Extra-digestive Manifestations of Helicobacter pylori Infection – An Overview

Helicobacter pylori (H. pylori) is well known as a group I human gastric cancer carcinogen by the International Agency for Research on Cancer. Although an exact causal relation‐ ship is unclear, H. pylori is expected to have been associated with non-digestive abnormal condition and/or diseases, such as metabolic syndrome, atherosclerosis and cardiovascu‐ lar diseases, which have substantially lots of prior studies; adaptive immune response – related disorders, such as autoimmune thyroid diseases (ATDs), urticaria, atopy and asthma; and the other extra-digestive diseases, such as chronic obstructive pulmonary disease (COPD), migraine, anemia and hyperemesis gravidarum. This chapter overviews several groups of extra-digestive diseases by H. pylori infection and discusses the role of H. pylori in relation to the diseases in the viewpoint of causality.