What are the symptoms of B12 deficiency?

March 24, 2020

What are the symptoms of B12 deficiency?

Are you getting enough vitamin B12? If not, you'll want to make sure you get your daily dose. Vitamin B12 is an essential nutrient your body can't live without, so getting enough is necessary. It aids DNA synthesis and helps grow red blood cells. 

Since your body can't produce it naturally, you need to get it from animal-based products or in a supplement form. Your body doesn't store vitamin B12 for long periods, so you need to make sure you get some every day. If you don't, you can develop a B12 deficiency. When this happens, you can develop the following symptoms. 

Vitamin B12 deficiency symptoms 

If you're vegan or vegetarian and abstain from animal products, such as meat, eggs, and milk, you may develop a vitamin B12 deficiency. Men and women who have had weight loss surgery are at higher risk, too. Harvard Health says that vegan, vegetarians, and weight loss surgery patients need to eat foods fortified with B12 or take a supplement. (1) If they don't, the following symptoms may occur. 


According to the Mayo Clinic, the most common symptom of a vitamin B12 deficiency is anemia. (2) The condition comes from having lower levels of specific vitamins, such as folate, vitamin C, and vitamin B12. Lower vitamin levels result in less healthy red blood cells. 

If you don't have foods high in these vitamins, anemia develops. It can also happen if you develop a medical condition impairing the absorption of vitamin B12, folate, or vitamin C.  If you suspect you're anemic, speak to your doctor about treatment. It may be as easy as changing your diet and taking vitamin B12 supplements. The signs of anemia, due to low levels of B12 and other vitamins include the following: 

  • Extreme tiredness
  • Jaundiced skin
  • Numbness in hands or feet
  • Mood changes
  • Shortness of breath
  • Cognitive confusion
  • Unsteady movements

It may take a few months or years to develop a vitamin deficiency. At first, the signs may be hard to spot but may worsen over time, making the symptoms more pronounced. 

Swollen tongue

Glossitis is when your tongue becomes swollen and smooth. In some cases, it can also change color and texture. When the texture changes, the bumps on the tongue become more seamless and less pronounced. The reason for the inflammation can be from an allergic reaction, an injury, or a vitamin B12 deficiency. (3) 

According to CMAJ, 25% of all people with a vitamin B12 deficiency present with glossitis. (4) In the case cited in the CMAJ article, "Glossitis secondary to vitamin B12 deficiency anemia," the woman with glossitis had a single injection of B12, and her symptoms went away.

Chronic Fatigue

Living with daily tiredness may be connected to anemia or other medical conditions, but some evidence suggests that vitamin B12 plays a role. For those with chronic fatigue syndrome (CFS), some limited studies show that vitamin B12 injections help improve symptoms when taken with folic acid. (5) 

CFS is extreme fatigue that has no discernible cause. Scientists theorize that CFS comes from psychological issues or viral threats. (6) You can also experience memory issues, headaches, sore throat, and unexplained muscle pain in addition to exhaustion. 

Difficult thinking

One sign of low B12 levels is cognitive impairment. When you have trouble thinking, you may have issues with memory. In some cases, research shows that low vitamin B12 is connected to neurodegenerative diseases, such as dementia, Alzheimer's Disease, and Parkinson's. 

In a review of 43 studies, 17 of them showed that treating these neurodegenerative diseases with vitamin B12 supplements was effective. It only helped individuals with previous low vitamin B12 levels before the treatment. (6) 

Pins and needles

If you have tingling in the hands and feet, you may have a vitamin B12 deficiency. The symptom comes from vitamin B12s importance in the nervous system. When you have low levels, men and women may experience nerve problems or damage. 

Around the nerves in the nervous system is a compound called myelin. Vitamin B12 helps generate this substance. Myelin surrounds and protects the nerves while assisting them in sending messages throughout the body. 

If you're short on B12, you may not have enough of the protective coating around your nerves. This can cause nerve damage. The most common areas to have "pins and needles" are the peripheral nerves in the hands and feet. Although the tingling nerve damage can occur in other parts of the body, too. 

Difficulties walking 

If you have low B12 levels, it can result in nerve damage and trouble walking. As your condition worsens, it may cause numbness and movement issues. 

You may have a hard time supporting yourself due to muscle weakness. People with this condition need support when walking or require a wheelchair. 

Feelings of sadness

Low vitamin B12 causes mood changes, such as irritability and even depression. A vitamin B12 deficiency may affect our behavioral well-being because of too much homocysteine in the brain. Some experts theorize that vitamin B12 helps break down homocysteine, and extra amounts result in mental health concerns. 

Recommended dose

The recommended daily allowance (RDA) for vitamin B12 depends on your sex and age. As outlined by the National Health Institute (NHI), people over age 14 need 2.4 micrograms (mcg) per day. (7)

Eating a healthy diet rich in animal-based foods or ones fortified with vitamin B12 helps you reach the RDA. However, taking a vitamin B12 supplement ensures you're getting your daily dose. 

Living with a vitamin B12 deficiency has severe impacts for your health. The good news is that relieving the B12 symptoms is possible with making dietary changes or trying a high-quality B12 supplement. 

  1. https://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780
  2. https://www.mayoclinic.org/diseases-conditions/vitamin-deficiency-anemia/symptoms-causes/syc-20355025
  3. https://www.medicalnewstoday.com/articles/322135#causes
  4. https://www.cmaj.ca/content/185/12/E582
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4406448/
  6. https://www.mayoclinic.org/diseases-conditions/chronic-fatigue-syndrome/symptoms-causes/syc-20360490
  7. https://www.ncbi.nlm.nih.gov/pubmed/22221769
  8. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/#h5