What Is FXR?
FXR is a receptor found in the liver and gut. It senses bile acids and adjusts cholesterol and fat metabolism accordingly.
When specific bile acids activate FXR, the liver produces less cholesterol and clears more LDL.
How Gut Bacteria Influence FXR
Gut bacteria fed by diverse fibre and polyphenols change the bile acid pool. These changes favour bile acids that activate FXR receptor.
As a result, cholesterol regulation improves at a metabolic level.
This relationship underpins many teachings within Baking as Lifestyle Medicine, where fermentation and fibre shape signalling pathways, not just digestion.
FXR and Sourdough Fermentation
Sourdough bread influences FXR activity through fermentation and fibre diversity. During long fermentation, sourdough changes how fibre and polyphenols reach the gut.
As a result, gut bacteria produce a different balance of bile acids. These bile acids are more likely to activate FXR. When FXR switches on, the liver reduces cholesterol production and clears more LDL from circulation.
This pathway explains why bread quality matters, not just fibre quantity. At The Sourdough School, this science underpins how we teach fermentation timing, wholegrain use, and botanical blends. It also shapes the formulation of Proven™ bread, which focuses on slow digestion rather than rapid carbohydrate release.
