The Digestive Process | The Integrated Role of Diamine Oxidase

The Digestive Process & The Separate, Integrated Role of Diamine Oxidase: Overview

In this article, we discuss key digestive processes while focusing on and extending the conversation separately to dietary histamine degradation. We highlight diamine oxidase and one of its key roles within the small intestines, and we finish the conversation by detailing digestive comfort and an exceptional tool that can aid in supporting the degradation of exogenous dietary histamine during digestion.

Digestion & Key Enzymatic Action

Digestion includes both mechanical and chemical processes working in concert. In expanding upon this notion, beginning with mechanical digestion in the oral cavity: mastication is characterized by the grinding of food by teeth, increasing the food's surface area and aiding in allowing chemical digestion to occur. Certain enzymes within saliva, specifically salivary alpha-amylase and lingual lipase, play significant roles in aiding the initial chemical digestion of starches and triglycerides, respectively. It can be noted that lingual lipase acts in the acidic environment of the stomach.

After a partially-digested bolus, or mass of chewed food, is swallowed and passes through the esophagus to the stomach, a variety of mechanical and chemical processes occur. The stomach is anatomically divided into regions including the cardia, fundus, body, and pylorus; and the gastric mucosa is the innermost layer of the stomach wall. The gastric mucosa can be subdivided into three components, one of which is regarded as the surface epithelium: This surface epithelium also dips deeper into the lamina propria to form what are referred to as gastric pits and gastric glands, whose architecture varies by region of the stomach. The surface epithelium is home to mucous cells, and while region-dependent, the deeper gastric glands often house cells including parietal cells, chief cells, and enteroendocrine cells. Expanding upon this notion: parietal cells secrete hydrochloric acid and something called intrinsic factor, while chief cells release pepsinogen and gastric lipase.

In briefly expanding upon hydrochloric acid, pepsinogen, and gastric lipase, these molecules and more play significant roles in aiding chemical digestion. Hydrochloric acid serves a variety of chemical digestive functions such as denaturing proteins and activating pepsinogen; pepsinogen is an inactive precursor of the proteolytic (protein-cleaving) enzyme pepsin, primarily activated to pepsin upon exposure to the highly acidic gastric environment. Moreover, gastric lipase is an enzyme which aids rather modestly in the digestion of lipids. Together, these secretions and processes aid in ensuring that food leaves the stomach prepared for further breakdown in the small intestine.

Following entrance into the duodenum — the first segment of the small intestine — bile and secretions from the pancreas are encountered. In more detail, the pancreas delivers juice including bicarbonate and enzymes: active hydrolases (pancreatic alpha-amylase; pancreatic lipase, which requires colipase; and more) and inactive zymogens (trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidases, procolipase, and prophospholipase A₂). Pancreatic amylase, similar to salivary amylase, continues the digestion of starch, yielding molecules such as maltose (a disaccharide) and maltotriose. Moreover, pancreatic lipase aids in facilitating the breakdown of triglycerides into monoacylglycerols and free fatty acids. As noted previously, the pancreas also releases an array of zymogens (Zymogens are regarded as inactive precursor forms of enzymes.) such as trypsinogen, chymotrypsinogen, proelastase, and procarboxypeptidase. Within the small intestine, trypsinogen is activated by brush-border enteropeptidase to form trypsin (Trypsin is a proteolytic enzyme of the small intestine.), which can subsequently convert other zymogens into their active enzymes such as chymotrypsin, elastase, and carboxypeptidase.

It may be noted that the brush border refers to the dense array of microscopic projections called microvilli that extend from the apical surface of intestinal epithelial cells (enterocytes). Each enterocyte carries a multitude of microvilli, creating a vast surface area for digestion and absorption. Moreover, alongside pancreatic secretions, brush border enzymes — including disaccharidases (such as lactase, sucrase–isomaltase, maltase–glucoamylase), peptidases, and more — work in concert to aid in chemical digestion.

Diamine Oxidase & Dietary Histamine

Through coordinated mechanical and chemical digestive processes, exogenous dietary histamine naturally present in certain dietary sources (resulting from microbial decarboxylation of histidine by bacteria through histidine decarboxylase activity) is released into the gastrointestinal lumen. Here, diamine oxidase (DAO)—an enzyme abundantly expressed by mature enterocytes of the small intestine—serves as the primary mechanism for degrading biogenic amines, such as histamine, and supporting homeostasis. More specifically, exogenous dietary histamine is tightly regulated by DAO activity during digestion.

Briefly expanding upon DAO production: The intestinal wall is composed of several layers, beginning with the mucosa, and the mucosa consists of three sublayers—the epithelium, the lamina propria, and the muscularis mucosae. In more detail, the intestinal epithelium is composed of a monolayer of epithelial cells including enterocytes, the main absorptive cells. As noted, DAO is largely produced by mature enterocytes, and once synthesized, it can catalyze the breakdown of this dietary histamine. In other words, DAO is the primary enzyme responsible for the oxidative deamination, a biochemical reaction in which an amine group (–NH₂) is removed, of dietary histamine in the small intestine.

The integrity of dietary histamine degradation pathways is central to preventing excessive accumulation, with enzymatic clearance at the intestinal mucosa serving as a primary mechanism. When absorption of exogenous dietary histamine proceeds without sufficient degradation, systemic symptoms such as flushing, nasal congestion, headache, digestive discomfort and gastrointestinal motility alterations can manifest. This phenomenon, termed histamine intolerance (HIT), is a non-immunologic condition arising from an imbalance between ingested histamine and the intestine’s degradative capacity, largely mediated by diamine oxidase (DAO).

Digestive Discomfort

In the small intestines, diamine oxidase contributes to the breakdown of biogenic amines, such as histamine, that may be present in ingested food or produced locally by microbes. By degrading these compounds before they are absorbed, DAO aids in supporting dietary histamine regulation within the gastrointestinal lumen. When DAO activity is reduced or insufficient, dietary histamine may contribute to digestive discomfort characterized by symptoms such as abdominal pain or cramping, excessive gas, altered bowel habits including diarrhea or constipation, and more. It should be noted that histamine intolerance represents only one of many possible influences on gastrointestinal function and digestive comfort.

Supporting Dietary Histamine Degradation | OmneDiem®

There are many reasons why diamine oxidase levels/activity may vary between individuals, from genetic differences in enzyme production to broader gastrointestinal influences and more. A diamine oxidase (DAO) supplement can be an exceptional tool to aid in breaking down dietary histamine for those with reduced endogenous DAO activity. In supporting dietary histamine degradation, OmneDiem® has a phenomenal line of natural diamine oxidase supplements.

OmneDiem® Histamine Digest® & Histamine Digest® PureMAX

OmneDiem® has an exceptional array of supplements featuring their natural diamine oxidase. OmneDiem's® Histamine Digest® and Histamine Digest® PureMAX  deliver 30,000 and 40,000 Histamine Digesting Units, respectively — underscoring exceptional enzymatic activity, and these phenomenal levels are achieved through OmneDiem’s® precise enzyme extraction and preservation processes. Moreover, OmneDiem's® supplements are designed for gastric resilience, as their targeted-release supplements deliver their natural diamine oxidase directly to the small intestine to aid in the efficient degradation of dietary histamine during digestion.

Patented science and clinical research form the cornerstone of OmneDiem’s® natural diamine oxidase, and by protecting the enzyme’s functional integrity through specialized processes, OmneDiem® sets an unwavering standard in diamine oxidase supplementation.

Redefining excellence, OmneDiem® undoubtedly represents the integration of cutting-edge science, exceptional enzyme quality, and a clear dedication to evidence-based advancement in digestive health. Use code STXAL9VI and explore their full collection here.

*Some links on this site are affiliate links. If you choose to purchase through them, The Synthesis of Wellness LLC may earn a commission at no additional cost to you.

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

*This content is for educational purposes only. Always consult a licensed healthcare professional for your medical needs and before taking any supplement.