What Causes Vitamin B12 Deficiency?
Causes of Vitamin B12 Deficiency
Vitamin B12 is essential for energy, red blood cell production, and nervous system health. But despite its importance, many people struggle to maintain healthy B12 levels. Understanding what causes a deficiency can help you take the right steps to prevent or correct it.
Low Dietary Intake
The most straightforward reason for low B12 levels is not getting enough through your diet. Since Vitamin B12 is found mainly in animal products like meat, fish, eggs, and dairy, people who follow vegetarian or vegan diets are at higher risk of deficiency.
- Vegans: Plant-based foods don’t naturally contain B12, so supplementation is often necessary.
- Vegetarians: While dairy and eggs offer some B12, it may not be enough without careful planning.
Poor Absorption in the Digestive Tract
Even if you eat enough B12, your body might not absorb it efficiently. This can happen for a number of reasons related to how your digestive system works:
- Pernicious Anaemia: A condition where the body can’t make enough intrinsic factor — a protein needed to absorb B12 from food.
- Low Stomach Acid: As we age or take certain medications, stomach acid levels drop, which can reduce B12 absorption.
- Digestive Conditions: Disorders like Crohn’s disease, coeliac disease, and bacterial overgrowth can interfere with the absorption process.
Medication Interference
Some medications can reduce the amount of B12 your body can absorb. These include:
- Metformin: Commonly prescribed for type 2 diabetes, this can interfere with B12 absorption over time.
- Proton Pump Inhibitors (PPIs): These reduce stomach acid, which your body needs to absorb B12 from food.
- Long-term Antacids or H2 blockers: Can have similar effects to PPIs when used regularly.
Alcohol and Smoking
Excessive alcohol consumption can damage the stomach lining and reduce your body’s ability to absorb nutrients, including B12. Smoking has also been shown to interfere with nutrient absorption and may contribute to lower B12 levels over time.
Age-Related Decline
As we age, our ability to absorb B12 decreases. Older adults are more likely to develop atrophic gastritis — a condition that thins the stomach lining and reduces acid production, affecting how well B12 is absorbed.
Surgical Causes
People who’ve had certain surgeries that affect the stomach or intestines may also have trouble absorbing B12:
- Gastric Bypass or Sleeve Surgery: These weight-loss surgeries reduce the stomach’s size and its ability to produce intrinsic factor.
- Bowel Surgery: Removing parts of the small intestine (especially the ileum) can interfere with where B12 is normally absorbed.
Genetic Conditions
Though rare, some people inherit conditions that affect how their body handles B12. These include inherited forms of pernicious anaemia or mutations that impact how the vitamin is processed.
Where to Learn More
If you’re concerned about low B12 or think something in your lifestyle might be affecting your levels, talk to your GP or healthcare provider. You can also explore more from a trusted medical source like the NIH Office of Dietary Supplements.