Why Dysbiosis, SIBO, Hydrogen Sulfide Intolerance, MCAS, and Long COVID May All Be Downstream of a Single Event — How butyrate becomes oxygen control: the mechanism, step by step

Healthy colonocytes don't run on sugar the way most of your cells do. They run, preferentially, on butyrate — a short-chain fatty acid (a small fat molecule) that anaerobic bacteria produce when they ferment dietary fiber and resistant starch. Up to roughly 70% of a colonocyte's energy comes from butyrate. This is one of the most beautiful arrangements in human biology: the bacteria feed the very cell that builds the home they need. Follow the butyrate as it enters the cell: Transport in. Butyrate crosses into the colonocyte through dedicated transporter proteins — chiefly MCT1 (monocarboxylate transporter 1, gene SLC16A1) and SMCT1 (sodium-coupled monocarboxylate transporter 1, gene SLC5A8). Hold onto that second one. SLC5A8 will come back later as a hidden lock in the whole system. Activation. Inside the cell, butyrate is tagged with coenzyme A to become butyryl-CoA, the "activated" form that the mitochondria can process. Beta-oxidation. Butyryl-CoA enters beta-oxidation inside the mitochondria — the metabolic assembly line that chops fats apart for energy — producing acetyl-CoA, the universal fuel molecule that feeds the cell's central furnace. The TCA cycle. Acetyl-CoA enters the tricarboxylic acid (TCA) cycle, also called the Krebs cycle — the spinning wheel at the center of cellular metabolism. Each turn of the wheel strips high-energy electrons off the fuel and loads the