Why too much sugar might hurt your gut and liver

When the lining of the intestines becomes less effective at blocking substances from passing into the bloodstream, it leads to higher levels of inflammatory markers in the body.

In rats and mice given a high-fructose drink for eight weeks, researchers observed reduced levels of key proteins that maintain intestinal barrier integrity, increased chemical modifications to these proteins, higher levels of bacterial toxins in the blood, and signs of liver inflammation and scarring, all of which were linked to the presence of the CYP2E1 enzyme.

In rodents, the enzyme CYP2E1 is required for fructose to cause damage to the intestinal barrier and inflammation in the liver. Without this enzyme, these effects do not occur.

In tissue samples from the small intestine of deceased humans, those with obesity and NASH show lower levels of proteins that maintain intestinal barrier integrity and higher levels of proteins associated with oxidative stress and inflammation compared to lean individuals without NASH.

In rodents, consuming fructose is linked to higher levels of proteins associated with liver scarring and lower levels of Sirt1 protein, which also undergoes specific chemical modifications that may contribute to the worsening of liver fibrosis.