What Are The Side Effects Of Too Much Vitamin B12?

Vitamin B12 is one of the 8 types of vitamins belonging to the B complex. It is a vitamin that dissolves in water (water-soluble). It is a fundamental element in the metabolic process of proteins, it helps to the formation of red blood cells and it is also necessary for the maintenance of the central nervous system.

The deficit of this type of vitamins causes that these processes do not develop normally, which can lead to health problems, anemia, memory problems, mood swings, fatigue and muscle weakness, among others.

What Are The Side Effects Of Too Much Vitamin B12?

However, an excess of vitamin B12 accumulated in the body also causes adverse effects.

Foods That Contain Vitamin B12

Only with a list of the richest food in this vitamin, you can get an idea of the caused damage by diets that prohibit their consumption.

The Data Below Is For Every 100 Grams Of Edible Portion:

-Sardines (also canned and in oil): 28 mcg. A serving of this delicious fish contributes the necessary amount for a month.

-Livers of animals: between 25 and 100 mcg. Remember that they are not suitable for sick people, pregnant women, infants and young children because of the accumulation of toxins in these viscera.

-Egg yolk: 4.9 mcg.

-Fish: between 2 and 5 mcg (cod, bonito, tuna, salmon …).

-Veal tongue: 7 mcg.

-Beef, cow, lamb: between 1 and 2 mcg, depending on the cut.

-Pork, turkey and duck meat: between 1 and 3 mcg.

-Fatty, cured and blue cheeses: between 0.8 and 1.5 mcg.

-Cow’s milk: 0.3 mcg.

So if you read the list and contrast with the recommended amounts, you will notice that is quite difficult to lose this micronutrient.

Can An Excess Of Vitamin B12 Be Produced?

As it was said, vitamin B12 is water-soluble, so, under normal circumstances, it is not stored in the body, but the excess (even taken artificially by pills) is eliminated through urine.

However, some people, usually due to kidney problems, do have an excessive accumulation of vitamin B12 in their body, which can lead to some health problems.

What Are The Side Effects Of Too Much Vitamin B12?

Nutrition experts recommend a daily intake of vitamin B-12 of 2.4 micrograms for adults. If we take more and our body is not able to adequately eliminate the excess, it is likely that we suffer adverse effects such as the following:

-Heart Failure: An excess of vitamin B12 in our body can cause the heart to stop pumping properly at some point, causing episodes of heart failure. For this reason, it is important that patients with previous heart problems refrain from taking extra amounts of vitamin B12 (especially in injections), but under strict medical supervision.

-Hepatic and Renal Insufficiency: Both liver and kidney cells can be damaged by overexposure to this type of vitamins, causing significant damage to these two organs.

-Formation of Blood Clots: Another adverse effect of the excess of vitamin B12 is that it facilitates the formation of blood clots, which can become highly dangerous because they impede normal blood flow through different organs of the body. If those who suffer blockage are the blood vessels that carry blood to vital organs such as the heart or brain, the consequences can be fatal, since they increase the chances of suffering a heart attack or a stroke (cerebrovascular accident). Therefore, people with a history of blood clots or heart or brain infarcts should also avoid extra or extra vitamin B12 intake.

-Problems in The Sight: It is also possible to suffer from cloudy or blurred vision due to an excessive accumulation of this vitamin in the body.


The most effective way to avoid an overdose of vitamin B12 is to ensure that you receive your daily ration through a balanced diet or a vitamin supplement. If you are not sure if you have vitamin B12 deficiency, it is better to avoid taking injections of this vitamin and get vitamin B12 serum test.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:November 29, 2023

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