What if I have high vitamin B12 levels? Causes and Symptoms

On other occasions we have talked about the negative effects of having a low cobalamin level but have you ever wondered… what happens when vitamin B12 is high?

This is one of the most important micronutrients in our body:

  • It performs a wide selection of vital functions for the proper functioning of the same, such as the production of red blood cells, which are responsible for transporting oxygen through the blood.
  • It is also an essential vitamin for the good maintenance of the central nervous system, bone and muscle systems.
  • Vitamin B12 also plays a key role in energy production, as vitamin B12 transforms fatty acids into energy.

Risks and causes of having high blood vitamin B12

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Well, there is a lot of talk about the dangers of micronutrient deficiencies in the body. It is a relatively common pathology due to the rise of vegan and vegetarian people. This micronutrient is mainly found in foods of animal origin. In this way, if people who follow a diet without diets do not take supplements, they may suffer from a deficiency of this nutrient. Even so, there are other collectives that suffer from this lack, but that is another issue.

Too much cobalamin is also harmful to the body. Like everything else in this life, it is essential to find the right balance to enjoy a good state of health. Well, in the next few points we will explain the risks of vitamin B12 high, as well as the symptoms that indicate this pathology. In addition, we provide some advice that is worth considering to avoid it.

Let’s see what happens or can happen when we consume this vitamin in excess:


One of the major health hazards of having high vitamin B12 is that the odds of developing cancer increase dramatically. A study in Denmark by researchers from the Department of Clinical Epidemiology and the Department of Clinical Biochemistry at Aarhus University Hospital has concluded that high levels of this micronutrient may pose an increased risk of developing certain types of cancer.

As we have pointed out, cyanocobalamin is an essential micronutrient for the body to function properly. However, this study points out that an excess of it can have serious health consequences. To conduct the study, researchers have reviewed data from 333,667 patients who did not have cancer with the aim of analyzing the incidence of this disease in this group within 12 years.

Well, they have observed that the risk of developing some types of cancer is higher when B12 levels are higher, especially in those patients where the value exceeds 800pmol/L.

During the first five years of the study, they also found that the risk of hematological cancer increases considerably, especially in patients with frequent use of alcohol and tobacco.

On the other hand, the team of scientists has tried to explain that having high vitamin B12 is not normally related to a habitual consumption of foods rich in it nor by the usual intake of supplements; they consider that high levels are related in the great majority of the occasions of a malignant process that requires a certain study.

An excess of B12 in the blood can be the warning sign of a certain disease, which is usually in the vast majority of cases related to a blood problem.

Symptoms present if we have elevated cobalamin levels

Excess symptoms of vitamin B12, nausea and vomiting

Given high levels of vitamin B12 in the body, there are a series of signs that can alert of the situation; these can be more or less noticeable depending on the origin of the excessive amount of this nutrient in the body, as well as the severity of the pathology.

Symptoms usually include the following:

  • Skin rashes with no apparent cause
  • Vomiting and nausea
  • Stomach aches and runny, aggressive stools
  • Insomnia
  • Common headaches
  • Palpitations
  • Nervousness
  • The most severe cases have also presented partial facial paralysis

As can be seen, the symptoms of this pathology are not in itself excessively serious, but suffering from them is not a good sign at all.

When a person presents this symptom but the amount of vitamin taken is not high, it is clear that there is a hidden problem that is the cause, and these problems are very serious. See you at the next point.

On the other hand, it should be noted that if the cause of our increased cobalamin level is due to increased intake, the solution is as simple as adjusting the dosage; there is no further complication in this respect.

Diseases and pathologies causing a toxic level of vitamin B12 in the body

There are some diseases and pathologies, as we have indicated, that cause the levels of cobalamin in our organism to increase considerably. Let’s see them.

Chronic myeloid leukemia

It is a type of cancer that originates in the bone marrow. As it progresses, it causes continued growth of immature blood cells, which form a type of white blood cell known as myeloid cells, hence the name of this disease.

About the causes of this type of cancer is an abnormality in the Philadelphia chromosome. A disease that is related to inflammation in the spleen and an excess of platelets. The first warning symptoms are small red spots that appear on the skin, as well as the appearance of bruises with no apparent cause.

Polycythemia vera

Bone marrow disease is a disease that originates when the bone marrow makes excess red blood cells. It is sometimes accompanied by high or low levels of both red blood cells and platelets. It is a rare disease, and occurs more often in men than women. Its cause is not 100% proven, but everything seems to indicate that it has to do with a mutation of the JAK2 gene.

About the symptoms it causes are as follows:

  • Dizziness
  • Excessive bleeding
  • Headaches
  • Difficulty breathing without apparent cause

Liver disease

Vitamin B12 is stored in the liver. When taken, either through supplements or food supplements, it is stored in the liver, where it has a life span of 2 to 3 years. During this period, the organism is taking the B12 that it needs at every moment.

Elevated levels of this vitamin may also indicate liver disease, such as cirrhosis or hepatitis. It should be noted that alcoholism has a particularly negative effect on the liver, which is also associated with increased levels of this nutrient in the blood. When the liver does not function properly, two situations may occur:

  • On the one hand, that vitamin B12 is released uncontrollably
  • And, on the other hand, and most commonly, the liver can’t remove cobalamin from the body.

Kidney disease

Without a doubt, kidneys are key to optimal health. One of its main functions is to process and remove any toxic substances from the body through urine. Thus, in a normal situation, the excess of this vitamin stored in the body must be released from the body through urine.

However, when the kidneys do not function properly, a high amount of cobalamin can build up in the body because the body is not getting rid of it. One of the kidney diseases that can cause this situation is kidney failure.

How to prevent the problem of having too high vitamin B12?

As you can see, having high levels of vitamin B12 in the body is not beneficial to health. Of course, deficiency is also a very serious disorder that must be avoided at all costs. Because, faced with a medium- and long-term deficiency in the body, it can even generate a loss of brain mass, accelerating the process of certain neurodegenerative diseases such as Alzheimer’s, especially in older people.

Therefore, the key to enjoying good physical and mental health is therefore to find the balance point; that is, to have adequate levels of cyanocobalamin in our body.

As we have said before, if there is no pathology behind our high B12 level, it means that we are simply taking too much. This should not be a problem in principle, as our body excretes it through the urine. However, we will always do our best to avoid it. To do this, we have no more than, as we have already indicated, redesigning our diet or reducing the dose of our supplements if we are taking them. Of course, knowing when this happens is by no means easy.

How can we then avoid suffering from excess or lack of this micronutrient?

  • First of all, it is essential for our doctor or nutritionist to design a rich and varied diet, which includes both animal and plant foods and includes all nutrients without exception.
  • On the other hand, it is important to lead a healthy lifestyle, which involves physical exercise between 3 and 4 times a week as well as not abusing toxic substances and industrialized products.
  • And finally, it is highly recommended to take supplements of this one you realize a vegan or vegetarian diet.

Why is that? Vitamin B12 supplements are never bad, as long as their intake is controlled. To do this, and if there are no other circumstances that discourage it, the best thing to do is to use the pill or tablet format. A single weekly pill of between 1000 and 2000 micrograms ensures you an adequate dose and has the advantage that it is not too many doses so you won’t forget.

People who are on a healthy and varied diet, with animal and vegetable foods, on a weekly pill of 1000 micrograms will have enough. In the case of vegan or vegetarian people, the ideal is that they take one pill a week of 2000 micrograms because, as we have pointed out, the vast majority of foods rich in this vitamin are of animal origin; therefore, those who do not take them will need a greater amount of this micronutrient through supplements to avoid suffering deficiencies.

Supplements to control B12 levels

Vitamin b12 supplements without excess

Once we have decided on the amount to take (it will be advisable for a professional to give us his advice and help), we will explain what kind of supplements of this nutrient exist. As we have mentioned, the most common are the pills, but there are also others.

Cobalamin supplements may also be given through injections or nasal gels. The great advantage of this type of supplement over pills is that they come in direct contact with the bloodstream; therefore, they are the most suitable option for people with problems absorbing this nutrient in their intestines and for some other cases. However, these formats require a prescription.

If you don’t want to see a doctor or the doctor doesn’t consider it, but you still want to supplement yourself, and the pills have sublingual formats, which dissolve easily under the tongue or drops, which are also not easy to administer because you can’t control the exact dose you take.


Although there is a lot of talk about how dangerous it is to have low levels of vitamin B12 in the body, the fact is that high levels of this nutrient can also cause serious health problems and, above all, mean something.

The process between both pathologies is exactly the opposite. While a deficiency of cobalamin in the body can lead to certain diseases such as depression or dementia, excess of this micronutrient is a direct consequence of a certain disease, such as cancer in the blood or a kidney disease.

To conclude, therefore, vitamin B12 supplementation should ideally be monitored, follow a healthy and varied diet, and visit your family doctor regularly for tests and check on your state of health.

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Did you know the health risks of having high vitamin B12 levels? If you have doubts, questions or want to express your experience or advice, don’t hesitate to comment, the community will thank you!

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

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Comments 2

  1. Rhonda Vollman 14 April, 2018
    • Vitamina B12 21 April, 2018

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