foods rich in vitamin b12 or cobalamin

13 Signs of a Vitamin B12 Deficiency

Cameron Hooper Nutrition

Do you struggle with constant fatigue? Or how about brain fog, depression, or frequent mood changes?

If you experience one or more of these issues, it could be a sign that you are among the 40% of people who are deficient in vitamin B12 (1).  

Vitamin B12, also called cobalamin, is a highly energizing vitamin that plays a vital role in your health. It’s required for healthy blood, DNA, and proper nervous system function.

So, if you’re not getting enough vitamin B12 through your diet, a wide range of issues can naturally arise. And since many of the symptoms of a vitamin B12 deficiency are often dismissed as a “normal part of life,” people can suffer for years without even knowing their life could be improved by supplementing vitamin B12.

That’s why being aware of the common signs of a vitamin B12 deficiency is crucial—so you can avoid needless suffering.

Here are 13 of the most common signs that your body is not getting enough vitamin B12.


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1. Fatigue & Weakness

Fatigue and general weakness are, hands-down, the most common symptoms of a vitamin B12 deficiency.

Your body needs vitamin B12 to make red blood cells, which transport oxygen to all parts of your body (2).  So when you don’t have enough vitamin B12, your whole body can be starving for oxygen due to a lack of red blood cells—doctors call this anemia.

This lack of oxygen results in constant fatigue and weakness.

2. Numbness or Tingling

When vitamin B12 deficiencies go on for long periods of time, it can result in a considerable amount of nerve damage (3).

That’s because vitamin B12 is an important compound involved in the production of myelin.

Myelin is a protective sheath that surrounds your nerves. This sheath protects, insulates, and improves the function of your nerves (4).

Without myelin, your nerve health begins to degrade over time. This can result in symptoms like paresthesia (the sensation of pins and needles) and numbness.

3. Depression & Mood Changes

Studies have found that people who experience mood disorders like depression, mood swings, and anxiety are often deficient in vitamin B12 (5, 6).

Doctors believe that vitamin B12 deficiencies can spike the levels of an amino acid called homocysteine (7). Elevated homocysteine levels can result in brain tissue damage and disrupt the balance of neurotransmitters in the brain. This, in turn, can result in mood disorders like anxiety and depression.

The good news is, people with vitamin B12 deficiencies often experience relief from mood disorders after supplementing vitamin B12 (8, 9).

4. Brain Fog

According to the prestigious Harvard University, vitamin B12 deficiencies can also cause a considerable amount of brain fog (10).  In other words, it can make it difficult to think, reason, and negatively impact your memory.

Since vitamin B12 plays such an important role in brain health and neurotransmitter regulation, it makes perfect sense that your brain function would be subpar if you’re not getting enough B12 through your diet.

So if you feel as if your brain is “in the clouds” or it is sluggish, you should certainly consider vitamin B12 supplementation after talking to your doctor.

5. Loss of Balance and Coordination

When your nerves begin to degrade due to a vitamin B12 deficiency, it can also negatively impact the way you move.

This is most often characterized by a lack of coordination, balance issues, and/or frequent falls. In people over 50-60, this can be a serious concern since the bones tend to weaken as you get older.

6. Swollen Tongue & Mouth Ulcers

One of the more specific symptoms of a vitamin B12 deficiency is a swollen and inflamed tongue—doctors call this glossitis (11).

Some people with glossitis also experience discoloration and a burning sensation on their tongue.

In other cases, people can experience mouth ulcers or an odd itching sensation in the mouth or on the tongue.

Scientists believe this is somehow linked to the anemia and nerve complications that arise from a vitamin B12 deficiency.

7. Blurred Vision

Your eyes heavily rely on the communication between the optic nerve and your brain. When you are deficient in vitamin B12 for a longer period of time, the optic nerve may not function properly.

When the optic nerve doesn’t function as it should, it can alter the signal that travels from your eye to your brain. This results in visual symptoms like blurred vision or the inability to see fine detail.

While this symptom is rare and scary, evidence suggests supplementing vitamin B12 can resolve this issue relatively quickly (12).

8. Short of Breath & Dizzy

If you feel dizzy or short of breath, it could be due to the anemia that’s caused by a vitamin B12 deficiency.

As explained earlier, when your body doesn’t have enough red blood cells, virtually all cells in the body don’t get the oxygen supply they need to function.

It’s important to note, however, that breathlessness and dizzy spells can be caused by other health complications. So it’s important to talk to your doctor if you’re experiencing these issues. You can also talk to them about the possibility of a vitamin B12 deficiency.

9. Pale Skin

Another issue that can arise from the anemia caused by a vitamin B12 deficiency is pale or yellow-tinged skin.

When your body cannot produce enough red blood cells, it changes the color of your skin. A vitamin B12 deficiency can also cause the liver to break down red blood cells more quickly which releases a substance called bilirubin.

Bilirubin is the compound that gives the skin a yellowish tone and is a common characteristic of jaundice.

10. Headaches or Migraines

If you frequently experience headaches or migraines, it could be another sign that you are not getting enough cobalamin or vitamin B12.

Some researchers believe that elevated homocysteine levels can lead to headaches or migraines (13). As explained earlier, vitamin B12 deficiencies can cause elevated homocysteine levels. This would explain why headaches are a common symptom of those who have a vitamin B12 deficiency.

If vitamin B12 doesn't do the trick, I have a lot of luck with taking a CBD oil to manage the pain.

11. Fast Heart Rate

Having a fast heart rate, or tachycardia, may be another sign of a vitamin B12 deficiency.

When your body doesn’t have enough red blood cells due to a lack of vitamin B12, your heart adapts to help give your cells the oxygen they need. Specifically, the heart increases its rate to push a greater volume of blood through the body.

12. Nausea & Heartburn

According to the National Heart, Lung, and Blood Institute, a vitamin B12 deficiency can also cause digestive issues like nausea, vomiting, heartburn, bloating, and a loss of your appetite (14).

While scientists are not quite sure why this happens, they do recognize that these symptoms can occur.

13. Weight Loss

Since B12 deficiencies can cause digestive discomfort like nausea and a loss of appetite, it can also cause you to lose weight.

Who is At-Risk for Vitamin B12 Deficiency?

If any of these criteria apply to you, vitamin B12 supplementation may be even more important:

  • You are over the age of 50
  • You have gut discomfort or gut complications; compromised gut bacteria could contribute to a B12 deficiency (15)
  • You got genetically tested and you have the MTHFR gene mutation
  • You are on the drug metformin for diabetes
  • You are on a vegan or vegetarian diet
  • You take heartburn medication (proton pump inhibitors)
  • You had surgery that removed the small intestine

Why Do We Need B12? 

Like any other vitamin, B12 is not produced by the body and therefore must be sourced from your diet.

As suggested above, B12 can be used as a supplement to improve symptoms of fatigue, anxiety and depression, chronic fatigue, muscle weakness, anemia, cardiovascular disease, and many other conditions. Some research even suggests that low B12 levels affect the brain and nervous system first when B12 levels are in the low-to-normal acceptable range determined by laboratories.

That being said, here are the systems in the body that rely the most on B12. 

Red Blood Cells 

B12 works together with B9 (folic acid or folate) and iron to form your red blood cells to transport oxygen throughout your body. If you do not have enough B12, you will have many different sizes of red blood cells on your lab work. B12 tells red blood cells when to start and stop growing (16).

Brain and Nerve Function 

B12 is a crucial ingredient in the production of myelin or the protective coating of your nerve fibers that run throughout your body. Once again, in conjunction with B9, Vitamin B12 helps with nervous system development in fetuses and helps prevent deficiencies that are associated with mood disorders and dementia in the elderly, as well as peripheral neuropathy (17).


Methylation is a molecular process that helps us process genetic information and affects a multitude of functions throughout the body. Some people are genetically poor methylators, which can contribute to issues from migraines, hormone imbalances, heart disease, and more. Supplementing B12 can make the methylation cycle run much more smoothly for these people. A functional medicine practitioner can help you determine whether you have a methylation deficit.

How Do You Get B12 From Your Diet? 

B12 is most commonly found in the highest quantities in animal products such as eggs, dairy, and meat. One of the highest plant sources of B12 is nutritional yeast—a food additive adored by vegans and nutritionists alike. Its umami flavor means it is used liberally in vegan cooking where cheese needs to be substituted. But if you have gut issues or candida, consume nutritional yeast in moderation.

While getting B12 from your diet is ideal, for many it remains a struggle to maintain adequate levels, so additional Vitamin B12 dietary supplementation is needed. Of course, the cause of chronic B12 deficiency should first be investigated by a doctor to ensure your B12 levels are within a safe and adequate range.  

What If I Suspect I’m B12 Deficient? 

If you suspect you have a B12 deficiency, you should check with your doctor to see just how deficient you are. Depending on your blood levels, he or she may prescribe B12 injections or oral supplementation.

Recent research suggests that oral supplementation is superior to injection to replete deficiency, which is good news for the needle-phobic. If you’re supplementing orally, you need to know that there are different kinds of B12, and not all are created equal 

Which Form of Vitamin B12 to Choose? 

Many cheaper forms of B12 are called cyanocobalamin because they are complexed with a small amount of cyanide. This is not the preferred form of B12 for any condition involving B12 deficiency or to raise B12 levels into the optimal range.  

The preferable form of B12 is methylcobalamin, the activated form the body finds easy to use and absorb; and may reap the most benefit from. Plus, methylcobalamin is also an excellent choice for people who have methylation deficiencies as mentioned above.  

If your energy is lacking and your mood is low, you may want to try a B12 supplement, but to get the most benefit, look for the methylcobalamin form. And remember to discuss whether you’re a candidate to get your B12 levels tested with your healthcare practitioner, to help make sure your body is in the normal range. This will help ensure you have healthy energy levels, normal cognition, and stable moods. 

Contributing Author Bio 

Vital Nutrients is dedicated to manufacturing high-quality supplements that promote health, wellness, and vitality. Our stringent standards and extensive laboratory analyses have led to our supplements being used and trusted by hospitals,healthcare practitionersand consumers worldwide. Nothing is more important than the quality of our supplements. 


Additional References:

Devalia V, Hamilton MS, Molloy AM; The British Committee for Standards in Haematology. Guidelines for the diagnosis and treatment of cobalamin and folate disorders. Brit J Haematol 2014;166:496–513.

Imbard A, Benoist JF, Blom HJ. Neural tube defects, folic acid and methylation. Int J Environ Res Public Health. 2013;10(9):4352-89. Published 2013 Sep 17. doi:10.3390/ijerph10094352

Andrès E, Loukili NH, Noel E, et al. Vitamin B12 (cobalamin) deficiency in elderly patients. Can Med Assoc J 2004;171:251–9.

Oh R, Brown DL. Vitamin B12 deficiency. Am Fam Physician. 2003 Mar 1;67(5):979-86. Review. PubMed PMID: 12643357.

Halfdanarson TR, Litzow MR, Murray JA. Hematologic manifestations of celiac disease. Blood. 2007;109(2):412-21.

Shipton MJ, Thachil J. Vitamin B12 deficiency - A 21st century perspective . Clin Med (Lond). 2015;15(2):145-50.

Thakkar K, Billa G. Treatment of vitamin B12 deficiency-methylcobalamine? Cyancobalamine? Hydroxocobalamin?-clearing the confusion. Eur J Clin Nutr. 2015 Jan;69(1):1-2. doi: 10.1038/ejcn.2014.165. Epub 2014 Aug 13. PubMed PMID: 25117994.