17 pH of gastric juice
Gastric juice is strongly acidic because the parietal cells of the stomach secrete hydrochloric acid (protons and chloride). The acid activates the digestive enzyme pepsin, which breaks down proteins, helps absorb iron and vitamin B12, and kills or inhibits many microorganisms swallowed with food. The pH of gastric juice varies with the time of day, meals, medicines, Helicobacter pylori infection and the condition of the stomach lining. In healthy young adults the median fasting gastric pH is about 1.7; after a meal the food buffers the acid, and pH briefly rises to about 6–7 before returning to the fasting level within about two hours.
Clinical significance
Low pH (high acidity)
Excess acid secretion: duodenal ulcer, Helicobacter pylori infection (antral gastritis), Zollinger–Ellison syndrome (gastrin-producing tumour). Symptoms: burning upper abdominal pain, heartburn, pain relieved by food.
High pH (low acidity)
Proton pump inhibitors and H2 blockers, atrophic gastritis (autoimmune or due to long-standing H. pylori), older age, after gastric surgery. Consequences: poor absorption of iron and vitamin B12, bacterial overgrowth, higher risk of intestinal infections; autoimmune atrophic gastritis leads to pernicious anaemia.
for vomiting blood or material like coffee grounds, black tarry stools, or sudden severe abdominal pain.
Persistent heartburn or upper abdominal pain, difficulty swallowing, weight loss, or anaemia need assessment, often with endoscopy and testing for H. pylori.
References
This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.
Published on 9 May 2024