Vitamin B12 Overdose

Cyanocobalamin, commonly referred to as vitamin B 12 is a water-soluble vitamin, which is essential in improving the functioning of Central Nervous System (CNS). Vitamin B12 also regulates the body’s metabolism and production of the red blood cells (RBCs) production. It is important to note that vitamin B12 should be taken in limited amount, otherwise you’ll suffer from vitamin B12 overdose. It’s imperative to follow the recommended daily intake closely.

Vitamin B12 Overdose

1. Overdose Causes

Different types of dairy products, eggs and meat are some of the rich sources of vitamin B12. Besides these natural sources, there are vitamin B12 supplements, which are mainly in the form of pills and tablets. Most cases of vitamin B12 overdose are mainly caused by such supplements.

2. Overdose Effects

  • Some of the symptoms of vitamin B12 overdose include itchiness on different body parts and numbness, improper heart functioning, giddiness and regular headaches.
  • The most serious side effect linked to overtime abuse of this vitamin, is increasing the risk of getting cancer. This vitamin helps in stimulating the process of cell division. It, however, cannot distinguish between the harmful and useful cells. Therefore, vitamin B12 prompts the growth and multiplication of even the cancerous cells.
  • If you are undergoing pernicious anemia, an overdose of this vitamin can lead to leukemia. If you are consuming a diet that has a high concentration of cholesterol along with different animal proteins, you stand a very high chance of getting cancer of the esophagus and stomach.

How to Avoid Vitamin B12 Overdose

1. Get Vitamin B12 from Food Sources

The side effects of vitamin B12 that are outlined above are quite rare. There are, however, certain instances when these side effects have been noted. Though supplements are good sources of vitamin B12, it is always advisable to obtain this vitamin from natural food sources. Getting vitamin B12 from natural food sources lowers your risk of falling victim to vitamin B12 overdose. It also ensures that your body receives it in the most bio-available form there is. Before taking vitamin B12 supplements, you need to visit your health specialist in order to get advice on the most suitable way of taking the supplements.

2. Follow the Recommended Daily Allowance (RDA)

If you have finally decided to take vitamin B12 supplements, please follow the recommended daily dosage. This is an effective way to help you avoid side effects linked to vitamin B12. Following the recommended daily dosage will further help in keeping the vitamin levels in check and also prevent you from using money on supplements you do not need. See the recommended daily dosage of vitamin B12 for different ages.

Age group

Follow recommended daily allowance (RDA)

0-6 months

For children in this age group, the ideal vitamin B12 dosage should be 0.4 mcg.

7- 12 months

For children between 7 months to one year old, the proper vitamin B12 dosage should be 0.5 mcg.

1-3 years

For children between the ages of one year to 3 years, the suitable dosage of vitamin B12 should be 0.9 mcg.

4- 8 years

Children within this age bracket should take 1.2 mcg of vitamin B12 per day.

9- 13 years

Children within the age bracket of 9- 13 years should take 1.8 mcg of vitamin B12.

Older children and adults

For older children and adults, the ideal vitamin B12 dosage should be 2.4 mcg

Pregnant women

Though vitamin B12 supplements should not be used for a long time by pregnant women, the ideal dosage should be 2.6 mcg.

Breast- feeding women

For breast- feeding women, the right vitamin B12 dosage should be 2.8 mcg

Persons over the age of 50 years

10% to 30% of people above the age of 50 years cannot absorb vitamin B12 easily like their younger counterparts. However, medical practitioners recommend eating foods rich in vitamin B12. For elder persons to maintain appropriate levels of vitamin B12 in their bodies, they should take between 25-100 mcg of vitamin B12 supplements on a daily basis.

For persons suffering from vitamin B12 deficiency and pernicious anemia

The recommended daily dosage is 300-10,000 mcg. There is also evidence suggesting that the most effective way of increasing vitamin B12 in such persons is through oral dosage of between 647-1032 mcg on a daily basis.

For those with high levels of homocysteine

A combination of 500 mcg of Vitamin B12 with 0.5-5 mg folic acid, as well as 16.5 mg pyridoxine is the best dosage for this group.


Persons with vitamin B12 allergies should never use supplements prior to talking to their doctors. By consulting with their doctors, these persons can get the right dosage that will apparently prevent their allergies from becoming severe and complicated. The doctor can further recommend alternative sources of vitamin B12 for such persons. Vitamin B12 effects ought to be taken very seriously. If you have just started using vitamin supplements and have observed some effects related to this vitamin, urgently seek medical attention from your medical practitioner lest these effects become severe.

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