11 Possible Symptoms of Vitamin B12 Deficiency


Narinder Singh
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In this article, you will read the 11 possible symptoms of a vitamin B12 deficiency. If you wish to know about the vegan sources of vitamin B12, please click here (link will open in new tab).

Vitamin B12, also known as Cobalamin, is a water-soluble vitamin that plays an essential role in the production of red blood cells and the proper functioning of the nervous system.

We get this vitamin from our diet, but for those who take a 100% vegan diet, the intake of vitamin B12 may not be adequate. In addition, a deficiency of this vitamin is likely in those over the age of 60 because the absorption of vitamin B12 in the body may diminish with age (source1, source2).

Before going further, I would like to emphasize that the symptoms of a vitamin B12 deficiency may take several years to become visible, by which time some damage would be already done. Therefore, one should be careful to include vitamin B12 in the regular diet.

So, what are the symptoms of a vitamin B12 deficiency? Let us see!

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The adverse effects of a vitamin B12 deficiency would be related to a lack of red blood cells or damage to the nervous system. Here are the 11 most likely symptoms (source1, source2):

1. Yellow or Pale Skin

Vitamin B12 deficiency may cause megaloblastic anemia, due to which the skin color may become yellow or pale. This happens because there are not enough red blood cells circulating under the skin to give it the normal color.

2. Faster Heart Rate

To compensate for the lack of red blood cells, the heart may start to beat faster to ensure that enough oxygen reaches all the organs and systems in the body. Therefore, a consistently faster heart rate may be a symptom of vitamin B12 deficiency.

3. Shortness of Breath and Dizziness

A lack of red blood cells and a resultant faster heart rate may cause a person to feel a shortness of breath. Therefore, constant breathing difficulty may indicate a vitamin B12 deficiency. However, breathing difficulty may also be due to an entirely different health condition requiring immediate attention.

4. Weakness and Fatigue

Because there are not enough red blood cells to carry sufficient amounts of oxygen to the cells in the body, a person suffering from a vitamin B12 deficiency will feel persistent weakness and fatigue.

5. Problems in the Mouth

Vitamin B12 deficiency may cause a red or swollen tongue, mouth ulcers, and a burning sensation in the mouth. It may also make the tongue look smooth because the tiny bumps on the tongue that contain taste buds flatten and disappear.

6. Tingling Sensation in Hands and Feet

A vitamin B12 deficiency causes the shortage of a nerve coating called myelin that protects the nerves. When there is not enough myelin, the peripheral nerves, particularly in the hands and feet, are affected, resulting in the tingling feeling, which is also called “pins and needles.”

7. Impaired Mobility

The damage to the nervous system caused by a deficiency of vitamin B12 affects how a person walks or moves. It may even affect the balance and coordination of the body and make the affected person prone to falling.

8. Cognitive Impairment

A reduced amount of oxygen reaching the brain may cause cognitive decline and affect a person’s thinking and reasoning abilities. It may even lead to other brain-related diseases such as Alzheimer’s, vascular dementia, and Parkinson’s.

9. Mood Changes and Depression

A vitamin B12 deficiency could damage the brain tissue, causing mood changes, depression, and dementia. It has been theorized that vitamin B-12 helps break down a brain chemical called homocysteine. A lack of this vitamin results in too much homocysteine in the brain, and that causes mental health problems.

10. Disturbed Vision

An untreated vitamin B12 deficiency may lead to damage to the optic nerve that leads to the eyes. The damage can affect the nervous signal that travels from the eyes to the brain, thus impairing vision. This condition is known as optic neuropathy.

11. Impaired Digestive Health

A prolonged vitamin B12 deficiency may lead to poor gut health and cause nausea, vomiting, diarrhea, decreased appetite, and weight loss.

Any of these symptoms should get you concerned, and prompt a consultation with a qualified medical professional. However, this list of symptoms is incomplete, and many of these symptoms may also be due to a different health condition or nutritional deficiency.

Vegan Sources of Vitamin B12

Please read this article for information on the vegan sources of vitamin B12.


This article is not meant to replace a proper medical diagnosis. Instead, this general information is only meant to increase awareness about the importance of vitamin B12 for those individuals who take a 100% vegan diet.

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