Vitamin B12 is a crucial nutrient essential for numerous physiological processes in the body. From red blood cell formation to neurological function and DNA synthesis, this water-soluble vitamin plays an important role in maintaining overall health and well-being. However, despite its importance, many people do suffer from Vitamin B12 deficiency, which leads to a range of health issues.

Causes of Vitamin B12 Deficiency:

  1. Dietary Factors:
    • Vegan and Vegetarian Diets: Individuals adhering to plant-based diets are at a higher risk of deficiency due to the limited availability of B12-rich foods.
    • Poor Dietary Intake: Inadequate consumption of animal-derived foods, such as meat, fish, eggs, and dairy products, can contribute to B12 deficiency.
  2. Malabsorption Issues:
    • Pernicious Anaemia: An autoimmune condition that attacks the stomach lining, leading to impaired production of intrinsic factors necessary for B12 absorption.
    • Gastrointestinal Disorders: Conditions like Crohn’s disease, celiac disease, and surgical procedures affecting the stomach or intestine can interfere with B12 absorption.
    • Liver Function: Impaired liver function can affect the body’s ability to store and utilise Vitamin B12, leading to deficiency.
  3. Other Contributing Factors:
    • Medications: Certain medications, including proton pump inhibitors, histamine-2 receptor antagonists, and metformin, can inhibit B12 absorption.
    • Genetic Predisposition: Variations in genes related to B12 metabolism can increase susceptibility to deficiency.
    • Alcohol Consumption: Excessive alcohol consumption can interfere with B12 absorption and utilisation, contributing to deficiency.

Symptoms of Vitamin B12 Deficiency:

Vitamin B12 deficiency can manifest in a variety of physical, neurological, and psychological symptoms. These may include:

  1. Physical Symptoms:
    • Fatigue and weakness
    • Pallor or jaundice
    • Shortness of breath and dizziness
    • Rapid heartbeat or palpitations
  2. Neurological Symptoms:
    • Numbness and tingling sensations in the hands and feet
    • Difficulty walking or maintaining balance
    • Memory loss and cognitive impairment
    • Mood swings, depression, and irritability
  3. Psychological Symptoms:
    • Depression and anxiety
    • Cognitive decline and dementia-like symptoms
    • Changes in personality and behaviour

Diagnosis of Vitamin B12 Deficiency:

Diagnosing Vitamin B12 deficiency typically involves a combination of medical history, physical examination, and laboratory tests:

  1. Blood Tests:
    • Measurement of serum Vitamin B12 levels can provide insight into the body’s B12 status. However, it’s essential to interpret results in conjunction with other factors, as serum levels may not always reflect tissue B12 levels accurately.
    • Elevated levels of methylmalonic acid (MMA) and homocysteine in the blood may indicate B12 deficiency, as these substances accumulate when B12-dependent metabolic pathways are impaired.
  2. Medical History and Physical Examination:
    • Evaluation of symptoms, dietary habits, and risk factors can help identify individuals at risk of B12 deficiency.
    • Neurological examination may reveal signs of nerve damage associated with B12 deficiency, such as loss of sensation or impaired reflexes.

Treatment and Prevention:

Addressing Vitamin B12 deficiency typically involves a multi-faceted approach aimed at replenishing B12 levels and addressing underlying causes:

  1. Dietary Changes and Supplementation:
    • Incorporating B12-rich foods into the diet, such as meat, fish, eggs, and dairy products, can help prevent or alleviate deficiency.
    • For individuals following a vegan or vegetarian diet, fortified foods or B12 supplements may be necessary to meet daily requirements.
  2. Supplementation and Medical Intervention:
    • Vitamin B12 supplements are available in various forms, including oral tablets, sublingual (under-the-tongue) sprays, and intramuscular injections.
    • Intramuscular injections of Vitamin B12 may be administered in cases of severe deficiency or malabsorption issues to bypass the digestive system and deliver the vitamin directly into the bloodstream.
    • Treatment of underlying conditions contributing to B12 deficiency, such as pernicious anaemia or gastrointestinal disorders, is essential for long-term management.


Now onto… The Liver and Vitamin B12:


It is liver function that plays a crucial role in the metabolism and utilisation of Vitamin B12 in the body. Several aspects of liver function can impact the body’s B12 status:

  1. Storage and Release: The liver serves as a primary storage site for Vitamin B12, storing excess B12 that is absorbed from the diet or obtained through supplementation. When the body requires Vitamin B12, the liver releases stored B12 into the bloodstream to meet physiological demands.
  2. Synthesis of Binding Proteins: The liver synthesises binding proteins, such as transcobalamin II (TC II), which facilitate the transport of Vitamin B12 in the bloodstream. TC II binds to Vitamin B12 and transports it to tissues throughout the body, where it is taken up and utilised for various metabolic processes.
  3. Detoxification Processes: The liver is responsible for detoxifying harmful substances and metabolising drugs and medications. Certain medications, such as proton pump inhibitors and metformin, can interfere with B12 absorption and utilisation, potentially leading to deficiency over time.
  4. Bile Production: Bile produced by the liver aids in the absorption of fat-soluble vitamins, including Vitamin B12. Impaired bile production or flow, as seen in conditions like cholestasis or obstructive jaundice, can disrupt the absorption of fat-soluble nutrients, potentially contributing to B12 deficiency.
  5. Maintenance of Overall Health: The liver plays a central role in maintaining overall health and vitality by regulating metabolic processes, synthesising essential proteins, and detoxifying harmful substances. Optimal liver function is essential for supporting the body’s ability to absorb, transport, and utilise nutrients effectively, including Vitamin B12.


This is why when dealing with ‘symptoms’ like B12 deficiency, we must always look at the root cause approach and look at the underlying function of the organ systems – it isn’t necessarily a deficiency, but an issue with the ability to metabolise/absorb/assimilate.

Vitamin B12 deficiency poses significant health risks and can have far-reaching implications for overall well-being. By understanding the causes, symptoms, and diagnostic methods associated with B12 deficiency, individuals can take proactive steps to prevent, detect, and manage this condition effectively. Through dietary modifications, supplementation, and medical intervention when necessary, individuals can optimise their B12 levels and support optimal health and vitality.

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Written by Ellie Dobbs