(HealthDay News) – Patients who take gastric acid inhibitors for two years or more are at higher risk of vitamin B12 deficiency, according to a study published in the Dec. 11 issue of the Journal of the American Medical Association.

Noting that proton pump inhibitors and histamine 2 receptor antagonists may affect vitamin B12 absorption through suppression of gastric acid, Jameson R. Lam, MPH, and colleagues from Kaiser Permanente in Oakland, CA, compared the use of these drugs among 25,956 patients diagnosed with vitamin B12 deficiency and 184,199 patients without vitamin B12 deficiency.

The researchers found a higher risk of vitamin B12 deficiency among those who had been dispensed at least a two years’ supply of both proton pump inhibitors (odds ratio, 1.65) or histamine 2 receptor antagonists (odds ratio, 1.25). For proton pump inhibitors, the risk was higher at doses of >1.5 pills per day (odds ratio, 1.95) compared with 0.75 pills per day (odds ratio, 1.63; P=0.007 for interaction).

“Previous and current gastric acid inhibitor use was significantly associated with the presence of vitamin B12 deficiency,” Lam and colleagues conclude. “These findings should be considered when balancing the risks and benefits of using these medications.”

One author disclosed receiving a grant or grant pending from Wyeth/Pfizer.

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