H. pylori is a gram-negative pathogen, etiologically associated with atrophic and non-atrophic gastritis, peptic ulcer, primary gastric B-cell lymphoma and gastric carcinoma. Several observations demonstrated a correlation between H. pylori and malabsorption of essential nutrients; epidemiological studies have shown an association between H. pylori infection and iron deficiency anemia, while the absorption of some vitamins such as vitamin B12, vitamin A, vitamin C, folic acid and Vitamin E may be affected by the infection. The main mechanism related to malabsorption of this components is the modified intragastric pH (hypo- achlorhydria) due to H. pylori infection. Moreover H. pylori is also able to determine a modification of gastrointestinal hormones by reducing plasma levels of ghrelin and increasing those of leptin and gastrin, thus affecting appetite and promoting the occurrence of dyspeptic symptoms. On the other hand, H. pylori eradication has been shown to improve serum level of iron and vitamin B12, has some effects on Vitamin A and Vitamin E absorption and has a late effects on ghrelin levels. As a consequence of those effects, H. pylori is also associated with childhood malnutrition in developing countries either for the occurrence of malabsorption or for an increased susceptibility to enteric infections caused by hypochlorhydria.