Which disease causes a lack of vitamin B? Unpacking malabsorption disorders

November 27, 2025 •

3 min read

According to the Cleveland Clinic, pernicious anemia is the most common cause of vitamin B12 deficiency in the UK and a key example of which disease causes a lack of vitamin B. This autoimmune condition attacks stomach cells, preventing the absorption of this essential nutrient and leading to potential health complications.

Quick Summary

Several malabsorption disorders like pernicious anemia, celiac disease, and Crohn's disease can impair the body's ability to absorb vital B vitamins.

Key Points

Pernicious Anemia: An autoimmune disease where the body cannot produce intrinsic factor, which is necessary for vitamin B12 absorption.
Celiac Disease: An autoimmune disorder causing damage to the small intestine's lining, leading to impaired absorption of multiple B vitamins, including folate and B12.
Crohn's Disease: A type of inflammatory bowel disease that inflames the digestive tract, often affecting the ileum, which is where vitamin B12 is primarily absorbed.
Atrophic Gastritis: A thinning of the stomach lining that reduces intrinsic factor and acid production, thereby causing vitamin B12 malabsorption.
Alcohol Use Disorder: Long-term excessive alcohol use damages the digestive system and interferes with the absorption and metabolism of B vitamins.
Surgical Procedures: Bariatric or other gastric surgeries can alter the digestive system's anatomy, leading to malabsorption of vitamin B12 and other nutrients.
Certain Medications: Long-term use of certain drugs, like proton pump inhibitors and metformin, can reduce stomach acid, impairing vitamin B12 absorption.

The Connection Between Malabsorption and Vitamin B Deficiency

While a poor diet is a common cause of vitamin B deficiency, many underlying diseases and conditions can disrupt the body's ability to absorb these critical nutrients from food, even with adequate intake. Most of these conditions are related to malabsorption, where the digestive tract fails to properly absorb nutrients into the bloodstream. The B vitamin complex is vital for many bodily functions, including energy levels, brain function, and cell metabolism. A deficiency can lead to a wide range of symptoms, from fatigue and weakness to severe neurological issues. This article explores several diseases known to cause a lack of vitamin B.

Pernicious Anemia and Vitamin B12

Pernicious anemia is an autoimmune disease where the body attacks stomach cells that produce intrinsic factor, a protein needed for vitamin B12 absorption in the small intestine. This leads to a deficiency, with symptoms like fatigue, pale skin, a red tongue, and neurological problems. Lifelong B12 injections are typically needed as oral supplements are not effective.

Celiac Disease and Nutrient Absorption

Celiac disease is an autoimmune disorder triggered by gluten that damages the small intestine lining, impairing the absorption of various B vitamins, including folate and B12. A gluten-free diet helps heal the intestine and restore absorption, but supplementation may be necessary.

Crohn's Disease and Intestinal Inflammation

Crohn's disease is an inflammatory bowel disease causing chronic inflammation in the digestive tract, often affecting the ileum where B12 is absorbed. This can lead to severe B12 deficiency. Treatment includes medication to manage inflammation and B12 supplementation.

Atrophic Gastritis and its Impact

Atrophic gastritis involves inflammation and thinning of the stomach lining, reducing the production of intrinsic factor and stomach acid. This impairs B12 absorption and can result in neurological symptoms and pernicious anemia. Lifelong B12 supplementation is often required.

Other Conditions Contributing to Vitamin B Deficiency

Beyond these primary diseases, several other conditions and factors can contribute to a lack of vitamin B. These include:

Alcohol Use Disorder: Interferes with B vitamin absorption and metabolism.
Bariatric Surgery: Limits absorption of B12 and other nutrients.
Long-Term Medication Use: Certain drugs like PPIs and metformin can reduce B12 absorption.
Vegan or Restrictive Diets: High risk of B12 deficiency without supplements or fortified foods.
HIV/AIDS: Can lead to malabsorption and increased nutritional needs.

Comparison of Key Disease Mechanisms


Disease	Primary Affected Vitamin(s)	Mechanism of Deficiency	Onset and Progression
Pernicious Anemia	Vitamin B12	Autoimmune attack on intrinsic factor-producing stomach cells.	Gradual, with symptoms appearing over years.
Celiac Disease	Folate, Vitamin B12, others	Immune-mediated damage to the small intestine lining due to gluten.	Varies, can be gradual and present with diverse symptoms.
Crohn's Disease	Vitamin B12, others	Chronic inflammation in the ileum (site of B12 absorption).	Often progressive and relapsing, with severity depending on location.
Atrophic Gastritis	Vitamin B12	Chronic inflammation and loss of stomach lining cells and intrinsic factor.	Slow progression, often asymptomatic initially.
Alcoholism	Thiamine (B1), Folate (B9)	Impaired absorption and increased flushing of nutrients by kidneys.	Can develop relatively quickly with heavy use.

Diagnosis and Management

Diagnosis involves assessing symptoms and blood tests, and sometimes tests for underlying causes like antibodies for pernicious anemia. Early diagnosis is vital to prevent irreversible damage. Management addresses the root cause, such as medication or dietary changes, often with supplements or injections to restore vitamin B levels. Lifelong supplementation may be needed for permanent malabsorption. Consulting a healthcare provider is essential for a proper diagnosis and treatment plan.

Conclusion

A vitamin B deficiency can indicate an underlying medical condition affecting nutrient absorption, such as pernicious anemia, celiac disease, or Crohn’s disease. Understanding this link is crucial for accurate diagnosis and effective treatment to prevent long-term health issues. Medical investigation is key to identifying the cause and restoring health. For more on pernicious anemia, a major cause of B12 deficiency, see The Cleveland Clinic.

Frequently Asked Questions

Pernicious anemia is the most common autoimmune disease that leads to a severe vitamin B12 deficiency. It involves the body's immune system attacking the stomach cells that produce intrinsic factor, a protein needed for B12 absorption.

Yes, Celiac disease can cause a deficiency in various B vitamins, including folate and vitamin B12, due to the immune-driven damage it causes to the small intestine lining, which impairs nutrient absorption.

Yes, Crohn's disease, especially when it affects the ileum (the last part of the small intestine), can severely impair the absorption of vitamin B12, leading to a deficiency.

Atrophic gastritis causes the stomach lining to thin and lose the parietal cells that produce intrinsic factor, which is essential for vitamin B12 absorption. The resulting lack of intrinsic factor leads to the deficiency.

Yes, since vitamin B12 is predominantly found in animal products, individuals on a strict vegan diet are at a high risk of deficiency unless they consume fortified foods or take regular supplements.

Symptoms of a B12 deficiency can include fatigue, weakness, a sore or red tongue, mouth ulcers, numbness or tingling in the hands and feet, memory problems, and a pale skin tone.

Diagnosis typically involves a physical exam, a review of symptoms, and blood tests to measure vitamin B levels. For specific diseases like pernicious anemia, tests for intrinsic factor antibodies may be performed.