Date of Award


Document Type

Scholarly Project

Degree Name

Master of Physician Assistant Studies (MPAS)


Physician Assistant Studies

First Advisor

Jeanie McHugo


proton pump inhibitor, PPI, weight, weight gain, weight loss, bacteria, microbiome, gastrointestinal flora, normal flora, intestinal flora, gut bacteria


The goal of this literature review was to determine what effects proton pump inhibitors (PPIs) have on the normal gastrointestinal (GI) flora and how that may lead to weight loss or weight gain. A literature search was performed using the database PubMed. Only articles from the last ten years (2009-2019) were included in this review. Keywords used in the search are listed below. After exclusion criteria was applied, 30 articles were relevant and used in this review. Five themes were identified in the literature review. An investigation of normal GI flora associated with weight loss and weight gain identified a common conclusion that the ratio of Firmicutes to Bacteroidetes was higher in obesity. The investigation of PPIs effects on the normal GI flora was less conclusive; however, a common finding was an increase in Streptococcaceae (phylum Firmicutes), which can commonly be found in the oral cavity. This finding suggests that oral flora may have a greater survival rate in lower parts of the GI system with treatment of PPIs due to the decreased gastric acidity. The final investigation, which looked into the association between PPI use and weight change revealed a greater likelihood that PPIs will cause weight gain with four studies supporting weight gain and two studies supporting weight loss. Alternative treatments such as H2 receptor antagonists, laparoscopic Roux-en-Y gastric bypass, probiotics, and lifestyle management were also explored. Although further research needs to be completed, it appears that PPIs are associated with an increase in Streptococcaceae of the phylum Firmicutes, which has been linked to weight gain.