Just Two Days of Fatty Food Can Damage Your Gut, New Study Finds

Sometimes, a nice, quick, juicy burger from a fast-food joint really hits the spot. However, a new study might make you think twice before placing your next order.

In May, researchers from the Walter and Eliza Hall Institute (WEHI) in Melbourne, Australia, published their pre-clinical study in the journal Immunity, demonstrating what may occur in the human gut immediately after consuming high-fat foods. The findings are, shall we say, eye-opening. 

To understand how high-fat foods could affect us, the team fed mice a high-fat diet, similar to what a person would consume by eating burgers and fries, for two days. They then examined the animals' gut tissue to assess the impact on their immune cells, specifically measuring the activity of a cell called ILC3s, which helps protect the gut from harmful bacteria. They also checked whether the gut lining remained sealed or began to leak.

The team discovered that after just 48 hours, the high-fat diet caused the mice's gut lining to begin breaking down, and those ILC3s to stop functioning normally.

“We’ve shown that every meal we consume actively shapes our gut health,” Dr Cyril Seillet, a senior author on the paper, said in a statement. “The more saturated fats we eat, the more inflammation that builds up, gradually weakening our gut defences and increasing our susceptibility to chronic inflammation.” 

As Seillet explained, they detected these changes in gut health after just a few meals, even though the mice showed no visible symptoms, including weight gain. This inflammation can build up and remain “hidden in our bodies until years later, where it can present as chronic inflammation,” Seillet added.

Furthermore, high-fat meals caused the gut to produce less of a protective protein called IL-22, which helps keep the gut lining sealed but, after damage, allows harmful bacteria or toxins to escape.

“IL-22 is a critically important protein for gut health and protection. Without it, the gut loses its ability to prevent inflammation,” Le Xiong, first author on the paper, said.

But here's the good news: The researchers were able to restore these critical gut functions by elevating their IL-22 levels, which they said could demonstrate the potential for creating a therapeutic intervention for humans.

However, for now, the team hopes their work will influence dietary guidelines and your next meal. As Dr. Seillet said, “While occasional high-fat meals won’t impair your gut protection barrier, a consistent diet that is high in saturated fats is laying the foundation for chronic gut inflammation to present in the future.”