Is there a store of vitamin B12 in the body?

Does the body have vitamin B12 reserves?


Many people are wondering if there may be a store of vitamin B12 in the body, especially because of the importance of this vitamin in vegetarian diets.

Is there a store of vitamin B12 in the body?

Yes, the body is able to store large amounts of this vitamin between 2 and 3 milligrams of vitamin B12 or cobalamin (which is stored in the liver as adenosylcobalamin).

Vitamin B12 is mainly stored in the liver, which is the main storehouse of the body, but all cells have a little B12 stored and this is found in liver, kidneys, heart, brain, muscle, erythrocytes, and in others body parts. For simplicity, the reserve is said to be primarily in the liver.

vegetarian diet

Photo of vegetarian diet. It is not a deficit one if it is well planned, but the advice of a dietitian expert in vegetarianism

Is the B12 reserve in the liver very large or small?

This store of B12 is large, considering that the recommended daily amount (CDR) of this vitamin is very small (measured in micrograms).

The daily requirement for vitamin B12 for an adult is estimated to be between 2.5 and 3 mcg daily (in milligrams: between 0.0025 mg and 0.003 mg of vitamin B12 per day).

Therefore, theoretically, if the CDR of vitamin B12 is 3mcg, and we have 3mg reserve of this vitamin, we have vitamin B12 stored to cover the adult CDR for a thousand days.

Attention with the B12 !!!

But attention, these calculations are theoretical and do not take into account many factors that can affect the requirements of this vitamin. In fact, the CDRs of vitamins are not always clear, since they are only determined to avoid deficiencies or diseases, but it is not possible to know what optimal levels of this vitamin, for example, to prevent diseases.

It is worth noting the danger of a B12 deficit, since the damage caused by its deficit is irreversible. Instead, more and more beneficial functions of this vitamin are being discovered.

All this suggests that it is preferable to get good levels of this vitamin, and not wait to deplete the hepatic store of B12.

Why is there no vitamin B12 deficiency if we do not eat meat on a daily basis?

If we do not eat meat one day we do not have vitamin B12 deficiency. Even some vegetarians have not had clear symptoms of B12 deficiency until after 4 years without eating meat.

This is because, in addition to the reserve that exists in the liver of this vitamin, given its vital importance of B12, it is a vitamin very well preserved in the body, that is to say, the body has mechanisms to prevent its excessive loss by urine or feces.

How the body saves Vitamin B12

One of the mechanisms by which the body retains B12 is the enterohepatic circulation, in which vitamin B12 is released into the intestine through bile, and then reabsorbed as it passes through the intestine. It is estimated that 75% of vitamin B12 released through bile can be reabsorbed.

In addition, there are proteins in the blood that hook the B12 and prevent it from being filtered by the kidneys, preventing its loss by urine.

These conservation systems, which also have other vitamins, allow that if one day not animal foods are eaten, there will not be major vitamin B12 deficits.

Can intestinal flora produce vitamin B12?

It is true that the microbiota or intestinal flora manufactures a certain amount of vitamin B12, although it is a very insufficient quantity to cover the daily needs. In addition, this manufacture depends on the type of bacteria that are in the intestine, which is very variable.

On the other hand, vitamin B12 is mainly absorbed in the small intestine, so bacterial fermentation in the colon, even supposing that it was sufficient, would practically not be absorbed.

That is, the microbiota or intestinal flora does not play an important role in the contribution of B12. The main source of this vitamin is the liver store or reservoirs.

Is the vegetarian diet low in vitamin B12?

Yes, vegetarian food is deficient in B12 and should be supplemented. There have been cases of vitamin B12 deficiency in vegetarians. These problems can be serious in babies of vegetarian mothers who are not supplemented.

Vegetarians who eat dairy or eggs are also recommended to supplement if they do not eat these foods daily, or if they eat less than 1 glass of milk and 2 eggs a day.

The reason for these precautions is that it has been proven that vitamin B12 does not only avoids anemia: It allows the renewal of myelin sheaths of the brain and reduces homocysteine ​​in the blood. A deficit causes malfunctioning of the nervous system and poor circulation.

a store of vitamin B12

It is a widespread myth that there is a store of vitamin B12 and therefore it is not necessary for vegetarians to take it

When do vegetarians have a deficit?

It is estimated that healthy adult vegetarians have a vitamin B12 deficiency at most from the age of 4 on a vegetarian diet, which does not mean that they do not suffer from side effects due to a very poor intake of this vitamin. It would be a state of insufficiency, prior to vitamin deficiency.

Vitamin B12 deficiency may occur before age 4 years, especially in absorption problems (irritable bowel, diarrhea, intestinal diseases) or high requirements of this vitamin (young people of growing age, pregnancy, lactation, old age).

Does an egg-lacto-vegetarian diet provide B12? How is a B12 deficit or insufficiency determined?

It is recommended that vegetarians perform a specific analysis with:

Levels of vitamin B12

Homocysteine ​​levels

Levels of methylmalonic acid

With these values ​​it is possible to determine the degree of lack of this vitamin that they present, if it is the case.

We recall that vitamin B12 not only prevents anemia: its deficiency causes malfunctioning of the nervous system and poor circulation by increasing homocysteine.

* See: Diagnosis of vitamin B12 deficiency

Dangers or risks of not taking vitamin B12 supplements in vegetarianism

Those whose vitamin B12 requirements are high or have problems of its absorption may be deficient in this vitamin, such as intestinal diseases, babies of vegetarian breastfeeding mothers, vegetarian children, elderly or pregnant women.

In addition, there are factors that may require a higher daily intake of B12. For example, the use of medications for Parkinson’s appears to increase the needs of vitamin B12 and B9.

Many times the vitamin B12 deficiency has no clear symptoms. In cases of danger of deficiency, it is recommended to take this supplement because it prevents avoidable health complications and it is not a toxic supplement (you can easily eliminate excess).

* Related information:

Diagnostic of vitamin B12 deficiency

Diagnostic of vitamin B12 deficiency

Vitamin B12 supplements

Vitamin B12 supplements for vegetarians

Vitamin B12 analogues

How to take vitamin b12 supplements

Deficiency of vitamin b12 in babies or vegetarian children

Vitamin B12 during pregnancy

punto rojoMore information on vitamin b12.

Written by Editorial Botanical-online team in charge of content writing

26 April, 2019

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