Functional medicine perspectives on the evaluation and management of hypochlorhydria and achlorhydria

Hypochlorhydria and achlorhydria, a condition of abnormally low and no gastric acid secretion, are often underdiagnosed due to its nonspecific symptoms and limited clinical awareness. Gastric acid plays a critical role in protein digestion, micronutrient absorption, and microbial defense. Functional medicine approaches emphasize the upstream causes and systemic impacts of hypochlorhydria, identifying its contribution to nutritional deficiencies, small intestinal bacterial overgrowth, and chronic gastrointestinal symptoms. This review explores the pathophysiology, diagnostic strategies—including serologic, endoscopic, and microbiome-based assessments—and root causes such as Helicobacter pylori infection, autoimmune gastritis, and medication-induced hypochlorhydria. Functional medicine interventions such as the 5R framework (remove, replace, reinoculate, repair, rebalance) offer a holistic model to restore gastric function and systemic health. Particular attention is given to the role of nutrient supplementation, targeted microbial therapies, and acid replacement strategies like betaine HCl. In addition to diagnostic accuracy, therapeutic timing is crucial to prevent irreversible mucosal atrophy and micronutrient depletion. Clinical implications extend to anemia, osteoporosis, vitamin B12 deficiency, and impaired methylation pathways. Functional medicine offers a unique paradigm to address these interconnected systems, presenting opportunities for both disease management and prevention.