This thesis concerns hydrolyzed collagen, also called gelatin, widely used in pharmaceutical industry both for its nutritional properties, in order to correct the deficiency arising from its insufficient dietary intake, and for its protective action towards aggressive agents, mainly used by topical route. Chemical composition, molecular structure and medical uses of collagen are described together with its metabolism in human body, with particular reference to hydrolyzed collagen. With the above premise, the research was focused on: a) the chemical-physical characterization of the barrier effect of collagen, measuring it towards the erosive action of hydrochloric acid; b) the influence of the aminoacidic composition and degree of hydrolysis on the barrier effect. c) the effectiveness of hydrolyzed collagen and different antacidsin controlling acidity levels in vitro. On the basis of these experimental results a food supplement, based on hydrolyzed collagen and tricalcium phosphate, was developed. Its efficacy and safety were tested by a clinical trial in patients affected from functional dyspepsia. These preliminary findings require validation with additional data from further investigations, including a double-blinded and randomized clinical trial. It is of note, however, that the present study deals with magnitudes in the order of 100 per cent. Their statistical confrontation provides the so called “factual” evidence, which is different from the “experimental” one. Moreover, the present study involved patients that did not respond to current treatments. Therefore, this food supplement should be evaluated from the point of view of “experimental therapy”, rather than “experimental research”.