Hydrochloric acid in the stomach plays an essential role in the absorption of vitamin B-12 from foods. A variety of conditions can reduce the stomach's secretion of hydrochloric acid, leading to insufficient absorption of vitamin B-12 and eventually causing vitamin B-12 deficiency anemia.
Hydrochloric Acid and B-12 Absorption
Vitamin B-12 that exists naturally in foods remains attached to protein, and the body must separate it from the protein before absorbing it. Hydrochloric acid secreted by the stomach separates the vitamin from the protein. Synthetic vitamin B-12 is already free, meaning hydrochloric acid plays no role in its absorption. Synthetic vitamin B-12 and naturally occurring vitamin B-12 separated from protein must attach to intrinsic factor, a glycoprotein, before the body can absorb the complex in the intestinal tract.
Atrophic Gastritis
Atrophic gastritis, a condition common in older adults, causes reduced levels of hydrochloric acid in the stomach. Individuals with atrophic gastritis absorb only small amounts of vitamin B-12 from food, but they can absorb synthetic vitamin B-12 from fortified foods and dietary supplements. The Institute of Medicine suggests that adults over the age of 50 take vitamin B-12 supplements to prevent deficiency, notes the National Institutes of Health.
Gastrointestinal Surgery
Gastrointestinal surgeries, including partial or total stomach removal surgery, weight loss surgery and other procedures in the gastrointestinal tract, can reduce the number of cells in the stomach that secrete hydrochloric acid as well as intrinsic factor. Individuals who have had such surgeries may not be able to absorb vitamin B-12 from foods or dietary supplements. Doctors typically monitor vitamin B-12 levels after gastrointestinal surgeries and may treat deficiencies with intramuscular injections.
Antacids
Antacids such as proton pump inhibitors and H2 receptor antagonists slow the release of hydrochloric acid and other gastric acids in the stomach, hindering the body's ability to absorb vitamin B-12. Long-term use of antacids as treatments for peptic ulcer disease and gastroesophageal reflux disease may contribute to vitamin B-12 deficiency.
Vitamin B-12 Deficiency Symptoms
Vitamin B-12 deficiency can cause weakness, fatigue, dizziness, shortness of breath, pale skin, sore tongue and difficulty concentrating. Severe or prolonged B-12 deficiency may cause neurological symptoms such as memory loss, confusion, depression and dementia. B-12 deficiency may also cause nerve damage, leading to feelings of numbness or tingling in the hands and feet.
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