The Effects of Proton Pump Inhibitors in Acid Hypersecretion-Induced Vitamin B12 Deficiency: A Systematic Review (2022)

Gastroesophageal reflux disease (GERD) is the most common disease, for which proton pump inhibitors (PPIs) are a widely used class of drugs. Due to their efficacy and relative safety profile, PPIs are used chronically by GERD patients. Although it is a safe drug, particular attention focuses on the long-term adverse effects of PPI. The association with vitamin deficiencies has received additional focus since chronic PPI treatment increases the incidence of vitamin B12 deficiency, especially in the elderly. However, numerous studies regarding the establishment of an association between PPI and vitamin B12 status revealed conflicting results. In this systematic review, we systematically examined observational studies that focused on the impact of chronic PPI effects on vitamin B12 absorption and diagnostic biomarkers of vitamin B12 deficiency. Our review showed significant changes in diagnostic biomarkers of vitamin B12 status in long-term PPI users, including elevated homocysteine and methylmalonic acid (MMA) concentration levels defining cellular vitamin B12 deficiency. Although there is uncertainty regarding the exact mechanism, it supports the concept that long-term intake of PPI can have clinical implications for vitamins.