Understanding Vitamin B12 Deficiency Anemia: Causes, Symptoms, and Treatments

• Dietary insufficiency: According to a study by Gilsing, A. M. et al. (2010) published in The American Journal of Clinical Nutrition, a shortage of foods rich in vitamin B12, like animal products, can result in a deficiency.
• Malabsorption: As per findings from the study by Carmel, R. (2008) in Hematology/Oncology Clinics of North America, digestive conditions such as pernicious anemia or celiac disease can hinder vitamin B12 absorption.
• Atrophic gastritis: According to insights from the study by Andrès, E. et al. (2007) in The Journal of Nutrition, Health & Aging, inflammation of the stomach lining may reduce stomach acid production, affecting vitamin B12 release from food.
• Autoimmune disorders: According to the study conducted by Toh, B. H. et al. (1997) in Immunology Today, conditions like pernicious anemia involve autoimmune responses damaging stomach cells crucial for vitamin B12 absorption.
• Intestinal surgery or disease: According to a study by de Bree, A. et al. (2002) published in The New England Journal of Medicine, certain surgeries or disorders in the small intestine can impede vitamin B12 absorption.
• Medications: As outlined in the study by Kibirige, D. et al. (2013) in Diabetes & Metabolic Syndrome: Clinical Research & Reviews, certain drugs, including proton pump inhibitors and metformin, can disrupt vitamin B12 absorption.
• Genetic factors: As indicated by research conducted by Savage, D. G. et al. (1994) in The American Journal of Hematology, inherited genetic mutations can affect enzymes linked to vitamin B12 metabolism.
• Aging: As per observations made by Hunt, A. & Harrington, D. (2018) in "Clinical Aspects of Natural and Added Phosphorus in Foods," age-related decline in stomach acid and intrinsic factors (important for vitamin B12 absorption) can contribute to deficiency.

The main types of vitamin B12 deficiency are:

• Dietary deficiency: This is the most common type of vitamin B12 deficiency, accounting for about 50% of cases, and occurs when a person's diet lacks sufficient sources of vitamin B12. It often affects individuals who follow strict vegetarian or vegan diets, as vitamin B12 is primarily present in animal products.

• Pernicious anemia: It accounts for about 20% of cases. Pernicious anemia is an autoimmune condition where the body's immune system attacks the cells in the stomach that produce intrinsic factor, a protein necessary for vitamin B12 absorption. Without intrinsic factors, vitamin B12 absorption is suboptimal, leading to deficiency.

• Malabsorption disorders: Certain medical conditions, such as celiac disease, Crohn's disease, and atrophic gastritis, can impair the body's ability to absorb vitamin B12 from the gastrointestinal tract.

• Gastrointestinal surgery: Individuals who have undergone gastrointestinal surgeries, such as weight loss surgery or surgeries to remove parts of the stomach or intestine, may experience reduced vitamin B12 absorption.

• Medication-induced deficiency: Long-term use of certain medications, such as proton pump inhibitors (PPIs) and metformin, can interfere with vitamin B12 absorption and contribute to deficiency.

Vitamin B12 deficiency can cause various symptoms, impacting multiple functions of the human body. These manifestations can vary in their intensity and may emerge gradually. The following are some prevalent symptoms of Vitamin B12 deficiency:

• Fatigue and weakness: Ongoing weariness and feebleness, irrespective of rest, stem from B12's role in generating energy within cells.
• Pale or jaundiced skin: Inadequate red blood cell production can lead to skin pallor or a yellowish hue (jaundice).
• Shortness of breath and dizziness: Impaired oxygen transport by the blood may lead to breathlessness and dizziness, notably during physical activity.
• Tingling or numbness: Nerve impairment due to deficiency can incite tingling, numbness, or a sensation akin to "pins and needles," often in the extremities.
• Difficulty walking: Balance issues, muscular frailty, and challenges in walking may arise from nerve damage linked to B12 deficiency.
• Cognitive changes: Memory lapses, trouble concentrating, and cognitive haziness may be due to B12's impact on the nervous system.
• Heart palpitations: Anemia resulting from insufficient red blood cell synthesis can give rise to heart palpitations and elevated heart rate.
• Mouth ulcers and glossitis: Inflammation of the tongue (glossitis) and mouth ulcers can result from Vitamin B12 deficiency.
• Vision changes: Blurred or distorted vision may occur due to harm to the optic nerve.
• Mood disturbances: Deficiency could contribute to mood fluctuations, encompassing depression, anxiety, and irritability.
• Digestive issues: Patients may experience digestive problems like constipation, diminished appetite, and weight loss with Vitamin B12 deficiency.

The best way to prevent Vitamin B12 deficiency anemia is by adopting nutritional dietary habits and considering supplements under the guidance of your doctor. The following are some preventive measures healthcare professionals recommend:

• Balanced diet: Consuming a well-rounded diet is essential. You should include Vitamin B12-rich food, such as meats like beef, poultry, and fish, and dairy products like milk, yogurt, and cheese. These animal-based sources provide a natural and direct supply of Vitamin B12.
• Fortified foods: Incorporating Vitamin B12 fortified foods into your diet can be a strategic move. Opt for items like fortified cereals, plant-based milk alternatives, and nutritional yeast. These products are rich in Vitamin B12 and convenient to intake.
• Regular meat consumption: Regular meat consumption can be a direct way to maintain adequate Vitamin B12 levels for those not following a vegetarian or vegan diet. Lean cuts of meat, including poultry and fish, are delicious and contribute to your B12 intake.
• Informed vegan/vegetarian choices: If you've chosen a vegan or vegetarian lifestyle, you can still prevent deficiency by making informed choices. You can opt for fortified plant-based foods like cereals and non-dairy milk. However, as plant sources may be less reliable, consider supplements after consulting a doctor.
• Supplements: Vitamin B12 supplements can be a direct solution to prevent its deficiency. Consulting a doctor is crucial if your dietary intake needs modifications. They can recommend the appropriate dosage and form of supplements based on your specific needs.
• Regular health check-ups: Periodic health check-ups are vital in preventing deficiency. Regular monitoring allows medical professionals to identify early signs of deficiency and tailor interventions accordingly, safeguarding your overall health.
• Manage digestive disorders: Managing these conditions is paramount for those with digestive disorders like celiac disease or inflammatory bowel disease. Seeking medical guidance helps ensure optimal nutrient absorption, including Vitamin B12.
• Intrinsic factor: If you have conditions that affect the production of intrinsic factors, a protein necessary for B12 absorption, collaborating closely with a doctor is essential. They can guide you in managing the underlying condition alongside addressing B12 needs.
• Lifestyle considerations: Be mindful of lifestyle factors that can impact B12 levels in your body. Limiting alcohol intake can be beneficial, as excessive alcohol can interfere with B12 absorption. Additionally, avoiding smoking is wise, as it can negatively affect B12 status.
• Medical supervision: A personalized approach to medical management is beneficial, especially if you have unique health considerations. A doctor can evaluate your physical and psychological status and create a tailored prevention plan per your body's needs.

The diagnosis of Vitamin B12 deficiency anemia involves various steps. The doctor can prescribe multiple tests to determine the condition's underlying cause and severity. These diagnostic tests include:

• Clinical assessment: Doctors conduct a thorough medical history and physical examination. The doctors can inquire about symptoms, dietary habits, medical conditions, and family history to understand the condition.
• Blood tests: Your doctor may perform a series of blood tests to evaluate different aspects:

1. Complete blood count (CBC): This assesses red blood cell count, hemoglobin, and hematocrit levels, helping identify anemia.
2. Peripheral blood smear: A doctor may examine a blood sample under a microscope to analyze the shape and size of red blood cells, revealing potential abnormalities.
3. Serum vitamin B12 levels: Vitamin B12 levels in the blood help a doctor understand the condition's root cause.
4. Homocysteine and methylmalonic acid levels: Elevated levels of these substances can indicate Vitamin B12 deficiency.
5. Intrinsic factor antibody test: This blood test checks for antibodies that might attack intrinsic factor, a protein necessary for Vitamin B12 absorption. Positive results may indicate pernicious anemia, an autoimmune condition causing B12 deficiency.

• Schilling test: Though less commonly used today, the Schilling test evaluates the absorption of Vitamin B12. It involves taking a small amount of radiolabeled Vitamin B12 orally and monitoring its excretion in urine.
• Bone marrow examination: Sometimes, your doctor may perform a bone marrow examination to assess red blood cell production and morphology. They may use this test typically for situations where other tests could not be more conclusive.
• Endoscopy: If intrinsic factor deficiency is suspected, your healthcare provider may conduct an endoscopy to examine the stomach lining and identify potential causes of reduced inherent factor production.
• Genetic testing: In certain instances, genetic testing can identify inherited conditions that affect Vitamin B12 metabolism.
• Imaging studies: If neurological symptoms are present, imaging studies like MRI or CT scans may help evaluate potential nerve damage.

Vitamin B12 deficiency anemia presents varying stages of severity, each characterized by distinct symptoms and corresponding levels of Vitamin B12 in the blood. The following are different severity stages:

Mild deficiency:

At this stage, Vitamin B12 levels are typically between 150 and 300 picograms per milliliter (pg/mL). There might be subtle symptoms such as fatigue, weakness, or tingling in extremities. Concentration and cognitive function may also be affected. Timely intervention through diet changes or oral supplements is crucial in preventing further deterioration of the condition.

Moderate deficiency:

Vitamin B12 levels generally range from 100 to 150 pg/mL in this stage. Symptoms become more noticeable and impactful. A patient may experience fatigue, weakness, pallor, and shortness of breath, especially during exertion, which becomes more frequent. Cognitive difficulties might interfere with daily tasks and neurological symptoms like tingling in hands and feet can emerge.

Severe deficiency:

Vitamin B12 levels drop to around 50 to 100 pg/mL in this stage. Symptoms intensify, and anemia-related issues become more prominent. Profound fatigue and weakness are common, even with minimal activity. Shortness of breath may occur at rest. Neurological symptoms such as tingling, numbness, and coordination problems worsen. Prompt and aggressive treatment, often including injections, is crucial to prevent further complications.

Complicated deficiency:

Vitamin B12 levels fall below 50 pg/mL, indicating a critical deficiency. Neurological damage becomes more severe and potentially irreversible. Symptoms might include difficulty walking, memory problems, and nerve-related pain. Cardiovascular complications can also arise due to the strain on the heart from anemia. Your strict adherence to the treatment plan suggested by the doctor helps manage symptoms and prevent further deterioration.

Managing and treating vitamin B12 deficiency anemia involves various steps, including rectifying the underlying deficiency and restoring the optimal Vitamin B12 levels. The following are the critical aspects of treatment:

Vitamin B12 supplementation:

Vitamin B12 supplementation is the cardinal therapeutic measure. Your healthcare practitioner may prescribe oral supplements or administer intramuscular injections depending on the severity of the deficiency. If the vitamin is severely deficient or absorbed poorly, intramuscular injections are preferred, ensuring direct assimilation of the vitamin.

Dietary intervention:

It would help if you optimized your dietary intake to include sources of Vitamin B12, which is abundant in animal-derived foods such as meats, fish, poultry, dairy, and eggs. Those adhering to vegetarian or vegan diets must incorporate fortified foods or Vitamin B12 supplements into their diets.

Targeting underlying etiology:

Addressing the root causes that contribute to malabsorption is essential. If conditions like pernicious anemia or gastrointestinal disorders are present, their management is pivotal to enhance Vitamin B12 absorption.

Ongoing monitoring:

For healthcare practitioners to determine the effectiveness of their treatments, regular monitoring of Vitamin B12 levels is essential, enabling them to tweak therapeutic strategies based on your response. Careful tracking allows them to determine the optimal dosage and frequency for Vitamin B12 injections.

Neurological considerations:

Prompt intervention is pivotal in cases with neurological manifestations to avert irreversible neurological damage. The doctor may prescribe appropriate treatments to mitigate these neurological complications.

Adjunctive folate supplementation:

Sometimes, the healthcare provider may advise the administration of supplemental folate because a deficiency in one vitamin can influence the metabolism of another. However, this approach requires close clinical supervision.

Patient empowerment:

Empowering patients with comprehensive education regarding treatment adherence, dietary modifications, and scheduled follow-ups is paramount. A collaborative partnership between patients and healthcare providers facilitates informed decision-making and optimal health outcomes.

As one of the best healthcare institutions that offers comprehensive and specialized medical care, Medanta offers several compelling reasons for individuals to consider its services for their vitamin B12 deficiency treatment and management:

• Expertise of medical professionals: Medanta consists of a team of highly skilled doctors, specialists, and healthcare professionals with extensive experience diagnosing and treating nutritional deficiencies, including Vitamin B12 deficiency anemia. Their expertise ensures accurate diagnosis, personalized treatment plans, and effective management.

• State-of-the-art facilities: Equipped with advanced medical technologies and state-of-the-art facilities, Medanta offers cutting-edge diagnostic tools and treatment options for Vitamin B12 deficiency. It enables precise evaluation of deficiency levels and tailored interventions.

• Comprehensive diagnostic approaches: Medanta employs a holistic approach to diagnosis, considering the symptoms, underlying causes, and contributing factors of Vitamin B12 deficiency anemia. This extensive assessment aids in developing targeted treatment strategies.

• Personalized treatment plans: To ensure optimal patient outcomes, Medanta healthcare providers design treatment plans according to the patient's unique medical history, severity of deficiency, and unique requirements.

• Multidisciplinary care: At Medanta, specialists from various fields work together to provide holistic treatment for Vitamin B12 deficiency anemia, which addresses both hematologic and neurological aspects.

• Patient-centric approach: Medanta prioritizes patient well-being and comfort. The institution is committed to ensuring that patients are well-informed about their condition, treatment options, and lifestyle modifications required to manage Vitamin B12 deficiency effectively.

• Continuum of care: From diagnosis to treatment and ongoing management, Medanta offers a continuum of care. It ensures that patients receive consistent support and monitoring throughout their journey towards optimal Vitamin B12 levels and improved health.

• Research and innovation: As a leading medical center, Medanta continues its excellence in research and innovation. Patients benefit from the institution's commitment to staying updated with the latest advancements in diagnosing and managing Vitamin B12 deficiency.

• The prognosis of Vitamin B12 deficiency anemia is generally favorable when addressed promptly and effectively. Early diagnosis and intervention are critical factors in achieving positive outcomes. The prognosis of Vitamin B12 deficiency anemia depends on:
• Timely correction: Swift identification and deficiency correction contribute to a better prognosis. Initiation of appropriate treatment helps restore Vitamin B12 levels and alleviates anemia-related symptoms.
• Resolution of hematologic symptoms: With adequate treatment, anemia-related symptoms such as fatigue, pallor, and weakness tend to subside. Restoration of red blood cell production and improvement in hemoglobin levels are expected outcomes.
• Neurological implications: Early intervention is crucial in neurological manifestations, such as neuropathy and cognitive impairments. Timely treatment may halt or even reverse specific neurological deficits.
• Sustained management: While immediate symptoms respond well to treatment, ongoing surveillance is essential. Continued Vitamin B12 supplementation, adherence to dietary modifications, and regular monitoring are integral to sustaining optimal Vitamin B12 levels.
• Individual variability: Prognosis varies based on factors like the severity of the deficiency, comorbid conditions, and individual responsiveness to treatment. Some people achieve complete symptom resolution, while others may require consistent management.
• Complication prevention: Effective management helps prevent complications associated with prolonged deficiency, including irreversible nerve damage and cognitive impairment. Rigorous adherence to treatment plans and periodic follow-up visits are paramount.

What is Vitamin B12 deficiency anemia?

Vitamin B12 deficiency anemia occurs when the body lacks adequate vitamin B12, essential for red blood cell production.

What are the causes of Vitamin B12 deficiency anemia?

Causes of Vitamin B12 deficiency anemia include dietary insufficiency, malabsorption, atrophic gastritis, autoimmune disorders, intestinal surgery, certain medications, genetic factors, and aging.

How does dietary insufficiency lead to deficiency anemia?

A diet lacking in vitamin B12-rich foods, primarily animal products, can result in insufficient intake of the vitamin, leading to anemia.

What is malabsorption-related Vitamin B12 deficiency?

Conditions like pernicious anemia or celiac disease can hinder the absorption of vitamin B12 in the digestive system, causing deficiency anemia.

How does atrophic gastritis contribute to deficiency anemia?

Inflammation of the stomach lining can reduce stomach acid production, affecting the release of vitamin B12 from food, leading to deficiency anemia.

How do autoimmune disorders relate to Vitamin B12 deficiency anemia?

Autoimmune conditions, such as pernicious anemia, involve immune responses targeting stomach cells needed for vitamin B12 absorption, causing vitamin B12 deficiency anemia.

What role does intestinal surgery or disease play in causing deficiency anemia?

Certain surgeries or disorders affecting the small intestine can impair the absorption of vitamin B12, contributing to deficiency anemia.

Can medications contribute to Vitamin B12 deficiency anemia?

Certain medications like proton pump inhibitors and metformin can disrupt vitamin B12 absorption, potentially leading to deficiency anemia.

Are genetic factors linked with Vitamin B12 deficiency anemia?

Inherited genetic mutations can impact enzymes involved in vitamin B12 metabolism, potentially leading to deficiency anemia.

How does aging affect Vitamin B12 levels and lead to anemia?

Aging can result in decreased stomach acid and intrinsic factor production, vital for vitamin B12 absorption, possibly causing anemia.

What are the symptoms of Vitamin B12 deficiency anemia?

Symptoms of Vitamin B12 deficiency include fatigue, weakness, pale skin, shortness of breath, tingling or numbness, balance issues, and cognitive changes.

Why does Vitamin B12 deficiency cause fatigue and weakness?

Vitamin B12 is necessary for red blood cell production, and anemia results in decreased oxygen transport, leading to fatigue and weakness.

How does Vitamin B12 deficiency contribute to pale skin?

Anemia affects the number and function of red blood cells, reducing oxygen supply to tissues and causing pale skin.

What is the relationship between Vitamin B12 deficiency and shortness of breath?

Insufficient red blood cells mean less oxygen is carried to tissues, causing shortness of breath during physical activities.

Why does Vitamin B12 deficiency lead to tingling or numbness?

Nerve damage from anemia can result in tingling, numbness, and other neurological symptoms known as peripheral neuropathy.

What is the link between Vitamin B12 deficiency and balance issues?

Neurological symptoms from deficiency can affect coordination and balance, causing instability and an increased risk of falls.

How can Vitamin B12 deficiency cause cognitive changes?

Neurological damage can result in cognitive changes, such as memory problems, confusion, and difficulty concentrating.

How is Vitamin B12 deficiency anemia diagnosed?

Diagnosis involves:

• Blood tests to measure vitamin B12 levels.
• Complete blood count.
• Sometimes, doctors may recommend additional tests to determine the underlying cause.

What are the normal Vitamin B12 levels in the blood?

Normal levels typically range from 200 to 900 picograms per milliliter (pg/mL) of blood.

What is a complete blood count (CBC) test?

A CBC test measures different blood components, including red blood cells, white blood cells, and platelets.

How is the cause of Vitamin B12 deficiency determined?

Additional tests like intrinsic factor antibody tests, homocysteine and methylmalonic acid levels, and endoscopy can help identify the underlying cause.

What is the intrinsic factor antibody test?

This test checks for the presence of antibodies that attack intrinsic factor, a protein necessary for vitamin B12 absorption.

What is homocysteine, and why is it relevant to Vitamin B12 deficiency?

Homocysteine is an amino acid, and elevated levels can indicate Vitamin B12 deficiency or other factors affecting metabolism.

How does Vitamin B12 deficiency affect homocysteine levels?

Vitamin B12 is needed to process homocysteine, so that that deficiency can lead to increased homocysteine levels.

What is methylmalonic acid, and how is it linked to Vitamin B12 deficiency?

Methylmalonic acid is a substance that accumulates when Vitamin B12 is deficient, making it a marker for deficiency.

What role does endoscopy play in diagnosing Vitamin B12 deficiency?

An endoscopy can reveal conditions like atrophic gastritis that might be causing Vitamin B12 malabsorption.

Is Vitamin B12 deficiency reversible?

One can reverse many cases of Vitamin B12 deficiency anemia with appropriate treatment and management.

How is Vitamin B12 deficiency anemia treated?

Treatment involves Vitamin B12 supplementation through injections, oral supplements, or nasal sprays.

What is the typical dosage for Vitamin B12 supplementation?

Dosages can vary but commonly range from 250 to 1000 micrograms per day initially.

Are there any potential side effects of Vitamin B12 supplementation?

Supplementation is generally safe, but some individuals might experience rare side effects like allergic reactions or skin rash.

How long does it take to see improvements after starting Vitamin B12 supplementation?

Improvements in symptoms can be noticeable within a few days to weeks of starting supplementation.

Do oral Vitamin B12 supplements work as effectively as injections?

For most cases, oral supplements are effective if absorption issues are not severe, but your doctor may recommend injections for severe deficiency.

How long is Vitamin B12 supplementation typically continued?

The duration varies based on the underlying cause and response to treatment. It might be lifelong for some individuals.

Can Vitamin B12 deficiency anemia lead to complications if left untreated?

Untreated vitamin B12 deficiency anemia may lead to various complications, such as heart problems, nerve damage, and developmental issues in children.

What heart problems can arise from untreated Vitamin B12 deficiency anemia?

Anemia strains the heart as it tries to compensate for reduced oxygen-carrying capacity, potentially leading to cardiovascular issues.

How does untreated deficiency anemia cause nerve damage?

Vitamin B12 is essential for nerve health. Therefore, prolonged deficiency can lead to irreversible nerve damage.

What developmental issues can occur in children due to untreated deficiency anemia?

Untreated deficiency can hinder children's average growth, cognitive development, and overall well-being.

Can Vitamin B12 deficiency anemia be prevented?

A balanced diet rich in vitamin B12 sources and addressing underlying medical conditions can help prevent deficiency.

Which foods are good sources of Vitamin B12?

Animal products like meat, fish, dairy, and eggs are excellent sources of Vitamin B12.

Can vegetarians or vegans prevent deficiency?

They can consume fortified foods like plant-based milk, Vitamin B12-fortified cereals, and Vitamin B12 supplements.

Is Vitamin B12 naturally found in plant-based foods?

No, Vitamin B12 is mainly prevalent in animal products, and natural sources in plant-based foods are limited.

What is the recommended dietary allowance (RDA) for Vitamin B12?

For adults, the RDA is typically around 2.4 micrograms per day.

Are there any factors that increase the risk of Vitamin B12 deficiency?

Factors such as age, vegetarian or vegan diets, digestive conditions, certain medications, and medical history can increase the risk of Vitamin B12 deficiency.

How does age increase the risk of deficiency?

Aging can decrease stomach acid and intrinsic factor production, reducing Vitamin B12 absorption.

How does being vegetarian or vegan impact the risk of deficiency?

Plant-based diets lack Vitamin B12, increasing the risk for individuals who don't consume animal products.

Can digestive conditions contribute to deficiency risk?

Digestive conditions like pernicious anemia or celiac disease can hinder Vitamin B12 absorption, raising the risk of Vitamin B12 deficiency.

Is Vitamin B12 deficiency common in pregnancy?

It is more common due to increased demands and potential dietary limitations, so your doctor may recommend supplementation. Healthcare providers might recommend prenatal supplements or fortified foods to ensure adequate intake.

What is the role of Vitamin B12 in pregnancy?

Vitamin B12 is crucial for fetal development, red blood cell production, and preventing developmental issues.

Can Vitamin B12 deficiency affect mental health?

Vitamin B12 deficiency can contribute to mood changes, depression, and cognitive impairment.

Can Vitamin B12 deficiency lead to nerve-related symptoms?

Neurological symptoms like tingling, numbness, and balance issues can arise due to nerve damage.

Can Vitamin B12 deficiency affect vision?

Severe deficiency might contribute to vision disturbances and blurry vision.

Does Vitamin B12 deficiency affect hair and skin health?

Vitamin B12 deficiency can affect skin tone, hair texture, and overall appearance.

Is Vitamin B12 deficiency linked to digestive issues?

Vitamin B12 deficiency can cause digestive problems like diarrhea, constipation, or loss of appetite.

Is it possible to overdose on Vitamin B12 supplements?

Vitamin B12 is water-soluble, making overdose rare. Excess amounts are typically excreted out of the body in urine.

Can certain medical conditions affect Vitamin B12 absorption?

Certain medical conditions like Crohn's disease or atrophic gastritis can hinder absorption, increasing the risk of deficiency.

Can Vitamin B12 deficiency be a result of heavy alcohol consumption?

Excessive alcohol intake can interfere with Vitamin B12 absorption and lead to deficiency.

Can Vitamin B12 deficiency anemia lead to hair loss?

Vitamin B12 deficiency anemia affects the oxygen supply to hair follicles, potentially leading to hair loss.

Is Vitamin B12 deficiency associated with autoimmune disorders?

Autoimmune conditions like pernicious anemia can target intrinsic factors needed for Vitamin B12 absorption, causing deficiency.