Exposure to fructose in laboratory models of the human intestine leads to chemical modifications of proteins that maintain the gut lining, causing these proteins to break down and weakening the...
Mechanism
Synthesis from 1 study
Eating too much fructose triggers harmful chemical changes in the gut's sealing proteins, causing them to be marked and destroyed. This breaks the barrier between intestinal cells, allowing toxins to leak into the body. Fructose can also kill gut cells directly, making the leak worse.
Most probable mechanism
When too much fructose is consumed, it triggers a chain reaction in the gut that produces harmful chemicals that damage the proteins holding intestinal cells together. These damaged proteins are marked for destruction, causing gaps to form in the gut lining, which lets toxins escape into the bloodstream.
Fructose metabolism increases the expression and activity of the enzyme CYP2E1 in intestinal epithelial cells.
Elevated CYP2E1 drives the production of reactive nitrogen species, including nitric oxide, which leads to tyrosine nitration of tight junction and adherent junction proteins such as claudin-1 and β-catenin.
Nitrated junctional proteins are recognized by the cellular degradation machinery and tagged with ubiquitin molecules.
Ubiquitinated junctional proteins are targeted for destruction by the proteasome, resulting in reduced levels of key barrier proteins.
Loss of tight junction proteins disrupts the physical seal between intestinal cells, increasing paracellular permeability.
Increased gut permeability allows bacterial endotoxins to translocate into the systemic circulation.
Less supported by current evidence, but not ruled out
Excess fructose can also cause intestinal cells to die prematurely through a stress pathway, which physically breaks the gut lining and contributes to leakage.
Fructose metabolism increases CYP2E1 expression in intestinal epithelial cells.
CYP2E1-generated reactive oxygen species activate the stress kinase JNK.
Activated JNK increases the expression of pro-apoptotic proteins such as Bax and triggers mitochondrial release of caspase-activating factors.
Caspase-3 is cleaved and activated, leading to programmed cell death of intestinal epithelial cells.
Loss of epithelial cells creates physical gaps in the intestinal barrier, increasing permeability.
Evidence from Studies
Supporting (1)
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Fructose Promotes Leaky Gut, Endotoxemia and Liver Fibrosis through CYP2E1-Mediated Oxidative and Nitrative Stress
Contradicting (0)
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