What if I have low vitamin b12? Causes and Symptoms

Having a lack of any nutrient is negative for our body; however, there are situations, such as low vitamin B12, that are somewhat more worrying than others. There are many causes why it lowers the levels of B12 in our body, we review the main symptoms and list possible solutions to this deficiency.

Talking a little bit about vitamin B12

Vitamin B12 is one of the B vitamins, which, speaking very broadly, help our body create the energy we need. This particular is one of the most important vitamins and at the same time it is the most complex of all the complex, worth to redundancy.

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It is also known as cobalamin because it contains cobalt. Vitamin B12 is water-soluble and is essential for the functioning of the brain, nervous system, and blood creation. Another of its functions is the creation of red blood cells and tissue regeneration. Thus, it is clear that a deficit of B12 can lead to serious health problems.

This micronutrient is found practically in animal products, especially meat, veal liver, chicken and poultry, eggs, fish, salmon and scallops and dairy products, to give just a few examples as the list is much more extensive.

This vitamin is created by a living body, so it is not found in fruits or vegetables. On the other hand, neither plants, animals nor fungi can produce this vitamin, since it is bacteria and archeobacteria that produce the enzymes necessary for its synthesis.

Having a low level of cobalamin is a considerable health problem, but with a balanced diet there should be no such lack of vitamin B12. Still, there are some causes, not just poor nutrition, why a person might have this type of deficiency.

What causes low vitamin B12 levels?

Pernicious anemia causes low vitamin B12 levels

The most common causes why we may have low blood vitamin B12, in addition to, as we say, poor nutrition, are anemia and poor absorption of the vitamin.

Anemia (pernicious anemia)

It is the final stage of an autoimmune inflammation of the stomach. People with this problem should take food supplements by mouth in capsules or injections with the required amount.


The body has insufficient absorption of vitamin B12 or any other nutrients. Malabsorption is due to a chronic inflammation called atrophic gastritis of the stomach mucous membrane, which occurs when there is a lack of metabolism that prevents the destruction of glandular cells that produce acid and release, in this case, B12 in the body.

People who have this problem do not need more vitamin B12, but need to take it in a special way, with fortified supplements and dietary supplements or, depending on the case, injected.

Suppression of the stomach or part of the small intestine

Having low vitamin B12 in the body is one of the consequences derived from gastric bypass, since during the intervention, the part of the stomach responsible for digesting food components is diverted and therefore never in contact with food, which causes the stomach area does not produce the intrinsic gastric factor, this causes the body does not absorb the necessary amount of vitamin B12.

Food intolerances, celiac disease

40% of patients with untreated celiac disease show a low B12 level. In these cases, a gluten-free diet and a readjustment in your diet with foods rich in vitamin B12 is enough to restore adequate levels in the body.


Drinking alcohol in large quantities not only affects the liver and pancreas, it also damages the intestines and therefore the absorption of nutrients in the body is more complicated. Alcoholics are at risk of inflammation that causes their body not to release the intrinsic factor, the component responsible for absorbing nutrients and vitamins, therefore, decreases the absorption of vitamin B12 and in the worst cases this translates into a lack of B12 with the health hazards listed above.

Returning to the subject of the liver, indicate that this is the main lodging place for cobalamin; if it is not able to assimilate it because it is damaged, the whole process necessary for the body to convert and use it cannot be initiated.


As we have seen in previous sections, this vitamin is very important for blood distribution in the body, neurological functioning and cognitive health. Patients with the HIV virus are not able to absorb vitamin B12 naturally so they must constantly replenish it through supplements.

A study by scientists at John Hopkins University has shown that vitamin B12 influences HIV progression: patients with lower-than-normal vitamin B12 levels showed a shorter period of AIDS-free time compared to those with B12 at normal levels.

Vitamin B12 lowers due to poor nutrition

Vitamin B12 lowers due to poor nutrition

A poor diet can trigger low vitamin B12 levels among many other problems such as obesity, sleep and character disturbances, diabetes, lack of muscle mass, fatigue, cardiovascular problems, osteoporosis, arthritis and anemia. It is essential for health to maintain a healthy and balanced diet for our well-being and quality of life.

In addition, some of the consequences of being undernourished favour the lack of B12 or enhance the effects of its deficiency; everything is in chain. We review some of the foods that may interfere with the assimilation process of this vitamin and its interaction with it.

Tea and coffee

These are foods that we take as beneficial, but that intervene negatively in the absorption of vitamins in the body. Excessive consumption of coffee and tea causes folic acid, vitamin A and vitamin B12 to be misabsorbed.

Age Counts

From the age of 50 years the body no longer absorbs nutrients in the same way and consequently neither cobalamin, which is why at the same time that we have to be fulfilling years we must be extremely careful and monitor our diet with more attention.


Some medications that are involved in vitamin B12 malabsorption include antacids, antibiotics, birth control pills, or ulcer medications. These drugs prevent the release of B12 in the body and therefore not even siqueira begins the process of use.


We all know that smoking is unhealthy; tobacco has several negative effects on our body and contains substances that affect the absorption of vitamins. Its effects on the body cause a decrease in vitamin B12 and vitamin A reserves, generates folic acid deficiency, increases cholesterol levels and reduces taste perception, among many other effects.

Vegetarian and vegan diets

People who follow a vegan or vegetarian diet are prone to have low vitamin B12, this is not entirely true since following a “bad” diet is not vegan or vegetarian, it can also produce deficiency of this vitamin, so the fact that following this type of diet does not lead to low levels of B12 if it is correctly followed and supplemented as required.

There are vegetarian products that contain vitamin B12, however the amount is usually not enough. The risk is greater in vegan people, i. e. they do not consume any animal products. Therefore, supplements are required to cover vitamin B12 deficiency in their diet, even when fortified foods are taken.

Can there be low levels of vitamin B12 in infants and children?

Vitamin B12 deficiency is usually found in adults, but there are causes why younger children may also have poor B12 levels.

Breastfeeding mothers on vegetarian diets

Mothers who maintain a vegetarian or vegan diet, if they do not take any supplement to make up for the lack of vitamin B12 in their diet, will generate breast milk that is free of this nutrient, so the baby does not receive it either, and the baby may have a deficiency in this vitamin.

This is especially serious because there is a belief that breast milk is the best option for the baby, but few people are concerned about whether the milk they drink contains all the nutrients because of poorly carried or mishandled feeding.

Hereditary genetic vitamin B12 deficiency

Although not very common, there are people who have vitamin B12 low for genetic reasons. Rarely, the baby is born with problems assimilating and absorbing B12. However, in the rare event that this happens, one of the two parents must also have that deficiency.

Anemia in pregnancy

Pregnant women are commonly anemic due to iron and low levels of vitamin B12. This occurs because during the gestation period the tendency of blood concentration of red blood cells and the hemoglobin they contain is declining.

On the other hand, vitamin B12 reserves in the liver are progressively decreasing as the volume of the mother’s plasma is doubled and therefore the kidneys work harder and this micronutrient is lost in the urine.

Pregnant mothers with Crhon’s disease, vegetarian, coeliac, with gastric bypass intervention, anorexia or bulimia tend to be more likely to develop a low cobalamin level during pregnancy.

Insufficient bacterial synthesis

Infants’ intestinal microbiota or intestinal bacteria do not have enough capacity to produce enough vitamin B12 to cover the food deficit. Even if the mother is a vegan, babies don’t usually need B12 until later in life. With the right breast feeds, your baby already receives nutrients to grow healthy. For babies who are bottle-feeding, they are prepared with specific formulas.

In both cases, from 9 months and one year onwards, vitamin B12 supplementation is already added to their diet with the corresponding doses for each dose.

Main symptoms of having low vitamin B12

Fatigue tiredness symptoms of having low vitamin B12

And now that we’re in a situation, let’s see what happens if I get vitamin B12 down. Clinical studies have shown that a level of cobalamin below the recommended level is not an isolated case; quite the opposite. In fact, one in four adults has a level below the recommended amount but is not considered serious.

As we have seen before, cobalamin, being a vitamin that is stored in the liver, kidneys and the rest of the organs, has a slower dissolution process than other vitamins that are diluted with water, so that many times the symptoms are not appreciated until some time has passed; thus, vitamin B12 deficiency may go unnoticed for years.

Although this is not a serious problem in the first world, there are different levels of severity, although all, with the right treatment, are reversed.

The most common symptoms of vitamin B12 deficiency are:

  1. Lack of memory
  2. Mental confusion
  3. Feeling of apathy, bad mood.
  4. Fatigue, lack of energy
  5. Muscle weakness and/or tingling in the arms and legs

As we have seen in the previous section, the symptoms associated with the low amount of B12 in the body can appear in a variety of ways, and depending on the severity, they require treatment or other (injections, dietary supplements, etc.), all of them under medical care.

Let’s see what the neurological symptoms are as a result of having cobalamin low and how they affect the body:


That is, a tingling sensation in the extremities, although it can occur throughout the body. Numbness causes you to have less sensation that affects your ability to grasp objects, walk, or maintain balance. In these cases, patients are treated with a diet richer in vitamin B12 and supplements in their diet for the mildest cases, and with injections of B12 for the most serious cases.


Another thing that happens with a low B12 level is that you start having tremors. Coordination in the movements is transformed into hard work for some people; they are fragile and weak. More serious patients, with a level well below the recommended amount of this vitamin, may become paralyzed.

This type of symptom is most often found in older people, as this segment of the population has more difficulty in ingesting and processing food properly and the medications they can take are also an incentive for their body not to absorb the necessary nutrients properly.

To compensate for vitamin B12 deficiency, they tend to follow a diet rich in vitamin B12, such as chicken breast, yoghurt, hard-boiled eggs and other foods that are compatible with the diet of older people.

Misaligned Brain Behavior

We talk about depression, mood swings, aggressive attitudes, dementia, hallucinations and psychosis. It may sound alarming, but the positive part is that with proper treatment to help the body regain normal levels of vitamin B12, these symptoms go away quickly.

Optical neuropathy

Vision loss or blurred vision may also be a reason to believe that this vitamin B complex is low. It is not the most common case, although it is also the most difficult to detect. There are people who are slowly losing sight and don’t realize it, they adapt to it. It is therefore a complicated case because the symptoms are not immediately apparent or in short periods of time; on the contrary, they are discovered in the long term; moreover, vision problems are not usually associated with this problem in the first instance, so in many cases, they are treated erroneously, without solving them.

Therefore, it is recommended that as soon as we notice an alteration in our vision, we turn to a specialist and on the other hand, we make routine check-ups since, with a complete blood test you can know the levels of all vitamins including, of course, our B12.

Diseases associated with low vitamin B12 levels


Although not the main cause of this disease, it has been shown that older people with a low vitamin B12 level are prone to atrophy, one of the characteristics of Alzheimer’s disease.

Pernicious anemia

Anaemia is the most common disease associated with low vitamin B12, although it is also caused by a lack of iron and folic acid. As we have already seen, cobalamin plays an important role in the production of cells in our body and also in the synthesis of DNA, so that when the body lacks red blood cells or produces them badly, anaemia emerges. The organism is not able to dissolve the components of B12.

This disease can lead, if not properly treated, to cerebrovascular problems and related heart problems.

Brain and cardiovascular diseases

Insufficient vitamin B12 and folic acid levels of homocysteine in the blood, which are the common factor in these diseases, are raised.


When there is a lack of vitamin B12, it causes damage to DNA and the vitamin traps folate so that folate cannot be used by the body. The most common cancers of low vitamin B12 are breast, cervical, and stomach cancers.

In short, and finally…

Cobalamin is one of the most important vitamins and at the same time the most complex of all. Its main function in the human body is the proper functioning of red blood cells and the healthy maintenance of neurons.

Prolonged vitamin B12 depletion causes progressive damage to the nervous system and does not produce adequate red blood cells in the blood. But also, as we have seen, it is the cause of dizziness, balance problems, character changes, loss of vision, tremors in the arms and legs and cardiovascular and brain problems, and it is also the cause of fetuses and babies having associated problems of all kinds.

We can reverse vitamin B12 deficiency with nutritional supplements or by eating foods rich in vitamin B12:

  • Fish and seafood: Alejas, oysters and mussels, caviar, octopus, crab, lobster, fish.
  • Meat and poultry: Beef, chicken, lamb, eggs.
  • Dairy and dairy products: cheese, milk, yogurt.
  • Some vegetables: broccoli, asparagus, some mushrooms like the trumpets of death or chantarella
  • Edible algae: they are also the source of this micronutrient, although we should remember that they are not sufficient to maintain adequate levels in the body if vegetables are not alternated with other foods of animal origin.

This condition is often due to an unbalanced diet, although not the only one, of course. However, it is an important factor, and the main one in most cases, in the development of a cobalamin deficiency.

Your symptoms do not appear right away. It may take a long time before you are diagnosed. Reserves in the body are diminishing over time if we don’t replenish them and the circumstances of each person can cause the body to need more reserves than usual, as we have seen, for example, in pregnant women.

Final conclusions

Maintaining a healthy, healthy diet rich in proteins and vitamins essential for the proper functioning of the body is the best method to prevent long-term health problems of any kind. On the other hand, routine medical check-ups should also be given importance, as they can prevent future problems in terms of vitamin A deficiency and its associated problems.

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Do you know if you have vitamin B12 deficiency? Have you ever had a deficit of this one? Discuss your doubts, experiences and advice, together we make this community bigger!

If you found it helpful or have any questions, please comment and share, thank you! 😉

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