Vitamin B12 Deficiency: Causes, Symptoms, Diagnosis & Treatment

Vitamin B12 deficiency is a common nutritional disorder that affects blood formation, nerve function, and brain health. Vitamin B12 (cobalamin) is essential for DNA synthesis and red blood cell production. Deficiency can lead to anemia and neurological complications, some of which may become irreversible if treatment is delayed.

 What Is Vitamin B12 and Why Is It Important?

Vitamin B12 is required for:

• Formation of healthy red blood cells

• Proper functioning of nerves and brain

• DNA synthesis

• Prevention of nerve degeneration

The body cannot produce vitamin B12, so it must be obtained from diet or supplements.

 Causes of Vitamin B12 Deficiency

🔹 Dietary Deficiency

• Strict vegetarian or vegan diet

• Poor nutritional intake

• Elderly individuals with reduced intake

🔹 Malabsorption (Most Common)

Cause

Mechanism

1.Pernicious anemia

Lack of intrinsic factor

2.Chronic gastritis

Reduced B12 absorption

3.Long-term acid-suppressing drugs

Reduced gastric acid

4.Post-gastrectomy or bariatric surgery

Loss of absorption sites

5.Celiac disease / Crohn’s disease

Intestinal damage

🔹 Other Causes

• Chronic alcohol use

• Pancreatic insufficiency

• Prolonged metformin use

• Parasitic infections (rare)

 Symptoms of Vitamin B12 Deficiency

General Symptoms

• Fatigue and weakness

• Pale or yellowish skin

• Shortness of breath

• Palpitations

Neurological Symptoms (Important)

• Numbness or tingling in hands and feet

• Difficulty walking or imbalance

• Memory loss or confusion

• Depression or mood changes

• Burning sensation in feet

Oral & GI Symptoms

• Smooth, sore tongue (glossitis)

• Mouth ulcers

• Loss of appetite

• Weight loss

 Late or severe deficiency can cause permanent nerve damage.

 Types of Anemia Caused

• Megaloblastic anemia

• High MCV (macrocytosis)

• Pancytopenia (severe cases)

 Diagnosis

Blood Tests

• Low serum vitamin B12 levels

• Elevated MCV

• Peripheral smear: macrocytosis

• Low hemoglobin

• Elevated homocysteine and methylmalonic acid (early markers)

Additional Tests (If Needed)

• Anti-intrinsic factor antibodies

• Anti-parietal cell antibodies

• Endoscopy for chronic gastritis

 Treatment & Management

1️⃣ Vitamin B12 Replacement

Method

Indication

1.Intramuscular injections

Severe deficiency, neurological symptoms

2.Oral B12 supplements

Mild deficiency, dietary causes

3.Lifelong therapy

Pernicious anemia

 Neurological symptoms require early and aggressive treatment.

2️⃣ Treat the Underlying Cause

• Manage malabsorption disorders

• Review long-term medications

• Dietary correction

 Dietary Sources of Vitamin B12

Vitamin B12 is found mainly in animal-based foods:

Source

Examples

Dairy

Milk, curd, cheese

Eggs

Egg yolk

Meat & fish

Liver, fish, chicken

Fortified foods

Cereals, plant milks

 Vegetarians often require supplementation.

 Complications if Untreated

• Irreversible nerve damage

• Cognitive decline

• Severe anemia

• Heart complications

• Poor pregnancy outcomes

• Increased risk of falls in elderly

 Prevention

• Balanced diet including B12 sources

• Routine screening in vegetarians

• Supplementation in elderly

• Monitoring in long-term metformin or PPI users

• Early treatment of gastritis or malabsorption

 When to Consult a Doctor

• Persistent fatigue or weakness
  
  

• Tingling or numbness in limbs
  
  

• Memory or balance issues
  
  

• Known vegetarian diet
  
  

• Poor response to iron therapy
  
  

Disclaimer:

The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified physician or other licensed healthcare provider with any questions you may have regarding a medical condition. Do not ignore or delay seeking medical advice because of information you read on this website. The use of any information provided here is solely at your own risk.