The germ Helicobacter pylori is the cause of most stomach ulcers, but a new review of the literature published in Alimentary Pharmacology&Therapeutics suggests that treating the bacteria is linked to weight gain.

The idea that Helicobacter pylori infection may have an effect on body mass index (BMI) is still controversial. A study found that individuals who underwent H. pylori eradication developed significant weight gain as compared to subjects with untreated H. pylori colonization.

It is estimated that 50% of the global population may be infected with H. pylori but only 20% of infected people experience any symptoms. This new evidence suggests that patients treated for the infection developed significant weight gain compared to subjects with untreated H. pylori colonization.

By reviewing data taken from forty-nine studies with data from ten European countries, Japan, the U.S. and Australia, Professor Gerald Holtmann identified a correlation between prevalence rates for H. pylori and obesity. They found an inverse correlation between H. pylori prevalence and rate of overweight/obesity in countries of the developed world.

Association between the prevalence of H. pylori (%) and prevalence of obesity in countries with a gross domestic product (GDP) per capita >US$ 25 000 (purchasing power parity (PPP) adjusted). The prevalence of obesity in a given population is inversely correlated with the H. pylori prevalence in the same population (r = −0.46, P < 0.01). Credit and link: DOI: 10.1111/apt.12790

They conclude that since a gradual decrease of the H. pylori colonization has been observed in recent decades (or factors associated with its decrease), it could be causally related to the obesity endemic observed in the Western world. You are off the hook, pizza.

"The rate of obesity and overweight were inversely and significantly correlated with the prevalence of H. pylori infection," said Holtmann. "The gradual decrease of the H. pylori colonisation observed in recent decades could be causally related to the obesity endemic observed in the Western world".