over time, also results in a yellowish and/or pale skin color. This is accompanied by widespread muscle weakness. This point is less common because it occurs in an advanced state, when we have been long with a very low level of this vitamin.
  • If a person lacks this micro-nutrient for a long period of time, their brain mass may even be reduced. This has been determined by a study by Oxford University, which establishes a direct relationship between the lack of this vitamin and Alzheimer’s disease.

Implications of B12 deficiency for our health

The lack of vitamin B12 in the body can lead to a wide range of pathologies and diseases in both the short and long term, whether physical or mental.


Depression is a mental illness that is related to a lack of connections made by the central nervous system. Well, it is cobalamin that makes these connections. Therefore, a lack of this micro-nutrient increases the likelihood of depression.


As we have pointed out in the previous section, if a person suffers from a B12 deficiency over a long period of time, he or she may lose brain substance and atrophy, giving rise to Alzheimer’s disease and, of course, a generalized loss of brain capacity.


B12 plays a key role in the formation of red blood cells in the body. Therefore, a chronic lack of this micronutrient can lead to an absence of red blood cells, causing what is known as anaemia. If this anemia is not treated, the health consequences can be dire because it increases the likelihood of cardiovascular problems.


The insufficient amount of cyanocobalamin in our body can also cause serious sleep problems, thus reducing the quality of life of those who suffer from this pathology and may trigger other pathologies associated with lack of sleep.


If a pregnant woman suffers from vitamin B12 deficiency, complications during childbirth are very likely. There may even be defects in the fetus, especially in the neural tube; in this way, the baby may suffer from diseases such as paralysis or anencephaly, which will accompany him throughout his life.

Neurological symptoms of vitamin B12 deficiency

Vitamin B12 deficiency symptoms

This lack of nutrients in the body can lead to a multitude of neurological symptoms of greater or lesser severity depending on the person’s state of health, as well as the chronicity of the lack of this nutrient.


Well, one of the most common neurological symptoms due to vitamin B12 deficiency is numbness and tingling in the legs, although there are cases in which it also occurs in the arms. You feel your limbs stiff and tingling very sharp and intense. For leg numbness, if B12 deficiency is chronic, the affected person may have severe walking difficulties.

Memory loss

Other neurological symptoms related to this pathology are loss of memory in both the short and long term. Usually, it is not a constant loss of memory, but rather a punctual one; the affected person may forget important information at a certain point in time, which he or she can remember later.


This deficit can also cause both spatial and temporal disorientation. It is common for people who suffer from micronutrient deficiencies to wake up without knowing where they are or with the notion of time being totally lost.


In the most severe cases, having low levels can lead to dementia, usually with sudden mood swings; the person is much more irritable and suspicious, i. e., practically changes his or her personality.

Optical neuropathy

Although this is one of the less common neurological symptoms of vitamin B12 deficiency, there have been some cases where vitamin B12 deficiency damages the optic nerves and muscles; this is known as optic neuropathy. In these cases, the person affected by the lack of this micronutrient suffers from blurred vision or, in the most severe cases, complete loss of vision.

All of these symptoms require urgent medical attention. Depending on the severity, adding foods rich in this nutrient to the diet may be sufficient. In more severe cases, medical personnel may choose to give vitamin B12 injections. However, a prompt diagnosis is essential if these damages are not to be permanent.

One of the main advantages of vitamin B12 in relation to neurological symptoms is that they occur very slowly. The warning signs are progressing progressively but very slowly. Therefore, people who suffer from this lack can adapt to the symptoms without relating them to each other and realize that something is not right. In the same way, it is also common that, since the symptoms are so diverse, a good diagnosis of the health problem suffered is not made. Therefore, it is especially important to know all this information and to have the routine check-ups and analyses recommended by the family doctor or any other doctor who has treated us.

Recommended daily intake for vitamin b12

Symptoms of vitamin B12 deficiency in the blood

The body’s daily need for this vitamin depends fundamentally on age. For example, an infant less than 6 months old needs just 0.4 micrograms of vitamin B12 per day for his or her body to function properly. Meanwhile, an average adult with optimal health needs 2.4 micrograms daily.

Although the need for vitamin B12 depends to a large extent on each person’s health status, the following doses are generally established.

  • Children over 14 years of age need 2.4 micrograms per day, the same dose as an adult.
  • Pregnant and lactating women are the ones who need the most, between 2.6 and 2.8 micrograms respectively.
  • For children, the dose should be increased in proportion to age.

When cobalamin is consumed through food, it is deposited in the liver. This organ acts as a “storehouse” in which it accumulates. In this way, it is the liver that is responsible for releasing it according to the body’s needs, which depend, as we have said, on age but also on health status and other extrinsic factors.

List of foods with the highest amount of cobalamin

Before listing foods with a large amount of this vitamin, we would like to make a small note. The vast majority of foods rich in vitamin B12 are of animal origin. Those of plant origin contain hardly any small amounts of it. Therefore, vegetarians or vegans are required to take a cyanocobalamin supplement in their daily diet.

  • Beef: Beef is one of the most nutritious beef available. As for its contribution, it varies according to the age of the animal and the piece of consumption. It is the sirloin of veal from an adult animal that provides the body with the most vitamin E. The clean cut of oxen and livers are also especially rich in cobalamin.
  • Chicken meat: Like beef, chicken meat is also very rich in B12. For example, a chicken breast contains 30 micrograms. In addition, one of the great advantages of this type of food is that it is highly digestible and has a very low calorie content.
  • Pate: Pate is a highly consumed food in many countries around the world. Well, the liver in its pure state from animals bred with 100% natural food is one of the best sources of this vitamin.

*Pate, which has been treated industrially, also contains a considerable amount of this vitamin. However, it is also a very high-fat food, so it is advisable to moderate its consumption and take it with absorbent seed bread.

  • Fish: As for fish, blues are the ones that have the greatest concentration. The species that provide most of this micronutrient to the body are salmon, mackerel, herring, cod, sardine and tuna. Salmon is also one of the healthiest foods that exist because it is rich in proteins and omega-3 fatty acids. Sardines, on the other hand, have selenium, iodine, phosphorus and other rich minerals.

*On the other hand, fish eggs, whether caviar or other, also make an important contribution.

  • Molluscs: Molluscan shellfish are also a great source of vitamin B12 that is worth taking into account. Among all mollusks, clams are the most important contributors of this nutrient. Equally important to prevent neurological symptoms of deficiency are mussels and oysters. Octopus is also a food that is rich in protein and selenium.
  • Eggs: An excellent way to consume this vitamin is through the eggs; the amount of this nutrient in them is 1.3 micrograms in each large sized egg. Virtually 100% of this vitamin intake is found in the yolk.
  • Animal products: Eggs and milk, especially skimmed milk, strong and cured cheeses and yogurts, are a very good source of cobalamin.


By way of conclusion, we must say, as is clear, that moderate intake is essential to avoid the pathologies generated by vitamin B12 deficiency. However, it should be remembered that everything in excess is negative for health, including the consumption of cobalamin. Therefore, we recommend that you do not consume more than the recommended daily allowance for each population group unless determined by a physician as treatment for compensation.

In the case of vegetarians and vegans, most foods containing large amounts of this micronutrient are of animal origin. Therefore, it is highly recommended to take B12 supplements, always under medical supervision and in a controlled manner.

Cobalamin deficiency must be avoided by all means because the health consequences can be very negative for people of all ages. As we have explained, brain activity can be seriously affected, presenting neurological symptoms that can become devastating, in addition to other health problems of various kinds.

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Have you been feeling tired lately? It may be due to a lack of this vitamin, tell us your experience, doubts or advice, so that together we can make the community grow more and better!

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