What is Vitamin B12?

The Basics

Vitamin B12 plays a very important role in the proper functioning of your nervous system as well as the production of your red blood cells. However, your body does not produce or store this important vitamin on its own. You must consume it as part of a balanced diet. Vitamin B12 is found in animal products such as red meat, fish, poultry and eggs. However, for those who do not eat animal products, it can be found in fortified cereals, plant-based milks and some fortified breads.

Unfortunately, vitamin B12 deficiency is common. According to the National Institutes of Health, an estimated 1.5 – 15% of people are affected by a vitamin B12 deficiency.


  • Pale or Jaundiced Skin – Pale or slightly yellowed skin is common with a vitamin B12 deficiency. This occurs when the lack of this vitamin interrupts the body’s production of red blood cells. If this becomes severe, it may cause a type of anemia known as megaloblastic anemia. In this condition, the red blood cells are too large or too fragile to pass into your blood circulation. They also break down more easily, which can cause a build-up of a substance called bilirubin. Large amounts of this brown-red substance can give the skin and the whites of your eyes a yellowish coloration.
  • Fatigue – When the red blood cells cannot do their job of transporting oxygen to the body’s tissues, you may feel weak or fatigued. Your body needs a substance called intrinsic factor, which is produced by your gut, to bind to vitamin B12 so that your body can absorb the vitamin. In older adults, they may not produce enough of this substance, which leads to an autoimmune condition called pernicious anemia. Megaloblastic anemia may also cause fatigue.
  • Tingling in Hands & Feet – Vitamin B12 plays a crucial role in your nervous system by helping the production of a fatty substance called myelin. This substance is an insulating coating that helps protect and shield the nerves along with helping transmit sensations. Without this protective coating, nerves can become damaged which may present as tingling or “pins and needles” sensations in the hands and feet.
  • Movement Difficulty – Over time, damage to your nervous system from vitamin B12 deficiency can lead to mobility difficulties. This damage may effect balance, coordination and strength making the patient more prone to falls.
  • Heart Rate Changes – Due to the reduction in red blood cells, the heart may try to compensate by increasing the speed it beats. Your heart attempts to ensure the body is receiving the oxygen it needs by pumping harder and faster. This may also lead to a shortness of breath or dizziness.
  • Vision Changes – Linking back to the nervous system again, nerve damage caused by B12 deficiency may damage the optic nerve that leads to your eyes. This may result in blurred or disturbed vision in rare cases.
  • Oral Pain – Lack of vitamin B12 may lead to several oral conditions and pain. These may include; mouth ulcers, a burning sensation or glossitis, which causes a swollen, smooth, red tongue.


There are several causes of a vitamin B12 deficiency. Even if you are consuming enough of the vitamin, certain underlying health conditions may affect the absorption of vitamin B12.

Some of these health conditions include:

  • Celiac disease
  • Pernicious anemia
  • Crohn’s disease
  • Atrophic gastritis

There are also a few risk factors that may make a person more likely to develop a deficiency of vitamin B12. These include:

  • Age – the older we get, the harder it may be to absorb vitamin B12
  • Eating a vegan or vegetarian diet – It is still possible to get enough of this vitamin with fortified cereals, milks and breads.
  • Over use of anti-acid medications – stomach acid is needed to absorb vitamin B12
  • Weight loss surgery – Again, this can interfere with the body’s ability to absorb the vitamin


In the event your doctor diagnoses you with a B12 deficiency, usually as a result of a simple blood test, they will discuss the best treatment options for you and your needs. For some, they can change dietary habits or add a supplement. For those that have difficultly absorbing vitamin B12, an injection may be necessary to treat the deficiency. These shots contain a high amount of a form of vitamin called cyanocobalamin and can be administered by a doctor.

Comprehensive Hematology Oncology offers B12 injections for patients that need them and a dedicated team of doctors ready to help treat all types of blood disorders.



  • https://ods.od.nih.gov/pdf/factsheets/Vitaminb12-Consumer.pdf
  • https://www.medicalnewstoday.com/articles/324265.php
  • https://www.healthline.com/nutrition/vitamin-b12-deficiency-symptoms#section9
  • https://www.webmd.com/a-to-z-guides/vitamin-b12-test#2