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What to know about B12 deficiency anemia

Deficiency of vitamin B12 Anemia is a disorder in which the body’s supply of healthy red blood cells is insufficient due to a deficiency of vitamin B12. If B12 is deficient, the body may not be able to make enough red blood cells to supply the body with enough oxygen.

Vitamin B12, also known as cobalamin, is a B vitamin that is essential for a variety of bodily activities, including red blood cell synthesis (RBCs). A person who is deficient in vitamin B12 may develop anemia, which is caused by a decrease in the amount of healthy circulating RBCs. This might happen as a result of malabsorption, an underlying ailment, or a particular diet. Vitamin B12 supplementation is commonly used as a treatment.

In this post, we’ll go over the many types of B12 deficiency anemia, as well as their causes and therapies.

When to consult a doctor

Symptoms of B12 deficiency anemia can be confused with those of a variety of different illnesses, and long-term insufficiency can worsen symptoms. A person who is having any symptoms should consult a doctor to determine the origin of their symptoms and begin treatment as soon as possible.

What is it?

consulting a doctor

Vitamin B12, often known as cobalamin, is a water-soluble vitamin that contains the mineral cobalt. It can be found in a variety of meals, including fish, meat, and dairy products. Vitamin B12 is required by the body for the following functions:

  • brain and neurological function
  • fat and protein metabolism
  • creating new RBCs
  • DNA synthesis

The recommended daily requirement for vitamin B12 varies by individual due to a variety of circumstances, but for most adults, it is around 2.4 micrograms.

B12 deficiency is a condition in which the body lacks the vitamin B12. When a person’s B12 levels are too low, the body is unable to manufacture enough healthy RBCs, resulting in anemia. When this happens, the body may not be able to manufacture enough RBCs to appropriately provide the body with oxygen. The body cannot function properly without enough oxygen, resulting in weariness, weakness, and other problems.

Megaloblastic anemia is a kind of megaloblastic anemia caused by a lack of vitamin B12. When RBCs do not mature regularly, this is referred to as this condition. Instead, they are much larger and more oval in shape than mature RBCs. Another type of megaloblastic anemia is folate deficiency, which is caused by a lack of another B vitamin.

Causes and risk factors

The following are some of the most common causes of vitamin B12 deficient anemia:

Autoimmune disorders

Pernicious anemia is an autoimmune disease that damages the stomach lining and hinders the generation of an intrinsic factor protein. The immune system produces antibodies that assault the parietal cells that lining the stomach and manufacture this protein. Intrinsic factor aids vitamin B12 absorption in the small intestine. Vitamin B12 deficiency can occur if a person does not consume enough of this protein.

Pernicious anemia is frequently linked to autoimmune diseases such type 1 diabetes, vitiligo, and thyroid problems. Pernicious anemia is a rare disorder, although research suggests that it is more common in adults of Northern European ancestry who are over 60 years old.

Intestinal problems

Chronic gastritis, or inflammation of the stomach lining, can impede the secretion of intrinsic factor and stomach acids, both of which aid in the absorption of vitamin B12.

Autoimmune diseases including Crohn’s disease and celiac disease can cause inflammation. It could also be caused by illnesses like Helicobacter pylori.


The gastrointestinal system may be rearranged or removed in some procedures, such as gastric bypass or small bowel resection. A person’s ability to absorb vitamin B12 may be hampered as a result of certain anatomical alterations.

Vitamin B12 shortage is frequent after this sort of surgery, according to research, with 13–60 percent of individuals developing a shortfall.


Long-term use of certain drugs might make it difficult for the body to absorb vitamin B12, resulting in a deficiency. The following drugs have been linked to inadequate vitamin B12 absorption:

  • Metformin: A medication that can help treat type 2 diabetes.
  • Proton pump inhibitors: A type of medication that suppresses stomach acid. A person may use this to treat conditions such as gastroesophageal reflux and peptic ulcers.
  • Colchicine: A medication people may use to treat gout and Mediterranean fever.


Only animal-based foods contain vitamin B12. People who eat low-fat, low-carbohydrate diets, such as vegan and vegetarian diets, may be deficient in vitamin B12.

Risk factors

The following are some factors that may increase a person’s risk of vitamin B12 deficiency anemia:

  • having a family member who suffers from the disease
  • thyroid disease, diabetes, and vitiligo are all autoimmune conditions linked to vitamin D deficiency
  • as you become older, your chance of B12 malabsorption rises


Symptoms of vitamin B12 deficiency anemia can appear gradually and differ from one person to another. Among the signs and symptoms are:

  • diarrhea
  • pale skin
  • sore and tender tongue
  • fast heart rate
  • difficulty walking
  • weakness
  • tingling or numbness in the hands and feet
  • nausea
  • decreased appetite
  • fatigue
  • weight loss
  • irritability

Click here to learn more about the symptoms of vitamin B12 deficiency.

While complications are uncommon, people with severe anemia are more likely to have heart and lung problems as a result of issues giving oxygen to important organs. In addition, patients with vitamin B12 deficient anemia may have the following symptoms:

  • stomach cancer
  • neural tube birth defects if the B12 deficient person is pregnant
  • neurological changes, such as vision and memory problems
  • infertility


Vitamin B12 deficiency anemia is difficult to detect because of its wide range of symptoms and frequent comorbidity with other illnesses. During a medical exam, a doctor may use a routine blood test to diagnose the illness.

A doctor may enquire about a person’s medical history, perform a physical exam, and order blood tests to detect vitamin B12 deficiency anemia. A complete blood count will detect any anomalies in RBCs and hemoglobin concentration, as well as a person’s serum vitamin B12 levels.

If the blood test reveals symptoms of anemia, more testing may be required to determine the cause. The following are examples of such tests:

  • a blood test for intrinsic factor antibodies associated with pernicious anemia
  • a blood test to see a person’s reticulocyte count and measure the number of young RBCs
  • bone marrow tests to see if a person’s bone marrow is making RBCs properly


Vitamin B12 supplementation is usually used to restore a person’s levels to a healthy level. Depending on the source of a person’s B12 deficiency, the length and type of treatment may differ.

A doctor may give oral B12 supplements to ease symptoms in persons who are deficient owing to dietary reasons. A person might also work with a dietitian to increase their intake of vitamin B12. Vitamin B12-rich foods include:

  • poultry
  • eggs
  • dairy products
  • fish
  • meat

Foods fortified with vitamin B12, such as yeast extracts, cereals, and some plant milks, can be consumed if a person chooses to include vitamin B12 in their diet without consuming animal products.

Treatment for malabsorption usually entails a doctor injecting B12 into the patient. By injecting the vitamin into a muscle, the body may absorb it without having to go via the digestive system. cyanocobalamin and hydroxocobalamin are two examples of these injections.

Before transitioning to monthly injections, a person may receive these injections regularly at the start of treatment to refill their stockpiles. For some people, this treatment may be required for the rest of their lives in order to maintain adequate vitamin B12 levels.


B12 insufficiency is a condition in which the body lacks the vitamin B12. Anemia is a condition in which the generation of healthy red blood cells is hampered due to a shortage of vitamin B12. People with anemia may feel symptoms such as weakness, exhaustion, and shortness of breath as a result of a smaller amount of healthy red blood cells.

Other underlying medical issues, specific medications, or surgery can all cause this illness. A doctor may recommend taking B12 supplements and eating B12-rich or fortified foods to help manage a deficiency.



Obianuju Chukwu

She has a degree in pharmacy and has worked in the field as a pharmacist in a hospital. Teaching, blogging, and producing scientific articles are some of her interests. She enjoys writing on various topics relating to health and medicine, including health and beauty-related natural treatments, the nutritional worth of various foods, and mental wellness.