Vitamin B12 (Cobalamin) deficiency: What Africans Need To Know


By: Victoria Iyeduala (Freelance Health and Wellness Writer). Medically reviewed by the DLHA Team


African woman holding a container of vitamin B12 supplements

African woman holding a container of vitamin B12 supplements.





Vitamin B12, or cobalamin, is an essential nutrient for the production of red blood cells and proper function of the nervous system (the brain, spinal cord and nerves). It's abundant in animal sources such as meat, fish, seafood, eggs and dairy products.


Vitamin B12 is a water-soluble vitamin. Although excess is removed from the body through urine, the liver stores large amounts of vitamin B12 for years.


According to this study, many Africans don't get adequate amounts of natural vitamin B12, and deficiency may be common.


When you have vitamin B12 deficiency, your body has an unhealthy low amount of vitamin B12.


B12 deficiency sets in when your body uses up its liver stores, and it's not replenished. This article explains vitamin B12 deficiency and how it can affect you.



What is vitamin B12 deficiency?


Vitamin B12 deficiency occurs when your body doesn't have enough vitamin B12 to function properly. It may take years for the symptoms of vitamin B12 to show up because your body stores large amounts in the liver.


Individuals with a high risk of B12 deficiency include:

  • Patients with certain medical conditions of red blood cells and the bowel, such as pernicious anaemia, atrophic gastritis, coeliac disease and Crohn's disease
  • People who have had some types of bowel surgeries, such as weight loss surgery, that remove part of the stomach
  • Vegetarians and vegans
  • Babies of pregnant and breastfeeding vegetarian and vegan mothers
  • Patients who have used drugs that decrease stomach acid production (gastric acid inhibitors), such as omeprazole and cimetidine, for over a year and metformin (a diabetes drug) for over four months
  • Older adults
  • People with alcohol use disorder



What are the signs and symptoms of vitamin B12 deficiency?


Symptoms of vitamin B12 deficiency can include anaemia signs, other physical signs, neurological problems and psychological disorders.


Anaemia signs include:

  • Fatigue
  • Shortness of breath 
  • Feeling faint
  • Irregular heartbeat
  • Pale skin
  • Smooth, swollen and painful red tongue (glossitis)
  • Inability to taste food
  • Jaundice (yellow skin)


Neurological and psychological signs include:

  • Numbness and tingling in hands or feet
  • Pain and weakness in hands or feet
  • Poor coordination and difficulty in maintaining balance
  • Difficulty in walking, speaking, eating and writing
  • Blurred or double vision
  • Memory loss
  • Feeling confused
  • Anxiety
  • Depression
  • Hallucinations


Other physical signs include:

  • Glossitis (inflammation of the tongue)
  • Diarrhoea
  • Headaches
  • Weight loss



What causes vitamin B12 deficiency?


The three causes of vitamin B12 deficiency are:

  • Pernicious Anaemia
  • Malabsorption of vitamin B12
  • Eating a diet low in vitamin B12


Pernicious Anaemia


For your body to absorb vitamin B12 from anything you eat, your stomach needs to produce intrinsic factor. Intrinsic factor is a special protein that helps your body absorb vitamin B12.


Pernicious anaemia is an autoimmune condition that prevents your body from producing effective intrinsic factor. Autoimmune disorders are medical conditions caused by the body mistakenly attacking its own normal cells.


Since your body can't absorb and use vitamin B12 without intrinsic factor, your body will lack the vitamin, resulting in anaemia.


Pernicious anaemia has been found to be the most common cause of vitamin B12 deficiency globally, but it's less common in people of African descent.


Malabsorption of vitamin B12


Stomach surgeries like gastric bypass and sleeve gastrectomy (weight loss surgeries) that remove a large portion of your stomach reduce the absorption of vitamin B12 from food and oral supplements by reducing the production of intrinsic factor.


Bowel diseases like Crohn's disease, which is associated with bowel autoimmune inflammation and coeliac disease (an autoimmune condition) cause damage to the small intestine, where vitamin B12 is absorbed into your body and inhibits its absorption.


Excess alcohol consumption, tapeworm infection and medications such as omeprazole (a proton pump inhibitor or PPI), cimetidine (an H2 blocker) and metformin also impair the absorption of vitamin B12 into your body.


A diet low in vitamin B12


Since vitamin B12 is naturally found mainly in animal-derived food products, you can develop vitamin B12 deficiency if they're absent in your diet. Following a strict vegan diet for about three years can cause vitamin B12 deficiency.


People such as vegetarians and older adults with a restrictive diet containing little animal products have a high risk of having B12 deficiency. Babies of pregnant and breastfeeding vegan/vegetarian mothers can also develop B12 deficiency.



What happens when vitamin B12 is low in your body?


Vitamin B12 deficiency causes a number of health complications including:

  • Megaloblastic anaemia or vitamin deficiency anaemia
  • Neurological disorders
  • Psychological disorders
  • Folate deficiency
  • Hhyperhomocysteinemia
  • Other severe health problems


Vitamin B12 deficiency anaemia (megaloblastic anaemia)


Vitamin deficiency anaemia or megaloblastic anaemia is caused by either vitamin B12 deficiency or folate (vitamin B9) deficiency. Vitamins B9 and B12 are necessary for making normal red blood cells.


Megaloblastic anaemia is a type of anaemia where your blood has fewer red blood cells to carry oxygen around your body because your body makes abnormally large red blood cells. 


Neurological and psychological disorders


Untreated vitamin B12 deficiency can damage the nervous system and lead to neurological and psychological disorders, including:

  • Peripheral neuropathy: This causes numbness, a tingling feeling, pain and weakness in your hands or feet.
  • Ataxia: This condition causes slurred speech and difficulty maintaining balance and controlling body movements (coordination) such as walking, running, writing, swallowing and eye movements.
  • Dementia: This condition causes difficulty concentrating and using your sense of intelligence and judgement, memory loss and confusion.
  • Mental health disorders: Examples are mental health conditions such as anxiety, major depression, bipolar disorder and insomnia.
  • Loss of proprioception: This is when the nerves that help you understand and control the movements and positioning of your body according to your environment don't work well.


Folate deficiency


Vitamin B12 plays a vital role in processing vitamin B9 (folate) to its usable form in the body. Insufficient vitamin B12 hinders this process and leads to folate deficiency.


Folate deficiency can cause anaemia and pregnancy and birth complications such as miscarriage, premature birth, neural tube defects (NTDs) and low birth weight.




Low levels of vitamin B12 can cause high levels of homocysteine (hyperhomocysteinemia). Homocysteine is a type of chemical substance (amino acid) that is necessary for processing essential proteins in your body.


Your body needs vitamin B12 to use homocysteine. So when there's insufficient B12 in your body, homocysteine accumulates.


Too much homocysteine can cause artery damage and blood clots, raising your risk of cardiovascular diseases and stroke.


Other Complications


Vitamin B12 deficiency anaemia can cause heart failure. Damage to the nervous system can cause irreversible neurological disorders that result in serious lifetime disabilities.


Since vitamin B12 is required for processing DNA, deficiency in pregnant women may cause early developmental defects of the nervous system in foetuses, called neural tube defects (NTDs) and deficiency in infants can cause slow development.


Long-term untreated B12 deficiency can cause pancytopenia, a condition where you have low red blood cells, white blood cells and blood platelets. B12 deficiency can also cause infertility.


Prolonged vitamin B12 deficiency may increase your risk of gastric cancer and autoimmune diseases such as type 1 diabetes and rheumatoid arthritis.



How can you prevent vitamin B12 deficiency?


You can prevent B12 deficiency by eating a vitamin B12-rich diet and reducing alcohol intake. A diet rich in vitamin B12 contains animal products such as meat, fish and seafood, milk and eggs. You can also add cobalamin-fortified foods such as cereals, flour, bread, soya milk, and juices.

Best sources of Vitamin B 12


Vegans, vegetarians and other people who can't get sufficient vitamin B12 from their diet should take vitamin B12 supplements. Oral vitamin B12 supplements (e.g. cyanocobalamin) are available as non-prescription medications.


Additionally, you should go for routine checkups to monitor your B12 levels if you're at risk of having a deficiency.



How is vitamin B12 deficiency diagnosed?


To be certain you have vitamin b12 deficiency, you need to see a doctor immediately if you start seeing suggestive symptoms.


Your doctor may carry out a complete blood count (CBC) or full blood count test, peripheral blood smear, and vitamins B12 and B9 levels check. Your doctor may also check your methylmalonic acid (MMA) and homocysteine levels.



How is vitamin B12 deficiency treated?


Although the duration and method of treatment depend on the cause of the deficiency, raising your levels of vitamin B12 will be the goal of your treatment plan. You can achieve this by eating a healthful diet rich in vitamin B12, taking vitamin B12 supplements and drinking less alcohol.


Your healthcare provider will treat any underlying medical condition or adjust any medications causing the deficiency while increasing your B12 levels with supplements and a healthy vitamin B12-rich diet.


Patients, especially those without severe neurological complications, recover well when vitamin B12 deficiency is diagnosed and treated early. However, younger patients recover better than older adults.





Your body needs vitamin B12 (cobalamin) to maintain healthy production of red blood cells and proper function of your nervous system. Vitamin B12 insufficiency causes anaemia, mental and abnormal behavioural health changes, as well as damage to your brain, spinal cord and nerves.


Early diagnosis and treatment will help you recover better from vitamin B12 deficiency and avoid complications.


Ultimately, you can prevent B12 deficiency by eating a healthy diet rich in vitamin B12, taking vitamin B12 supplements and avoiding excess drinking.




  • Ankar, A. & Kumar, A. (2022, October 22). Vitamin B12 Deficiency. StatPearls - NCBI Bookshelf. Retrieved October 10, 2023.
  • Office of Dietary Supplements. National Institute of Health. Vitamin B12. (Updated 2022 Dec. 2)  Retrieved October 10, 2023.







Published: October 16, 2023

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