(d) Gastrin is a major physiological regulator of gastric acid secretion. It also has an important trophic or growth-promoting influence on the gastric mucosa. During a meal,gastrin stimulates the stomach to release gastric acid. This allows the stomach to break down proteins swallowed as food and absorb certain vitamins. It also acts as a disinfectant and kills most of the bacteria that enter the stomach with food, minimising the risk of infection within the gut.