Does Gastric Cause B12 Deficiency? Understanding the Connection

November 17, 2025 •

2 min read

According to research, chronic gastritis, particularly the atrophic type, is a common cause of vitamin B12 deficiency. This critical connection between the inflammation of the stomach lining and impaired nutrient absorption is often missed, leading to long-term health issues if not addressed promptly.

Quick Summary

Chronic inflammation of the stomach lining can disrupt the absorption of vitamin B12. This occurs because gastritis can reduce the production of stomach acid and intrinsic factor, both essential for B12 assimilation. The malabsorption leads to a deficiency, which can cause anemia and neurological problems.

Key Points

Gastritis Impairs B12 Absorption: Inflammation of the stomach lining (gastritis) disrupts the body's ability to absorb vitamin B12 from food sources.
Low Stomach Acid is Key: Hydrochloric acid is needed to release B12 from food; gastritis can reduce its production, leading to malabsorption.
Intrinsic Factor is Crucial: Parietal cells in the stomach produce intrinsic factor, which is necessary for B12 binding and absorption; these cells are targeted in autoimmune gastritis.
Pernicious Anemia Link: Autoimmune gastritis is a cause of pernicious anemia, a severe B12 deficiency resulting from the lack of intrinsic factor.
H. pylori is a Culprit: Chronic infection with the bacterium H. pylori can cause atrophic gastritis and is a known risk factor for B12 deficiency.
Lifelong Treatment May Be Needed: Depending on the cause, managing B12 deficiency from gastritis often requires long-term supplementation, such as injections or high-dose oral options.

The Gastric-B12 Connection: A Closer Look

Vitamin B12, or cobalamin, is an essential nutrient vital for red blood cell formation, neurological function, and DNA synthesis. Its absorption is a complex process that relies heavily on a healthy stomach. Gastritis, or inflammation of the stomach lining, directly impacts this process, explaining why the answer to "Does gastric cause B12 deficiency?" is a definitive yes.

How Stomach Health Affects Vitamin B12 Absorption

Normal B12 absorption requires two main steps within the stomach: release from food proteins by hydrochloric acid and binding to intrinsic factor, produced by parietal cells, for absorption in the small intestine. Gastritis interferes with these steps, leading to malabsorption, especially in chronic and atrophic forms.

Types of Gastritis That Cause B12 Deficiency

Several forms of gastritis can lead to B12 deficiency:

Autoimmune Atrophic Gastritis: The immune system attacks parietal cells, reducing hydrochloric acid and intrinsic factor production. This leads to pernicious anemia.
H. pylori-induced Gastritis: Chronic H. pylori infection causes inflammation and atrophy of the stomach lining, impairing acid and intrinsic factor production. Eradicating H. pylori can sometimes reverse the deficiency.
Medication-induced Gastritis: Long-term use of PPIs or H2RAs reduces stomach acid, preventing B12 release from food.

Other Contributing Factors and Symptoms

Other factors like bariatric surgery and certain diets can also affect B12 levels. Symptoms of B12 deficiency develop slowly and can include:

Common Symptoms of B12 Deficiency

Physical: Fatigue, pale skin, weight loss, sore tongue.
Neurological: Numbness, tingling, balance problems, memory issues.
Psychological: Depression, irritability.

Comparison of Common B12 Malabsorption Causes


Cause	Underlying Mechanism	Primary Effect	Treatment Approach
Autoimmune Atrophic Gastritis	Immune system destroys parietal cells.	Lack of intrinsic factor and hydrochloric acid.	Lifelong B12 injections.
H. pylori Infection	Chronic inflammation and atrophy of stomach lining.	Reduced acid and intrinsic factor production.	Antibiotics to eradicate H. pylori, plus B12 supplementation.
Medication Use (e.g., PPIs)	Suppression of stomach acid production.	Impaired release of B12 from food.	High-dose oral B12 supplements or injections.
Bariatric Surgery	Modification of the gastrointestinal tract.	Reduced absorption surface area and intrinsic factor.	Lifelong B12 supplementation, often injections.

Treatment and Management

Managing B12 deficiency from gastritis involves treating the cause and supplementing B12. H. pylori is treated with antibiotics. Autoimmune gastritis requires lifelong B12 supplementation. Supplementation options include injections or high-dose oral supplements, chosen based on severity and cause. Consulting a healthcare professional is crucial. For more information on gastritis, visit the NIDDK: https://www.niddk.nih.gov/health-information/digestive-diseases/gastritis-gastropathy/definition-facts.

Conclusion

Gastric conditions, particularly chronic atrophic gastritis and H. pylori infection, commonly cause B12 deficiency by impairing the stomach's production of hydrochloric acid and intrinsic factor. This prevents proper B12 absorption. Early diagnosis and management, often including lifelong supplementation, are vital to prevent serious neurological complications.

Frequently Asked Questions

Gastritis is a specific condition referring to the inflammation of the stomach lining. A 'gastric issue' is a broader, less specific term for any problem affecting the stomach. Gastritis is a type of gastric issue, but not all gastric issues are gastritis.

Yes, long-term use of medications that suppress stomach acid, such as proton pump inhibitors (PPIs), can interfere with B12 absorption from food and cause a deficiency.

Gastritis can cause anemia in two primary ways: by impairing the absorption of vitamin B12 (leading to pernicious anemia) or by causing inflammation that affects iron absorption, leading to iron-deficiency anemia.

Diagnosis typically involves a blood test to check B12 levels. Further tests, like an endoscopy with a biopsy or checks for specific antibodies, may be conducted to confirm the presence and type of gastritis.

Vitamin B12 injections can prevent further neurological damage and often help improve symptoms if treatment is started early. However, if severe nerve damage has persisted for a long time, it may not be fully reversible.

For those with malabsorption due to a lack of intrinsic factor, oral supplements are often not enough unless administered in very high doses, as they do not address the underlying absorption problem. Injections are often necessary.

Yes, aside from B12, chronic atrophic gastritis can also cause deficiencies in iron and calcium due to reduced stomach acid.