Symptoms of excessive vitamin b12 levels

Vitamin B12 or cobalamin is one of the most important and complex of our organism, regulating the flow of red blood cells and the work and quality of neurons. The importance of this vitamin is such that when it fails in our body has effects on all of it. People with vitamin A deficiency usually take supplements in their diet, which is not bad, the problem is that they take too much.

It is important to know the symptoms of excessive vitamin B12 in order to be able to help in its diagnosis and solve the problem as soon as possible. The correct levels of vitamin B12 mainly avoid anaemia and consequently fatigue and weakness in people, although there are many more diseases and health problems related to inadequate levels of both lack and excess B12 in the body.

Do I need to take vitamin B12 supplements?

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In a healthy person, the process of absorption of vitamin B12 into the body occurs as follows: hydrochloric acid separates vitamin B12 from the protein present in food, and then B12 is combined with intrinsic factor in the stomach to facilitate absorption of the vitamin.

Whether it’s because of health problems that impede good metabolism, punctual situations or the lack of this nutrient in food, thanks to science, people who need it can take supplements that help regulate the proper levels in the body.

There are, as we say, several reasons why a person has to take vitamin B12 supplements: it can happen that your body does not absorb it properly, by pregnancy, alcoholism, suppression of the stomach or part of the small intestine, by age… Be that as it may, there are situations in which you can end up having low vitamin B12 or be at risk of it.

For all of these cases, the solution is to take food supplements enriched with this vitamin, but if not taken in the correct dosage we may find an excess in vitamin B12 levels that is as harmful as deficiency.

Types of B12 Supplements

First of all, multivitamins already contain vitamin B12. There are also supplements for the diet with vitamin B12 only, with nutrients with other vitamins of the B group or the same with folic acid nutrients.

Prescription nasal gels and injectable ones are available. This type of supplement is usually used in patients with malabsorption.

Vitamin B12 supplements in sublingual form are also available on the market, they dissolve under the tongue.

In any case, whatever the method of administration of vitamin B12, you should always look at the amount of cobalamin it contains to be able to measure the amount to take into account our diet and avoid a high B12 level.

Natural sources of vitamin B12

When taking cobalamin supplements, it should be borne in mind that the higher the dose, the lower the absorption percentage is, so always consider the amounts to avoid having high vitamin B12 in our body and also for the opposite case, to arrive at the necessary dose for our body to function properly.

Vitamin B12 is largely found in foods of animal origin such as meat, veal liver, poultry and chicken. But it is also present in eggs, dairy products such as milk and dairy products such as yogurt or cheese. Finally we can find vitamin B12 in fish and shellfish (clams, scallops, crab).

Fortified vegetable products also contain vitamin B12, such as some breakfast cereals, beverages and yeast.

Below we see what are some foods and the amounts of vitamin B12 they provide, always depending on the quality of the part and the processes to which it is subjected:


  • Pork liver: 39 micrograms of vitamin B12 per 100 grams.
  • Lamb kidneys: 55 micrograms of vitamin B12 per 100 grams.
  • Beef: beef sirloin earns the beef sirloin by beating the other cuts, with 13 micrograms of vitamin B12 per 100 grams.
  • Lamb meat: 2.6 micrograms of vitamin B12 per 100 grams.

Seafood and fish

  • Clams: 98 micrograms of vitamin B12 per 100 grams.
  • Mackerel: 19 micrograms of vitamin B12 per 100 grams.
  • Sardines: 8.9 micrograms of vitamin B12 per 100 grams.
  • Herrings: 8.5 micrograms of vitamin B12 per 100 grams.
  • Salmon: 3.5 micrograms of vitamin B12 per 100 grams.

Eggs and dairy products

  • Cheeses: among the different cheeses, the ones containing the largest amount of B12 are:
  • Swiss cheese: 3.3 micrograms of vitamin B12 per 100 grams.
  • Parmesan cheese: 2.3 micrograms of vitamin B12 per 100 grams.
  • Egg: the egg yolk contains 2 micrograms of vitamin B12 per 100 grams

Symptoms of excessive vitamin B12 levels in the bloodstream

Headache symptoms excess Vitamin B12

A healthy person with an adequate diet expels or removes excess amounts of vitamin B12 naturally and even those who take it artificially, either in supplements or in enriched foods as well. Thus, a toxicity by taking this vitamin is not common. However, there are cases in which due to various pathologies, the person may present an excessive level of vitamin B12.

In large part, patients with this anomaly present severe cases of liver problems, stomach absorption and, ultimately, genetic problems. The latter occurs very rarely; they are almost isolated.

As soon as a high dose of vitamin B12 is produced in the body, the following symptoms occur:

  • Memory loss, headache, dizziness and dislocation.
  • Trouble falling asleep.
  • Nervousness.
  • Skin rash. Itching problems.
  • Vomiting, gastric disorder.
  • Paralysis of a part of the face: this occurs in very serious cases and are exceptions.

Negative side effects of vitamin B12 toxicity

Behind a toxicity of vitamin B12 in the body there are side effects besides the symptoms seen in the previous section:

Cardiovascular side effects

When a high dose of vitamin B12 is produced in the body, it negatively affects our cardiovascular system causing heart failure, air forms in the lungs, clots in the blood vessels, and peripheral thrombosis.

It also affects breathing, causing limb aches and pains and paralysis of the arms.

This type of effect is given in people who have high vitamin B12 given intravenously.

Dermatological side effects

Too much B12 in the body can cause skin problems. The effects are manifested through acne or folliculitis, which can range from mild to severe.

Injection or consumption in high doses can also cause redness or rosacea with pustules, rashes on the face and body, and itching in the body.

Diseases due to excessive vitamin B12 in the body

So far we have seen that having a high amount of B12 in the blood is largely due to dietary supplements; in fact, it is the most common cause of high levels of this nutrient.

But this excess may also be the cause of reproduction of a blood-flow related disease; the most common are chronic myeloid leukemia and polycythemia vera. These two diseases are characterized by an excess production of blood cells.

Chronic myeloid leukemia

It is a type of cancer that is characterized by an uncontrollable production of immature blood cells in the body that make white blood cells. These white blood cells are called myeloid cells.

Chronic myeloid leukemia begins in the bone marrow, where blood cells are made.

Having elevated B12 levels is one of the causes of this disease, but the main cause is an abnormality in the philadelphia chromosome, a difference presented by chromosomes 9 and 22, associated with inflammation of the spleen, excess platelets, petechiae (small red pips in the skin) and hematomas.

Liver disease

When there are high B12 values in the liver, which is the main place in the body where the nutrient is stored, it can cause hepatitis or cirrhosis.

Another cause that can affect the liver and also affects vitamin B12 levels is frequent and heavy alcohol consumption.

When the liver is severely damaged by alcohol, cirrhosis, or hepatitis, the amount of vitamin B12 that had been stored by dead liver cells is released.

Malfunctioning of the liver, in turn, can also cause excess vitamin B12 in the human body.

Kidney disease

Under normal conditions, vitamin B12 saturation is naturally expelled. The kidneys have the function of destroying and processing all toxic substances through urine. However, when these organs are affected, and therefore unable to develop their purpose, this translates into high blood levels of vitamin B12 in the body, and many others.


Vitamin B12 supplements and tablets

Taking medications can also affect our body’s cobalamin levels by having power over how to perform absorption and expulsion. Although not all drugs are usually taken on prescription, taking them wrongly can adversely affect some aspects of our bodies.

Above all, when a variety of drugs are being taken that supplement the effects or counteract the side effects of others, a situation may arise in which the metabolism and proper functioning of the body is impaired.

Avoid and reverse excess vitamin B12 with high blood levels

Whenever it is in our hands, we should avoid taking more vitamin B12 from the bill. This is achieved, in turn, by avoiding having to take vitamin supplements and thus improving nutrition.

However, when the situations of each individual do not depend on themselves or our diet does not provide the necessary vitamin B12 indexes to obtain the optimal amounts and therefore it is necessary to resort to artificial supplements, it is important that we always pay attention to the amount of vitamin B12 that they contain and that we take.

It is also necessary to know well the amount needed in each case and person for which we always advise you to visit your family doctor to recommend the appropriate dose depending on your diet, your characteristics and your background.

If we find a high level of vitamin B12, we will have to see why, what is the cause and then reduce the amounts in each intake or eliminate it completely in a timely manner.


Vitamin B12 supplementation helps people who lack vitamin B12 to compensate for their body levels, thereby helping to improve the body’s functioning, in particular the production of red blood cells, improving the quality and functionality of neurons and the production of DNA.

Vitamin B12 is so important in our body that a lack or excess of it can cause various diseases and cause serious damage.

I reiterate the importance of the role that feeding plays here, and in all aspects of our well-being. In this case, the list of products that provide us with vitamin B12 is long and extensive, so obtaining vitamin B12 is not a problem if we follow a balanced diet in both animal and vegental foods.

When, because of the circumstances, the person has to resort to artificial support, either because of illness or because the person has chosen to follow a vegan or vegetarian diet, a specialist should inform him/her about the most appropriate amount of cyanocobalamin for him/her, and determine the quantities and doses of the daily and weekly intake. It should be borne in mind that the more you eat, the slower the absorption.

Correct dosage of vitamin B12 in humans

As we say, supplements are not a problem if we know how to take them to the right extent. Failure to do so can lead to an excessive level of vitamin B12.

Since cobalamin is a nutrient that ensures the proper functioning of neurons and red blood cells, contributes to the formation of DNA and has other main functions, taking the correct dose is absolutely necessary.

The correct or recommended dosage of vitamin B12 depends on different factors. The table below shows the recommended daily amounts in micrograms (mcg) as stipulated by the EFSA European Food Safety Authority for a healthy person according to his age and circumstances:

Recommended daily allowance of Vitamin B12 according to EFSA


Quantity (mcg*)

Up to 6 months

0.4 mcg

From 7 to 12 months

0.5 mcg

From 1 to 3 years

0.9 mcg

From 4 to 8 years old

1.2 mcg

From 9 to 13 years old

1.8 mcg

14 to 18 years old

2.4 mcg


2.4 mcg

Pregnant women

2.6 mcg

Breastfeeding women

2.8 mcg


In a society that is fast going everywhere, in which people are doing more and more things and no matter how much we eat well and exercise, sometimes our bodies need something else to keep up with the rhythm, it is not uncommon to receive an affirmative answer if you ask someone if they take any vitamin supplements.

20% of the population, mostly young people and people with a medium-high purchasing power, take some vitamin supplement, even if they don’t need it.

We are in the 21st century and, thanks to advances in medicine and science, there are products that help us cope with the stress of everyday life and compensate for altered levels of nutrients in our body.

There is a great diversity of nutritional supplements that help us to regulate the essential nutrients in our body and compensate for the lack of some of our vitamins. There are vitamins for bones and joints, to prevent tiredness and fatigue, for low iron levels and the list goes on and on.

The consumption of any kind of artificial aid for our defenses should always be done responsibly and preferably under medical supervision (in some specific cases vitamin B12 is necessary). However, excess dietary intake of these supplements can cause severe effects on our body and in some cases can be toxic to the body, with the negative symptoms that this entails. These are of varying severity and although it is not common to find a large number of people with excess vitamin B12 levels, it is important to diagnose this problem early and put it right quickly.

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Did you know the problems that high levels of B12 in our body could have for health? If you want to add, comment or ask something, don’t hesitate to comment!

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

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  1. Stephanie 30 April, 2018
    • Vitamina B12 4 May, 2018

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