Vitamin B12 Deficiency: Causes, Symptoms and Prevention

Last updated on April 4th, 2025 at 01:09 pm

Vitamin B12 is a water-soluble vitamin found in several forms, mostly in mineral cobalt. It is mostly found in some foods and can be taken as a medication. It helps in the metabolism of every cell in our bodies. It also helps in manufacturing DNA and red blood cells.

During the analysis made by the CDC, 40%-50% of Nepali women had B-12 deficiency, especially in rural Nepal. Some studies have shown that about 1-2% of the young population and 10-15% of the elderly in the world suffer from low Vitamin B-12.

So, it is important for us to understand its benefits, problems caused by its deficiency, causes, and what can be done to minimize its effects.

Benefits of Vitamin B 12

Vitamin B-12 has many benefits. Some of them are:

• Manufacture of red blood cells
• Reduce anemia
• Prevent birth defects
• Support bone health
• Helps our brain by preventing the loss of neurons
• Healthy growth of hair, nail, etc.

Since Vitamin B12 has many benefits, it is necessary for us to intake the right amount. The daily intake amount of Vitamin B 12 according to age is listed below(mcg = microgram):

• Child(>6 months) – 0.4 mcg
• Child(7-12 months) – 0.5 mcg
• Child(1-3 years) – 0.9 mcg 
• Child(4-8 years) – 1.2 mcg
• Child(9-13 years) – 1.8 mcg
• Teens and adults – 2.4 mcg (2.6 mcg if pregnant and 2.8 if breastfeeding)

Note: The intake amount listed is for a normal healthy person. So, your intake amount may vary if you have pre-existing conditions. Consult with a doctor to find your intake amount.

Causes of Vitamin B 12 Deficiency

As we age, it gets harder for us to intake and absorb B-12, so you may experience its deficiency for various causes. Some of the reasons for low B-12 vitamin are:

1. Crohn disease, celiac disease(small intestine diseases)
2. Atrophic gastric(i.e your stomach lining gets thinner)
3. Weak Immune system
4. Pernicious anemia
5. Taking medication that interferes with the absorption of B-12 vitamin
6. Vegan diet
7. Had surgery (stomach-related) recently, etc.

Symptoms of Vitamin B-12 Deficiencies

We should intake the right amount of this vitamin. In case of deficiency, you may show symptoms such as:

• Loss of appetite
• Depression and mood changes due to lack of appetite.
• Trouble balancing yourself or change in the way you walk, because a deficiency in vitamin B-12 can lead to permanent changes in nerves of your brain, 
• Problem remembering things,
• Fatigue, because deficiency of this vitamin lowers your red blood cells, which in turn lowers the amount of oxygen transported to your cells,
• Constipation (having trouble in stools, frequently or even bloody),
• Weight loss, due to loss of appetite, etc.

If you are experiencing any or all of the symptoms , please consult with a doctor for proper treatment and medication. 

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Who is most at risk of Vitamin B-12 deficiency?

Following are at most risk:

• Vegans are at most risk of B-12 deficiency. Vitamin B-12 is mostly found in meat-related foods, so vegans cannot get the right amount of this vitamin simply by eating vegetables.
• People with pernicious anemia (Creating antibodies that kill healthy cells)
• Older adults over the age of 65 are really vulnerable. As we get older, it gets harder for our bodies to absorb vitamin B-12 through food.
• Pregnant women following a strict vegan diet (i.e not eating the right amount of meat and vitamin B-12 rich foods),
• People with small intestine problems. The function of the small intestine is to absorb nutrients from food. If you have a medical condition related to it, you are very vulnerable to vitamin B-12 deficiencies
• People with inflammatory bowel disease (i.e inflammation of the digestive tracts), such as Crohn’s disease and Ulcerative colitis, etc.

What are the tests to determine Vitamin B-12 deficiency?

Blood test

Your doctor might order a blood test to find:

• The number of red blood cells in your blood. People with B-12 deficiency have a lower number of red blood cells than a normal person.
• The total amount of folate (which helps in making red blood cells) in your blood. 

After the blood test, if it shows vitamin B-12 deficiency, your doctor will perform other tests (with your blood) to pinpoint the cause of your deficiency. Some of the subsequent tests are :

Antibodies test

People with vitamin B-12 deficiency generate a high amount of antibodies that kill healthy cells, also called pernicious anemia.

Methylmalonic acid test

This test is done to find the presence of methylmalonic acid in your blood. People with a deficiency in vitamin B 12 have a high amount of this acid.

If your tests return positive for these, you should follow a healthy or balanced diet and take supplements when necessary.

What are the complications of Vitamin B12 deficiency?

Low Vitamin B-12 can lead to various problems in your body. Some of these are:

• Reduced sensation in your hands and feet.
• Trouble balancing your body.
• Infants deficient in B-12 may show unusual behavior/movements, such as feeding problems, facial tremors, irritation and growth problems.
• Permanent damage to your nerves and brain damage
• Anemia
• Weight loss
• Diarrhea
• Menstrual problems
• Pale or yellow skin, etc.

How can you prevent Vitamin B-12 Deficiency?

To prevent Vitamin B-12 deficiency, you can do/eat the following:

1. Eat cooked meat, dairy products, fish, fruits, and vegetables.
2. Eat the following foods, especially for vegans:
   • Breakfast cereal
   • Nutritional yeast
   • Plant-based drinks, etc.
3. Take supplements when required.
4. Stay careful with medication (i.e some medication prevents absorption of vitamin B 12).
5. Get a Vitamin B-12 shot

Get a Vitamin B12 injection in Kathmandu

• One way to increase Vitamin B-12 levels is to get prescribed Vitamin B-12 injections.
• You can take Vitamin B-12 shots to bring your body’s B-12 level to a normal level.
  • Taking this shot may help you :
    • Bring red blood cells to a normal level.
    • Prevent Vitamin B-12 deficiency-related diseases/effects.
    • Prevent nerve and brain damage.
    • Prevent depression.
    • Increase bone mass (i.e healthy bone).
    • Prevent/Reduce risks of age-related macular degeneration.
    • Get treatment for cyanide poisoning.
    • Lower levels of homocysteine in the blood.
    • Increase effectiveness for cancer treatment, cataracts, cognitive function, etc.
  • There are no known effects of this injection. However, the following may happen
    • In rare cases, you may feel an allergic reaction (because of cobalt).
    • You may feel mild side effects such as pain, itching, redness at the injection spot, mild diarrhea, swelling of the body, etc.
    • Taking a larger amount of this injection may cause some effects in a pregnant woman. So, the normal amount as prescribed above should be taken.
    • DON’T take vitamin B-12 if you have Leber disease because it can damage the nerve cells in the eyes.

If you feel any side effects, please consult a doctor immediately.

Vitamin B-12 is a very important vitamin for your body. Eating the right diet (for both vegan and non-vegan) and taking the right amount of this vitamin can help you prevent its deficiency.