# What is the Normal pH of the Gut? The human gastrointestinal tract hosts a range of pH environments that support digestion, nutrient absorption, and microbial communities. pH — a measure of acidity or alkalinity — shifts along the tract to create conditions suited to different enzymes and microbes. Understanding typical gut pH ranges helps explain why specific regions favor particular bacterial groups and functions. ## pH along the intestine After the stomach’s highly acidic environment (roughly pH 1.5–3.5), the small intestine becomes more alkaline to protect the mucosa and allow digestive enzymes to work. The small intestine typically has a pH between about 6.0 and 7.4. Broadly speaking, the overall intestinal tract ranges from pH 6 to 7.5, gradually shifting from slightly acidic in the upper small intestine to neutral or slightly alkaline further along. The large intestine (colon) is different: fermentation by resident microbes produces short-chain fatty acids and other metabolites that lower local pH. Typical colonic pH values range approximately from 5.5 to 7; the proximal colon (closer to the small intestine) tends to be more acidic, while the distal colon approaches neutral. For a concise overview of the normal pH of the gut and its regional variation see this resource: [normal pH of the gut](https://www.innerbuddies.com/blogs/gut-health/normal-ph-of-the-gut). ## Intestinal mucus and pH The mucosal layer that coats the gut epithelium generally reflects the pH of its immediate environment, often ranging from slightly acidic to neutral. Mucus serves as a physical barrier, a habitat for microbial populations, and a medium where pH-sensitive immune and epithelial processes occur. Maintaining a compatible mucus pH supports healthy interactions between microbes and the gut lining. ## Are intestines alkaline or acidic? The intestine is neither uniformly alkaline nor uniformly acidic. The small intestine is typically slightly alkaline, whereas the large intestine features more acidic microenvironments due to microbial fermentation. This gradient permits diverse microbial niches and allows digestive chemistry to vary by location. ## Why gut pH matters - Enzyme activity: Many digestive enzymes have narrow pH optima; deviations can reduce digestion efficiency. - Microbial balance: pH influences which bacterial taxa thrive, affecting the production of metabolites such as short-chain fatty acids. - Barrier function: Extreme pH shifts can stress the mucosa and alter mucus integrity. Factors that influence gut pH include diet (fiber and fermentable substrates), antibiotic use, gastrointestinal diseases, stress, and transit time. For connections between microbiome composition and systemic health, see Gut wellness connection and the role of microbial pathways in aging at Gut microbiome and healthy aging. Additional context on microbial pathways and longevity is discussed in The Science of Healthy Aging. Optionally, microbiome testing may help characterize individual gut conditions: microbiome test. ## Summary There is no single "normal" gut pH; instead, pH varies by region. The small intestine is generally slightly alkaline (about 6.0–7.4), the large intestine ranges from roughly 5.5 to 7, and mucus typically mirrors local conditions. These gradients are central to digestion and microbial ecology and are influenced by diet, medications, and health status.