Glutamate is known as the umami substance in the diet and umami taste has been traditionally preferred in East Asian countries. Recent our and others' studies showed that glutamate has potential to protect the gastrointestinal mucosa against noxious agents. In contrast, Helicobacter pylori infection and non-steroidal anti-inflammatory drugs (NSAIDs) are recognized as the two major causes of gastrointestinal diseases characterized by gastritis or gastrointestinal ulcers. We examined whether dietary supplementation of glutamate prevents the Helicobacter pylori infection- and NSAIDs-induced gastrointestinal damages in animal models. In this paper, we first review how these noxious agents develop gastrointestinal damages, and secondly discuss the possible candidates of protective factors as well as the mechanisms how glutamate prevents these gastrointestinal damages. We propose that our daily intake of glutamate has important roles in protecting the gastrointestinal mucosa against Helicobacter pylori and NSAIDs and possibly contributes to the maintenance of our healthy lives.